Cell survival in rabbit gastric glands: effect of extracellular pH, osmolarity, and anoxia

Although backdiffusion of luminal acid is regarded as a common mechanism of gastric injury, the extracellular pH (pHo) at which cells are irreversibly injured is not well defined. Exclusion of the fluorescent dye propidium iodide was used to estimate cell survival in rabbit gastric glands incubated in buffers of pHo 8.0-2.0. Mean survival (+/- SE) for n = 6 experiments at 2 h in a HEPES buffer of 300 mosM at pHo 8.0, 7.0, 6.0, 4.0, and 2.0 was 80 +/- 3, 91 +/- 2, 90 +/- 2, 71 +/- 2, and 17 +/- 4%, respectively. Survival at acidic pHo was improved in a high KCl buffer: 78 +/- 3 and 38 +/- 7% at pHo 4.0 and 2.0, respectively. Survival in HCO3- buffers was 73 +/- 3, 88 +/- 2, and 92 +/- 3% at pHo 8.0, 7.4, and 6.0. Brief (5 min) exposure to pHo 4.0 followed by reexposure to pHo 7.4 had no effect on acid secretion as estimated by [14C]aminopyrine uptake or cellular viability over 4 h. The influence on cell survival of changes in pHo under conditions of chemical anoxia and in buffers of different osmolarity was investigated. Chemical anoxia was induced using 2.5 mM KCN and 2.0 mM iodoacetic acid (IAA) to inhibit oxidative phosphorylation and anaerobic glycolysis. Survival in glands exposed to KCN and IAA in HEPES buffer was 54 +/- 5, 82 +/- 3, and 87 +/- 2% at pHo 8.0, 7.0, and 6.0.(ABSTRACT TRUNCATED AT 250 WORDS)