title: Binding to alpha-adrenergic receptors: differential pharmacological potencies and binding affinities of benzodioxanes.
abstract: We have compared the influence of a series of benzodioxane alpha-adrenergic antagonists on 3H-WB-4101 and 3H-clonidine binding to alpha-receptor sites in the brain and peripheral tissues with their pharmacological properties. The drug specificity of 3H-WB-4101 binding is quite similar in central and peripheral tissues. Pharmacological potencies of benzodioxanes at postsynaptic alpha-receptors in the rat vas deferens correlate with potencies at 3H-WB-4101 but not at 3H-clonidine binding sites. These findings suggest pharmacological effects of these drugs are mediated by "alpha-1 postsynaptic receptors" labeled by 3H-WB-4101. For several benzodioxanes absolute pharmacological potencies at postsynaptic alpha-receptors of the rat vas deferens are substantially less than their potencies at 3H-WB-4101 sites. The potencies of benzodioxane analogues at 3H-clinidine binding sites are similar to their pharmacological potencies at presynaptic autoreceptors in the rat vas deferens.
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism; D003000:Clonidine / Q000494:pharmacology; D006892:Hydroxydopamines / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009638:Norepinephrine / Q000378:metabolism; D010880:Piperidines / Q000378:metabolism*; D010883:Piperoxan / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D011941:Receptors, Adrenergic / Q000378:metabolism*; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D013574:Synaptosomes / Q000378:metabolism
chemical_list: D006892:Hydroxydopamines; D010880:Piperidines; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D010883:Piperoxan; D003000:Clonidine; D009638:Norepinephrine