ae801 sensor element

AE801 Multi-Purpose Sensor Element: Abstracts

Abstracts

This page contain abstracts from more than 30 published research papers that have used the AE801 Sensor to obtain the data needed for the research.

UI

-

99388113

AU

-

Campbell SP

AU

-

Williams DA

AU

-

Frueh BR

AU

-

Lynch GS

TI

-

Contractile activation characteristics of single permeabilized fibres from levator palpebrae superioris, orbicularis oculi and vastus lateralis muscles from humans [In Process Citation]

LA

-

Eng

DA

-

19990925

DP

-

1999 Sep 1

IS

-

0022-3751

TA

-

J Physiol (Lond)

PG

-

615-22

SB

-

M

CY

-

ENGLAND

VI

-

519 Pt 2

JC

-

JQV

AA

-

AUTHOR

AB

-

1. We investigated the contractile activation characteristics of single membrane-permeabilized fibres from the following muscles from humans: the levator palpebrae superioris (LPS), an extraocular muscle; the orbicularis oculi (OO), a facial muscle; and the vastus lateralis (VL), a major muscle of the thigh. 2. Single permeabilized muscle fibres were isolated from each of the different muscles, attached to a sensitive force transducer and activated by rapid immersion in buffered solutions of varying [Ca2+] and [Sr2+]. Fibres were allocated into discrete populations based on their contractile characteristics, including their differential force responses during Ca2+ and Sr2+ activation. 3. With the exception of one fibre from the LPS, all 152 fibres sampled from the three different human muscles could be classified into either population I (slow, type I) or population II (fast, type II) based on their force-pCa(pSr) relations. The LPS muscle fibre which was unable to be classified into the two major fibre populations displayed a combination of the typical force-pCa(pSr) relations for mammalian fast and slow muscle fibres. 4. Although fibres from the LPS, OO and VL muscles had similar differential sensitivities to Ca2+and Sr2+, the steepness of the force-pCa(pSr) curves for fibres from the LPS and OO muscles were highly variable compared with those for fibres from the VL muscle. Specific forces (N cm-2) of the smaller diameter fibres from the LPS and OO muscles were significantly lower than those of fibres from the VL muscle. 5. The differences in the contractile activation characteristics between fibres from the VL muscle and those of fibres from facial (OO) muscles and extraocular (LPS) muscles, reflect the differences in their fibre composition that are responsible for their functional specificity.

AD

-

Muscle and Cell Physiology Laboratory, Department of Physiology, The University of Melbourne, Parkville, Victoria 3052, Australia.

RO

-

O:099

PMID

-

0010457076

PID

-

PHY_9327

4100

-

http://www.journals.cup.org/owa_dba/owa/approval?sjid=PHY&said=9327&spii =S0022375199093278

SO

-

J Physiol (Lond) 1999 Sep 1;519 Pt 2:615-22

UI

-

99388104

AU

-

Edman KA

TI

-

The force bearing capacity of frog muscle fibres during stretch: its relation to sarcomere length and fibre width [In Process Citation]

LA

-

Eng

DA

-

19990925

DP

-

1999 Sep 1

IS

-

0022-3751

TA

-

J Physiol (Lond)

PG

-

515-26

SB

-

M

CY

-

ENGLAND

VI

-

519 Pt 2

JC

-

JQV

AA

-

AUTHOR

AB

-

1. Single fibres isolated from the anterior tibialis muscle of Rana temporaria were tetanized (0.9-1.8 C) while a marked ( approximately 1 mm) segment was held at constant length by feedback control. Force enhancement was produced by applying a controlled stretch ramp to the fibre segment during the tetanus plateau, the steady force reached during stretch being used as a measure of the maximum force that the myosin cross-bridges can hold before they detach. 2. The amplitude of force enhancement during stretch did not vary in proportion to the isometric force as the sarcomere length was changed, maximum force enhancement being attained near 2.4 &mgr;m sarcomere length compared with 2.0 &mgr;m for the isometric force. 3. The influence of fibre width on the force enhancement-sarcomere length relationship was evaluated by normalizing force enhancement to the tetanic (pre-stretch) force in this way allowing for the differences in myofilament overlap at the various lengths. The amplitude of force enhancement (normalized to the tetanic force) increased by approximately 70 % as the relative width of the myofilament lattice was reduced from a nominal value of 1.05 at a sarcomere length of 1.8 &mgr;m to 0.85 at a sarcomere length of 2.8 &mgr;m. 4. Changes in fibre width equivalent to those produced by altering the sarcomere length were produced by varying the tonicity of the extracellular medium. Force enhancement, normalized to the control isometric force at each tonicity, exhibited a width dependence that agreed well with that described in the previous point. Stretch ramps applied to frog skinned muscle fibres during calcium-induced contracture likewise resulted in a greater force enhancement during stretch after reducing the fibre width by osmotic compression. 5. The results suggest that the strength of binding of the myosin cross- bridges, unlike the isometric force, varies with the lateral distance between the myofilaments.

AD

-

Department of Pharmacology, University of Lund, Solvegatan 10, S-223 62 Lund, Sweden.

RO

-

O:099

PMID

-

0010457067

PID

-

PHY_8921

4100

-

http://www.journals.cup.org/owa_dba/owa/approval?sjid=PHY&said=8921&spii =S0022375199089218

SO

-

J Physiol (Lond) 1999 Sep 1;519 Pt 2:515-26

UI

-

99310898

AU

-

Parris JR

AU

-

Cobban HJ

AU

-

Littlejohn AF

AU

-

MacEwan DJ

AU

-

Nixon GF

TI

-

Tumour necrosis factor-alpha activates a calcium sensitization pathway in guinea-pig bronchial smooth muscle.

LA

-

Eng

MH

-

p42(Mapk) Kinase/metabolism

MH

-

Animal

MH

-

Bronchi/*drug effects

MH

-

Calcium/metabolism/physiology

MH

-

Calcium Signaling/*drug effects

MH

-

Guinea Pigs

MH

-

In Vitro

MH

-

Male

MH

-

Muscle Contraction/drug effects

MH

-

Muscle, Smooth/*drug effects

MH

-

Myosin Light Chains/metabolism

MH

-

Recombinant Proteins/pharmacology

MH

-

Sphingomyelin Phosphodiesterase/metabolism

MH

-

Support, Non-U.S. Gov't

MH

-

Tumor Necrosis Factor/*pharmacology

RN

-

EC 2.7.10.- (p42(Mapk) Kinase)

RN

-

EC 3.1.4.12 (Sphingomyelin Phosphodiesterase)

RN

-

0 (Myosin Light Chains)

RN

-

0 (Recombinant Proteins)

RN

-

0 (Tumor Necrosis Factor)

RN

-

7440-70-2 (Calcium)

PT

-

JOURNAL ARTICLE

DA

-

19991020

DP

-

1999 Jul 15

IS

-

0022-3751

TA

-

J Physiol (Lond)

PG

-

561-9

SB

-

M

CY

-

ENGLAND

VI

-

518 ( Pt 2)

JC

-

JQV

AA

-

Author

EM

-

199912

AB

-

1. The effects of tumour necrosis factor-alpha (TNF) on guinea-pig bronchial smooth muscle contractility were investigated. 2. The Ca2+- activated contractile response of permeabilized bronchial smooth muscle strips was significantly increased after incubation with 1 microgram ml- 1 TNF for 45 min. This TNF-induced effect was not due to a further increase in intracellular Ca2+. 3. The TNF-induced Ca2+ sensitization was, at least partly, the result of an increase in myosin light chain20 phosphorylation. 4. The intracellular signalling pathway involved in this effect of TNF was further investigated. Sphingomyelinase, a potential mediator of TNF, had no effect on Ca2+ sensitivity of permeabilized bronchial smooth muscle. Also, p42/p44 mitogen-activated protein kinase (p42/p44mapk), activated by TNF in some cell types, did not show an increased activation in bronchial smooth muscle after TNF treatment. 5. In conclusion, TNF may activate a novel signalling pathway in guinea-pig bronchial smooth muscle leading to an increase in myosin light chain20 phosphorylation and a subsequent increase in Ca2+ sensitivity of the myofilaments. This pathway does not appear to involve sphingomyelinase-liberated ceramides or activation of p42/p44mapk. Given the importance of TNF in asthma, this TNF-induced Ca2+ sensitization of the myofilaments may represent a mechanism responsible for airway hyper-responsiveness.

AD

-

Department of Biomedical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK.

PMID

-

0010381600

PID

-

PHY_8883

4100

-

http://www.journals.cup.org/owa_dba/owa/approval?sjid=PHY&said=8883&spii =S0022375199088833

SO

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J Physiol (Lond) 1999 Jul 15;518 ( Pt 2):561-9

UI

-

99288149

AU

-

He ZH

AU

-

Chillingworth RK

AU

-

Brune M

AU

-

Corrie JE

AU

-

Webb MR

AU

-

Ferenczi MA

TI

-

The efficiency of contraction in rabbit skeletal muscle fibres, determined from the rate of release of inorganic phosphate.

LA

-

Eng

MH

-

Adenosine Triphosphate/analogs & derivatives/metabolism

MH

-

Adenosinetriphosphatase/*metabolism

MH

-

Animal

MH

-

In Vitro

MH

-

Kinetics

MH

-

Muscle Contraction/*physiology

MH

-

Muscle Fibers/*physiology

MH

-

Muscle, Skeletal/*physiology

MH

-

Phosphates/*metabolism

MH

-

Photolysis

MH

-

Rabbits

MH

-

Sarcomeres/*physiology

MH

-

Temperature

RN

-

EC 3.6.1.3 (Adenosinetriphosphatase)

RN

-

0 (Phosphates)

RN

-

56-65-5 (Adenosine Triphosphate)

RN

-

67030-27-7 (P(3)-1-(2-nitro)phenylethyladenosine 5'-triphosphate)

PT

-

JOURNAL ARTICLE

DA

-

19990802

DP

-

1999 Jun 15

IS

-

0022-3751

TA

-

J Physiol (Lond)

PG

-

839-54

SB

-

M

CY

-

ENGLAND

VI

-

517 ( Pt 3)

JC

-

JQV

AA

-

Author

EM

-

199910

AB

-

1. The relationship between mechanical power output and the rate of ATP hydrolysis was investigated in segments of permeabilized fibres isolated from rabbit psoas muscle. 2. Contractions were elicited at 12 degrees C by photolytic release of ATP from the P3 -1-(2-nitrophenyl) ester of ATP (NPE-caged ATP). Inorganic phosphate (Pi) release was measured by a fluorescence method using a coumarin-labelled phosphate binding protein. Force and sarcomere length were also monitored. 3. ATPase activity was determined from the rate of appearance of Pi during each phase of contraction. The ATPase rate was 10.3 s-1 immediately following release of ATP and 5. 1 s-1 during the isometric phase prior to the applied shortening. It rose hyperbolically with shortening velocity, reaching 18.5 s-1 at a maximal shortening velocity > 1 ML s-1 (muscle lengths s-1). 4. Sarcomeres shortened at 0.09 ML s-1 immediately following the photolytic release of ATP and at 0.04 ML s-1 prior to the period of applied shortening. The high initial ATPase rate may be largely attributed to initial sarcomere shortening. 5. During shortening, maximal power output was 28 W l-1. Assuming the free energy of hydrolysis is 50 kJ mol-1, the efficiency of contraction was calculated from the power output at each shortening velocity. The maximum efficiency was 0.36 at a shortening velocity of 0.27 ML s-1, corresponding to a force level 51 % of that in the isometric state. 6. At the maximal shortening velocity, only 10 % of the myosin heads are attached to the thin filaments at any one time.

AD

-

National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK.

PMID

-

0010358123

PID

-

PHY_8978

4100

-

http://www.journals.cup.org/owa_dba/owa/approval?sjid=PHY&said=8978&spii =S0022375199089784

SO

-

J Physiol (Lond) 1999 Jun 15;517 ( Pt 3):839-54

UI

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99288148

AU

-

Hanley PJ

AU

-

Young AA

AU

-

LeGrice IJ

AU

-

Edgar SG

AU

-

Loiselle DS

TI

-

3-Dimensional configuration of perimysial collagen fibres in rat cardiac muscle at resting and extended sarcomere lengths.

