Direct measurement of extracellular proton flux from isolated gastric glands

Am J Physiol. 1994 Nov;267(5 Pt 1):C1473-82. doi: 10.1152/ajpcell.1994.267.5.C1473.

Abstract

We used the microphysiometer, a sensitive extracellular pH sensor, to resolve luminal (or apical) H+ secretion and basolateral release of OH- as well as liberation of acidic metabolites in rabbit gastric glands. Stimulation of glands via the adenosine 3',5'-cyclic monophosphate pathway produced a biphasic change in the extracellular acidification rate (EAR): after an initial transient decrease below the unstimulated baseline (-40.9 +/- 3.4%), the EAR increased to a steady-state maximal plateau (+98.1 +/- 5.3%) within 30 min (n = 37). We interpret the biphasic EAR profile as an initial excess of basolaterally released OH- followed by delayed luminal efflux of simultaneously produced H+. The elevated EAR at steady state reflected liberation of metabolic acid attributed to H(+)-K(+)-ATPase enzymatic activity. The presence of H2-4,4'-diisothiocyanostilbene-2,2'-disulfonic acid prevented OH- release and reduced steady-state EAR. Basolateral OH- release and steady-state EAR were also inhibited by the H(+)-K(+)-ATPase inactivators omeprazole and SCH-28080. Inhibition of Na+/H+ exchange did not reduce steady-state EAR and did not affect apical H+ production, as judged by the accumulation of the weak base aminopyrine. Sodium thiocyanate (1 mM), which short circuits intraluminal H+ accumulation, blocked OH- release, demonstrating its dependence on H(+)-OH- separation at the apical membrane. A computerized model was developed to illustrate how the observed biphasic EAR profile would result from a delayed luminal efflux of H+ due to transitory intraluminal compartmentalization.

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

  • 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / pharmacology
  • Animals
  • Antiporters / antagonists & inhibitors
  • Chloride-Bicarbonate Antiporters
  • Extracellular Space / metabolism*
  • Female
  • Gastric Acid / metabolism
  • Gastric Mucosa / metabolism*
  • H(+)-K(+)-Exchanging ATPase / metabolism
  • In Vitro Techniques
  • Male
  • Protons*
  • Rabbits
  • Stimulation, Chemical
  • Thiocyanates / pharmacology

Substances

  • Antiporters
  • Chloride-Bicarbonate Antiporters
  • Protons
  • Thiocyanates
  • sodium thiocyanate
  • H(+)-K(+)-Exchanging ATPase
  • 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid