(Na+-K+)-ATPase activity and ouabain-binding sites in the cerebral cortex of young and aged Fischer-344 rats.

(Na+-K+)-ATPase is an enzyme responsible for ionic homeostasis in excitable tissues. Thus, the activity of this enzyme is essential for the maintenance of optimal function of the cerebral cortex. Although abnormalities of cerebral oxidative metabolism have been described in aging, these abnormalities do not appear to be associated with changes in the in vitro enzyme characteristics of (Na+-K+)-ATPase. Specifically, there were no significant differences between preparations from the cerebral cortex of 3- and 28-month-old Fischer-344 rats in their: (i) high-affinity binding to [3H]-ouabain, (ii) number of ouabain-binding sites, or (iii) K+-p-nitrophenylphosphatase activity.