Glucocorticoids stimulate rabbit proximal convoluted tubule acidification

J Clin Invest. 1993 Jan;91(1):110-4. doi: 10.1172/JCI116158.

Abstract

Glucocorticoids have an important role in renal acidification; however, a direct effect of glucocorticoids on proximal convoluted tubule (PCT) acidification has not been directly demonstrated. In the present in vitro microperfusion study PCT from animals receiving dexamethasone (600 micrograms/kg twice daily for 2 d and 2 h before killing) had a significantly higher rate of bicarbonate absorption than did controls (92.0 +/- 13.3 vs 59.9 +/- 3.2 pmol/mm.min, P < 0.01). To examine if glucocorticoids had a direct epithelial action, dexamethasone was added to the bath of PCT perfused in vitro. After 3 h of incubation in paired experiments 10(-6) M and 10(-5) M dexamethasone resulted in an approximately 30% stimulation in the rate of bicarbonate absorption. 10(-7) M dexamethasone and 10(-6) M aldosterone had no effect on bicarbonate absorption. The stimulation of acidification by 10(-5) M dexamethasone was blocked by actinomycin D and cycloheximide. These data are consistent with a direct effect of glucocorticoids on PCT acidification, and this effect is dependent upon protein synthesis.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aldosterone / pharmacology*
  • Animals
  • Bicarbonates / metabolism
  • Biological Transport / drug effects
  • Cycloheximide / pharmacology
  • Dactinomycin / pharmacology
  • Dexamethasone / pharmacology*
  • Dose-Response Relationship, Drug
  • Hydrogen-Ion Concentration
  • In Vitro Techniques
  • Kidney Cortex / drug effects
  • Kidney Cortex / physiology*
  • Kidney Medulla / drug effects
  • Kidney Medulla / physiology*
  • Kidney Tubules, Proximal / drug effects
  • Kidney Tubules, Proximal / physiology*
  • Kinetics
  • Rabbits

Substances

  • Bicarbonates
  • Dactinomycin
  • Aldosterone
  • Dexamethasone
  • Cycloheximide