The effect of cimetidine on adaptive cytoprotection by mild irritant dose of HCl in the rat gastric mucosa.

While cimetidine (CIM) is strikingly effective in inhibiting gastric acid secretion, its effect on the defensive mechanisms of the gastric mucosa has been controversial. The aims of the present study were to test if administration of CIM at an antisecretory dose is protective against acid-induced injury and to assess its effect on adaptive cytoprotection induced by non-necrotizing concentrations of HCl in rats. A dose of 100 mg/kg of CIM was administered once, or twice a day for 5 days intraperitoneally. To study the effect of CIM on HCl-induced damage, 0.6 N HCl was given orally one hour after the last administration of CIM. To study the effect of CIM on adaptive cytoprotection, 0.35 N HCl was given orally one hour after the last administration of CIM. Fifteen minutes later, 0.6 N HCl was given orally. Thirty minutes after the administration of 0.6 N HCl, the stomach was removed and ulcer indices were calculated. Pretreatment with CIM did not prevent 0.6 N HCl induced gastric damage. Prior administration of 0.35 N HCl significantly reduced ulcer indices caused by 0.6 N HCl. Short or long term treatment with CIM did not have significant effects on the reduction of ulcer indices. These results suggest that CIM at an antisecretory dose neither acts as a protective agent nor modulates the protective process of the gastric mucosa.