In vitro insulin action on different ATPases of erythrocyte membranes in normal and diabetic rats.

The in vitro effect of porcine insulin on Na+ + K+, Ca2+- and Mg2+-ATPases of the rat erythrocyte membrane of normal and alloxan-induced diabetic rats was investigated. Na+ + K+- and Ca2+-stimulated enzyme activities were significantly decreased in diabetic rats in comparison to normal animals. The specific activities of both these ATPases in the latter group were markedly reduced on pre-incubating the ghosts with insulin. Similar treatment of the erythrocyte membranes of diabetic animals, however, resulted in a significant increase of these activities. These qualitatively different effects of the hormone in the two groups increased progressively with hormone concentration and duration of pre-incubation. Mg2+-stimulated ATPase activity was not significantly affected in diabetes or by insulin.