LA

-

Eng

MH

-

Muscle Fibers/*physiology

MH

-

Analysis of Variance

MH

-

Animal

MH

-

Collagen/*ultrastructure

MH

-

Heart/physiology

MH

-

Heart Ventricle

MH

-

Image Processing, Computer-Assisted

MH

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Microscopy, Confocal

MH

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Microscopy, Electron

MH

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Models, Structural

MH

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Myocardium/cytology/*ultrastructure

MH

-

Rats

MH

-

Rats, Wistar

MH

-

Sarcomeres/*physiology/*ultrastructure

MH

-

Support, Non-U.S. Gov't

RN

-

9007-34-5 (Collagen)

PT

-

JOURNAL ARTICLE

DA

-

19990802

DP

-

1999 Jun 15

IS

-

0022-3751

TA

-

J Physiol (Lond)

PG

-

831-7

SB

-

M

CY

-

ENGLAND

VI

-

517 ( Pt 3)

JC

-

JQV

AA

-

Author

EM

-

199910

AB

-

1. We have used fluorescence confocal laser scanning microscopy to attain the three-dimensional (3-D) microstructure of perimysial collagen fibres over the range of sarcomere lengths (1.9-2.3 micrometers) in which passive force of cardiac muscle increases steeply. 2. A uniaxial muscle preparation (right ventricular trabecula of rat) was used so that the 3-D collagen configuration could be readily related to sarcomere length. Transmission electron microscopy showed that these preparations were structurally homologous to ventricular wall muscle. 3. Trabeculae were mounted on the stage of an inverted microscope and fixed at various sarcomere lengths. After a trabecula was stained with the fluorophore Sirius Red F3BA and embedded in resin, sequential optical sectioning enabled 3-D reconstruction of its perimysial collagen fibres. The area fraction of these fibres, determined from the cross-sections of seven trabeculae, was 10.5 +/- 3.9 % (means +/- s.d.). 4. The reconstructed 3-D images show that perimysial collagen fibres are wavy (as distinct from coiled) cords which straighten considerably as the sarcomere length is increased from 1.85 +/- 0.06 micrometer (near-resting length) to 2.3 +/- 0.04 micrometer (means +/- s.d., n = 4). These observations are consistent with the notion that the straightening of these fibres is responsible for limiting extension of the cardiac sarcomere to a length of approximately 2.3 micrometers.

AD

-

Department of Physiology, School of Medicine and Health Science, University of Auckland, Auckland, New Zealand. p_hanley98@hotmail.com

PMID

-

0010358122

PID

-

PHY_9009

4100

-

http://www.journals.cup.org/owa_dba/owa/approval?sjid=PHY&said=9009&spii=S0022375199090092

SO

-

J Physiol (Lond) 1999 Jun 15;517 ( Pt 3):831-7

UI

-

99272460

AU

-

Yoshii A

AU

-

Iizuka K

AU

-

Dobashi K

AU

-

Horie T

AU

-

Harada T

AU

-

Nakazawa T

AU

-

Mori M

TI

-

Relaxation of contracted rabbit tracheal and human bronchial smooth muscle by Y-27632 through inhibition of Ca2+ sensitization.

LA

-

Eng

MH

-

Amides/*pharmacology

MH

-

Animal

MH

-

Bronchi/*metabolism

MH

-

Calcium/*antagonists & inhibitors

MH

-

Carbachol/pharmacology

MH

-

Cholinergic Agents/pharmacology

MH

-

Detergents/pharmacology

MH

-

Dose-Response Relationship, Drug

MH

-

Endothelin-1/pharmacology

MH

-

G-Proteins/metabolism

MH

-

Guanosine 5'-O-(3-Thiotriphosphate)/pharmacology

MH

-

Human

MH

-

Muscle Contraction

MH

-

Muscle, Smooth/*metabolism

MH

-

Myosin-Light-Chain Kinase/metabolism

MH

-

Octoxynol/pharmacology

MH

-

Oxazoles/pharmacology

MH

-

Phosphodiesterase Inhibitors/pharmacology

MH

-

Phospholipase C/pharmacology

MH

-

Protein-Serine-Threonine Kinases/metabolism

MH

-

Pyridines/*pharmacology

MH

-

Rabbits

MH

-

Signal Transduction

MH

-

Support, Non-U.S. Gov't

MH

-

Trachea/*metabolism

MH

-

1-Methyl-3-isobutylxanthine/pharmacology

RN

-

EC 2.7.1.117 (Myosin-Light-Chain Kinase)

RN

-

EC 2.7.10 (Protein-Serine-Threonine Kinases)

RN

-

EC 2.7.10.- (Rho-associated kinase)

RN

-

EC 3.1.4.3 (Phospholipase C)

RN

-

0 (Amides)

RN

-

0 (Cholinergic Agents)

RN

-

0 (Detergents)

RN

-

0 (Endothelin-1)

RN

-

0 (G-Proteins)

RN

-

0 (Oxazoles)

RN

-

0 (Phosphodiesterase Inhibitors)

RN

-

0 (Pyridines)

RN

-

101932-71-2 (calyculin A)

RN

-

138381-45-0 (Y 27632)

RN

-

28822-58-4 (1-Methyl-3-isobutylxanthine)

RN

-

37589-80-3 (Guanosine 5'-O-(3-Thiotriphosphate))

RN

-

51-83-2 (Carbachol)

RN

-

7440-70-2 (Calcium)

RN

-

9002-93-1 (Octoxynol)

PT

-

JOURNAL ARTICLE

DA

-

19990707

DP

-

1999 Jun

IS

-

1044-1549

TA

-

Am J Respir Cell Mol Biol

PG

-

1190-200

SB

-

M

CY

-

UNITED STATES

IP

-

6

VI

-

20

JC

-

AOB

AA

-

Author

EM

-

199909

AB

-

The mechanism of Ca2+ sensitization of contraction has not been elucidated in airway smooth muscle (SM). To determine the role of a small G protein, rhoA p21, and its target protein, rho-associated coiled coil-forming protein kinase (ROCK), in receptor-coupled Ca2+ sensitization of airway SM, we studied the effect of (+)-(R)-trans-4-(1- aminoethyl)-N-(4-pyridyl)cyclohexane carboxamide dihydrochloride, monohydrate (Y-27632), a ROCK inhibitor, on isometric contractions in rabbit tracheal and human bronchial SM. Y-27632 completely reversed 1 microM carbachol (CCh)-induced contraction of intact trachea with a concentration producing half-maximum inhibition of effect (IC50) of 1.29 +/- 0.2 microM (n = 5). Although 4beta-phorbol 12,13-dibutyrate (1 microM)-induced Ca2+ sensitization was relatively resistant to Y-27632 in alpha-toxin-permeabilized trachea, CCh (100 microM) plus guanosine triphosphate (GTP) (3 microM)- and guanosine 5'-O-(3'-thiotriphosphate) (10 microM)-induced contractions were relaxed completely by Y-27632 with IC50 of 1.44 +/- 0.3 (n = 6) and 1.15 +/- 0.3 microM (n = 6). Endothelin-1 (1 microM) plus GTP (3 microM)- developed force was also reversed by Y-27632 with IC50 of 4. 10 +/- 1.1 microM (n = 6) in the alpha-toxin-permeabilized bronchus. Both the rabbit and human SM expressed rhoA p21, ROCK I, and its isoform ROCK II. Collectively, rho/ROCK-mediated Ca2+ sensitization plays a central role in the sustained phase of airway SM contraction, and selective inhibition of this pathway may become a new strategy to resolve airflow limitation in asthma.

AD

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First Department of Internal Medicine, Faculty of Medicine, School of Medicine, Gunma University, Maebashi, Gunma, Japan.

PMID

-

0010340938

SO

-

Am J Respir Cell Mol Biol 1999 Jun;20(6):1190-200

UI

-

99045480

AU

-

He ZH

AU

-

Ferenczi MA

AU

-

Brune M

AU

-

Trentham DR

AU

-

Webb MR

AU

-

Somlyo AP

AU

-

Somlyo AV

TI

-

Time-resolved measurements of phosphate release by cycling cross- bridges in portal vein smooth muscle.

LA

-

Eng

MH

-

Adenosine Triphosphate/analogs & derivatives/metabolism

MH

-

Adenosinetriphosphatase/metabolism

MH

-

Animal

MH

-

Biophysics

MH

-

In Vitro

MH

-

Kinetics

MH

-

Muscle Contraction/physiology

MH

-

Muscle, Smooth, Vascular/*metabolism/physiology

MH

-

Myosin/metabolism

MH

-

Permeability

MH

-

Phosphates/*metabolism

MH

-

Phosphorylation

MH

-

Photolysis

MH

-

Portal Vein/metabolism/physiology

MH

-

Rabbits

MH

-

Support, Non-U.S. Gov't

MH

-

Support, U.S. Gov't, P.H.S.

RN

-

EC 3.6.1.3 (Adenosinetriphosphatase)

RN

-

0 (Myosin)

RN

-

0 (Phosphates)

RN

-

56-65-5 (Adenosine Triphosphate)

RN

-

67030-27-7 (P(3)-1-(2-nitro)phenylethyladenosine 5'-triphosphate)

PT

-

JOURNAL ARTICLE

ID

-

HL19242/HL/NHLBI

DA

-

19990125

DP

-

1998 Dec

IS

-

0006-3495

TA

-

Biophys J

PG

-

3031-40

SB

-

M

CY

-

UNITED STATES

IP

-

6

VI

-

75

JC

-

A5S

AA

-

Author

EM

-

199903

AB

-

The rate of release of inorganic phosphate (Pi) from cycling cross- bridges in rabbit portal-anterior mesenteric vein smooth muscle was determined by following the fluorescence of the Pi-reporter, MDCC-PBP (Brune, M., J. L. Hunter, S. A. Howell, S. R. Martin, T. L. Hazlett, J. E. T. Corrie, and M. R. Webb. 1998. Biochemistry. 37:10370-10380). Cross-bridge cycling was initiated by photolytic release of ATP from caged-ATP in Triton-permeabilized smooth muscles in rigor. When the regulatory myosin light chains (MLC20) had been thiophosphorylated, the rate of Pi release was biphasic with an initial rate of 80 microM s-1 and amplitude 108 microM, decreasing to 13.7 microM s-1. These rates correspond to fast and slow turnovers of 1.8 s-1 and 0.3 s-1, assuming 84% thiophosphorylation of 52 microM myosin heads. Activation by Ca2+- dependent phosphorylation subsequent to ATP release resulted in slower Pi release, paralleling the rate of contraction that was also slower than after thiophosphorylation, and was also biphasic: 51 microM s-1 and 13.2 microM s-1. These rates suggest that the activity of myosin light chain kinase and phosphatase ("pseudo-ATPase") contributes <20% of the ATP usage during cross-bridge cycling. The extracellular "ecto- nucleotidase" activity was reduced eightfold by permeabilization, conditions in which the ecto-ADPase was 17% of the ecto-ATPase. Nevertheless, the remaining ecto-ATPase activity reduced the precision of the estimate of cross-bridge ATPase. We conclude that the transition from fast to slow ATPase rates reflects the properties and forces directly acting on cross-bridges, rather than the result of a time- dependent decrease in activation (MLC20 phosphorylation) occurring in intact smooth muscle. The mechanisms of slowing may include the effect of positive strain on cross-bridges, inhibition of the cycling rate by high affinity Mg-ADP binding, and associated state hydrolysis.

AD

-

National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom.

PMID

-

0009826623

SO

-

Biophys J 1998 Dec;75(6):3031-40

UI

-

99007358

AU

-

He Z

AU

-

Stienen GJ

AU

-

Barends JP

AU

-

Ferenczi MA

TI

-

Rate of phosphate release after photoliberation of adenosine 5'- triphosphate in slow and fast skeletal muscle fibers.

LA

-

Eng

MH

-

Adenosine Diphosphate/pharmacology

MH

-

Adenosine Triphosphate/*analogs & derivatives/metabolism

MH

-

Animal

MH

-

Calcium/pharmacology

MH

-

Carrier Proteins/metabolism

MH

-

Coumarins/metabolism

MH

-

Fluorescent Dyes

MH

-

Kinetics

MH

-

Muscle Contraction/physiology

MH

-

Muscle Fibers, Fast-Twitch/*metabolism

MH

-

Muscle Fibers, Slow-Twitch/*metabolism

MH

-

Muscle, Skeletal/*physiology

MH

-

Phosphates/*metabolism

MH

-

Photolysis

MH

-

Psoas Muscles/physiology

MH

-

Rabbits

MH

-

Sarcomeres/metabolism

MH

-

Support, Non-U.S. Gov't

RN

-

0 (phosphate-binding proteins)

RN

-

0 (Carrier Proteins)

RN

-

0 (Coumarins)

RN

-

0 (Fluorescent Dyes)

RN

-

0 (Phosphates)

RN

-

156571-46-9 (N-(2-(1-maleimidyl)ethyl)-7-(diethylamino)coumarin-3- carboxamide)

RN

-

56-65-5 (Adenosine Triphosphate)

RN

-

58-64-0 (Adenosine Diphosphate)

RN

-

67030-27-7 (P(3)-1-(2-nitro)phenylethyladenosine 5'-triphosphate)

RN

-

7440-70-2 (Calcium)

PT

-

JOURNAL ARTICLE

DA

-

19981204

DP

-

1998 Nov

IS

-

0006-3495

TA

-

Biophys J

PG

-

2389-401

SB

-

M

CY

-

UNITED STATES

IP

-

5

VI

-

75

JC

-

A5S

AA

-

Author

EM

-

199902

AB

-

Inorganic phosphate (Pi) release was determined by means of a fluorescent Pi-probe in single permeabilized rabbit soleus and psoas muscle fibers. Measurements of Pi release followed photoliberation of approximately 1.5 mM ATP by flash photolysis of NPE-caged ATP in the absence and presence of Ca2+ at 15 degrees C. In the absence of Ca2+, Pi release occurred with a slow rate of 11 +/- 3 microM . s-1 (n = 3) in soleus fibers and 23 +/- 1 microM . s-1 (n = 10) in psoas fibers. At saturating Ca2+ concentrations (pCa 4.5), photoliberation of ATP was followed by rapid force development. The initial rate of Pi release was 0.57 +/- 0.05 mM . s-1 in soleus (n = 13) and 4.7 +/- 0.2 mM . s-1 in psoas (n = 23), corresponding to a rate of Pi release per myosin head of 3.8 s-1 in soleus and 31.5 s-1 in psoas. Pi release declined at a rate of 0.48 s-1 in soleus and of 5.2 s-1 in psoas. Pi release in soleus was slightly faster in the presence of an ATP regenerating system but slower when 0.5 mM ADP was added. The reduction in the rate of Pi release results from an initial redistribution of cross-bridges over different states and a subsequent ADP-sensitive slowing of cross- bridge detachment.

