Gastric bicarbonate secretion: effect of topical and intravenous 16,16-dimethyl prostaglandin E2

Abstract

These studies were designed to compare intravenous and topical 16,16-dimethyl prostaglandin E2 (dmPGE2) as stimulants of gastric mucosal HCO3- secretion. In six Heidenhain pouch (HP) dogs, basal acid secretion was inhibited by cimetidine. With 100 ml 0.15 M NaCl as the fluid circulating through the HP, intrapouch titration to pH 6.0 was performed with 0.5 M HCl as titrant. After measuring basal HCO-3 secretion for 30 min, dmPGE2 was given intravenously or the fluid circulating in the HP was replaced by one containing dmPGE2. Intravenous dmPGE2 at infusion rates of 0, 0.5, 1.0, and 2.0 microgram . kg-1 . h-1 produced alkaline secretion rates of 34 +/- 9, 52 +/- 20, 72 +/- 21, and 70 +/- 20 (SE) mu mol . h-1, respectively. Topical dmPGE2 at concentrations of 0, 0.05, 1.25, and 2.50 microgram . ml-1 produced alkaline secretion rates of 22 +/- 7, 74 +/- 16, 134 +/- 28, and 144 +/- 35 mu mol . h-1, respectively (P less than 0,05 for each concentration). Glucosamine output, as an index of mucus secretion, increased significantly with HCO-3 secretion. We conclude that intragastric titration is a valid method for recording HCO-3 secretion from an HP, that topical dmPGE2 stimulates HCO3- secretion more effectively than intravenous dmPGE2, and that topical dmPGE2 stimulates mucus secretion as well as HCO-3 secretion,