Role of troponin components in determining characteristic sensitivity to asidosis of the Ca2+ activated myofibrillar ATPase activity of fast and slow skeletal muscles

The effects of gramnegative endotoxin-induced myocardial failure in the pentobarbital-anesthetized dog were examined by monitoring its influence on cardiac myofibrillar ATPase activity. Myofibrils were isolated from endo- and epicardial portions of the left ventricular wall. ATPase activities were determined in animals treated with 4 mg/kg endotoxin and monitored 5 h, in animals monitored for 5 h without endotoxin (controls), and in animals implanted with a unilateral femoral shunt and given endotoxin. No differences were seen in the activities between the endo- and epicardial portions of any preparation. Activity was significantly depressed in endotoxemic animals. Increasing venous return by 313 +/- 71 ml/min significantly increased coronary flow by reducing coronary vascular resistance and prevented any observed depression of myofibrillar ATPase activity. In in vitro studies, adding endotoxin directly to a myofibril preparation did not modify normal activity. It appears that the mechanical and myofibrillar dysfunctions are due to the action of endotoxin at sites not associated with the actomyosin ATPase, but may be due to the production of an intermediary agent in concert with a decreased venous return.

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Troponin Isoform Dependent pH Dependence of the Ca2+-Activated Myofibrillar ATPase Activity of Avian Slow and Fast Skeletal Muscles

Biochemical and Biophysical Research Communications ◽

10.1006/bbrc.1995.1228 ◽

1995 ◽

Vol 207 (2) ◽

pp. 585-592 ◽

Cited By ~ 2

Author(s):

A. Kawashima ◽

S. Morimoto ◽

A. Suzuki ◽

F. Shiraishi ◽

I. Ohtsuki

Keyword(s):

Atpase Activity ◽

Skeletal Muscles ◽

Ph Dependence ◽

Myofibrillar Atpase ◽

Myofibrillar Atpase Activity

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Relationship between calpastatin activity and the slow and fast myosin heavy chain content of ovine skeletal muscles

Proceedings of the British Society of Animal Science ◽

10.1017/s1752756200008292 ◽

2002 ◽

Vol 2002 ◽

pp. 173-173

Author(s):

A.Q. Sazili ◽

P.L. Sensky ◽

T. Parr ◽

R.G. Bardsley ◽

P.J. Buttery

Keyword(s):

Atpase Activity ◽

Myosin Heavy Chain ◽

Heavy Chain ◽

Skeletal Muscles ◽

Myofibrillar Atpase ◽

Heavy Chains ◽

Fast Myosin ◽

Myofibrillar Atpase Activity ◽

Fast Myosin Heavy Chain ◽

The Relationship

Calpastatin, the specific endogenous inhibitor of the calpain system, is considered to be a principle contributor to variations in meat tenderisation (Parr et al., 1999). Previous studies have suggested that the differences in calpastatin activity in different ovine skeletal muscles could be influenced by muscle metabolic and contractile characteristics according to myofibrillar ATPase activity (Ouali and Talmant, 1990). The type of myofibrillar ATPase activity is largely determined by the content of slow or fast myosin heavy chains (Rivero et al., 1999). The present study was designed to investigate the relationship between calpastatin inhibitory activity and slow myosin heavy chain (MHC-s) and fast myosin heavy chain (MHC-f) expression.

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