Alterations in synaptosomal membrane Na,K-ATPase of the gerbil cortex and hippocampus following reversible brain ischemia.

The present experiments were designed to determine the kinetic pattern of Na,K-ATPase in the presence of varying concentrations of Na+ and K+ ions in controls and gerbils exposed to 1 and 5 min of ischemia, respectively, and 60 min and 4 days of recirculation following 5 min of transient ischemia. The pattern of Na,K-ATPase activity in the control cerebral cortex and hippocampus is different. The cortical Na,K-ATPase apparently is more resistant in keeping an optimal activity than the enzyme in the hippocampus. After ischemic insult of either 1 or 5 min in duration, the enzyme activity is inhibited in both brain structures. 4 days after 5 min of ischemia, indicating greater flexibility of the cortical enzyme or less damage than in the hippocampus. Furthermore, the data obtained show that only through the enzyme behavior and kinetic parameters is it possible to reach conclusions about the enzyme function or dysfunction under pathological conditions.