(Na+ +K+)-ATPase activity in kidney basolateral membranes of non insulin dependent diabetic rats

Insulin resistant, Type II diabetes mellitus (NIDD) in a rat animal model results in profound changes in basal and insulin-stimulated membrane (Ca2+ +Mg2+)-ATPase activity in kidney basolateral membrane (BLM) preparations. We find that NIDD in these animals does not result in similar changes in membrane (Na+ +K+)-ATPase activity. Basal enzyme activity was the same in diabetic and control animals. Insulin treatment of diabetic animals in vivo resulted in hyperinsulinemia and increased BLM (Na+ +K+)-ATPase, while food restriction for 18 hr resulted in lowered enzyme activity. There was no direct effect of insulin on (Na+ +K+)-ATPase activity in isolated membranes from any of the animal groups. Thus, physiologic perturbations which alter insulin sensitivity and glucose homeostasis are accompanied by altered levels of (Na+ +K+)-ATPase activity. Lower levels of this membrane enzyme activity appear to be associated with optimal insulin action.