Quantitative determination of stress-induced myocardial damage in rats

The degree of myocardial damage produced in rats by exposing them to unsignalled, irregular foot-shock stress was determined in three ways: by measuring (1) enzymes (LDH, GOT and GPT) released into the circulation, (2) the rate of release of one of these enzymes (LDH) from isolated perfused hearts into the perfusate, and (3) the cardiac uptake, in vivo, of the radioactively labeled bone-seeking agents, technetium-99m-stannous pyrophosphate or technetium-99m-methylene diphosphonate. The latter two methods permitted quantitative determination of the degree of myocardial damage produced. Determination of cardiac technetium-99m uptake was found to be simple, quantitative, highly sensitive and truly indicative of cardiac damage, and therefore most suitable for studies of the effects of stress on cardiac injury.