Increased renal tubular sodium pump and Na+,K+-adenosine triphosphatase in streptozotocin-diabetic rats.
The effects of chronic glucose osmotic diuresis on renal tubular sodium pump and Na+,K+-adenosine triphosphatase (ATPase) activities were studied in chronic streptozotocin-induced diabetic rats. Four to seven weeks after streptozotocin (60 mg/kg i.p.) injection, specific renal Na+,K+-ATPase activity showed a 34.8% increase as compared to the saline-citrate treated controls, whereas the nonspecific Mg++-ATPase was not altered. The concentration of Na+,K+-ATPase, estimated from the maximum [3H]ouabain binding site concentration, also showed a significant increase in the chronic streptozotocin-diabetic rats. To determine further the specificity of this increase in Na+,K+-ATPase, the activity of the sodium pump, estimated from ouabain-sensitive 86Rb uptake, was measured in nonenzymatically isolated renal tubules. Again, a significant (+106.4%) increase in the renal tubular sodium pump activity was observed in the streptozotocin-diabetic rats, whereas the nonspecific, ouabain-insensitive 86Rb uptake was not altered. Neither was there any difference in 86Rb uptake by the isolated renal glomeruli. Thus, it appears that chronic streptozotocin-induced diabetes in rats is associated with a significant increase in renal tubular sodium pump and Na+,K+-ATPase. The latter effects may represent an important physiologic adaptation of the kidneys to maintain electrolyte homeostasis in diabetes.
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D007678:Kidney Glomerulus / Q000378:metabolism; D007684:Kidney Tubules / Q000378:metabolism*; D007700:Kinetics; D010042:Ouabain / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012413:Rubidium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D010042:Ouabain; D012964:Sodium; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium