Depression of Sarcolemmal Phospholipase C Activity in Congestive Heart Failure
The bioactivc phospholipids of the cardiac cell membrane (sarcolemma) and their signaling pathways are emerging as important mediators of the myocardial response to external stimuli, including catecholamines . It is known that the activity of the sympathetic nervous system is increased in congestive heart failure; this results in elevated levels of plasma catecholamines, which downregulate the β-adrenoceptors in failing hearts, leading to subsensitivity of the β-agonist-mediated biochemical and mechanical responses . The α1-adrenoceptors, which are associated with the positive inotropic effect of catecholamines via activation of the membranal phosphoinositide-phospholipase C (PLC) , were found to remain unchanged  or to increase [4,5] in heart failure. In view of the downregulation of the β-adrenoceptors, the α1 type reflects a greater proportion of the total adrenoceptor population in the failing ventricle [3–5]. Thus α1-adrenoceptors can be seen to play a dominant role in eliciting the positive inotropic action of catecholamines in failing heart .
KeywordsHydrolysis Catheter Hydrogen Peroxide Depression Tyrosine
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