Angiotensin II: a potent regulator of acidification in the rat early proximal convoluted tubule

J Clin Invest. 1987 Jul;80(1):272-5. doi: 10.1172/JCI113059.

Abstract

The early proximal convoluted tubule (PCT) is the site of 50% of bicarbonate reabsorption in the nephron, but its control by angiotensin II has not been previously studied. In vivo microperfusion was used in both the early and late PCT in Munich-Wistar rats. Systemic angiotensin II administration (20 ng/kg X min) or inhibition of endogenous angiotensin II activity with saralasin (1 microgram/kg X min) caused profound changes in bicarbonate absorption in the early PCT (169 +/- 25 and -187 +/- 15 peq/mm X min, respectively). Because the bicarbonate absorptive capacity of the early PCT under free-flow conditions is 500 peq/mm X min, angiotensin II administration or inhibition affected greater than 60% of proton secretion in this segment. Both agents less markedly affected bicarbonate absorption in the late PCT (+/- 28 peq/mm X min) or chloride absorption (+/- 68-99 peq/mm X min) in both the early and late PCT. Because of its potential for controlling the majority of bicarbonate absorption in the early PCT (hence greater than or equal to 30% of bicarbonate absorption in the entire nephron), angiotensin II may be a powerful physiologic regulator of renal acidification.

Publication types

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

MeSH terms

  • Absorption
  • Angiotensin II / antagonists & inhibitors
  • Angiotensin II / pharmacology*
  • Animals
  • Bicarbonates / metabolism*
  • Chlorides / metabolism
  • Hydrogen-Ion Concentration
  • Kidney Tubules, Proximal / drug effects
  • Kidney Tubules, Proximal / metabolism*
  • Kinetics
  • Male
  • Rats
  • Rats, Inbred Strains
  • Saralasin / pharmacology

Substances

  • Bicarbonates
  • Chlorides
  • Angiotensin II
  • Saralasin