The influence of systemic ethanol and/or the vagus on ionic secretion and on glandular mucosal blood flow (GMBF) was studied in an ex-vivo gastric chamber preparation in rats. Sub-diaphragmatic vagotomy decreased H+ secretion and Na+ outflux from the gastric mucosa. Subcutaneous injection of 50% ethanol significantly potentiated these responses, but not the concentrations of 25% and 100%. The three doses of ethanol did not affect the secretion of both H+ and Na+ in vagus-intact animals. Ethanol, however dose-dependently reduced the GMBF in both vagus-intact and sub-diaphragmatic vagotomised rats, and the effect was greater in the latter-operated animals. It is concluded that vagus nerves greatly influence the secretion of both H+ and Na+ the gastric mucosa but the effect is unrelated to GMBF. Systemic ethanol reduced the secretion of these ions only in vagotomised animals, indicating the vagus could play a role in modulating the action of ethanol in the stomach.

The present study examines the protective effect of zinc sulphate against ethanol-induced gastric mucosal ulcers in rats. Absolute ethanol decreased the gastric mucosal blood flow and produced haemorrhagic lesions in the glandular mucosa. Zinc sulphate preincubation in an ex-vivo stomach chamber preparation prevented the formation of ethanol-induced lesions and attenuated the decrease of blood flow produced by ethanol. Subcutaneous injection of the same doses of the drug at 15 and 30 min before ethanol exposure, markedly reduced the blood flow and also aggravated ethanol-induced gastric injury; however, when injected at 23 and 24 h before ethanol administration, zinc sulphate protected against lesion formation but had no effect on the vascular changes induced by ethanol in the gastric glandular mucosa. These findings show that the antiulcer effect of zinc sulphate occurs only when the drug is given orally, or injected s.c. 23 and 24 h before ethanol challenge. Furthermore, this protective action is probably not entirely mediated by preservation of the gastric mucosal blood flow.