The action of beta-adrenoceptor agonists on acid secretion by the rat isolated stomach.

1. The action of beta-adrenoceptor agonists on acid secretion by an immature rat isolated stomach preparation has been studied. 2. Isoprenaline, salbutamol, salmefamol, adrenaline and noradrenaline all stimulated acid output over a concentration range of 2 X 10(-7) M--10(-5) M. 3. These responses were antagonized by propranolol (2 X 10(-5) M), pindolol and timolol (10(-6) M). 4. The antagonism of isoprenaline and salmefamol by propranolol was consistent with competitive inhibition. 5. Selective beta-adrenoceptor antagonists (practolol, atenolol, butoxamine and ICI 118 551) caused significant inhibition of noradrenaline-stimulated secretion but not of that due to the other agonists. 6. An adult rat isolated mucosa preparation responded to adrenaline in a similar manner to the immature stomach preparation. 7. Acid secretion stimulated by beta-adrenoceptor agonists was not antagonized by atropine (10(-5) M), metiamide (10(-4) M) or prostaglandin E2 (10(-5) M). The concentrations of these three antagonists caused marked inhibition of the responses to submaximal concentrations of bethanechol, histamine and pentagastrin respectively. 8. The results are discussed in relation to the possible mechanisms of action of beta-adrenoceptor stimulation of acid secretion: it is concluded that the response is probably mediated by beta-receptors on the parietal cell.