Glycolytic ATP and its production during ischemia in isolated Langendorff-perfused rat hearts.

The perfused rat heart was used to assess the possible contribution of glycolytically produced ATP to the maintenance of the action potential in the normoxic heart, and to the maintenance of membrane integrity in the underperfused, ischemic heart. During normoxia, pyruvate (10 mM) was nearly as able as glucose (10 mM) to maintain the normal action potential. During ischemia (reduction of perfusion pressure of Langerdorff heart from 100 to 20 cm H2O), total tissue values of ATP and creatine phosphate were similar in pyruvate and in glucose hearts. However, pyruvate-perfused hearts had higher tissue levels of cyclic AMP during the ischemic period, and during the reperfusion period they had an increased release of lactate dehydrogenase and an increased incidence of arrhythmias when compared with glucose hearts. It is proposed that these differences can be related to a higher rate of production of glycolytic ATP. The anatomical, biochemical, and pharmacological evidence favoring a cytoplasmic compartment of ATP located in relation to the cell membrane is reviewed.