Abstract
The effects of some agonists on isolated preparations of guinea-pig ileum, atria and bronchial muscle have been compared with those of carbachol. The concentrations producing comparable responses were used to estimate the equipotent molar ratio relative to carbachol. Arecaidine propargyl ester was 4 to 5 times as active as carbachol on the ileum but more than 10 times as active as carbachol on atrial rate or atrial force, so the results confirm that this compound has a 2 to 3 fold selectivity for receptors in atria. Ethoxyethyltrimethylammonium iodide was one-quarter to one-third as active as carbachol on ileum but only one-tenth as active as carbachol on atrial rate or atrial force and so shows a 3 to 4 fold selectivity for receptors in ileum. The other compounds tested, which included acetylcholine, methacholine, n-pentyltrimethyl-ammonium iodide and bethanechol showed less selectivity. There were no obvious differences between effects on atrial rate and effects on atrial force, though with esters it was often difficult to obtain effects on atrial rate in the absence of an inhibitor of cholinesterase. Activity on bronchial muscle was generally similar to activity on ileum.
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- Barlow R. B., Burston K. N., Vis A. Three types of muscarinic receptors? [proceedings]. Br J Pharmacol. 1980 Jan;68(1):141P–142P. [PMC free article] [PubMed] [Google Scholar]
- Barlow R. B., Franks F. M., Pearson J. D. A comparison of the affinities of antagonists for acetylcholine receptors in the ileum, bronchial muscle and iris of the guinea-pig. Br J Pharmacol. 1972 Oct;46(2):300–312. doi: 10.1111/j.1476-5381.1972.tb06875.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Barlow R. B., Kitchen R. The actions of some esters of 4-hydroxyquinuclidine on guinea-pig ileum, atria and rat fundus strip. Br J Pharmacol. 1982 Nov;77(3):549–557. doi: 10.1111/j.1476-5381.1982.tb09330.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Barlow R. B., Shepherd M. K. A search for selective antagonists at M2 muscarinic receptors. Br J Pharmacol. 1985 Jun;85(2):427–435. doi: 10.1111/j.1476-5381.1985.tb08878.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hammer R., Giachetti A. Muscarinic receptor subtypes: M1 and M2 biochemical and functional characterization. Life Sci. 1982 Dec 27;31(26):2991–2998. doi: 10.1016/0024-3205(82)90066-2. [DOI] [PubMed] [Google Scholar]
- ING H. R., KORDIK P., WILLIAMS D. P. H. T. Studies on the structure-action relationships of the choline group. Br J Pharmacol Chemother. 1952 Mar;7(1):103–116. doi: 10.1111/j.1476-5381.1952.tb00696.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mutschler E., Hultzsch K. Uber Struktur-Wirkungs-Beziehungen von ungesättigten Estern des Arecaidins und Dihydroarecaidins. Arzneimittelforschung. 1973 May;23(5):732–737. [PubMed] [Google Scholar]
- ROSZKOWSKI A. P. An unusual type of sympathetic ganglionic stimulant. J Pharmacol Exp Ther. 1961 May;132:156–170. [PubMed] [Google Scholar]