INTRAVENOUS ASPARTATE INFUSION AFTER A CORONARY OPERATION - EFFECTS ON MYOCARDIAL-METABOLISM AND HEMODYNAMIC STATE

Background. In a previous study glutamate infusion after coronary arte ry bypass grafting was associated with beneficial effects on myocardia l metabolism and myocardial performance. It has been claimed that aspa rtate is more important than glutamate for the recovery of myocardial metabolism after cardioplegic arrest. Therefore, the metabolic and hem odynamic effects of aspartate were studied after coronary artery bypas s grafting. Methods. Fifty to 240 mL of a 0.1 mol/L aspartic acid solu tion was infused intravenously during 60 minutes in 10 patients early after coronary artery bypass grafting. Myocardial metabolism was studi ed using the coronary sinus catheter technique. Results. Aspartate inf usion caused a significant increase in the arterial levels of both asp artate and glutamate. This was associated with a significant increase in myocardial uptake of aspartate and a decrease in myocardial uptake of glutamate. Myocardial exchange of other substrates remained unaffec ted. There were no changes in hemodynamic state except an increase of heart rate and pulmonary vascular resistance. Conclusions. Interaction s with glutamate metabolism, compatible with competitive inhibition of myocardial glutamate uptake, which may have outweighed potential effe cts of aspartate, were observed. Recognition of these amino acid inter actions is important as they are used together as additives in cardiop legic solutions. (C) 1998 by The Society of Thoracic Surgeons.