Effect of experimental diabetes on Na/K-ATPase activity in red blood cells, peripheral nerve and kidney.

A decrease in Na/K-ATPase activity is probably involved in the pathogenesis of diabetic neuropathy. In human diabetes, Na/K-ATPase activity is almost always studied in red blood cells, readily accessible, and it could represent a marker of predisposition to diabetic neuropathy. But, we wanted to establish whether diabetes induced similar changes of Na/K-ATPase activity in erythrocytes, and in other tissues, especially the peripheral nerve and the kidney. So, we compared Na/K-ATPase activity measured in the erythrocyte, sciatic nerve and kidney of rats with streptozotocin-induced diabetes after 8 weeks (n = 9) and normal rats (n = 9). Na/K-ATPase activity was 39-44% lower in the RBC, sciatic nerve and kidney of diabetic rats compared to controls (RBC: 229 +/- 79 vs. 413 +/- 102 p < 0.05; sciatic nerve: 3250 +/- 692 vs. 5532 +/- 1260 p 0.05; kidney: 12920 +/- 4010 vs. 22410 +/- 5310 p < 0.05; results in nmol Pi.mg protein-1.h-1; mean +/- SD). A significant positive correlation was observed between Na/K-ATPase activities in the red blood cells and sciatic nerve (r = 0.81, p < 0.05) in the whole population of rats. This study shows that diabetes induces a parallel decrease in Na/K-ATPase activity in the red cell, sciatic nerve and kidney. The levels of this enzyme activity are significantly correlated in the red cell and sciatic nerve so that diabetes-induced changes of Na/K-ATPase activity in the erythrocyte seem to reflect those in the peripheral nerve.