Increased cardiac myosin ATPase activity as a biochemical adaptation to running training: Enhanced response to catecholamines and a role for myosin phosphorylation

1981 ◽  
Vol 13 (7) ◽  
pp. 679-694 ◽  
Author(s):  
T Resink
Keyword(s):  
Atpase Activity ◽  
Myosin Atpase ◽  
Cardiac Myosin ◽  
Running Training ◽  
Myosin Phosphorylation ◽  
Biochemical Adaptation ◽  
Myosin Atpase Activity

Effects of physical training on cardiac myosin ATPase activity

1975 ◽  
Vol 228 (4) ◽  
pp. 1178-1182 ◽  
Author(s):  
AK Bhan ◽  
J Scheuer
Keyword(s):  
Ethylene Glycol ◽  
Atpase Activity ◽  
Conformational Change ◽  
Physical Training ◽  
Active Site ◽  
Myosin Atpase ◽  
Control Group ◽  
Cardiac Myosin ◽  
Heavy Meromyosin ◽  
Myosin Atpase Activity

Cardiac myosin from rats exercised 90 or 150 min daily for 8 wk was compared with the myosin from the hearts of matched sedentary controls. The Ca++-ATPase activity was increased 17 percent in rats exercised 90 min and 30 percent in rats exercised 150 min daily. In the exercised group 0.18 M KCl increased the myosin ATPase activity by 50 percent but had no effect in the control group. Ethylene glycol activated the Ca++-ATPase in control myosin preparations, but had no significant effect on myosin from conditioned hearts. Heavy meromyosin (HMM) from conditioned hearts had a higher Ca++-ATPase activity than from controls. Fluorescence with 8-anilinonaphthalene sulfonate (ANS) was increased 30 percent in HMM from conditioned hearts. The results suggest that the increased myosin ATPase activity in the hearts of exercised animals may be due to a local conformational change at or near the active site.

scholarly journals Catecholamine sensitivity and cardiac myosin ATPase activity in dogs treated with propranolol.

1983 ◽  
Vol 24 (3) ◽  
pp. 427-439 ◽  
Author(s):  
Makie HIGUCHI ◽  
Keiichi ENOMOTO ◽  
Takeo ASAKAWA
Keyword(s):  
Atpase Activity ◽  
Myosin Atpase ◽  
Cardiac Myosin ◽  
Myosin Atpase Activity

scholarly journals Nonmuscle Myosin IIA Regulates Platelet Contractile Forces Through Rho Kinase and Myosin Light-Chain Kinase

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Shirin Feghhi ◽  
Wes W. Tooley ◽  
Nathan J. Sniadecki
Keyword(s):  
Atpase Activity ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Rho Kinase ◽  
Myosin Atpase ◽  
Nonmuscle Myosin ◽  
Myosin Phosphorylation ◽  
Myosin Atpase Activity ◽  
Contractile Forces

Platelet contractile forces play a major role in clot retraction and help to hold hemostatic clots against the vessel wall. Platelet forces are produced by its cytoskeleton, which is composed of actin and nonmuscle myosin filaments. In this work, we studied the role of Rho kinase, myosin light-chain kinase, and myosin in the generation of contractile forces by using pharmacological inhibitors and arrays of flexible microposts to measure platelet forces. When platelets were seeded onto microposts, they formed aggregates on the tips of the microposts. Forces produced by the platelets in the aggregates were measured by quantifying the deflection of the microposts, which bent in proportion to the force of the platelets. Platelets were treated with small molecule inhibitors of myosin activity: Y-27632 to inhibit the Rho kinase (ROCK), ML-7 to inhibit myosin light-chain kinase (MLCK), and blebbistatin to inhibit myosin ATPase activity. ROCK inhibition reduced platelet forces, demonstrating the importance of the assembly of actin and myosin phosphorylation in generating contractile forces. Similarly, MLCK inhibition caused weaker platelet forces, which verifies that myosin phosphorylation is needed for force generation in platelets. Platelets treated with blebbistatin also had weaker forces, which indicates that myosin's ATPase activity is necessary for platelet forces. Our studies demonstrate that myosin ATPase activity and the regulation of actin–myosin assembly by ROCK and MLCK are needed for the generation of platelet forces. Our findings illustrate and explain the importance of myosin for clot compaction in hemostasis and thrombosis.

