Prostaglandin requirements are greater for protection in cold restraint-induced than alcohol-induced gastric mucosal injury.

Exogenous prostaglandins inhibit visible gastric mucosal lesions produced by both absolute ethanol and cold restraint in the rat. Pretreatment with "mild irritants" significantly reduces the magnitude of ethanol-induced lesions presumably by stimulating endogenous prostanoid production. The effect of mild irritant pretreatment on cold restraint-induced lesion formation has not been previously reported. This study was designed to compare the protective effect of pretreatment with two "mild irritants," 4% NaCl and 0.35 M HCl, and the synthetic prostanoid, 16,16 dimethyl PGE2(16,16-dm PGE2), on lesions produced by cold restraint or absolute ethanol. Pretreatment with both mild irritants produced complete visible protection against ethanol-induced injury but had variable effects against cold restraint-induced injury. Whereas 5 micrograms/kg 16,16-dmPGE2 provided complete visible protection against ethanol-induced injury, 20 micrograms/kg 16,16-dmPGE2 was required for complete visible protection against cold restraint-induced injury. We conclude that prostaglandin requirements for protection against cold restraint injury are greater than for protection against ethanol-induced gastric mucosal injury.