Open AccessCharacteristics of 125I-iodocyanopindolol binding to .BETA.-adrenergic and serotonin-1B receptors of rat brain: Selectivity of .BETA.-adrenergic agents.
Author(s) -
Hiroshi Tsuchihashi,
Yoko Nakashima,
Junji Kinami,
Takafumi Nagatomo
Publication year - 1990
Publication title -
japanese journal of pharmacology/japanese journal of pharmacology
Language(s) - English
Resource type - Journals
eISSN - 1347-3506
pISSN - 0021-5198
DOI - 10.1254/jjp.52.195
Subject(s) - iodocyanopindolol , adrenergic receptor , beta (programming language) , selectivity , adrenergic , chemistry , serotonin , receptor , adrenergic agent , pharmacology , medicine , biology , biochemistry , intrinsic activity , computer science , programming language , catalysis , agonist
The present study was designed to examine the specificity of beta-adrenergic antagonists for beta 1-, beta 2-adrenergic and 5HT1B-serotonergic receptors by the competitive interaction with 125I-iodocyanopindolol (125I-ICYP) as a radioligand. The beta 1-adrenoceptors were preferred by acebutolol, atenolol, betaxolol, practolol, and l-, dl- and d-metoprolol, while butoxamine and lCl-118,551 preferred beta 2-adrenoceptors. The selectivities of these beta 1- and beta 2-antagonists are well-known, but alprenolol which is known as a non-selective antagonist was 7.2-fold more selective for the beta 2-adrenoceptors in the present study. All beta-antagonists used were more selective towards beta-adrenoceptors as compared with 5HT1B-receptors. Good correlations were observed between the potencies of beta-adrenoceptor antagonists for inhibition of 125I-ICYP binding to beta 1- and beta 2-adrenoceptor sites and their potencies for inhibiting the binding of the same radioligand to 5HT1B-serotonergic receptor sites. These results suggest that beta-adrenoceptor antagonists can bind to beta-adrenoceptors and 5HT1B-receptors.