CHRONIC OUABAIN TREATMENT ENHANCES CARDIAC MYOSIN ATPase ACTIVITY IN RATS

2008 ◽  
Vol 35 (7) ◽  
pp. 801-806 ◽  
Author(s):  
Alessandra S Padilha ◽  
Cleci M Moreira ◽  
Eduardo F Meira ◽  
Fabiana DM Siman ◽  
Ivanita Stefanon ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Myosin Atpase ◽  
Cardiac Myosin ◽  
Myosin Atpase Activity

scholarly journals The Role of Myosin Phosphorylation in Regulating Actin-Myosin Interaction in Human Blood Platelets

1977 ◽  
Author(s):  
R.S. Adelstein ◽  
B. Barylko ◽  
M.A. Conti
Keyword(s):  
Atpase Activity ◽  
Human Blood ◽  
Blood Platelets ◽  
Fold Increase ◽  
Biochemical Properties ◽  
Myosin Atpase ◽  
Myosin Phosphorylation ◽  
Myosin Atpase Activity ◽  
Myosin Interaction ◽  
Human Blood Platelets

Human blood platelets contain actin and myosin which are similar in many of their structural and biochemical properties to the contractile proteins found in muscle. Platelet myosin is composed of six polypeptide chains, two heavy chains of 200,000 daltons and two pair of light chains of 20,000 and 15,000 daltons. Platelets also contain a specific enzyme capable of phosphory-lating the 20,000 dalton light chain of platelet myosin. The kinase has been purified 600-fold and has been shown not to require Ca2+ or cyclic AMP for its activity (Daniel, J.L. & Adelstein, R.S., Biochemistry 15, 2370, 1976). Phosphorylation of platelet myosin results in a 7-10 fold increase in the actin-activated myosin ATPase activity but has no effect on the myosin K+-EDTA ATPase activity measured in 0.5 M KCl. The phosphatase responsible for dephosphorylation of platelet myosin has been partially purified. Dephosphorylation of platelet myosin results in a decrease in the actin-activated myosin ATPase activity, without affecting the myosin ATPase activity measured in the presence of K+-EDTA in 0.5 M KCl.Thus, using the actin-activated ATPase activity as an indication of actin-myosin interaction, myosin phosphorylation-dephosphorylation appears to function as a reversible regulatory mechanism. That this type of regulation is not confined to platelets is indicated by finding a similar mechanism in proliferative rat myoblasts grown in culture (Scordilis, S.P., and Adelstein, R.S., Biophysical J., 17, 268a, 1977) and guinea pig vas deferens smooth muscle (Chacko, S., et al., PNAS. 74, 129, 1977).B.B. is on leave from the Nencki Institute, Warsaw, Poland.

Abnormal cardiac biochemistry in spontaneously diabetic Bio-Breeding/Worcester rat

1985 ◽  
Vol 249 (5) ◽  
pp. H1051-H1055 ◽  
Author(s):  
A. Malhotra ◽  
J. P. Mordes ◽  
L. McDermott ◽  
T. F. Schaible
Keyword(s):  
Atpase Activity ◽  
Diabetic Rats ◽  
Myosin Atpase ◽  
Cardiac Myosin ◽  
Myosin Atpase Activity ◽  
Cardiac Contractile ◽  
Insulin Dependent ◽  
Onset Of Diabetes ◽  
Cardiac Contractile Proteins ◽  
Altered Thyroid

Diabetes produced by injection of alloxan or streptozotocin results in cardiac dysfunction in rats that is associated with lower cardiac contractile protein ATPase activity. The purpose of this investigation was to examine cardiac myosin biochemistry in the Bio-Breeding Worcester (BB/W) rat, a strain in which diabetes occurs spontaneously and closely resembles insulin-dependent diabetes in humans. Hearts from diabetic BB/W rats were studied at 1, 4, and 7 mo after the onset of diabetes and were compared with age-matched BB/W rats that were bred for resistance to diabetes. Calcium-stimulated myosin ATPase activity was significantly decreased after 4 and 7 mo of diabetes, and actin-activated myosin ATPase was significantly depressed at all time points. Differences between hearts from control and diabetic animals increased with the duration of diabetes. Closely associated with reductions in myosin ATPase activity in the diabetes was a shift in the isomyosin content from the normally predominant V1 to the V3 isoenzyme. Thus diabetes that results from genetic causes leads to depressed myosin enzymatic activity in the rat. Furthermore, since previous studies have shown that BB/W diabetic rats do not develop hypothyroidism, the present results support the view that altered thyroid function does not mediate the abnormalities in cardiac contractile proteins in diabetes.

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