Metabolic Oxidation of Pyruvate and Lactate

We have previously described the rates of oxidation for long-chain fatty acids and glucose in stunned myocardium during early reflow after moderately severe regional ischemia. The purpose of these studies was to characterize the rates of pyruvate and lactate oxidation during comparable periods of reflow. In the main protocol, pyruvate oxidation was defined at two conditions of coronary flow and at two levels of fatty acids in the coronary perfusate. Twenty animals were prepared using the extracorporeally perfused, working swine heart model. In five control (group 1) hearts, flow in the left anterior descending coronary artery was maintained at aerobic levels during a 115-minute perfusion trial. In 15 hearts (groups 2 and 3), flow was held at aerobic levels for 30 minutes, reduced acutely by 60 % for 45 minutes, and restored again to aerobic levels for the final 40-minute reflow. In the five control hearts and in 10 of the reperfused hearts (group 2), 20 % Intralipid (KabiVitrum, Alameda, California) with heparin was infused to raise serum fatty acids to an average of 0.95+±0.08,umol/ml, whereas in the five remaining nonsupplemented group 3 hearts, serum levels of fatty acids were 0.49±+0.10,umol/ml. Ischemia in supplemented and nonsupplemented hearts caused a decline in regional mechanical performance (-40A % and-39A % below aerobic values in active shortening) that failed to recover completely (-16A % and-25A % below aerobic values in active shortening