Abstract
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.
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|