The role of beta1- and beta2-adrenoceptors in the inhibition of gastric acid secretion in the dog.

1. Characterization of the beta-adrenoceptors mediating inhibition of gastric acid secretion in the conscious Heidenhain pouch dog has been investigated by determination of the effects of propranolol, (+)-propranolol, practolol and H35/25 on salbutamol and isoprenaline-induced inhibition of gastric acid secretion. 2. The gastric antisecretory effect of salbutamol was significantly blocked by propranolol and H35/25 but not by practolol or (+)-propranolol. The effect of isoprenaline was significantly blocked by propranolol and practolol but not by H35/25 or (+)-propranolol. 3. It is concluded that both beta1- and beta2-adrenoceptors can mediate inhibition of pentagastrin-induced gastric secretion in conscious dogs with a Heidenhain pouch. Salbutamol exerts its antisecretory effect through beta2-adrenoceptors, whereas isoprenaline mediates its effects primarily through beta1-adrenoceptors. 4. The results are discussed with regard to the sub-classification of beta-adrenoceptors and to the possible role of adrenoceptors in the physiological control of gastric secretion. 5. In this study it is concluded that the tachycardia induced by isoprenaline or salbutamol is mediated primarily through reflexes activated by beta2-adrenoceptor mediated vasodilatation.