Prostaglandin e analogue inhibition of intrinsic factor release

In many mammalian species (including humans) the parietal cell secretes both acid and intrinsic factor (IF). The aim of this study was to examine the direct effect of prostaglandin E analogues on basal and stimulated IF release in isolated, enriched rabbit parietal cells. The effects of graded concentrations (10^-12 to 10^-6 M) of 16,16-dimethyl prostaglandin E₂ (DMPGE₂) and 16-methyl,16-hydroxyl prostaglandin E, (misoprostol) on submaximal histamine-stimulated (10^-6 M) secretion were tested. Both analogues failed to alter basal release of IF or aminopyrine accumulation (indirect measure of acid secretion). Increasing concentrations of DMPGE₂ resulted in a dose-dependent inhibition of IF release (22 ± 8% decrease at 10^-9 M; p < 0.05) and a maximal effective response at 10^-7 M (54 ± 9%; p < 0.005). Dose-dependent inhibition of IF secretion was also observed with increasing concentrations of misoprostol, with a 22 ± 7% decrease at 10^-9 M (p < 0.05) and maximal effective inhibition at 10^-6 M (47 ± 8%; p < 0.01). Misoprostol and DMPGE₂ inhibition of acid secretion paralleled IF release. Prostaglandin analogues appear to block IF release potently in histamine-stimulated parietal cells.