A response to isoprenaline unrelated to α‐and β‐adrenoceptor agonism
Open Access
- 19 July 1987
- journal article
- research article
- Published by Wiley in British Journal of Pharmacology
- Vol. 91 (3), 683-686
- https://doi.org/10.1111/j.1476-5381.1987.tb11262.x
Abstract
1 The hypothesis that β-adrenoceptor agonism might explain a reported lack of competitive antagonism between α2-adrenoceptor antagonists and agonists of the phenylethylamine class was tested in the electrically field stimulated ileum of the guinea-pig. The β-adrenoceptor agonist, isoprenaline, was used as the phenylethylamine and inhibition of ‘twitch’ response evoked by cholinergic stimulation was measured. 2 In the presence of idazoxan (3 μm), to block inhibitory α2-adrenoceptors, propranolol (0.1 to 5.0 μm) failed to act competitively toward isoprenaline. Isoprenaline responses totally resistant to inhibition by propranolol were obtained. 3 As inhibitory α1-adrenoceptors are absent from guinea-pig ileum, a recognition site distinct from the currently defined α-and β-adrenoceptors is postulated. Agonism by phenylethylamine based agonists at this site may explain their inability to act competitively with α-and β-adrenoceptor antagonists.This publication has 23 references indexed in Scilit:
- Differential blocking actions of idazoxan against the inhibitory effects of 6-fluoronoradrenaline and clonidine in the rat vas deferensBritish Journal of Pharmacology, 1985
- Prejunctional dopamine receptors modulate twitch responses to parasympathetic nerve stimulation in the rabbit isolated rectococcygeus muscleBritish Journal of Pharmacology, 1984
- The rat lipolytic β-adrenoceptor: Studies using novel β-adrenoceptor agonistsEuropean Journal of Pharmacology, 1984
- Atypical β-adrenoceptor on brown adipocytes as target for anti-obesity drugsNature, 1984
- Dissociation of presynaptic α2-adrenoceptors following prazosin administration: Presynaptic effect of prazosinEuropean Journal of Pharmacology, 1983
- Pre-junctional α2-adrenoceptor activity of B-HT920Journal of Pharmacy and Pharmacology, 1983
- Molecular properties of the adrenergic .alpha. receptor. 2. Optimum covalent inhibition by two different prototypes of polyamine disulfidesJournal of Medicinal Chemistry, 1978
- PHARMACOLOGICAL CHARACTERIZATION OF THE PRESYNAPTIC α-ADRENOCEPTORS REGULATING CHOLINERGIC ACTIVITY IN THE GUINEA-PIG ILEUMBritish Journal of Pharmacology, 1978
- Pharmacological classification of adrenergic α receptors in the guinea pigNature, 1978
- Pharmacology of nadolol (SQ 11725), a β-adrenergic antagonist lacking direct myocardial depressionEuropean Journal of Pharmacology, 1975