Na,K-ATPase alterations in diabetic rats: Relationship with lipid metabolism and nerve physiological parameters

Type 1 diabetes induces several metabolic and biochemical disturbances whic h result in the alteration of Na,K-ATPase, an enzyme implicated in the phys iopathology of neuropathy. Several fatty acid supplementations lessen this alteration. The aims of this study were to determine the possible relations hips between Na,K-ATPase activity in nerves and red blood cells (RBCs) and, on one hand, the fatty acid alterations induced by diabetes in these tissu es and plasma and on the other, on nerve physiological parameters. Two grou ps of rats, control and diabetic (n=15), were sacrified 8 weeks after induc tion of diabetes with streptozotocin. Nerve conduction velocity (NCV), nerv e blood flow (NBF), Na,K-ATPase activity and membrane fatty acid compositio n of sciatic nerves, red blood cells (RBCs) and plasma were measured. NCV, NBF and Na,K-ATPase activity in RBCs and in sciatic nerves were significant ly decreased in diabetic rats. We revealed a positive correlation between N a,K-ATPase activity in sciatic nerves and both NBF and NCV and between Na,K -ATPase activity in RBCs and NBF and the same activity in sciatic nerve. Di abetes induced major changes in plasma fatty acids and RBC membranes and le ss important changes in sciatic nerve membranes. Na,K-ATPase activity corre lated negatively with C20: 4 (n-6) and C22: 4 (n-6) levels in nerves and wi th C18: 2 (n-6) levels in RBCs. During diabetes, changes in the membrane fa tty acid composition suggest the existence of a tissue-specific regulation, and the decrease in Na,K-ATPase activity correlates with the alteration in the level of specific fatty acids in RBCs and sciatic nerves. Modification s in the lipidic environment of Na,K-ATPase would be involved in the altera tion of its activity. Na,K-ATPase activity seems to be implicated in the de crease of both NCV and NBF during diabetes.