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Characterization of α 1D ‐adrenoceptor subtype in rat myocardium, aorta and other tissues
Author(s) -
Deng Xing Fei,
Chemtob Sylvain,
Varma Daya R.
Publication year - 1996
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1996.tb15981.x
Subject(s) - phenylephrine , vas deferens , medicine , prazosin , endocrinology , aorta , antagonist , chemistry , receptor , blood pressure
1 This study was done to characterize the functional role of α 1D ‐adrenoceptors in rat myocardium, aorta, spleen, vas deferens and prostate by use of the selective antagonist BMY 7378. 2 BMY 7378 inhibited [ 3 H]‐prazosin binding to aortic membranes with a potency (p K i 9.8 ± 0.40) approximately 100 fold higher than in right ventricular membranes (p K i 7.47 ± 0.11) and approximately 1,000 fold higher than that in plasma membranes of the prostate (p K i 6.62 ± 0.39), vas deferens (p K i 6.67 ± 0.15), salivary gland (p K i 6.46 ± 0.38) and liver (6.58 ± 0.06). 3 BMY 7378 antagonized the positive inotropic effects of phenylephrine (in the presence of 1 μ m propranolol) on right ventricles (pA 2 7.0 ± 0.11), left atria (p K B 7.04 ± 0.18) and papillary muscles (p K B 6.9 ± 0.1) and inhibited phenylephrine‐induced increase in inositol phosphates. 4 BMY 7378 was approximately 100 fold more potent as an antagonist of phenylephrine on aortic strips (pA 2 9.0 ± 0.13) than on vas deferens (p K B 7.17 ± 0.08) and spleen (p K B 7.16 ± 0.21); it was ineffective on the prostate. 5 Chloroethylclonidine suppressed the maximal effects of phenylephrine on spleen; 5‐methylurapidil antagonized the effects of phenylephrine on aortic strips (pA 2 7.98 ± 0.08), vas deferens (p K B 8.89 ± 0.07) and prostate (p K B 8.85 ± 0.21). 6 BMY 7378 caused a dose (0.1–100 nmol kg −1 )‐dependent decrease in mean blood pressure of urethane‐anaesthetized rats and its hypotensive efficacy was equal to that of hexamethonium. 7 The data suggest that α 1D ‐adrenoceptors play a significant role in rat aorta, a minor role in the heart, vas deferens and spleen and virtually no role in the prostate.