Effect of chronic hyperglycemia and vanadate treatment on erythrocyte Na/K-ATpase and Mg-ATpase in streptozotocin diabetic rats.

We have studied Na/K-ATPase and Mg-ATPase activities in red blood cells of diabetic rats treated in vivo with sodium vanadate. To our knowledge the effect of in vivo vanadate treatment on these two enzymes has not been studied. Red blood cell Na/K-ATPase plays a central role in the regulation of intra- and extra cellular cation homeostasis. Alteration of this transport enzymes is thought to be linked to several complications of diabetes mellitus: hypertension, nephropathy, peripherical neuropathy and microangiopathy. An Mg2+-dependent ATPase activity located in the erythrocyte membrane appears to be responsible for controlling the smoothing of echinocytic erythrocytes to discocytes and stomatocytes. Our results show that in alloxan diabetes activities of both ATPases are reduced (especially the activity of Na/K-ATPase). Vanadate treatment of normal animals reduced the activities of both enzymes: with 33.08% for Na/K-ATPase and 22.76% for Mg-ATPase. Vanadate treatment of diabetic animals did not affect significantly the inhibition process for Na/K-ATPase. For Mg-ATPase we have obtained a significant cumulative inhibition. These results stand out the different functions and physiologic control mechanism of these two ionic pump in red blood cells.