Intragastric polyethylene glycol-400 protects against ethanol-induced gastric mucosal lesions despite pretreatment with indomethacin or iodoacetamide.

It has been shown that intragastric administration of polyethylene glycol-400 (PEG-400) by gavage needle protected the rat gastric mucosa from 96% ethanol-induced lesions in a dose-dependent fashion. The inhibitions of the lesions were 10.5, 53.5, 94.6, and 99.2% at doses of 275, 1375, 2750, and 5500 mg/kg, respectively. The duration of the protective effect was approximately 12 hr. The gastroprotection offered by PEG-400 was not modified by pretreatment with either subcutaneous indomethacin (25 mg/kg) or iodoacetamide (100 mg/kg). Gastric motility, measured by a balloon method, was dose-dependently inhibited by intragastric administration of PEG-400. The inhibited gastric motility (amplitude gastric contraction) induced by PEG-400 was not modified by pretreatment with either indomethacin or iodoacetamide. The gastric emptying rate, investigated by measuring the disappearance of intragastrically administered [99mTc]DTPA from the stomach of rats treated with PEG-400 (5500 mg/kg) was markedly retarded. There was an increase in both the fluid volume and the mucus volume retained in the gastric lumen only for PEG-400 (5500 mg/kg) at 1, 2, and 4 hr after administration. The rats treated with 0.7 ml of vehicle plus 96% ethanol had significantly less damage than those treated with 0.2 ml of vehicle plus 96% ethanol. These results indicate that intragastric PEG-400-protective effect was not mediated by endogenous prostaglandins, sulfhydryl compounds of the gastric mucosa, or changes in gastric contractile patterns. We conclude that the protective effect of intragastric PEG-400 may be the result of retarded gastric emptying together with an osmotic pull of fluid into the stomach and the increase in gastric mucus volume.(ABSTRACT TRUNCATED AT 250 WORDS)