Effect of bath and luminal potassium concentration on ammonia production and secretion by mouse proximal tubules perfused in vitro

J Clin Invest. 1990 Jul;86(1):32-9. doi: 10.1172/JCI114702.

Abstract

To determine the effects of acute changes in K+ concentration in vitro on ammonia production and secretion by the proximal tubule, we studied mouse S2 segments perfused with and bathed in Krebs-Ringer bicarbonate buffers containing various K+ concentrations. All bath solutions contained L-glutamine as the ammoniagenic substrate. High bath and luminal K+ concentrations (8 mM), but not high luminal K+ concentration alone, inhibited total ammonia production rates by 26%, while low bath and luminal K+ concentrations (2 mM), but not low luminal K+ concentration alone, stimulated total ammonia production rates by 33%. The stimulation of ammonia production by low bath K+ concentration was not observed when L-glutamine was added to the luminal perfusion solution. On the other hand, high luminal K+ concentration stimulated, while low luminal K+ concentration inhibited, net luminal secretion of total ammonia in a way that was: (a) independent of total ammonia production rates, (b) independent of Na(+)-H+ exchange activity, and (c) not due to changes in transepithelial fluxes of total ammonia. These results suggest that luminal potassium concentration has a direct effect on cell-to-lumen transport of ammonia.

Publication types

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

MeSH terms

  • Amiloride / pharmacology
  • Ammonia / metabolism*
  • Animals
  • Carrier Proteins / drug effects
  • Carrier Proteins / physiology
  • Glutamine / pharmacology
  • Hydrogen-Ion Concentration
  • In Vitro Techniques
  • Kidney Tubules, Proximal / metabolism*
  • Male
  • Mice
  • Potassium / pharmacology*
  • Secretory Rate / drug effects
  • Sodium-Hydrogen Exchangers

Substances

  • Carrier Proteins
  • Sodium-Hydrogen Exchangers
  • Glutamine
  • Ammonia
  • Amiloride
  • Potassium