Molecular properties of the adrenergic alpha-receptors.4.Topographical and structural differences betweentissue-specific binding sites as revealedby benextramine and analogues.

Until recently, it has been tacitly assurned that the postsynaptic or alpha1-adrenoreceptors of diverse biologicat origins are phar-macologicalll,similar. Quantitative evidence is now available that significant diiffcrences may exist between alpha1-adreceptors oi differenttissues and species. We submit experimental evidence which demonstrates that the alpha-receptor binding sites of the rat vas deferensand rabbit aorta or left atrium exhibit stereochemical and structural differences. Furthermore, the topographical dualism underling the respective effects oi Benextramine and AOC on rat vas deferens apply also to rabbit aorta. In addition, the tetraminedisulfides incorporating catechol nuclei showed high potency toward the alpha1-receptors of both rat vas deferens and rabbit aorta.Optimmm actìvity was sharply associatecl on both tissues with those 3'.4'-dihydroxybenzyl ccrnpouncls having a six- and eight-carbonchains. The mechanistic and topographicat significance of this dualism is discussed