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Pharmacological characterization of α 1 ‐adrenoceptor subtypes in the bovine tail artery
Author(s) -
Ioudina M. V.,
Dyer D. C.
Publication year - 2002
Publication title -
journal of veterinary pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.527
H-Index - 60
eISSN - 1365-2885
pISSN - 0140-7783
DOI - 10.1046/j.1365-2885.2002.00414.x
Subject(s) - prazosin , phenylephrine , agonist , contraction (grammar) , antagonist , medicine , endocrinology , chemistry , adrenergic receptor , adrenergic , pharmacology , receptor , blood pressure
Ioudina, M. V., Dyer, D. C. Pharmacological characterization of α 1 ‐adrenoceptor subtypes in the bovine tail artery. J. vet. Pharmacol. Therap . 25, 363–369. The purpose of this study was to identify the α 1 ‐adrenoreceptor subtypes present in the bovine tail artery which mediate contractions to adrenergic agonists. A61603, an α 1A ‐selective agonist, was more potent compared with norepinephrine and phenylephrine. The p K A value of A61603 was 6.93 ± 0.19 μM ( n =6). Antagonists, BMY 7378, WB 4101 and 5‐methylurapidil, caused a parallel shift to the right of the concentration–response curve to A61603 with pA 2 values of 6.62, 9.27 and 8.86, respectively. Prazosin, BMY 7378 and WB 4101 inhibited phenylephrine induced contraction with pA 2 values of 9.47, 7.17 and 9.73, respectively. The pA 2 values obtained for 5‐methylurapidil, WB 4101, BMY 7378 and prazosin against α 1 ‐adrenoceptor agonists were significantly correlated with p K i values (Zhu, Zhang & Han, 1997, Eur. J. Pharmacol. 329, 55–61) for the cloned α 1a ‐adrenoceptor but not with the cloned α 1b ‐ or α 1d ‐adrenoceptor. BMY 7378, a selective α 1D ‐adrenoceptor antagonist, was significantly more potent against the nonsubtype selective agonist phenylephrine than to A61603. Chloroethylclonidine (50 μ M for 10 min) did not affect contractile responses to A61603, but caused a significant inhibition of contractile responses to phenylephrine. In conclusion, it appears that α 1A ‐ and α 1D ‐adrenoceptors play a role in adrenergic mediated contraction in the bovine tail artery.