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

Abstract

I.v. and topical 16,16-dimethyl prostaglandin E2 (dmPGE2) were compared as stimulants of gastric mucosal HCO3- secretion. In 6 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 HCO3- secretion for 30 min, dmPGE2 was given i.v. or the fluid circulating in the HP was replaced by 1 containing dmPGE2. I.v. dmPGE2 at infusion rates of 0, 0.5, 1.0 and 2.0 .mu.g.cntdot.kg-1 per h produced alkaline secretion rates of 34 .+-. 9, 52 .+-. 20, 72 .+-. 21 and 70 .+-. 20 (SE) .mu.mol.cntdot.h-1, respectively. Topical dmPGE2 at concentrations of 0, 0.05, 1.25 and 2.50 .mu.g.cntdot.ml-1 produced alkaline secretion rates of 22 .+-. 7, 74 .+-. 16, 134 .+-. 28 and 144 .+-. 35 .mu.mol.cntdot.h-1, respectively (P < 0.05 for each concentration). Glucosamine output, as an index of mucus secretion, increased significantly with HCO3- secretion. Apparently intragastric titration is a valid method for recording HCO3- secretion from an HP; topical dmPGE2 stimulates HCO3- secretion more effectively than i.v. dmPGE2, and topical dmPGE2 stimulates mucus secretion as well as HCO3- secretion.