Effects of ammonia on bicarbonate transport in the cortical collecting duct

Am J Physiol Renal Physiol. 2000 Feb;278(2):F219-26. doi: 10.1152/ajprenal.2000.278.2.F219.


Both acidosis and hypokalemia stimulate renal ammoniagenesis, and both regulate urinary proton and potassium excretion. We hypothesized that ammonia might play an important role in this processing by stimulating H(+)-K(+)-ATPase-mediated ion transport. Rabbit cortical collecting ducts (CCD) were studied using in vitro microperfusion, bicarbonate reabsorption was measured using microcalorimetry, and intracellular pH (pH(i)) was measured using the fluorescent, pH-sensitive dye, 2', 7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF). Ammonia caused a concentration-dependent increase in net bicarbonate reabsorption that was inhibited by luminal addition of either of the H(+)-K(+)-ATPase inhibitors, Sch-28080 or ouabain. The stimulation of net bicarbonate reabsorption was not mediated through apical H(+)-ATPase, basolateral Na(+)-K(+)-ATPase, or luminal electronegativity. Although ammonia caused intracellular acidification, similar changes in pH(i) induced by inhibiting basolateral Na(+)/H(+) exchange did not alter net bicarbonate reabsorption. We conclude that ammonia regulates CCD proton and potassium transport, at least in part, by stimulating apical H(+)-K(+)-ATPase.

Publication types

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

MeSH terms

  • Ammonia / pharmacology*
  • Animals
  • Bicarbonates / pharmacokinetics*
  • Enzyme Inhibitors / pharmacology
  • Female
  • Hydrogen-Ion Concentration / drug effects
  • Imidazoles / pharmacology*
  • Kidney Tubules, Collecting / drug effects*
  • Kidney Tubules, Collecting / metabolism
  • Ouabain / pharmacology
  • Proton Pump Inhibitors*
  • Rabbits


  • Bicarbonates
  • Enzyme Inhibitors
  • Imidazoles
  • Proton Pump Inhibitors
  • Sch 28080
  • Ouabain
  • Ammonia