[Correction of contractile function and metabolism in canine ischemic myocardium due to exogenous glutamic acid].

The effect of intravenous glutamic acid infusion (3 mg/kg/min) was studied during myocardial ischemia and reperfusion in anesthetized dogs. Left ventricular ischemia was induced by underperfusion of the anterior descending and circumflex coronary arteries. Glutamic acid reduced the ischemic contractile depression 2 min after a 60%-reduction of the coronary blood flow. The left ventricular systolic pressure was decreased by 9% versus 22%, dP/dt by 16% versus 29%, left ventricular systolic pressure heart rate product by 16% versus 31%. Reperfusion with glutamic acid improved the recovery of cardiac performance without any increase in myocardial oxygen consumption. Glutamic acid infusion resulted in a 2-fold augmentation of glutamate uptake by the ischemic myocardium. It led to cessation of ammonia release by the heart due to activation of glutamine synthesis, enhancement of alanine formation coupled with pyruvate utilization and did not change lactate production. The mechanisms of the protective action of glutamic acid are discussed.