Increased Affinity and Preference of Halogenated Derivatives of BE 2254 for a1-Adrenoceptors Demonstrated by Functional and Binding Experiments: PDF OnlyIncreased Affinity and Preference of Halogenated Derivatives of BE 2254 for α1-Adrenoceptors Demonstrated by Functional and Binding ExperimentsSchlicker, E.*; Brodde, O.-E.†; Göthert, M.*; Schaperdoth, M.†Author Information Received May 16, 1984; revision accepted July 13, 1984. Address correspondence and reprint requests to Dr. Göthert at Department of Pharmacology, University of Essen, Hufeland-strasse 55, D-4300 Essen 1, F.R.G. *Department of Pharmacology and †Division of Renal and Hypertensive Diseases, Medizinische Klinik und Poliklinik, University of Essen, Essen, F.R.G. Journal of Cardiovascular Pharmacology: November 1984 - Volume 6 - Issue 6 - p 1238-1244 Free Abstract Summary: The effects of congeners of BE 2254 (2-[β-(4′-hydroxyphenyl)-ethyl-aminomethyl]-tetralone), an α1-adrenoceptor antagonist, were compared in functional and binding experiments. In detail, we studied the effects of the compounds on the electrically evoked 3H overflow (α2-adrenoceptor-mediated) and on the evoked contractions (α1-adrenoceptor-mediated) of strips from rabbit pulmonary artery preincubated with [3H]noradrenaline as well as their effects on [3H]yohimbine binding to human platelet membranes (α2-adrenoceptors) and [3H]prazosin binding to rat liver plasma membranes (α1-adrenoceptors). The potencies of the drugs at the presynaptic α2-adrenoceptors of the rabbit pulmonary artery and their affinities for [3H]yohimbine binding sites of human platelets were closely correlated. The same held true for their potencies at the postsynaptic α1-adrenoceptors of the rabbit pulmonary artery and their affinities for [3H]prazosin binding sites of rat hepatic membranes. Compared with the parent compound, the monohalogenated derivatives of BE 2254 (i.e., the 3′-I, 3′-Br, and 3′-Cl analogues) exhibited an even higher affinity (equal to that of prazosin) and a higher selectivity for α1-adrenoceptors (inferior to that of prazosin, but similar to that of corynanthine). © Lippincott-Raven Publishers.