AD

-

National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom.

PMID

-

0009788934

SO

-

Biophys J 1998 Nov;75(5):2389-401

UI

-

98399940

AU

-

Slawnych MP

AU

-

Morishita L

AU

-

Bressler BH

TI

-

Image-analysis-based assessment of the effects of the "Ca2+-jump" technique on sarcomere uniformity.

LA

-

Eng

MH

-

Animal

MH

-

Calcium/*diagnostic use

MH

-

Image Processing, Computer-Assisted

MH

-

In Vitro

MH

-

Muscle Contraction/physiology

MH

-

Muscle Fibers/*physiology/*ultrastructure

MH

-

Muscle Relaxation/physiology

MH

-

Muscle, Skeletal/*physiology/*ultrastructure

MH

-

Rabbits

MH

-

Sarcomeres/*physiology/*ultrastructure

MH

-

Solutions

MH

-

Spectroscopy, Fourier Transform Infrared

MH

-

Support, Non-U.S. Gov't

RN

-

0 (Solutions)

RN

-

7440-70-2 (Calcium)

PT

-

JOURNAL ARTICLE

DA

-

19981105

DP

-

1998 Sep

IS

-

8750-7587

TA

-

J Appl Physiol

PG

-

955-61

SB

-

M

CY

-

UNITED STATES

IP

-

3

VI

-

85

JC

-

HEG

AA

-

Author

EM

-

199901

AB

-

A new image analysis-based technique was used to quantitatively examine the effects of the "Ca2+-jump" activation protocol on the maintenance of fiber quality in skinned rabbit psoas muscle fiber segments. Specifically, contractions in pCa 4.6 were preceded by short-duration "preactivation" soaks in a solution in which EGTA was replaced with the low-Ca2+ buffering capacity analog hexamethylenediamine-N, N, N', N'- tetraacetate, which facilitated rapid Ca2+ equilibration within the fiber segments. Fiber quality was assessed by examining the Fourier spectra of the muscle fiber images before, during, and after activation. Segment lengths were typically below 500 micrometer, thus allowing the majority of the sarcomeres to be visualized in the field of view (x200 and x400 magnification). The preactivation protocol resulted in less deterioration of fiber quality with repetitive activation. In addition, there was also a significant reduction in the time required to reach the 50% level of maximum tension, with no significant change in the maximum tension level.

AD

-

Department of Anatomy, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3. slawnych@cortex.biomed.mcgill.ca

PMID

-

0009729569

SO

-

J Appl Physiol 1998 Sep;85(3):955-61

UI

-

98365280

AU

-

Sun Y

AU

-

Caputo C

AU

-

Edman KA

TI

-

Effects of BAPTA on force and Ca2+ transient during isometric contraction of frog muscle fibers.

LA

-

Eng

MH

-

Animal

MH

-

Calcium/*metabolism

MH

-

Chelating Agents/*pharmacology

MH

-

Egtazic Acid/*analogs & derivatives/pharmacology

MH

-

In Vitro

MH

-

Isometric Contraction/*drug effects

MH

-

Kinetics

MH

-

Muscle Fibers/drug effects/*physiology

MH

-

Muscle, Skeletal/drug effects/*physiology

MH

-

Rana temporaria

MH

-

Sarcomeres/drug effects/physiology

MH

-

Support, Non-U.S. Gov't

MH

-

Time Factors

RN

-

0 (Chelating Agents)

RN

-

67-42-5 (Egtazic Acid)

RN

-

7440-70-2 (Calcium)

RN

-

85233-19-8 (1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid)

PT

-

JOURNAL ARTICLE

DA

-

19980916

DP

-

1998 Aug

IS

-

0002-9513

TA

-

Am J Physiol

PG

-

C375-81

SB

-

M

CY

-

UNITED STATES

IP

-

2 Pt 1

VI

-

275

JC

-

3U8

AA

-

Author

EM

-

199811

AB

-

The effects of 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) on force and intracellular Ca2+ transient were studied during isometric twitches and tetanuses in single frog muscle fibers. BAPTA was added to the bathing solution in its permeant AM form (50 and 100 microM). There was no clear correlation between the changes in force and the changes in Ca2+ transient. Thus during twitch stimulation BATA did not suppress the Ca2+ transient until the force had been reduced to <50% of its control value. At the same time, the peak myoplasmic free Ca2+ concentration reached during tetanic stimulation was markedly increased, whereas the force was slightly reduced by BAPTA. The effects of BAPTA were not duplicated by using another Ca2+ chelator, EGTA, indicating that BAPTA may act differently as a Ca2+ chelator. Stiffness measurements suggest that the decrease in mechanical performance in the presence of BAPTA is attributable to a reduced number of active cross bridges. The results could mean that BAPTA, under the conditions used, inhibits the binding of Ca2+ to troponin C resulting in a reduced state of activation of the contractile system.

AD

-

Department of Pharmacology, University of Lund, S-223 62 Lund, Sweden.

PMID

-

0009688591

SO

-

Am J Physiol 1998 Aug;275(2 Pt 1):C375-81

UI

-

98349546

AU

-

Palmer S

AU

-

Kentish JC

TI

-

Roles of Ca2+ and crossbridge kinetics in determining the maximum rates of Ca2+ activation and relaxation in rat and guinea pig skinned trabeculae [see comments]

LA

-

Eng

MH

-

Actomyosin/*metabolism

MH

-

Animal

MH

-

Calcium/*pharmacology/physiology

MH

-

Comparative Study

MH

-

Diastole/drug effects/physiology

MH

-

Egtazic Acid/analogs & derivatives/metabolism/radiation effects

MH

-

Guinea Pigs

MH

-

Heart/*drug effects

MH

-

Ion Transport

MH

-

Kinetics

MH

-

Male

MH

-

Myocardial Contraction/*drug effects

MH

-

Myocardium/*metabolism

MH

-

Myofibrils/*drug effects

MH

-

Photolysis

MH

-

Rats

MH

-

Rats, Wistar

MH

-

Species Specificity

MH

-

Support, Non-U.S. Gov't

MH

-

Troponin C/*metabolism

RN

-

0 (Troponin C)

RN

-

0 (2-nitrophenyl-EGTA)

RN

-

67-42-5 (Egtazic Acid)

RN

-

7440-70-2 (Calcium)

RN

-

9013-26-7 (Actomyosin)

PT

-

JOURNAL ARTICLE

DA

-

19980811

DP

-

1998 Jul 27

IS

-

0009-7330

TA

-

Circ Res

PG

-

179-86

SB

-

M

CY

-

UNITED STATES

IP

-

2

VI

-

83

JC

-

DAJ

AA

-

Author

EM

-

199810

AB

-

We examined the influences of Ca2+ and crossbridge kinetics on the maximum rate of force development during Ca2+ activation of cardiac myofibrils and on the maximum rate of relaxation. Flash photolysis of diazo-2 or nitrophenyl-EGTA was used to produce a sudden decrease or increase, respectively, in [Ca2+] within Triton-skinned trabeculae from rat and guinea pig hearts (22 degrees C). Trabeculae from both species had similar Ca2+ sensitivities, suggesting that the rate of dissociation of Ca2+ from troponin C (k(off)) is similar in the 2 species. However, the rate of relaxation after diazo-2 photolysis was 5 times faster in the rat (16.1 +/- 0.9 s(-1), mean +/- SEM, n = 11) than in the guinea pig (2.99 +/- 0.26 s(-1), n = 7). This indicates that the maximum relaxation rate is limited by crossbridge kinetics rather than by k(off). The maximum rates of rapid activation by Ca2+ after nitrophenyl-EGTA photolysis (k(act)) and of force redevelopment after forcible crossbridge dissociation (k(act)) were similar and were approximately 5-fold faster in rat (k(act)= 14.4 +/- 0.9 s(-1), k(tr)= 13.0 +/- 0.6 s(-1)) than in guinea pig (k(act)= 2.57 +/- 0.14 s(-1), k(tr)= 2.69 +/- 0.30 s(-1)) trabeculae. This too may be mainly due to species differences in crossbridge kinetics. Both k(act) and k(tr) increased as [Ca2+] increased. This Ca2+ dependence of the rates of force development is consistent with current models for the Ca2+ activation of the crossbridge cycle, but these models do not explain the similarity in the maximal rates of activation and relaxation within a given species.

AD

-

Department of Pharmacology, United Medical and Dental Schools, St. Thomas's Hospital, London, UK.

CM

-

Comment in: Circ Res 1998 Jul 27;83(2):230-2

PMID

-

0009686757

SO

-

Circ Res 1998 Jul 27;83(2):179-86

UI

-

98319626

AU

-

Walker LA

AU

-

Gailly P

AU

-

Jensen PE

AU

-

Somlyo AV

AU

-

Somlyo AP

TI

-

The unimportance of being (protein kinase C) epsilon.

LA

-

Eng

MH

-

Animal

MH

-

Calcium/metabolism

MH

-

Down-Regulation (Physiology)

MH

-

Enzyme Inhibitors/pharmacology

MH

-

Ferrets

MH

-

Isoenzymes/metabolism/*physiology

MH

-

Male

MH

-

Muscle Contraction/drug effects/*physiology

MH

-

Peptides, Cyclic/pharmacology

MH

-

Phosphoprotein Phosphatase/antagonists & inhibitors

MH

-

Portal Vein/enzymology/metabolism

MH

-

Protein Kinase C/metabolism/*physiology

MH

-

Support, Non-U.S. Gov't

MH

-

Support, U.S. Gov't, P.H.S.

RN

-

EC 2.7.1.- (protein kinase C epsilon)

RN

-

EC 2.7.1.- (Protein Kinase C)

RN

-

EC 3.1.3.16 (Phosphoprotein Phosphatase)

RN

-

EC 3.1.3.53 (myosin-light-chain phosphatase)

RN

-

0 (Enzyme Inhibitors)

RN

-

0 (Isoenzymes)

RN

-

0 (Peptides, Cyclic)

RN

-

7440-70-2 (Calcium)

RN

-

77238-39-2 (microcystin)

PT

-

JOURNAL ARTICLE

ID

-

PO1 HL48807/HL/NHLBI

DA

-

19980730

DP

-

1998 Jul

IS

-

0892-6638

TA

-

FASEB J

PG

-

813-21

SB

-

M

SB

-

X

CY

-

UNITED STATES

IP

-

10

VI

-

12

JC

-

FAS

AA

-

Author

EM

-

199810

AB

-

The purpose of our study was to determine the mechanism through which phorbol esters and smooth muscle myosin phosphatase inhibitors can induce contraction of smooth muscle in the absence of Ca2+. Protein kinase C-epsilon (PKC-epsilon) was previously implicated in this process based largely on its supposed absence in the ferret portal vein, and a correlation was drawn between the presence of this isoform and the ability of smooth muscle to contract independently of Ca2+ and phosphorylation of the 20 kDa regulatory light chains of myosin (MLC20). We demonstrate here, with two antibodies, one to the NH2 terminus and the other to the COOH terminus of PKC-epsilon, that epsilon is present in both ferret portal vein and rabbit portal vein smooth muscle, neither of which exhibits phorbol ester-induced contraction in the absence of Ca2+. However, in the presence of clamped submaximal Ca2+, phorbol es ter increased MLC20 phosphorylation from 17.7+/-1.7% to 46.4+/-3.6% in ferret portal vein smooth muscle and evoked an increase in force. Prolonged (48 h) incubation of ferret portal vein with phorbol esters completely down-regulated PKC-epsilon, as shown by Western blots, and abolished the phorbol ester-evoked contraction at submaximal Ca2+, but not Ca2+-independent, contractions induced by the phosphatase inhibitor microcystin. Contractions induced by microcystin in Ca2+-free solution were associated with increased phosphorylation of myosin light chain kinase (MLCK). Activation of MLCK by autophosphorylation in the absence of Ca2+ occurs in vitro (1). We conclude that PKC-epsilon is neither necessary nor sufficient for Ca2+- independent regulation of myosin II in smooth muscle, but contractions induced by agents that inhibit smooth muscle myosin phosphatase in the absence of Ca2+ may be mediated by MLCK autophosphorylated or activated by another Ca2+-independent kinase.

AD

-

Department of Molecular Physiology and Biological Physics, University of Virginia, Health Sciences Center, Charlottesville 22906-0011, USA.

PMID

-

0009657521

SO

-

FASEB J 1998 Jul;12(10):813-21

UI

-

98297685

AU

-

Sabido-David C

AU

-

Brandmeier B

AU

-

Craik JS

AU

-

Corrie JE

AU

-

Trentham DR

AU

-

Irving M

TI

-

Steady-state fluorescence polarization studies of the orientation of myosin regulatory light chains in single skeletal muscle fibers using pure isomers of iodoacetamidotetramethylrhodamine.

