Effects of stimulation and inhibition of acid secretion on gastric damage induced by platelet-activating factor.

Intravenous administration of platelet-activating factor (PAF) induces extensive damage in rat gastric mucosa. The aim of the present study was to examine whether the presence or absence of acid in the gastric lumen could modify the PAF-induced gastric damage. The effects of inhibition of basal and pentagastrin-stimulated acid secretion by ranitidine on the deep histological gastric damage induced by 30 min of infusion of PAF (100 ng/kg/min) were assessed by using a histological score. Inhibition of basal gastric acid secretion did not prevent the histological gastric damage induced by PAF. Stimulation of gastric acid secretion by pentagastrin significantly increased PAF-induced gastric damage, and this effect was reversed by a dose of ranitidine that returns acid secretion to baseline levels. This acid-related damage was confined to the deep mucosa, since scanning electron microscope analysis ruled out an additional surface damage in PAF-infused rats when gastric acid was stimulated. The data indicate that a certain amount of acid may worsen the deep gastric mucosal damage induced by PAF.