CHANGES IN MYOCARDIAL CONCENTRATION OF GLUTAMATE AND ASPARTATE DURINGCORONARY-ARTERY SURGERY

Myocardial ischemic arrest, using a cold crystalloid cardioplegic solu tion, decreases intracellular concentrations of glutamate (from 6.2 +/ - 0.5 to 4.5 +/- 0.45 mu mol/g wet weight, n = 19, P < 0.05) and ATP ( from 3.0 +/- 0.4 to 1.9 +/- 0.3 mu mol/g wet weight, n = 9, P < 0.05) but not aspartate. After 20 min of normothermic reperfusion, the fall in glutamate and ATP was maintained (4.5 +/- 0.52 and 2.0 +/- 0.2 mu m ol/g wet weight, respectively), and there was a fall in aspartate (fro m 1.32 +/- 0.12 to 0.9 +/- 0.1 mu mol/g wet weight). Myocardial arrest with cold blood cardioplegic solution did not cause a significant fal l in tissue ATP, glutamate, or aspartate. However, after reperfusion a ll three fell significantly. With the exception of a fall in tissue va line during ischemia with cold crystalloid cardioplegic solution and a rise in alanine during ischemia with cold blood cardioplegic solution , there were no significant changes in tissue alanine, valine, leucine , or isoleucine during ischemia or after reperfusion using crystalloid or blood cardioplegic solutions. This work documents the changes in t he intracellular concentrations of important metabolites in the hearts of patients undergoing coronary artery surgery using different myocar dial protection techniques.