LA

-

Eng

MH

-

Animal

MH

-

Chickens

MH

-

Chromatography, High Pressure Liquid

MH

-

Fluorescence Polarization/methods

MH

-

Fluorescent Dyes

MH

-

Gizzard

MH

-

In Vitro

MH

-

Muscle Contraction/*physiology

MH

-

Muscle Fibers/cytology/*physiology

MH

-

Muscle Relaxation

MH

-

Muscle, Skeletal/cytology/*physiology

MH

-

Muscle, Smooth/metabolism

MH

-

Myosin Light Chains/*analysis

MH

-

Rabbits

MH

-

*Rhodamines

MH

-

Sarcomeres/physiology/ultrastructure

MH

-

Sensitivity and Specificity

MH

-

Solutions

MH

-

Support, Non-U.S. Gov't

RN

-

0 (Fluorescent Dyes)

RN

-

0 (Myosin Light Chains)

RN

-

0 (Rhodamines)

RN

-

0 (Solutions)

RN

-

81235-33-8 (tetramethylrhodamine iodoacetamide)

PT

-

JOURNAL ARTICLE

DA

-

19980824

DP

-

1998 Jun

IS

-

0006-3495

TA

-

Biophys J

PG

-

3083-92

SB

-

M

CY

-

UNITED STATES

IP

-

6

VI

-

74

JC

-

A5S

AA

-

Author

EM

-

199810

AB

-

The regulatory light chain (RLC) from chicken gizzard myosin was covalently modified on cysteine 108 with either the 5- or 6-isomer of iodoacetamidotetramethylrhodamine (IATR). Labeled RLCs were purified by fast protein liquid chromatography and characterized by reverse-phase high-performance liquid chromatography (HPLC), tryptic digestion, and electrospray mass spectrometry. Labeled RLCs were exchanged into the native myosin heads of single skinned fibers from rabbit psoas muscle, and the ATR dipole orientations were determined by fluorescence polarization. The 5- and 6-ATR dipoles had distinct orientations, and model orientational distributions suggest that they are more than 20 degrees apart in rigor. In the rigor-to-relaxed transition (sarcomere length 2.4 microm, 10 degrees C), the 5-ATR dipole became more perpendicular to the fiber axis, but the 6-ATR dipole became more parallel. This orientation change was absent at sarcomere length 4.0 microm, where overlap between myosin and actin filaments is abolished. When the temperature of relaxed fibers was raised to 30 degrees C, the 6-ATR dipoles became more parallel to the fiber axis and less ordered; when ionic strength was lowered from 160 mM to 20 mM (5 degrees C), the 6-ATR dipoles became more perpendicular to the fiber axis and more ordered. In active contraction (10 degrees C), the orientational distribution of the probe dipoles was similar but not identical to that in relaxation, and was not a linear combination of the orientational distributions in relaxation and rigor.

AD

-

The Randall Institute, King's College London, England.

PMID

-

0009635762

SO

-

Biophys J 1998 Jun;74(6):3083-92

UI

-

98252441

AU

-

Dekker LR

AU

-

Rademaker H

AU

-

Vermeulen JT

AU

-

Opthof T

AU

-

Coronel R

AU

-

Spaan JA

AU

-

Janse MJ

TI

-

Cellular uncoupling during ischemia in hypertrophied and failing rabbit ventricular myocardium: effects of preconditioning.

LA

-

Eng

MH

-

Animal

MH

-

Arrhythmia/etiology

MH

-

Calcium/metabolism

MH

-

Heart Failure, Congestive/*physiopathology

MH

-

Heart Hypertrophy/*physiopathology

MH

-

*Ischemic Preconditioning, Myocardial

MH

-

Myocardial Ischemia/*physiopathology

MH

-

Rabbits

MH

-

Time Factors

RN

-

7440-70-2 (Calcium)

PT

-

JOURNAL ARTICLE

DA

-

19980528

DP

-

1998 May 5

IS

-

0009-7322

TA

-

Circulation

PG

-

1724-30

SB

-

A

SB

-

M

CY

-

UNITED STATES

IP

-

17

VI

-

97

JC

-

DAW

AA

-

Author

EM

-

199807

AB

-

BACKGROUND: Patients with heart failure show a very high incidence of arrhythmias and sudden death that is often preceded by ischemia; however, data on electrophysiological changes during ischemia in failing myocardium are sparse. We studied electrical uncoupling during ischemia in normal and failing myocardium. METHODS AND RESULTS: Tissue resistance, intracellular Ca2+ concentration (Indo-1 fluorescence ratio), and mechanical activity were simultaneously determined in arterially perfused right ventricular papillary muscles from 11 normal and 15 failing rabbits. Heart failure was induced by combined volume and pressure overload. Before sustained ischemia, muscles were subjected to control perfusion (non-PC) or ischemic preconditioning (PC). The onset of uncoupling during ischemia was equal in non-PC normal (13.6+/-0.9 minutes of ischemia) and non-PC failing hearts (13.3+/-0.7 minutes of ischemia). PC postponed uncoupling in normal hearts by 10 minutes. In failing hearts, however, PC caused a large variability in the onset of uncoupling during ischemia (mean, 12.2+/- 2.1; range, 5 to 22 minutes of ischemia). The duration of uncoupling process was prolonged in failing hearts (12.9+/-0.9 minutes) compared with normal hearts (7.8+/-0.4 minutes). The degree of heart failure and relative heart weight of the failing hearts significantly correlated with the earlier uncoupling after PC and the duration of uncoupling. In every experiment, the start of Ca2+ rise and contracture preceded uncoupling during ischemia. CONCLUSIONS: The duration of the process of ischemia-induced electrical uncoupling in failing hearts is prolonged compared with that in normal hearts. Ischemic PC has detrimental effects in severely failing papillary muscles because it advances the moment of irreversible ischemic damage.

AD

-

Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands. LRDekker@AMC.UVA.NL

PMID

-

0009591767

SO

-

Circulation 1998 May 5;97(17):1724-30

UI

-

98225225

AU

-

Wu X

AU

-

Haystead TA

AU

-

Nakamoto RK

AU

-

Somlyo AV

AU

-

Somlyo AP

TI

-

Acceleration of myosin light chain dephosphorylation and relaxation of smooth muscle by telokin. Synergism with cyclic nucleotide-activated kinase.

LA

-

Eng

MH

-

Animal

MH

-

Cyclic AMP-Dependent Protein Kinases/*metabolism

MH

-

Cyclic GMP/analogs & derivatives/pharmacology

MH

-

Cyclic GMP-Dependent Protein Kinases/*metabolism

MH

-

Forskolin/pharmacology

MH

-

In Vitro

MH

-

Kinetics

MH

-

Muscle Proteins/genetics/isolation & purification/*pharmacology

MH

-

Muscle Relaxation

MH

-

Muscle, Smooth/*drug effects/metabolism/physiology

MH

-

Myosin-Light-Chain Kinase/*metabolism

MH

-

Phosphorylation

MH

-

Rabbits

MH

-

Recombinant Proteins/genetics/isolation & purification/pharmacology

MH

-

Sulfhydryl Compounds/metabolism

MH

-

Support, U.S. Gov't, P.H.S.

RN

-

EC 2.7.1.117 (Myosin-Light-Chain Kinase)

RN

-

EC 2.7.10.- (Cyclic AMP-Dependent Protein Kinases)

RN

-

EC 2.7.10.- (Cyclic GMP-Dependent Protein Kinases)

RN

-

0 (telokin)

RN

-

0 (Muscle Proteins)

RN

-

0 (Recombinant Proteins)

RN

-

0 (Sulfhydryl Compounds)

RN

-

31356-94-2 (8-bromocyclic GMP)

RN

-

66428-89-5 (Forskolin)

RN

-

7665-99-8 (Cyclic GMP)

PT

-

JOURNAL ARTICLE

ID

-

PO1-HL48807/HL/NHLBI

ID

-

PO1-HL19242/HL/NHLBI

DA

-

19980602

DP

-

1998 May 1

IS

-

0021-9258

TA

-

J Biol Chem

PG

-

11362-9

SB

-

M

SB

-

X

CY

-

UNITED STATES

IP

-

18

VI

-

273

JC

-

HIV

AA

-

Author

EM

-

199808

AB

-

Incorporation of 32P into telokin, a smooth muscle-specific, 17-18-kDa, acidic (pI 4.2-4.4) protein, was increased by forskolin (20 microM) in intact rabbit ileum smooth muscle (ileum) and by 8-bromo-cyclic GMP (100 microM) in alpha-toxin-permeabilized ileum. Native telokin (5-20 microM), purified from turkey gizzard, and recombinant rabbit telokin, expressed in Escherichia coli and purified to >90% purity, induced dose- dependent relaxation, associated with a significant decrease in regulatory myosin light chain phosphorylation, without affecting the rate of thiophosphorylation of regulatory myosin light chain of ileum permeabilized with 0.1% Triton X-100. Endogenous telokin was lost from ileum during prolonged permeabilization (>20 min) with 0.1% Triton X- 100, and the time course of loss was correlated with the loss of 8- bromo-cyclic GMP-induced calcium desensitization. Recombinant and native gizzard telokins were phosphorylated, in vitro, by the catalytic subunit of cAMP-dependent protein kinase, cGMP-dependent protein kinase, and p42/44 mitogen-activated protein kinase; the recombinant protein was also phosphorylated by calmodulin-dependent protein kinase II. Exogenous cGMP-dependent protein kinase (0.5 microM) activated by 8- bromo-cyclic GMP (50 microM) phosphorylated recombinant telokin (10 microM) when added concurrently to ileum depleted of its endogenous telokin, and their relaxant effects were mutually potentiated. Forskolin (20 microM) also increased phosphorylation of telokin in intact ileum. We conclude that telokin induces calcium desensitization in smooth muscle by enhancing myosin light chain phosphatase activity, and cGMP- and/or cAMP-dependent phosphorylation of telokin up-regulates its relaxant effect.

AD

-

Department of Molecular Physiology and Biological Physics, University of Virginia Health Sciences Center, Charlottesville, Virginia 22906- 0011, USA.

PMID

-

0009556631

SO

-

J Biol Chem 1998 May 1;273(18):11362-9

UI

-

98260334

AU

-

Ohizumi Y

AU

-

Matsunaga K

AU

-

Nakatani K

AU

-

Kobayashi J

TI

-

Potent stimulation of myofilament force and ATPase activity of skeletal muscle by eudistomin M, a novel Ca(++)-sensitizing agent from a Caribbean tunicate.

LA

-

Eng

MH

-

Adenosinetriphosphatase/*metabolism

MH

-

Animal

MH

-

Calcium/*metabolism

MH

-

Carbolines/pharmacology

MH

-

Guinea Pigs

MH

-

Male

MH

-

Microfilaments/*drug effects

MH

-

Muscle, Skeletal/*drug effects

MH

-

Myosin/analysis

MH

-

Rabbits

MH

-

Support, Non-U.S. Gov't

RN

-

EC 3.6.1.3 (Adenosinetriphosphatase)

RN

-

0 (Carbolines)

RN

-

0 (Myosin)

RN

-

7440-70-2 (Calcium)

RN

-

88704-39-6 (eudistomin M)

PT

-

JOURNAL ARTICLE

DA

-

19980608

DP

-

1998 May

IS

-

0022-3565

TA

-

J Pharmacol Exp Ther

PG

-

695-9

SB

-

M

CY

-

UNITED STATES

IP

-

2

VI

-

285

JC

-

JP3

AA

-

Author

EM

-

199808

AB

-

In the course of our survey of biologically active compounds from natural sources, eudistomins were isolated from a Caribbean tunicate Eudistoma olivaceum. In the present experiments, eudistomin M (Eud-M, > 10(-5) M) caused a concentration-dependent increase in the contractile response of skinned fibers from guinea pig skeletal psoas muscles to Ca++. The superprecipitation and ATPase activity of myosin B from fast skeletal muscles of rabbit back and leg were potentiated by this compound (> 10(-5) M) in a concentration-dependent manner. In skinned fibers, superprecipitation and the ATPase activity of myosin B, Eud-M shifted the concentration-response curve for Ca++ to the upper direction. Ca(++)-, K(+)-EDTA- or Mg(++)-ATPase was not affected by Eud- M. This compound had no effect on the ATPase activity of actomyosin reconstituted from actin and myosin in the presence or absence of troponin. However, the ATPase activity of actin-myosin-troponin- tropomyosin reconstituted system was increased significantly by Eud-M. These results suggest that Eud-M increases the Ca++ sensitivity of the contractile apparatus in skeletal muscles at least partially mediated through troponin-tropomyosin system and thus enhances the ATPase activity of myosin B and the contractile force of myofilament.

AD

-

Department of Pharmaceutical Molecular Biology, Faculty of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.

PMID

-

0009580615

SO

-

J Pharmacol Exp Ther 1998 May;285(2):695-9

UI

-

98204620

AU

-

Regnier M

AU

-

Martyn DA

AU

-

Chase PB

TI

-

Calcium regulation of tension redevelopment kinetics with 2-deoxy-ATP or low [ATP] in rabbit skeletal muscle.

LA

-

Eng

MH

-

Adenosine Triphosphate/*pharmacology

MH

-

Animal

MH

-

Biophysics

MH

-

Calcium/*pharmacology

MH

-

Deoxyadenine Nucleotides/*pharmacology

MH

-

In Vitro

MH

-

Kinetics

MH

-

Models, Biological

MH

-

Muscle Contraction/*drug effects/physiology

MH

-

Myosin ATPase/metabolism

MH

-

Psoas Muscles/*drug effects/*physiology

MH

-

Rabbits

MH

-

Support, U.S. Gov't, P.H.S.

