Reduction by cytoprotective agents of ethanol-induced damage to the rat gastric mucosa: a correlated morphological and physiological study.

Acute haemorrhagic erosions were produced in chambered gastric mucosae of rats by infusion into the chamber of 40% ethanol (v/v) for 10 min, followed by 50 mM HCl for 1 h. This procedure produced erosions which extended over nearly 70% of the glandular mucosa. When one of 2% ethanol, prostaglandin E2 (75 micrograms/kg in either 2% ethanol or in aqueous solution), or isoproterenol (50 micrograms/kg) was placed in the chamber for 10 min prior to infusion of 40% ethanol, the resultant lesions were significantly reduced in area (mean lesion area 25-31% of the glandular mucosa). When compared with the effects of 40% ethanol without pretreatment, there was no consistent correlation between pretreatment with these agents and changes in mucosal potential difference (PD) or net fluxes of Na+ and H+. All of the pretreatment groups did show a reduced loss of Cl from the chamber in the final 10-min period of the experiments. Exposure to the "protective" agents did not result in qualitative changes in mucosal structure at either the light or electron microscopic levels. Rather, the ultimate effect of pretreatment was to reduce the extent of deep mucosal vasocongestion. The reduction in lesion area could be directly related to these reductions in vasocongestion and not to any enhanced resistance of the luminal epithelium to the damaging effects of 40% ethanol.