[1 of the possible causes of an increase in acid hydrolase activity in homogenates of heart muscle following myocardial infarct].

A "free" activity of acidic hydrolases (acidic phosphatase, acidic ribonuclease and cathepsin D) was increased in homogenates of dog heart muscle with simultaneous decrease of the enzymes activity in the fraction enriched by lysosomes, within 4-5 hrs after ligation of the descending ramus of sinister mitral artery. The adenylate cyclase activity and content of c-AMP were decreased as compared with unaffected part of myocardium. The data obtained suggest that the decrease of the c-AMP content in the impaired region caused a labilization of lysosomal membranes and the secretion of acidic hydrolases into cell cytoplasm.