RN

-

EC 3.6.1.32 (Myosin ATPase)

RN

-

0 (Deoxyadenine Nucleotides)

RN

-

1927-31-7 (2'-deoxyadenosine triphosphate)

RN

-

56-65-5 (Adenosine Triphosphate)

RN

-

7440-70-2 (Calcium)

PT

-

JOURNAL ARTICLE

ID

-

HL52558/HL/NHLBI

ID

-

HL51277/HL/NHLBI

ID

-

NS08384/NS/NINDS

DA

-

19980608

DP

-

1998 Apr

IS

-

0006-3495

TA

-

Biophys J

PG

-

2005-15

SB

-

M

CY

-

UNITED STATES

IP

-

4

VI

-

74

JC

-

A5S

AA

-

Author

EM

-

199808

AB

-

The correlation of acto-myosin ATPase rate with tension redevelopment kinetics (k(tr)) was determined during Ca(+2)-activated contractions of demembranated rabbit psoas muscle fibers; the ATPase rate was either increased or decreased relative to control by substitution of ATP (5.0 mM) with 2-deoxy-ATP (dATP) (5.0 mM) or by lowering [ATP] to 0.5 mM, respectively. The activation dependence of k(tr) and unloaded shortening velocity (Vu) was measured with each substrate. With 5.0 mM ATP, Vu depended linearly on tension (P), whereas k(tr) exhibited a nonlinear dependence on P, being relatively independent of P at submaximum levels and rising steeply at P > 0.6-0.7 of maximum tension (Po). With dATP, Vu was 25% greater than control at Po and was elevated at all P > 0.15Po, whereas Po was unchanged. Furthermore, the Ca(+2) sensitivity of both k(tr) and P increased, such that the dependence of k(tr) on P was not significantly different from control, despite an elevation of Vu and maximal k(tr). In contrast, lowering [ATP] caused a slight (8%) elevation of Po, no change in the Ca(+2) sensitivity of P, and a decrease in Vu at all P. Moreover, k(tr) was decreased relative to control at P > 0.75Po, but was elevated at P < 0.75Po. These data demonstrate that the cross-bridge cycling rate dominates k(tr) at maximum but not submaximum levels of Ca(2+) activation.

AD

-

Department of Bioengineering, University of Washington, Seattle 98195, USA. mregnier@u.washington.edu

PMID

-

0009545059

SO

-

Biophys J 1998 Apr;74(4):2005-15

UI

-

98204590

AU

-

Uttenweiler D

AU

-

Weber C

AU

-

Fink RH

TI

-

Mathematical modeling and fluorescence imaging to study the Ca2+ turnover in skinned muscle fibers.

LA

-

Eng

MH

-

Animal

MH

-

Biophysics

MH

-

Caffeine/pharmacology

MH

-

Calcium/*metabolism

MH

-

Comparative Study

MH

-

Fluorescent Dyes

MH

-

Fura-2

MH

-

In Vitro

MH

-

Ion Transport/drug effects

MH

-

Kinetics

MH

-

Male

MH

-

Mathematics

MH

-

Mice

MH

-

Mice, Inbred BALB C

MH

-

*Models, Biological

MH

-

Muscle Fibers, Fast-Twitch/drug effects/*metabolism

MH

-

Sarcoplasmic Reticulum/metabolism

MH

-

Support, Non-U.S. Gov't

RN

-

0 (Fluorescent Dyes)

RN

-

58-08-2 (Caffeine)

RN

-

7440-70-2 (Calcium)

RN

-

96314-98-6 (Fura-2)

PT

-

JOURNAL ARTICLE

DA

-

19980608

DP

-

1998 Apr

IS

-

0006-3495

TA

-

Biophys J

PG

-

1640-53

SB

-

M

CY

-

UNITED STATES

IP

-

4

VI

-

74

JC

-

A5S

AA

-

Author

EM

-

199808

AB

-

A mathematical model was developed for the simulation of the spatial and temporal time course of Ca2+ ion movement in caffeine-induced calcium transients of chemically skinned muscle fiber preparations. Our model assumes cylindrical symmetry and quantifies the radial profile of Ca2+ ion concentration by solving the diffusion equations for Ca2+ ions and various mobile buffers, and the rate equations for Ca2+ buffering (mobile and immobile buffers) and for the release and reuptake of Ca2+ ions by the sarcoplasmic reticulum (SR), with a finite-difference algorithm. The results of the model are compared with caffeine-induced spatial Ca2+ transients obtained from saponin skinned murine fast- twitch fibers by fluorescence photometry and imaging measurements using the ratiometric dye Fura-2. The combination of mathematical modeling and digital image analysis provides a tool for the quantitative description of the total Ca2+ turnover and the different contributions of all interacting processes to the overall Ca2+ transient in skinned muscle fibers. It should thereby strongly improve the usage of skinned fibers as quantitative assay systems for many parameters of the SR and the contractile apparatus helping also to bridge the gap to the intact muscle fiber.

AD

-

Ruprecht-Karls-Universitat Heidelberg, II Institute of Physiology, Germany.

PMID

-

0009545029

SO

-

Biophys J 1998 Apr;74(4):1640-53

UI

-

98151502

AU

-

Sugi H

AU

-

Iwamoto H

AU

-

Akimoto T

AU

-

Ushitani H

TI

-

Evidence for the load-dependent mechanical efficiency of individual myosin heads in skeletal muscle fibers activated by laser flash photolysis of caged calcium in the presence of a limited amount of ATP.

LA

-

Eng

MH

-

Acetic Acids/*metabolism

MH

-

Adenosine Diphosphate/metabolism

MH

-

Adenosine Triphosphate/*metabolism

MH

-

Animal

MH

-

Calcium/*metabolism

MH

-

Chelating Agents

MH

-

Ethylenediamines/*metabolism

MH

-

Kinetics

MH

-

Lasers

MH

-

Muscle Contraction/*physiology

MH

-

Muscle Fibers/*physiology/ultrastructure

MH

-

Muscle, Skeletal/*physiology

MH

-

Phosphates/metabolism

MH

-

Photolysis

MH

-

Rabbits

MH

-

Solutions

MH

-

Time Factors

RN

-

0 (Acetic Acids)

RN

-

0 (Chelating Agents)

RN

-

0 (Ethylenediamines)

RN

-

0 (Phosphates)

RN

-

0 (Solutions)

RN

-

117367-86-9 (1-(2-nitro-4,5-dimethoxyphenyl)-N,N,N',N'- tetrakis((oxycarbonyl)methyl)-1,2-ethanediamine)

RN

-

56-65-5 (Adenosine Triphosphate)

RN

-

58-64-0 (Adenosine Diphosphate)

RN

-

7440-70-2 (Calcium)

PT

-

JOURNAL ARTICLE

DA

-

19980409

DP

-

1998 Mar 3

IS

-

0027-8424

TA

-

Proc Natl Acad Sci U S A

PG

-

2273-8

SB

-

M

SB

-

X

CY

-

UNITED STATES

IP

-

5

VI

-

95

JC

-

PV3

AA

-

Author

EM

-

199806

AB

-

Although a contracting muscle regulates its energy output depending on the load imposed on it ("Fenn effect"), the mechanism underlying the load-dependent energy output remains obscure. To explore the possibility that the mechanical efficiency, with which chemical energy derived from ATP hydrolysis is converted into mechanical work, of individual myosin heads changes in a load-dependent manner, we examined the auxotonic shortening of glycerinated rabbit psoas muscle fibers, containing ATP molecules almost equal in number to the myosin heads, after laser-flash photolysis of caged calcium. Immediately before laser- flash activation, almost all of the myosin heads in the fiber are in the state M.ADP.Pi, and can undergo only one ATP hydrolysis cycle after activation. When the fibers were activated to shorten under various auxotonic loads, the length, force, and power output changes were found to be scaled according to the auxotonic load. Both the power and energy outputs were maximal under a moderate auxotonic load. The amount of M.ADP.Pi utilized at a time after activation was estimated from the amount of isometric force developed after interruption of fiber shortening. This amount was minimal in the isometric condition and increased nearly in proportion to the distance of fiber shortening. These results are taken as evidence that the efficiency of chemomechanical energy conversion in individual myosin heads changes in a load-dependent manner.

AD

-

Department of Physiology, School of Medicine, Teikyo University, Itabashi-ku, Tokyo 173, Japan. sugi@med.teikyo-u.ac.jp

PMID

-

0009482875

SO

-

Proc Natl Acad Sci U S A 1998 Mar 3;95(5):2273-8

UI

-

98171004

AU

-

Horikawa Y

AU

-

Goel A

AU

-

Somlyo AP

AU

-

Somlyo AV

TI

-

Mitochondrial calcium in relaxed and tetanized myocardium.

LA

-

Eng

MH

-

Animal

MH

-

Calcium/*metabolism/pharmacology

MH

-

Electric Stimulation

MH

-

Electron Probe Microanalysis/methods

MH

-

Freezing

MH

-

Hamsters

MH

-

Heart Ventricle

MH

-

In Vitro

MH

-

Kinetics

MH

-

Male

MH

-

Mitochondria, Heart/*metabolism/ultrastructure

MH

-

Myocardial Contraction/drug effects/*physiology

MH

-

Papillary Muscles/drug effects/*physiology/ultrastructure

MH

-

Rats

MH

-

Rats, Sprague-Dawley

MH

-

Ryanodine/pharmacology

MH

-

Support, U.S. Gov't, P.H.S.

RN

-

15662-33-6 (Ryanodine)

RN

-

7440-70-2 (Calcium)

PT

-

JOURNAL ARTICLE

ID

-

HL-48807/HL/NHLBI

DA

-

19980512

DP

-

1998 Mar

IS

-

0006-3495

TA

-

Biophys J

PG

-

1579-90

SB

-

M

CY

-

UNITED STATES

IP

-

3

VI

-

74

JC

-

A5S

AA

-

Author

EM

-

199807

AB

-

The elemental composition of rat cardiac muscle was determined with electron probe x-ray microanalysis (EPMA) of rapidly frozen papillary muscles and trabeculae incubated with ryanodine (1 microM) in either 1.2 or 10 mM [Ca2+]o-containing solutions, paced at 0.6 Hz or tetanized at 10 Hz. Total mitochondrial calcium increased significantly, by 4.2 mmol/kg dry weight during a 7 s tetanus, only in muscles tetanized in the presence of 10 mM [Ca2+]o when cytoplasmic Ca2+ is 1-4 microM (Backx, P. H., W.-D. Gao, M. D. Azan-Backx, and E. Marban. 1995. The relationship between contractile force and intracellular [Ca2+] in intact rat trabeculae. J. Gen. Physiol. 105:1-19). Comparison of total mitochondrial with free mitochondrial Ca2+ reported in the literature indicates that the total/free ratio is approximately 6000 at physiological or near-physiological levels of total mitochondrial calcium. Increases in free mitochondrial [Ca2+] consistent with regulation of mitochondrial enzymes should be associated with increases in total mitochondrial calcium detectable with EPMA. However, such increases in mitochondrial calcium occur only as the result of prolonged, unphysiological elevations of cytosolic [Ca2+].

AD

-

Department of Molecular Physiology and Biological Physics, University of Virginia Health Sciences Center, Charlottesville 22906-0011, USA.

PMID

-

0009512053

SO

-

Biophys J 1998 Mar;74(3):1579-90

UI

-

98170992

AU

-

Iwamoto H

TI

-

Thin filament cooperativity as a major determinant of shortening velocity in skeletal muscle fibers.

LA

-

Eng

MH

-

Animal

MH

-

Calcium/metabolism

MH

-

In Vitro

MH

-

Isometric Contraction/drug effects/*physiology

MH

-

Muscle Fibers/drug effects/*physiology/ultrastructure

MH

-

Muscle, Skeletal/*physiology/ultrastructure

MH

-

Phosphates/pharmacology

MH

-

Rabbits

MH

-

Sarcomeres/drug effects/*physiology/ultrastructure

MH

-

Support, Non-U.S. Gov't

MH

-

Time Factors

RN

-

0 (Phosphates)

RN

-

7440-70-2 (Calcium)

PT

-

JOURNAL ARTICLE

DA

-

19980512

DP

-

1998 Mar

IS

-

0006-3495

TA

-

Biophys J

PG

-

1452-64

SB

-

M

CY

-

UNITED STATES

IP

-

3

VI

-

74

JC

-

A5S

AA

-

Author

EM

-

199807

AB

-

The mechanism underlying the calcium sensitivity of the velocity of shortening of skeletal muscle fibers was investigated using a multiple shortening protocol: within a single contraction, skinned rabbit psoas fibers were made to shorten repetitively under a light load by briefly stretching back to their initial length at regular intervals. At saturating [Ca2+], the initial fast shortening pattern was repeated reproducibly. At submaximal [Ca2+], the first shortening consisted of fast and slow phases, but only the slow phase was observed in later shortenings. When the fibers were held isometric after the first shortening, the velocity of the second shortening recovered with time. The recovery paralleled tension redevelopment, implying a close relationship between the velocity and the number of the preexisting force-producing cross-bridges. However, this parallelism was lost as [Ca2+] was increased. Thus, the velocity was modified in a manner consistent with the cooperative thin filament activation by strong binding cross-bridges and its modulation by calcium. The present results therefore provide evidence that the thin filament cooperativity is primarily responsible for the calcium sensitivity of velocity. The effect of inorganic phosphate to accelerate the slow phase of shortening is also explained in terms of the cooperative activation.

