title: [Importance of radioreceptor assays in determining the mechanism of action of hypotensive alpha-adrenergic compounds].
abstract: In rat central nervous system, 3H-prazosin and 3H-clonidine bind to two different classes of alpha-adrenoceptors: - 3H-prazosin binds to alpha1-adrenoceptors with high affinity (KD 25 degrees C = 0.30 nM) with a number of binding sites of 81.6 fmoles/mg of protein. -3H-clonidine binds to alpha 2-adrenoceptors with high affinity (KD 25 degrees C - 2.1 nM) with a number of binding sites of 190.0 fmoles/mg of protein. The radioreceptor assay may help to determine rapidly in vitro the neurochemical profile of new antihypertensive compounds. Thus S3341 will exert its hypotensive action at the level of alpha 2-adrenoceptors as clonidine (Catapressan*) but with a specificity 2-3 times greater.
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000378:metabolism / Q000494:pharmacology*; D003000:Clonidine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011869:Radioligand Assay; D051381:Rats; D011941:Receptors, Adrenergic / Q000378:metabolism*; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology
chemical_list: D000959:Antihypertensive Agents; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D003000:Clonidine; D011224:Prazosin
vernacular_title: Intérĕt du radiorécepteur essai pour préciser le mécanisme d'action des composés alpha-adrénergiques hypotenseurs.