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

Abstract

SUMMARY1. The action of fl-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-v 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 f-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 ,f-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 fl-adrenoceptor stimulation of acid secretion: it is concluded that the response is probably mediated by f-receptors on the parietal cell.

The effect of α2‐adrenoceptor agonists on the acid secretory responses of rat isolated gastric mucosa to electrical field stimulation

“…Thus it appears there is a lack of involvement of histamine in the secretagogue action of acetylcholine in isolated stomach preparations of the rat in contrast to those from the mouse. The increases in acid secretion which we observed at high concentrations of noradrenaline have been reported by Canfield et al (1981) to be due to an action at P-adrenoceptors.…”

A comparison of the effects of sympathomimetic agents on gastric acid secretion by the rat stomach in vivo and in vitro.

“…Alternatively it may act indirectly via a mechanism involving either cholinergic, histamine or gastrin receptors. We have investigated the action of sympathomimetic compounds in the in vitro preparation in more detail and these results are presented in the following paper (Canfield et al 1981).…”

The inhibitory effects of 5‐hydroxytryptamine on gastric acid secretion by the rat isolated stomach

“…This problem has not been examined in the rat preparation but it has previously been found necessary to use high concentrations of atropine, metiamide and P-adrenoceptor antagonists to obtain significant effects. (Canfield, Hughes, Price & Spencer, 1981). It may also be that the access of 5-HT to the stomach is restricted in this preparation.…”