Glycolysis, Oxidative Metabolism, and Brain Potassium Ion Clearance

Studies were directed toward defining relationships between brain ion transport, glycolysis, and oxidative phosphorylation. This was done by examining the relative sensitivity to hypoxemia and to iodoacetate (IAA)-induced inhibition of glycolysis in rats anesthetized with pentobarbital. Both insults had minimal effects on K+o baseline. In response to neuronal activation, IAA increased the time required for K+o clearance from maximal values to half-recovery of baseline. Hypoxemia slowed the later phase of K+o clearance, when K+o was approaching "resting" levels. Hypoxemia produced greater declines in high-energy intermediates than did IAA, which indicated that the IAA effect was not due to a greater overall insult to metabolism and suggested a direct link between ATP produced by glycolysis and ion transport activity. These data demonstrate that K+o clearance requires energy from glycolysis and oxidative phosphorylation for different phases of the recovery process and that inhibition specific to glycolysis or oxidative phosphorylation may be temporally resolved within a single stimulus.