Inhibition of basal and insulin-stimulated gastric acid secretion by phenoxybenzamine or phentolamine.

The present study in the rat was undertaken to investigate the possible involvement of alpha- and beta-adrenoceptors in mediating gastric acid secretion in response to insulin-hypoglycaemia. Phenoxybenzamine, 15 mg kg-1, depressed the basal acid secretion to a level similar to that associated with vagotomy; phentolamine, 15 mg kg-1, had a similar effect. Insulin (1 unit kg-1) significantly stimulated gastric acid secretion. Vagotomy or phenoxybenzamine or phentolamine, 15 mg kg-1 prevented this action. The beta-adrenoceptor blocking drug, propranolol, 5-15 mg kg-1, had no significant effect on the basal acid secretion or its stimulation by insulin. The similarity in action between vagotomy and large doses of phenoxybenzamine and phentolamine suggests that, in the rat, vagal alpha-adrenoceptor stimulation is involved in the mechanisms of basal and insulin-stimulated gastric acid secretion.