Influence of glutamate on the recovery of myocardial metabolism during early reperfusion in patients operated for unstable angina

• Background. A previous study on glutamate infusion after elective coronary bypass surgery demonstrated increased myocardial uptake of glutamate and improved lactate metabolism. The present study investigates myocardial metabolism in high-risk patients during early reperfusion and evaluates the influence of glutamate on the recovery of myocardial metabolism.Methods. 19 patients with unstable angina requiring intravenous nitroglycerine were randomized to intravenous glutamate or saline. Myocardial metabolism during reperfusion was studied from one minute after unclamping the aorta to 15 minutes after weaning from cardiopulmonary bypass (CPB).Results. Compared with before CPB there was a shift towards glucose uptake during early reperfusion. Immediately after unclamping there was a low oxygen extraction and a lactate release. At the end of the study period oxygen extraction had normalized but in the control group there was still no uptake of lactate. Glutamate infusion resulted in myocardial uptake of glutamate and a significant myocardial uptake of lactate was found at the end of the study period. A substantial uptake of FFAs was observed in both groups.Conclusion. Myocardial metabolism during early reperfusion was characterized by dynamic changes including low oxygen extraction, lactate release and a shift towards increased myocardial glucose uptake. Intravenous glutamate infusion resulted in a significant uptake of glutamate, which was associated with metabolic findings suggesting earlier recovery of the oxidative metabolism during reperfusion.

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MEDICIN

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