Myocardial Necrosis in Rats: Serum Enzymes, Adrenal Steroid and Histopathological Alterations

Abstract

Acute infarctoid myocardial necrosis has been produced in virgin rats by injection of isoproterenol. The lesions are essentially identical, both grossly and microscopically, with naturally occurring acute infarcts which we have observed in arteriosclerotic breeder rats. During the establishment of drug-induced necrosis the animals displayed signs of shock and congestive heart failure. Serum transaminases and lactic dehydrogenase levels underwent changes which coincided with the establishment and repair of the myocardial damage. The male rats had a higher mortality rate than the females. The male rats also developed more massive myocardial necrosis and showed a decreased capacity to repair myocardial damage. The adrenal glands became greatly hypertrophied and the thymus became severely involuted coincident with the acute establishment of the myocardial lesion. In vitro studies indicated that changes in adrenal function also accompanied the acute onset of myocardial destruction. The adrenal hypertrophy decreased during recovery from shock and during repair of the lesion.