Abstract
The adrenergic blocking agents tolazoline, phentolamine, piperoxan, yohimbine, phenoxybenzamine, bretylium and guanethidine block the excitatory actions both of cholinergic nerves and of added acetylcholine on a variety of vertebrate smooth muscle preparations. These cholinergic blocking actions often occurred with concentrations lower than those required to block the response of the guinea-pig vas deferens to stimulation of the adrenergic hypogastric nerve. The anti-acetylcholine activities of these drugs have been studied in detail, using the guinea-pig rectum and the toad bladder as test organs. In preparations sensitive to eserine, the anticholinesterase actions of the drugs competed with their anti-acetylcholine actions, so that either potentiation or block of responses to acetylcholine and to cholinergic nerve stimulation occurred with different concentrations. The responses of the toad bladder to acetylcholine were not potentiated by eserine. This enabled the antagonism of acetylcholine by the anti-adrenergic drugs to be estimated without interference from their anticholinesterase activity. When blocking activity was assessed on guinea-pig rectum previously treated with dyflos, the results were qualitatively similar to those on the toad bladder. Phenoxybenzamine often completely blocks responses both to added acetylcholine and to cholinergic nerve stimulation in concentrations less than those required to block adrenergic nerves. Guanethidine and piperoxan also show strong cholinergic blocking activity. Bretylium, yohimbine, tolazoline and phentolamine were less potent. However, in concentrations required to block the effect on the vas deferens of hypogastric nerve stimulation, these drugs at least halved the effects of acetylcholine and often of cholinergic nerve stimulation. It is concluded that these adrenergic blocking agents cannot be used to distinguish conclusively between adrenergic and cholinergic nerves. For reliable analysis of autonomic innervation, the substances released upon nerve stimulation must be identified by specific biochemical techniques or bioassay.
Full text
PDFSelected References
These references are in PubMed. This may not be the complete list of references from this article.
- ASHFORD A., PENN G. B., ROSS J. W. Cholinergic activity of atropine. Nature. 1962 Mar 17;193:1082–1083. doi: 10.1038/1931082b0. [DOI] [PubMed] [Google Scholar]
- BOURA A. L., GREEN A. F. The actions of bretylium: adrenergic neurone blocking and other effects. Br J Pharmacol Chemother. 1959 Dec;14:536–548. doi: 10.1111/j.1476-5381.1959.tb00961.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- BULBRING E. Measurements of oxygen consumption in smooth muscle. J Physiol. 1953 Oct;122(1):111–134. doi: 10.1113/jphysiol.1953.sp004983. [DOI] [PMC free article] [PubMed] [Google Scholar]
- BURN J. H. A new view of adrenergic nerve fibres, explaining the action of reserpine, bretylium, and guanethidine. Br Med J. 1961 Jun 10;1(5240):1623–1627. doi: 10.1136/bmj.1.5240.1623. [DOI] [PMC free article] [PubMed] [Google Scholar]
- BURNSTOCK G. Membrane potential changes associated with stimulation of smooth muscle by adrenalin. Nature. 1960 May 28;186:727–728. doi: 10.1038/186727b0. [DOI] [PubMed] [Google Scholar]
- Brandon K. W., Rand M. J. Acetylcholine and the sympathetic innervation of the spleen. J Physiol. 1961 Jun;157(1):18–32. doi: 10.1113/jphysiol.1961.sp006702. [DOI] [PMC free article] [PubMed] [Google Scholar]
- DUMONT L. L'innervation cholinergique du muscle vésical. C R Hebd Seances Acad Sci. 1954 Jul 12;239(2):194–196. [PubMed] [Google Scholar]
- FURCHGOTT R. F. Dibenamine blockade in strips of rabbit aorta and its use in differentiating receptors. J Pharmacol Exp Ther. 1954 Jul;111(3):265–284. [PubMed] [Google Scholar]
- GARRY R. C., GILLESPIE J. S. The responses of the musculature of the colon of the rabbit to stimulation, in vitro, of the parasympathetic and of the sympathetic outflows. J Physiol. 1955 Jun 28;128(3):557–576. doi: 10.1113/jphysiol.1955.sp005325. [DOI] [PMC free article] [PubMed] [Google Scholar]
- KOSTERLITZ H. W., LEES G. M. Action of bretylium on the isolated guinea-pig ileum. Br J Pharmacol Chemother. 1961 Aug;17:82–86. doi: 10.1111/j.1476-5381.1961.tb01106.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- STONE C. A., LOEW E. R. Specificity and potency of aryl-haloalkylamine adrenergic blocking drugs as determined on isolated seminal vesicles of guinea pigs. J Pharmacol Exp Ther. 1952 Oct;106(2):226–234. [PubMed] [Google Scholar]
- URSILLO R. C. Investigation of certain aspects of atropine-resistant nerve effects. J Pharmacol Exp Ther. 1961 Feb;131:231–236. [PubMed] [Google Scholar]
- VARAGIC V. An isolated rabbit hypogastric-nerve-uterus preparation, with observations on the hypogastric transmitter. J Physiol. 1956 Apr 27;132(1):92–99. doi: 10.1113/jphysiol.1956.sp005504. [DOI] [PMC free article] [PubMed] [Google Scholar]
- WILLEY G. L. Some pharmacological actions of choline 2:6-xylyl ether bromide. Br J Pharmacol Chemother. 1957 Mar;12(1):128–132. doi: 10.1111/j.1476-5381.1957.tb01374.x. [DOI] [PMC free article] [PubMed] [Google Scholar]