Effects of adrenergic blocking agents on gastric secretion and stress-induced gastric ulcer in rats.

Recently interest in investigations of adrenergic agents (stimulants and inhibitors) on gastric secretion, motility, and ulceration in experimental animals has increased (1-7). Pradhan and Wingate (6) have demonstrated that phentolamine and tolazoline enhanced the spontaneous gastric secretion in dogs while phenoxybenzamine and dichloroisopro terenol showed inhibitory effects on spontaneous as well as induced secretion by food, bethanechol, and histamine. Bass and Patterson (3) have shown that both adrenergic and adrenergic blocking agents (including phentolamine and tolazoline) possessed anti secretory properties on rat gastric secretion. Hence, if gastric acid is a primary element in experimental ulcer, adrenergic and adrenergic blocking aegnts which have antisecretory effect should inhibit gastric ulceration. However, phentolamine, MJ 1999, and isopro terenol did not affect the incidence of histamine-induced ulcer in guinea pigs (6). More over, propranolol and phenoxybenzamine increased the incidence of ulceration in fasted rats immobilized for 8 hours (7). In this study, therefore, an attempt was made to in vestigate the effect of several adrenergic blocking agents on gastric secretion and stress induced ulcer in rats and to clarify a part of the mechanism of gastric ulceration by stress.