Effect of 16,16-dimethyl prostaglandin E2 and ethanol on the constituents of gastric mucus.

Abstract

The effect of ethanol, 16,16-dimethyl prostaglandin E2 (DMPGE2), and ethanol after DMPGE2 pretreatment on the solubilization of protein, glycoprotein, and glycolipid constituents of gastric mucus was investigated. The Lucite chamber stomach-flap preparation was used in dogs whose basal H+ secretion was inhibited by intravenous cimetidine. Graded concentrations (5-80%) of ethanol produced a dose-dependent decrease in potential difference (PD) which was accompanied by an increase in the content of proteins, glycoproteins, and glycolipids of the instillates. This effect was most pronounced at 40% ethanol. Exposure of gastric mucosa to DMPGE2 at 0.01 microgram/ml had no effect on the transmucosal PD, and the content of investigated components in the instillates increased only slightly over the saline control levels. DMPGE2 at 0.1 microgram/ml, although it did not induce an evident fall of PD, evoked a moderate increase in glycoprotein and glycolipid liberation. Higher doses (above 1.0 microgram/ml) of DMPGE2 were associated with the fall of PD and the increased solubilization of proteins, glycoproteins, and glycolipids. Pretreatment of the mucosa with DMPGE2 in a dose of 1.0 microgram/ml diminished the liberation of the investigated components from the gastric mucosa by 5 and 10% ethanol, but did not prevent the changes evoked by higher concentrations (20-80%) of ethanol. These data indicate that DMPGE2 applied topically protects in part the gastric mucosa against the ethanol-induced solubilization of mucus constituents.