Beneficial metabolic effects of methylprednisolone sodium succinate in acute myocardial ischemia.

The metabolic and hemodynamic effects of methylprednisolone sodium succinate (40 mg/kg body weight) after acute myocardial ischemia were determined in 24 heparinized mongrel dogs. Myocardial ischemia was produced by ligation of the left anterior descending coronary artery. Catheters in the coronary sinus and the vein draining the left anterior descending coronary arterial area were used to collect blood samples from nonischemic and ischemic myocardium. Lactate, pyruvate, glucose, free fatty acids and oxygen were measured in arterial and venous blood from ischemic and nonischemic areas before and 3, 30 and 60 minutes after myocardial ischemia in animals with (Group II) and without (Group I) steroid treatment. In both Groups I and II glucose, lactate, free fatty acids, oxygen and coronary blood flow in nonischemic areas were not significantly changed, whereas glucose uptake in ischemic areas was significantly increased with myocardial ischemia and remained elevated. In Group I lactate uptake in ischemic areas became negative after coronary arterial ligation and remained so; in Group II, it increased after 30 (70%) and 60 (111%) minutes. Free fatty acid uptake in ischemic areas was reduced after myocardial ischemia in Group I, but in Group II it increased after 30 (224%) and 60 minutes (173%), and there was a concomitant increase in oxygen uptake. Pyruvate uptake in nonischemic areas decreased after 60 minutes in Group I, whereas it was reduced after 30 (68%) and 60 minutes (513%) in Group II. The changes were similar in ischemic myocardium. There were no significant changes in hemodynamic indexes. Coronary blood flow in ischemic areas decreased in Group I after myocardial ischemia and further after 30 and 60 minutes, but in Group II it increased after 30 (82%) and 60 minutes (53%). The data indicate that administration of methylprednisolone results in improved collateral blood flow into the infarcted area and a significantly improved metabolic response of ischemic myocardium. The glucocorticoid may also have a direct benefical effect on carbohydrate metabolism and cause the increased pyruvate neccesary to maintain the generation of energy-producing substrates. The results also suggest that methylprednisolone increases cell survival time and results in greater salvage of ischemic myocardium.