Effects of glucocorticosteroids in rats with acute myocardial infarction.

A method was developed which allows exact determination of the extent of the myocardial zone which is excluded from the circulation by ligation of a coronary artery. It consists of the perfusion of the coronary system with Evans blue, and the calculation of the size of the ischemic area after determining the dye content of the heart. Data obtained in animals with experimental myocardial infarction can thus be properly related to the size of the ischemic zone in the heart. Results from different experimental animals can be compared exactly. With this technique the effects of dexamethasone, and cortisol were investigated in rats with ligation of the left coronary artery. With both glucocorticosteroids a significant increase of the survival times and survival rates was obtained. The increase of the serum creatine kinase, characteristic of myocardial infarction, was significantly diminished. The typical elevation of the ST-segment in the electrocardiogram was significantly delayed. Effects on arterial and central venous pressures were recorded which may reflect an improvement in; the condition of the myocardium. Cardiac arrhythmias, occurring typically between 10 and 20 min after coronary artery occlusion were, however, not antagonized, but rather aggravated, by the glucocorticosteroids.