[Isoproterenol toxicity in the myocardium in an experiment]

The effect of toxic doses of isoproterenol (ISP) on total activities and isoenzyme patterns of creatine kinase (CK) and lactate dehydrogenase (LDH) in rat sera was investigated and correlated with histopathological changes in the myocardial tissue. A single dose of 25 mg ISP per 100 g body weight caused a statistically important elevation of CK and LDH total activities and of the activities of cardiospecific isoenzymes CK-MB, LDH-1 and LDH-2 six hours after intraperitoneal administration. The isomorphic LDH isoenzyme pattern, which was also observed, was taken to be a proof of the ISP-induced cardiogenic shock. The increase in the activity of CK-MM and LDH-5 isoenzymes could be explained as a secondary consequence of cardiogenic shock and of the consecutive damage of the tissue with anaerobic metabolism such as liver. The findings were confirmed by a histopathological analysis showing the development of coagulative necrosis and myocytolysis as well as undulations of heart muscle cells as a sign of cardiogenic shock.