Stretch-induced increase in the Ca2+ sensitivity of myofibrillar ATPase activity in skinned fibres from pig ventricles

1990 ◽  
Vol 415 (6) ◽  
pp. 741-746 ◽  
Author(s):  
H. J. Kuhn ◽  
C. Bletz ◽  
J. C. Rüegg
Keyword(s):  
Atpase Activity ◽  
Skinned Fibres ◽  
Myofibrillar Atpase ◽  
Myofibrillar Atpase Activity

A Study on the Cardiac Myofibrillar ATPase Activity in Diabetic Rats

1987 ◽  
Vol 17 (3) ◽  
pp. 479
Author(s):  
Wang Seong Ryu ◽  
Un Ho Ryoo ◽  
Jung Don Seo ◽  
Young Woo Lee
Keyword(s):  
Atpase Activity ◽  
Diabetic Rats ◽  
Myofibrillar Atpase ◽  
Myofibrillar Atpase Activity

Coordination of cardiac myofibrillar and sarcotubular activities in rats exercised by swimming

1984 ◽  
Vol 247 (6) ◽  
pp. H909-H915 ◽  
Author(s):  
E. D. Pagani ◽  
R. J. Solaro
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Atpase Activity ◽  
Functional Activity ◽  
Storage Capacity ◽  
Training Effect ◽  
Myofibrillar Atpase ◽  
Transport Activity ◽  
Cross Bridge ◽  
Myofibrillar Atpase Activity ◽  
The Mean

We measured the functional activity of both myofibrils and fragmented sarcoplasmic reticulum (FSR) in microsomal fractions and homogenates of hearts of sedentary rats and rats exercised by swimming 75 min twice daily for 8 wk. Ca2+ transport was measured under conditions that restricted uptake of Ca2+ to the SR vesicles in the homogenates or microsomal fractions. There was a significant increase in myosin Ca2+-ATPase activity of myofibrils prepared from hearts of swimmers, indicating that a “training effect” had occurred. The mean rate of Ca2+ transport and mean storage capacity were the same for SR vesicles in the homogenates and microsomal fractions from hearts of controls and swimmers. At the same free Ca2+ concentration, the velocity of Ca2+ transport by FSR in homogenate preparations was inversely related to the myofibrillar ATPase activity in a series of preparations from hearts of swimmers, but there was little correlation between the same activities measured in preparations from a series of sedentary rats. Our results suggest that the increase in the rate of relaxation of hearts from exercised rats is not due to an increase in the rate of Ca2+ transport by the SR but may be due to other factors, which include an increase in the rate of cross-bridge cycling or an alteration in the relation and coordination between cross-bridge cycling and SR Ca2+ transport activity.

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