Enzyme release and glycolytic energy production.

In substrate-free anoxia, activities of released cytosolic enzymes (LDH, MDH) correlate inversely with the actual ATP level (for both: r = -0.98). At the same time there is a close correlation between lactate production from glycogen and the ATP content (r = 0.98). With external glucose present enzyme release is greatly delayed, but this could be due to the stimulation of glycolysis as well as to the maintenance of high ATP levels. When glycolysis is blocked by iodoacetate under aerobic conditions, the cells also become depleted of high-energy phosphates. This depletion is delayed in the presence of pyruvate. Cytosolic enzyme release again is correlated with total ATP contents, by the same relation in the presence or absence of pyruvate. Glycolytic energy production is negligible in both cases and does not seem to determine enzyme release directly.