AD

-

Department of Physiology, School of Medicine, Teikyo University, Tokyo, Japan.

PMID

-

0009512041

SO

-

Biophys J 1998 Mar;74(3):1452-64

UI

-

98147195

AU

-

Dijkman MA

AU

-

Heslinga JW

AU

-

Sipkema P

AU

-

Westerhof N

TI

-

Perfusion-induced changes in cardiac contractility depend on capillary perfusion.

LA

-

Eng

MH

-

Animal

MH

-

Blood Pressure

MH

-

Capillaries/*physiology

MH

-

Coronary Vessels/physiology

MH

-

Microspheres

MH

-

*Myocardial Contraction

MH

-

Oxygen Consumption

MH

-

Papillary Muscles/anatomy & histology/*physiology

MH

-

Perfusion

MH

-

Rats

MH

-

Rats, Wistar

PT

-

JOURNAL ARTICLE

DA

-

19980317

DP

-

1998 Feb

IS

-

0002-9513

TA

-

Am J Physiol

PG

-

H405-10

SB

-

M

CY

-

UNITED STATES

IP

-

2 Pt 2

VI

-

274

JC

-

3U8

AA

-

Author

EM

-

199805

AB

-

The perfusion-induced increase in cardiac contractility (Gregg phenomenon) is especially found in heart preparations that lack adequate coronary autoregulation and thus protection of changes in capillary pressure. We determined in the isolated perfused papillary muscle of the rat whether cardiac muscle contractility is related to capillary perfusion. Oxygen availability of this muscle is independent of internal perfusion, and perfusion may be varied or even stopped without loss of function. Muscles contracted isometrically at 27 degrees C (n = 7). During the control state stepwise increases in perfusion pressure resulted in all muscles in a significant increase in active tension. Muscle diameter always increased with increased perfusion pressure, but muscle segment length was unaffected. Capillary perfusion was then obstructed by plastic microspheres (15 microns). Flow, at a perfusion pressure of 66.6 +/- 26.2 cmH2O, reduced from 17.6 +/- 5.4 microliters/min in the control state to 3.2 +/- 1.3 microliters/min after microspheres. Active tension developed by the muscle in the unperfused condition before microspheres and after microspheres did not differ significantly (-12.8 +/- 29.4% change). After microspheres similar perfusion pressure steps as in control never resulted in an increase in active tension. Even at the two highest perfusion pressures (89.1 +/- 28.4 and 106.5 +/- 31.7 cmH2O) that were applied a significant decrease in active tension was found. We conclude that the Gregg phenomenon is related to capillary perfusion.

AD

-

Laboratory for Physiology, Vrije Universiteit Amsterdam, The Netherlands.

PMID

-

0009486241

SO

-

Am J Physiol 1998 Feb;274(2 Pt 2):H405-10

UI

-

98062941

AU

-

Blanchard EM

AU

-

Iizuka K

AU

-

Christe M

AU

-

Conner DA

AU

-

Geisterfer-Lowrance A

AU

-

Schoen FJ

AU

-

Maughan DW

AU

-

Seidman CE

AU

-

Seidman JG

TI

-

Targeted ablation of the murine alpha-tropomyosin gene.

LA

-

Eng

MH

-

Animal

MH

-

Gene Targeting

MH

-

Male

MH

-

Mice

MH

-

Mice, Knockout

MH

-

Myocardium/pathology

MH

-

Support, Non-U.S. Gov't

MH

-

Tropomyosin/*genetics/physiology

RN

-

0 (Tropomyosin)

PT

-

JOURNAL ARTICLE

DA

-

19971231

DP

-

1997 Dec

IS

-

0009-7330

TA

-

Circ Res

PG

-

1005-10

SB

-

M

CY

-

UNITED STATES

IP

-

6

VI

-

81

JC

-

DAJ

AA

-

Author

EM

-

199803

AB

-

We created a mouse that lacks a functional alpha-tropomyosin gene using gene targeting in embryonic stem cells and blastocyst-mediated transgenesis. Homozygous alpha-tropomyosin "knockout" mice die between embryonic day 9.5 and 13.5 and lack alpha-tropomyosin mRNA. Heterozygous alpha-tropomyosin knockout mice have approximately 50% as much cardiac alpha-tropomyosin mRNA as wild-type littermates but similar alpha-tropomyosin protein levels. Cardiac gross morphology, histology, and function (assessed by working heart preparations) of heterozygous alpha-tropomyosin knockout and wild-type mice were indistinguishable. Mechanical performance of skinned papillary muscle strips derived from mutant and wild-type hearts also revealed no differences. We conclude that haploinsufficiency of the alpha- tropomyosin gene produces little or no change in cardiac function or structure, whereas total alpha-tropomyosin deficiency is incompatible with life. These findings imply that in heterozygotes there is a regulatory mechanism that maintains the level of myofibrillar tropomyosin despite the reduction in alpha-tropomyosin m>RNA.

AD

-

Howard Hughes Medical Institute, Boston, Mass., USA.

PMID

-

0009400381

SO

-

Circ Res 1997 Dec;81(6):1005-10

UI

-

98042194

AU

-

Wannenburg T

AU

-

Janssen PM

AU

-

Fan D

AU

-

de Tombe PP

TI

-

The Frank-Starling mechanism is not mediated by changes in rate of cross-bridge detachment.

LA

-

Eng

MH

-

Adenosine Triphosphate/*metabolism

MH

-

Animal

MH

-

Calcium/pharmacology

MH

-

Heart/*physiology

MH

-

In Vitro

MH

-

Kinetics

MH

-

*Models, Cardiovascular

MH

-

Myocardial Contraction/drug effects/*physiology

MH

-

Myocardium/metabolism

MH

-

Myosin ATPase/*metabolism

MH

-

NAD/metabolism

MH

-

Rats

MH

-

Regression Analysis

MH

-

Sarcomeres/physiology

MH

-

Support, Non-U.S. Gov't

MH

-

Support, U.S. Gov't, P.H.S.

RN

-

EC 3.6.1.32 (Myosin ATPase)

RN

-

53-84-9 (NAD)

RN

-

56-65-5 (Adenosine Triphosphate)

RN

-

7440-70-2 (Calcium)

PT

-

JOURNAL ARTICLE

ID

-

HL-52322/HL/NHLBI

ID

-

HL-03255/HL/NHLBI

DA

-

19971216

DP

-

1997 Nov

IS

-

0002-9513

TA

-

Am J Physiol

PG

-

H2428-35

SB

-

M

CY

-

UNITED STATES

IP

-

5 Pt 2

VI

-

273

JC

-

3U8

AA

-

Author

EM

-

199802

AB

-

We tested the hypothesis that the Frank-Starling relationship is mediated by changes in the rate of cross-bridge detachment in cardiac muscle. We simultaneously measured isometric force development and the rate of ATP consumption at various levels of Ca2+ activation in skinned rat cardiac trabecular muscles at three sarcomere lengths (2.0, 2.1, and 2.2 microns). The maximum rate of ATP consumption was 1.5 nmol.s- 1.microliter fiber vol-1, which represents an estimated adenosinetriphosphatase (ATPase) rate of approximately 10 s-1 per myosin head at 24 degrees C. The rate of ATP consumption was tightly and linearly coupled to the level of isometric force development, and changes in sarcomere length had no effect on the slope of the force- ATPase relationships. The average slope of the force-ATPase relationships was 15.5 pmol.mN-1.mm-1. These results suggest that the mechanisms that underlie the Frank-Starling relationship in cardiac muscle do not involve changes in the kinetics of the apparent detachment step in the cross-bridge cycle.

AD

-

Section on Cardiology, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina 27157-1045, USA.

PMID

-

0009374781

SO

-

Am J Physiol 1997 Nov;273(5 Pt 2):H2428-35

UI

-

98042192

AU

-

Janssen PM

AU

-

de Tombe PP

TI

-

Protein kinase A does not alter unloaded velocity of sarcomere shortening in skinned rat cardiac trabeculae.

LA

-

Eng

MH

-

Animal

MH

-

Calcium/metabolism

MH

-

Connective Tissue/*physiology

MH

-

Cyclic AMP-Dependent Protein Kinases/*pharmacology

MH

-

Enzyme Inhibitors/pharmacology

MH

-

Heart/*physiology

MH

-

In Vitro

MH

-

Kinetics

MH

-

Myocardial Contraction

MH

-

Rats

MH

-

Rats, Inbred Strains

MH

-

Receptors, Adrenergic, beta/physiology

MH

-

Regression Analysis

MH

-

Sarcomeres/drug effects/*physiology

MH

-

Support, Non-U.S. Gov't

MH

-

Support, U.S. Gov't, P.H.S.

MH

-

Time Factors

RN

-

EC 2.7.10.- (Cyclic AMP-Dependent Protein Kinases)

RN

-

0 (Enzyme Inhibitors)

RN

-

0 (Receptors, Adrenergic, beta)

RN

-

7440-70-2 (Calcium)

PT

-

JOURNAL ARTICLE

ID

-

HL-52322/HL/NHLBI

DA

-

19971216

DP

-

1997 Nov

IS

-

0002-9513

TA

-

Am J Physiol

PG

-

H2415-22

SB

-

M

CY

-

UNITED STATES

IP

-

5 Pt 2

VI

-

273

JC

-

3U8

AA

-

Author

EM

-

199802

AB

-

Whether beta-adrenergic stimulation affects the cross-bridge cycling rate independently of its effect on Ca2+ handling by the cardiac myocyte is still unknown. An increase in cross-bridge cycling rate may result in increased unloaded velocity of sarcomere shortening (V0). To test this hypothesis directly, skinned rat cardiac trabeculae were attached between a silicon strain gauge (approximately 3.5 kHz resonant frequency) and a fast displacement motor. V0 was measured by a modified "Edman slack test" during a single maximal activation using seven to eight sarcomere-length step releases (measured by laser diffraction) ranging between 0.12 and 0.20 micron (15.0 +/- 0.1 degrees C). beta- Adrenergic stimulation was mimicked by exposing the trabeculae to the catalytic subunit of protein kinase A (PKA). Treatment with PKA (3 micrograms/ml; 45 min) caused a significant (P < 0.01) increase (41 +/- 13%) in the Ca2+ concentration required for half-maximal steady-state tension development. Neither maximum tension nor V0 was affected by treatment with PKA, suggesting that beta-adrenergic stimulation does not affect the rate-limiting step of cross-bridge cycling during unloaded shortening in myocardium.

AD

-

Department of Physiology and Biophysics, University of Illinois at Chicago 60607-7171, USA.

PMID

-

0009374779

SO

-

Am J Physiol 1997 Nov;273(5 Pt 2):H2415-22

UI

-

97460444

AU

-

Wier WG

AU

-

ter Keurs HE

AU

-

Marban E

AU

-

Gao WD

AU

-

Balke CW

TI

-

Ca2+ 'sparks' and waves in intact ventricular muscle resolved by confocal imaging [see comments] [published erratum appears in Circ Res 1997 Nov;81(5):893]

LA

-

Eng

MH

-

Aniline Compounds

MH

-

Animal

MH

-

Calcium/*metabolism

MH

-

Fluorescent Dyes

MH

-

Heart Ventricle

MH

-

Microscopy, Confocal

MH

-

Myocardial Contraction

MH

-

Myocardium/*metabolism

MH

-

Rats

MH

-

Rats, Inbred BN

MH

-

Support, Non-U.S. Gov't

MH

-

Support, U.S. Gov't, P.H.S.

