The role of adrenoceptors in the mechanism of reserpine-induced stimulation of gastric acid secretion in the rat

The role of alpha- and beta-adrenoceptors in the mechanism of reserpine-induced stimulation of gastric acid secretion in the rat has been examined. After 6 h reserpine (0.1 mg kg-1 i.p.) significantly stimulated acid secretion relative to control values (176 +/- 4 vs 60 +/- 3 mumol, mean +/- s.e.m., n = 10, P less than 0.001). Neither coeliac ganglionectomy nor propranolol (5-15 mg kg-1) influenced this action. Vagotomy prevented acid stimulation by reserpine and was associated with H+ output similar to that of vagotomy controls (13 +/- 1 vs 14 +/- 1 mumol, mean +/- s.e.m., n = 10). Dose-dependent inhibition of the reserpine-induced acid secretion was produced by phenoxybenzamine or phentolamine; an inhibition similar to that achieved by vagotomy was noted with the 15 mg kg-1 dose (13 +/- 1 and 15 +/- 1 mumol, respectively, vs 176 +/- 4 mumol, mean +/- s.e.m., n = 10, P less than 0.001). The similarity in action between vagotomy and large doses of phenoxybenzamine or phentolamine suggests that, in the rat, vagal alpha-adrenoceptor stimulation is directly involved in the mechanism of reserpine-induced stimulation of gastric acid secretion.