Effect of luminal acid on intracellular pH in oxynticopeptic cells in intact frog gastric mucosa.
The effect of changes in luminal [H+] on intracellular pH in oxynticopeptic cells was examined using intact sheets of frog (Rana catesbeiana) gastric mucosa in which oxynticopeptic cells were selectively loaded with the pH-sensitive fluorescent dye 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF). The serosal solution was buffered with either HCO3- or N-2-hydroxymethylpiperazine-N'-2-ethanesulfonic acid (HEPES). Luminal pH was decreased from 7.2 to 1.5 and changed back to 7.2. In stimulated (forskolin-treated) tissues, intracellular pH decreased at luminal pH 1.5 only in HEPES, with complete recovery at 7.2. In resting (omeprazole-treated) tissues, intracellular pH began to decrease at luminal pH 2.0 in HEPES and at 1.5 in HCO3-, with complete recovery at 7.2 in both. In resting tissues bathed in Cl(-)-free HEPES, the recovery of intracellular pH at luminal pH 7.2 was completely prevented by serosal amiloride (1 mmol/L) but was not affected by serosal 4,4'-diisothiocyanatodihydrostilbene-2-2'-disulfonic acid (H2-DIDS; 0.5 mmol/L). In resting tissues bathed in Cl(-)-free HCO3-, the recovery of intracellular pH at luminal pH 7.2 was not affected by amiloride but was prevented partially by H2-DIDS and completely by combination of H2-DIDS and amiloride or by removal of ambient Na+. These results suggest that during exposure to high luminal [H+]: (a) stimulated oxynticopeptic cells maintain a steady intracellular pH more readily than resting cells; (b) serosal HCO3- protects oxynticopeptic cells from intracellular acidosis; and (c) both Na+/H+ exchange and Na(+)-HCO3- cotransport are involved in the recovery from intracellular acidosis in resting oxynticopeptic cells.
Yanaka
A
A
Department of Surgery, Beth Israel Hospital, Harvard Medical School, Boston, Massachusetts.
Carter
K J
KJ
Goddard
P J
PJ
Silen
W
W
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000136:Acid-Base Equilibrium / Q000187:drug effects*; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001639:Bicarbonates / Q000493:pharmacokinetics / Q000494:pharmacology; D001693:Biological Transport, Active; D005452:Fluoresceins / Q000494:pharmacology*; D005456:Fluorescent Dyes / Q000494:pharmacology*; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism*; D006531:HEPES / Q000494:pharmacology; D006859:Hydrogen / Q000493:pharmacokinetics; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D066298:In Vitro Techniques; D010295:Parietal Cells, Gastric / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D011892:Rana catesbeiana; D012492:Salts / Q000494:pharmacology; D012964:Sodium / Q000493:pharmacokinetics / Q000494:pharmacology; D017693:Sodium Bicarbonate
D001639:Bicarbonates; D005452:Fluoresceins; D005456:Fluorescent Dyes; D012492:Salts; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D000584:Amiloride; D006859:Hydrogen; C043829:2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein; D017693:Sodium Bicarbonate; D012964:Sodium; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D006531:HEPES