MH

-

Ventricular Function

MH

-

Xanthenes

RN

-

0 (Aniline Compounds)

RN

-

0 (Fluorescent Dyes)

RN

-

0 (Xanthenes)

RN

-

121714-13-4 (Fluo-3)

RN

-

7440-70-2 (Calcium)

PT

-

JOURNAL ARTICLE

ID

-

HL-02466/HL/NHLBI

ID

-

HL-29473/HL/NHLBI

ID

-

HL-50435/HL/NHLBI

ID

-

+

DA

-

19971030

DP

-

1997 Oct

IS

-

0009-7330

TA

-

Circ Res

PG

-

462-9

SB

-

M

CY

-

UNITED STATES

IP

-

4

VI

-

81

JC

-

DAJ

AA

-

Author

EM

-

199801

AB

-

The [Ca2+]i transient in heart is now thought to involve the recruitment and summation of discrete and independent "units" of Ca2+ release (Ca2+ "sparks") from the sarcoplasmic reticulum, each of which is controlled locally by single coassociated L-type Ca2+ channels ("local control theory of excitation-contraction coupling"). All prior studies on Ca2+ sparks, however, have been performed in single enzymatically dissociated heart cells under nonphysiological conditions. In order to understand the possible significance of Ca2+ sparks to normal working cardiac muscle, we used confocal microscopy to record Ca2+ sparks, spatially averaged [Ca2+]i transients and Ca2+ waves in individual cells of intact rat right ventricular trabeculae (composed of < 15 cells in cross section) microinjected with the Ca2+ indicator fluo 3 under physiological conditions ([Ca2+]o, 1 mmol/L; temperature, 33 +/- 1 degree C). Twitch force was recorded simultaneously. When stretched to optimal length (sarcomere length, 2.2 microns) and stimulated at 0.2 Hz, the trabeculae generated approximately equal to 700 micrograms of force per cell. Spatially averaged [Ca2+]i transients recorded from individual cells within a trabecula were similar to those recorded previously from single cells. The amplitude distribution of the peak ratio of Ca2+ sparks was bimodal, with maxima at ratios of 1.8 +/- 0.3 and 2.7 +/- 0.2 (mean +/- SD), respectively. The amplitude of the peak of Ca2+ sparks was approximately equal to 170 nmol/L. Ca2+ sparks occurred at a frequency of 12.0 +/- 0.8/s (mean +/- SEM) in line scans covering 94 sarcomeres. Ca2+ waves occurred randomly at a frequency of 0.57 +/- 0.08/s and propagated with a velocity of 29.5 +/- 1.7 microns/s. The extent of Ca2+ wave propagation was 3.9 +/- 0.3 sarcomere lengths (sarcomere length, 2.2 microns). Ca2+ sparks could be identified along the leading edge of the waves at intervals of 1.30 +/- 0.11 sarcomere length. Our observations suggest that (1) Ca2+ sparks, similar to those recorded in single cells, occur in trabeculae under physiological conditions and (2) coupling of Ca2+ spark generation between neighboring sites occurs and may lead to (3) the development of Ca2+ waves, which propagate under physiological conditions at a low velocity over limited distances. The results suggest that concepts of excitation-contraction coupling recently derived from isolated myocytes are applicable to intact cardiac trabeculae [corrected].

AD

-

Department of Physiology, University of Maryland School of Medicine, Baltimore 21201, USA. gwier001@umabnet.ab.umd.edu

CM

-

Comment in: Circ Res 1997 Oct;81(4):636-8

RO

-

M:MWS

PMID

-

0009314826

LR

-

19980402

SO

-

Circ Res 1997 Oct;81(4):462-9

UI

-

97276757

AU

-

Shah AM

AU

-

Mebazaa A

AU

-

Yang ZK

AU

-

Cuda G

AU

-

Lankford EB

AU

-

Pepper CB

AU

-

Sollott SJ

AU

-

Sellers JR

AU

-

Robotham JL

AU

-

Lakatta EG

TI

-

Inhibition of myocardial crossbridge cycling by hypoxic endothelial cells: a potential mechanism for matching oxygen supply and demand?

LA

-

Eng

MH

-

Adenosinetriphosphatase/metabolism

MH

-

Animal

MH

-

Calcium/metabolism

MH

-

*Cell Hypoxia

MH

-

Cells, Cultured

MH

-

Comparative Study

MH

-

Data Interpretation, Statistical

MH

-

Endothelium, Vascular/*cytology/*physiology

MH

-

Human

MH

-

In Vitro

MH

-

Microfilaments/metabolism/physiology

MH

-

*Myocardial Contraction

MH

-

Myocardial Stunning/metabolism/physiopathology

MH

-

Myocardium/cytology/*metabolism

MH

-

Myosin/metabolism

MH

-

Oxygen/*metabolism

MH

-

Sheep

MH

-

Signal Transduction/physiology

MH

-

Support, Non-U.S. Gov't

MH

-

Support, U.S. Gov't, P.H.S.

MH

-

Swine

RN

-

EC 3.6.1.3 (Adenosinetriphosphatase)

RN

-

0 (Myosin)

RN

-

7440-70-2 (Calcium)

RN

-

7782-44-7 (Oxygen)

PT

-

JOURNAL ARTICLE

ID

-

RO-1 HL-39138-03/HL/NHLBI

DA

-

19970516

DP

-

1997 May

IS

-

0009-7330

TA

-

Circ Res

PG

-

688-98

SB

-

M

CY

-

UNITED STATES

IP

-

5

VI

-

80

JC

-

DAJ

AA

-

Author

EM

-

199707

AB

-

Previous studies have shown that cardiac endothelial cells release substances that influence myocardial contraction. Since PO2 is an important stimulus that modulates endothelial function, we investigated the effects of acute moderate hypoxia and reoxygenation on the release of cardioactive factors by endothelial cells. Endothelial cells cultured from several vascular beds were superfused with normoxic (equilibrated with room air; PO2, approximately 160 mm Hg) or hypoxic (PO2, 40 to 50 mm Hg) physiological buffer solution, and the superfusates were reequilibrated to a PO2 of approximately 160 mm Hg and then tested for their effects on various myocardial assays. Endothelial cell viability and buffer ionic composition were unaltered after the superfusion procedures. The superfusates of hypoxic endothelial cells induced rapid, potent, reversible inhibition of isolated cardiac myocyte contraction without reducing cytosolic Ca2+ transients. This activity was not lost after heating (95 degrees C) and was present in low molecular weight (Mr, <500) superfusate fractions. Hypoxic endothelial superfusate reduced unloaded shortening velocity of human skinned soleus muscle fibers. It markedly depressed in vitro actin motility over cardiac myosin and reduced the rate of actin- activated cardiac myosin ATPase activity but had no effect on corresponding smooth muscle myosin assays. Reoxygenation of hypoxic endothelial cells resulted in loss of this inhibitory activity. These data indicate that cultured endothelial cells respond to acute moderate hypoxia by releasing an unidentified substance(s) that inhibits myocardial crossbridge cycling, independent of Ca2+ or other second messenger signaling pathways. Such a mechanism could have important implications for the regulation of oxygen supply-demand balance in the heart and be relevant to conditions such as myocardial hibernation.

AD

-

Department of Cardiology, University of Wales College of Medicine, Cardiff, UK. shaham2@cf.ac.uk

PMID

-

0009130450

SO

-

Circ Res 1997 May;80(5):688-98

UI

-

97276756

AU

-

Palmer S

AU

-

Kentish JC

TI

-

Differential effects of the Ca2+ sensitizers caffeine and CGP 48506 on the relaxation rate of rat skinned cardiac trabeculae.

LA

-

Eng

MH

-

Animal

MH

-

Azocines/*pharmacology

MH

-

Caffeine/*pharmacology

MH

-

Calcium/*metabolism

MH

-

Cardiotonic Agents/*pharmacology

MH

-

Chelating Agents/diagnostic use

MH

-

Comparative Study

MH

-

Heart/*drug effects

MH

-

In Vitro

MH

-

Male

MH

-

Myocardial Contraction/*drug effects

MH

-

Myofibrils/drug effects

MH

-

Photolysis

MH

-

Rats

MH

-

Rats, Wistar

MH

-

Software

MH

-

Statistics

MH

-

Support, Non-U.S. Gov't

RN

-

0 (Azocines)

RN

-

0 (Cardiotonic Agents)

RN

-

0 (Chelating Agents)

RN

-

124029-65-8 (diazo-2)

RN

-

166020-57-1 (BA 41899)

RN

-

58-08-2 (Caffeine)

RN

-

7440-70-2 (Calcium)

PT

-

JOURNAL ARTICLE

DA

-

19970516

DP

-

1997 May

IS

-

0009-7330

TA

-

Circ Res

PG

-

682-7

SB

-

M

CY

-

UNITED STATES

IP

-

5

VI

-

80

JC

-

DAJ

AA

-

Author

EM

-

199707

AB

-

During heart failure, force production by the heart decreases. This may be overcome by Ca2+-sensitizing drugs, which increase myofibril Ca2+ sensitivity without necessarily altering intracellular Ca2+ concentration. However, Ca2+ sensitizers slow the relaxation of intact cardiac muscle. We used diazo-2, a caged chelator of Ca2+, to study the effects of the Ca2+ sensitizers caffeine and CGP 48506 on the intrinsic relaxation rate of cardiac myofibrils. Trabeculae from rat right ventricles were skinned by 1% Triton X-100 and were activated in a 10- microL bath. In steady state experiments, CGP 48506 (10 micromol/L) shifted the force-pCa curve leftward by 0.41+/-0.03 pCa units (mean+/- SEM, n=6). An identical shift was induced by caffeine (20 mmol/L). Photolysis of diazo-2 by a flash of light (160 mJ, 310 to 400 nm) caused an immediate decrease in Ca2+-activated force produced by the trabeculae. Relaxation was fitted by a double-exponential decay, and the rate constants were found to be independent of force and preflash Ca2+ concentration. The initial fast rate, corresponding to myofibrillar relaxation, was increased from 17.3+/-2.0 to 30.9+/-3.7 s(- 1) (n=4) by caffeine but was unaffected by CGP 48506 (16.6+/-1.7 and 14.4+/-2.3 s(-1) in the absence and presence of drug, respectively; n=5). Thus, myofibril relaxation need not be slowed by Ca2+-sensitizing agents but can even be accelerated. Despite similarities in their effects on myofibril Ca2+ sensitivity, caffeine and CGP 48506 affect the myofibrils at least partly via different mechanisms.

AD

-

Department of Pharmacology, United Medical and Dental Schools, St. Thomas's Hospital, London, UK.

PMID

-

0009130449

SO

-

Circ Res 1997 May;80(5):682-7

UI

-

97171296

AU

-

Fredberg JJ

AU

-

Jones KA

AU

-

Nathan M

AU

-

Raboudi S

AU

-

Prakash YS

AU

-

Shore SA

AU

-

Butler JP

AU

-

Sieck GC

TI

-

Friction in airway smooth muscle: mechanism, latch, and implications in asthma.

LA

-

Eng

MH

-

Airway Resistance/*physiology

MH

-

Animal

MH

-

Asthma/*physiopathology

MH

-

Dogs

MH

-

Friction

MH

-

Muscle, Smooth/*physiology

MH

-

Support, U.S. Gov't, P.H.S.

MH

-

Trachea/*physiology

PT

-

JOURNAL ARTICLE

ID

-

PO1 HL-33009/HL/NHLBI

ID

-

HL-45532/HL/NHLBI

DA

-

19970409

DP

-

1996 Dec

IS

-

8750-7587

TA

-

J Appl Physiol

PG

-

2703-12

SB

-

M

CY

-

UNITED STATES

IP

-

6

VI

-

81

JC

-

HEG

AA

-

Author

EM

-

199706

AB

-

In muscle, active force and stiffness reflect numbers of actin-myosin interactions and shortening velocity reflects their turnover rates, but the molecular basis of mechanical friction is somewhat less clear. To better characterize molecular mechanisms that govern mechanical friction, we measured the rate of mechanical energy dissipation and the rate of actomyosin ATP utilization simultaneously in activated canine airway smooth muscle subjected to small periodic stretches as occur in breathing. The amplitude of the frictional stress is proportional to eta E, where E is the tissue stiffness defined by the slope of the resulting force vs. displacement loop and eta is the hysteresivity defined by the fatness of that loop. From contractile stimulus onset, the time course of frictional stress amplitude followed a biphasic pattern that tracked that of the rate of actomyosin ATP consumption. The time course of hysteresivity, however, followed a different biphasic pattern that tracked that of shortening velocity. Taken together with an analysis of mechanical energy storage and dissipation in the cross-bridge cycle, these results indicate, first, that like shortening velocity and the rate of actomyosin ATP utilization, mechanical friction in airway smooth muscle is also governed by the rate of cross-bridge cycling; second, that changes in cycling rate associated with conversion of rapidly cycling cross bridges to slowly cycling latch bridges can be assessed from changes of hysteresivity of the force vs. displacement loop; and third, that steady-state force maintenance (latch) is a low-friction contractile state. This last finding may account for the unique inability of asthmatic patients to reverse spontaneous airways obstruction with a deep inspiration.

AD

-

Department of Environmental Health, Harvard School of Public Health, Boston, Massachsetts 02115, USA. jfredber@hsph.harvard.edu

PMID

-

0009018525

SO

-

J Appl Physiol 1996 Dec;81(6):2703-12

UI

-

96355254

AU

-

Takeshima H

AU

-

Ikemoto T

AU

-

Nishi M

AU

-

Nishiyama N

AU

-

Shimuta M

AU

-

Sugitani Y

AU

-

Kuno J

AU

-

Saito I

AU

-

Saito H

AU

-

Endo M

AU

-

Iino M

AU

-

Noda T

TI

-

Generation and characterization of mutant mice lacking ryanodine receptor type 3.

LA

-

Eng

MH

-

Animal

MH

-

Base Sequence

MH

-

Calcium/physiology

MH

-

Calcium Channels/*physiology

MH

-

Cell Division

MH

-

Genes, Structural

MH

-

Lymphocyte Transformation

MH

-

Mice

MH

-

Mice, Knockout

MH

-

Molecular Sequence Data

MH

-

Motor Activity

MH

-

Muscle Contraction

MH

-

Muscle Proteins/*physiology

MH

-

Muscle, Smooth, Vascular/physiology

MH

-

Restriction Mapping

MH

-

Spleen/cytology

MH

-

Support, Non-U.S. Gov't

RN

-

0 (Calcium Channels)

RN

-

0 (Muscle Proteins)

RN

-

0 (Ryanodine Receptor Calcium Release Channel)

RN

-

7440-70-2 (Calcium)

PT

-

JOURNAL ARTICLE

DA

-

19961003

DP

-

1996 Aug 16

IS

-

0021-9258

TA

-

J Biol Chem

PG

-

19649-52

SB

-

M

SB

-

X

CY

-

UNITED STATES

IP

-

33

VI

-

271

JC

-

HIV

AA

-

Author

EM

-

199612

AB

-

The ryanodine receptor type 3 (RyR-3) functions as a Ca2+-induced Ca2+ release (CICR) channel and is distributed in a wide variety of cell types including skeletal muscle and smooth muscle cells, neurons, and certain non-excitable cells. However, the physiological roles of RyR-3 are totally unclear. To gain an insight into the function of RyR-3 in vivo, we have generated mice lacking RyR-3 by means of the gene targeting technique. The mutant mice thus obtained showed apparently normal growth and reproduction. Although Ca2+-induced Ca2+ release from intracellular Ca2+ stores of the mutant skeletal muscle differed in Ca2+ sensitivity from that of wild-type muscle, excitation-contraction coupling of the mutant muscle seemed to be normal. Moreover, we could not find any significant disturbance in the smooth muscle and lymphocytes from the mutant mice. On the other hand, the mutant mice showed increased locomotor activity, which was about 2-fold greater than that of the control mice. These results indicate that the loss of RyR-3 causes no gross abnormalities and suggest that the lack of RyR-3- mediated Ca2+ signaling results in abnormalities of certain neurons in the central nervous system.

AD

-

Department of Pharmacology, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan.

PMID

-

0008702664

CU

-

1997

SI

-

GENBANK/D84236

SI

-

GENBANK/D84237

SO

-

J Biol Chem 1996 Aug 16;271(33):19649-52

UI

-

96305042

AU

-

Dekker LR

AU

-

Fiolet JW

AU

-

VanBavel E

AU

-

Coronel R

AU

-

Opthof T

AU

-

Spaan JA

AU

-

Janse MJ

TI

-

Intracellular Ca2+, intercellular electrical coupling, and mechanical activity in ischemic rabbit papillary muscle. Effects of preconditioning and metabolic blockade.

LA

-

Eng

MH

-

Animal

MH

-

Biomechanics

MH

-

Calcium/*metabolism

MH

-

Electric Conductivity

MH

-

Female

MH

-

Fluorescent Dyes

MH

-

Hydrogen-Ion Concentration

MH

-

Indoles

MH

-

Intracellular Membranes/metabolism/*physiology

MH

-

Iodoacetates/pharmacology

MH

-

Male

MH

-

Myocardial Contraction

MH

-

Myocardial Ischemia/metabolism/*physiopathology

MH

-

*Myocardial Reperfusion

MH

-

Papillary Muscles/drug effects/metabolism/*physiopathology

MH

-

Rabbits

MH

-

Time Factors

RN

-

0 (Fluorescent Dyes)

RN

-

0 (Indoles)

RN

-

0 (Iodoacetates)

RN

-

64-69-7 (Iodoacetic Acid)

RN

-

7440-70-2 (Calcium)

RN

-

96314-96-4 (indo-1)

PT

-

JOURNAL ARTICLE

DA

-

19961212

DP

-

1996 Aug

IS

-

0009-7330

TA

-

Circ Res

PG

-

237-46

SB

-

M

CY

-

UNITED STATES

IP

-

2

VI

-

79

JC

-

DAJ

AA

-

Author

EM

-

199702

AB

-

During myocardial ischemia, electrical uncoupling and contracture herald irreversible damage. In the present study, we tested the hypothesis that an increase of intracellular Ca2+ is an important factor initiating these events. Therefore, we simultaneously determined tissue resistance, mechanical activity, pH(0), and intracellular Ca2+ (with the fluorescent indicator indo 1, Molecular Probes, Inc) in arterially perfused rabbit papillary muscles. Sustained ischemia was induced in three experimental groups: (1) control, (2) preparations preconditioned with two 5-minute periods of ischemia followed by reperfusion, and (3) preparations pretreated with 1 mmol/L iodoacetate to block anaerobic metabolism and minimize acidification during ischemia. In a fourth experimental group, intracellular Ca2+ was increased under nonischemic conditions by perfusing with 0.1 mmol/L ionomycin and 0.1 mumol/L gramicidin. Ca2+ transients and contractions rapidly disappeared after the induction of ischemia. In the control group, diastolic Ca2+ began to rise after 12.6 +/- 1.3 minutes of ischemia; uncoupling, after 14.5 +/- 1.2 minutes of ischemia; and contracture, after 12.6 +/- 1.5 minutes of ischemia (mean +/- SEM). Preconditioning significantly postponed Ca2+ rise, uncoupling, and contracture (21.5 +/- 4.0, 24.0 +/- 4.1, and 23.0 +/- 5.3 minutes of ischemia, respectively). Pretreatment with iodoacetate significantly advanced these events (1.9 +/- 0.7, 3.6 +/- 0.9, and 1.9 +/- 0.2 minutes of ischemia, respectively). In all groups, the onset of uncoupling always followed the start of Ca2+ rise, whereas the start of contracture was not different from the rise in Ca2+. Perfusion with ionomycin and gramicidin permitted estimation of a threshold [Ca2+] for electrical uncoupling of 685 +/- 85 nmol/L. In conclusion, the rise in intracellular Ca2+ is the main trigger for cellular uncoupling during ischemia. Contracture is closely associated with the increase of intracellular Ca2+ during ischemia.

AD

-

Department of Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands.

PMID

-

0008756000

CU

-

1998

SO

-

Circ Res 1996 Aug;79(2):237-46

UI

-

96025773

AU

-

Zimmermann B

AU

-

Somlyo AV

AU

-

Ellis-Davies GC

AU

-

Kaplan JH

AU

-

Somlyo AP

TI

-

Kinetics of prephosphorylation reactions and myosin light chain phosphorylation in smooth muscle. Flash photolysis studies with caged calcium and caged ATP.

LA

-

Eng

MH

-

Adenosine Triphosphate/*analogs & derivatives/metabolism

MH

-

Animal

MH

-

Calcium/*metabolism

MH

-

Calmodulin/metabolism

MH

-

Chelating Agents/*pharmacology

MH

-

Comparative Study

MH

-

Egtazic Acid/*analogs & derivatives/pharmacology

MH

-

In Vitro

MH

-

Kinetics

MH

-

Mesenteric Veins/metabolism

MH

-

Models, Biological

MH

-

Muscle, Smooth, Vascular/*metabolism

MH

-

Myosin Light Chains/*metabolism

MH

-

Phosphorylation

MH

-

Photolysis

MH

-

Rabbits

MH

-

Support, Non-U.S. Gov't

MH

-

Support, U.S. Gov't, P.H.S.

MH

-

Time Factors

RN

-

0 (Calmodulin)

RN

-

0 (Chelating Agents)

RN

-

0 (Myosin Light Chains)

RN

-

0 (2-nitrophenyl-EGTA)

RN

-

56-65-5 (Adenosine Triphosphate)

RN

-

67-42-5 (Egtazic Acid)

RN

-

67030-27-7 (P(3)-1-(2-nitro)phenylethyladenosine 5'-triphosphate)

RN

-

7440-70-2 (Calcium)

PT

-

JOURNAL ARTICLE

ID

-

HL 19242-19/HL/NHLBI

ID

-

HL 48807-03/HL/NHLBI

DA

-

19951204

DP

-

1995 Oct 13

IS

-

0021-9258

TA

-

J Biol Chem

PG

-

23966-74

SB

-

M

SB

-

X

CY

-

UNITED STATES

IP

-

41

VI

-

270

JC

-

HIV

AA

-

Author

EM

-

199602

AB

-

The pre-myosin light chain (MLC20) phosphorylation components of the lag phase (td) of contractile activation were determined in permeabilized smooth muscles activated by photolytic release of ATP from caged ATP and/or Ca2+ from 4-(2-nitrophenyl)-EGTA (NP-EGTA). Calmodulin (CaM) shortened the td (470 ms at 0 added CaM) that followed Ca2+ release, but its effect (td = approximately 200 ms) saturated at 40 microM. Photolysis of caged ATP following preequilibration with identical [Ca4CaM] shortened td to 41 ms. The rate of phosphorylation was very fast (3.5 s-1 at 22 degrees C in the presence of 5 microM exogenous CaM) following photolysis of caged ATP, and, following Ca2+ release, phosphorylation was accelerated by CaM. Simultaneous photolysis of caged ATP and NP-EGTA was followed by a td of 194 ms at 5 microM CaM and a rate of MLC20 phosphorylation intermediate between these parameters following photolysis of, respectively, NP-EGTA and caged ATP. In the presence of the normal, total endogenous CaM content (37 +/- 4 microM) of protal vein smooth muscles td was 565 ms. Steady state maximum force at pCa 5.5 was increased by much lower (100 nM) exogenous [CaM] than was required (> 2.5 microM) to shorten the td. We estimate the endogenous CaM available under steady state conditions in vivo to be approximately 0.25 microM and probably less during a rapid Ca2+ transient. We conclude that the [CaM] dependence of the kinetics of MLC20 phosphorylation and force development (t1/2 and td) initiated by Ca2+ reflects the recruitment of a slowly diffusible component of total CaM. The relatively long duration of td (197 ms) at saturating [CaM] suggests the contribution to td of an additional component, possibly a prephosphorylation activation/isomerization of the Ca4CaM myosin light chain kinase complex (Torok, K., and Trentham, D. R. (1994) Biochemistry 33, 12807-12820). The relatively short delay (108 ms in the presence of 40 microM CaM) following simultaneous photolysis of NP-EGTA and caged ATP suggests that preincubation with ATP (prior to photolysis of NP-EGTA) may inhibit the formation of a preactive Ca2CaM myosin light chain kinase complex.

AD

-

Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville 22908, USA.

PMID

-

0007592592

SO

-

J Biol Chem 1995 Oct 13;270(41):23966-74

UI

-

95339576

AU

-

Lesh RE

AU

-

Somlyo AP

AU

-

Owens GK

AU

-

Somlyo AV

TI

-

Reversible permeabilization. A novel technique for the intracellular introduction of antisense oligodeoxynucleotides into intact smooth muscle.

LA

-

Eng

MH

-

Animal

MH

-

Bacterial Toxins/metabolism

MH

-

Base Sequence

MH

-

Cell Nucleus/metabolism

MH

-

Comparative Study

MH

-

Cytoplasm/metabolism

MH

-

Electrophoresis, Polyacrylamide Gel

MH

-

Fluorescence

MH

-

Guinea Pigs

MH

-

Ileum

MH

-

In Vitro

MH

-

Male

MH

-

Microscopy, Confocal

MH

-

Microscopy, Electron

MH

-

Molecular Sequence Data

MH

-

Muscle Contraction

MH

-

Muscle, Smooth/*cytology/ultrastructure

MH

-

Oligonucleotides, Antisense/*administration & dosage/analysis/genetics

MH

-

*Organ Culture

MH

-

Permeability

MH

-

Rats

MH

-

Staphylococcus aureus

MH

-

Support, U.S. Gov't, P.H.S.

MH

-

Time Factors

RN

-

0 (Bacterial Toxins)

RN

-

0 (Oligonucleotides, Antisense)

PT

-

JOURNAL ARTICLE

ID

-

1K11-AR-01871/AR/NIAMS

ID

-

1PO1-HL-48807/HL/NHLBI

ID

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PO1-HL-19242/HL/NHLBI

DA

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19950822

DP

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1995 Aug

IS

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0009-7330

TA

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Circ Res

PG

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220-30

SB

-

M

CY

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UNITED STATES

IP

-

2

VI

-

77

JC

-

DAJ

AA

-

Author

EM

-

199510

AB

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Antisense oligodeoxynucleotides (ODNs) have been used to modify gene expression in vitro and are also promising therapeutic agents. Although there are numerous reports of antisense ODN-mediated changes in protein expression of cultured cells, use of these compounds to achieve antisense regulation of specific proteins in intact tissue has been limited. The aims of this study were (1) to define organ culture conditions for ileum smooth muscle that would permit long-term maintenance of force-generating capabilities and normal ultrastructure and (2) to develop a method for efficient introduction of antisense ODNs into intact tissue. Sheets of ODN-containing, reversibly permeabilized rat outer longitudinal ileum were maintained in a serum- free organ culture medium for 1 week without significant decreases in tension response to membrane depolarization or carbachol stimulation; the G protein-coupled calcium sensitization pathway was also intact after 7 days. Reversible permeabilization, a method previously used to load smooth and cardiac muscle with aequorin and heparin, was effective for loading > 95% of ileum smooth muscle cells with a fluorescein- conjugated antisense ODN (5'-AAGGGCCATTTTGTT-FITC-3'). Confocal microscopy of reversibly permeabilized smooth muscle loaded with fluorescent antisense ODNs revealed intense nuclear fluorescence and less intense, homogeneous, cytoplasmic fluorescence. Internally radiolabeled ODNs (homologous to the above sequence) showed complete degradation between 4 and 16 hours after introduction into the cells. In summary, we have demonstrated methods for long-term organ culture and high-efficiency introduction of antisense ODNs into intact smooth muscle sheets. Such methods have broad potential utility for investigating many questions in smooth muscle biology. At present, however, a major limitation of this approach is the short half-life of phosphorothioated ODNs.

AD

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Department of Anesthesiology, University of Virginia Health Sciences Center, Charlottesville 22908, USA.

PMID

-

0007614709

SO

-

Circ Res 1995 Aug;77(2):220-30