Alpha-adrenoceptor mediated responses of the cauda epididymis of the guinea-pig

British Journal of Pharmacology
J M Haynes, S J Hill

Abstract

1. The subtypes of alpha-adrenoceptor mediating the contractile responses of the cauda epididymis of the guinea-pig were investigated. The alpha 1-adrenoceptor agonist phenylephrine, but not the alpha 2-adrenoceptor agonist, xylazine (up to 10 microM), elicited concentration-dependent contractions from preparations of cauda epididymis (EC50 3.4 microM). The L-type Ca2+ channel antagonist, nifedipine (10 microM), reduced the maximal response to phenylephrine (by 77%). Preincubation of tissues with the alpha 1B-adrenoceptor-alkylating agent, chloroethylclonidine (50 microM, 30 min), shifted phenylephrine concentration-response curves to the right (4 fold) only when the alpha 2-adrenoceptor antagonist idazoxan (100 nM) was included during the pre-incubation with chloroethylclonidine. 2. Xylazine (1 microM) significantly shifted phenylephrine concentration-response curves to the left (3 fold); this effect was attenuated by idazoxan (100 nM). Both the incubation of preparations with nifedipine (10 microM) and the pre-incubation of preparations with chloroethylclonidine (50 microM, 30 min) attenuated the potentiating effects of xylazine (1 microM). Protection of alpha 2-adrenoceptors with idazoxan (100 nM) during the chloroethylcloni...Continue Reading

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Citations

Mar 21, 2008·Cell and Tissue Research·Daniel Barboza Cava QueirózMaria Christina W Avellar
Nov 11, 1999·European Journal of Pharmacology·M A SilvaC S Porto
May 19, 1998·Trends in Pharmacological Sciences·L A Selbie, S J Hill
Aug 22, 2007·Reproduction : the Official Journal of the Society for the Study of Fertility·Marco MeweChristiane K Bauer
Feb 4, 2014·European Journal of Pharmacology·Edilson Dantas da Silva JúniorNeide H Jurkiewicz
May 1, 2021·Animals : an Open Access Journal From MDPI·Sylwia ProchowskaWojciech Niżański
Dec 16, 1998·European Journal of Pharmacology·J R Docherty
Oct 2, 2021·Pflügers Archiv : European journal of physiology·Retsu MitsuiDirk F van Helden

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