Isoproterenol prevents ethanol-induced microvascular stasis and deep histologic injury in rat gastric mucosa

The effect of topical isoproterenol (5.8 x 10(-5) M) on the microvascular stasis and histologic injury produced in the rat gastric mucosa by absolute ethanol was investigated using in vivo microscopic and histologic techniques. Our findings show that in control animals, absolute ethanol applied to the gastric mucosa caused a rapid decrease in microvascular blood flow, leading to complete stasis by 3 min. In contrast, prior treatment of the gastric mucosa with topical isoproterenol increased microvascular blood flow initially and then maintained microvascular flow in the majority of microvessels studied after the application of absolute ethanol. Treatment with topical isoproterenol also reduced the histologic injury score and percent mucosal necrosis caused by absolute ethanol. Pretreatment of animals with a beta-adrenergic antagonist propranolol (2 mg/kg subcutaneously), completely blocked these protective effects. We observed no systemic effects attributable to the topical use of isoproterenol. These results indicate that prior treatment of the gastric mucosa with topical isoproterenol maintains microvascular blood flow and reduces the deep histologic injury in the stomach caused by 100% ethanol.