title: Binding of yohimbine stereoisomers to alpha-adrenoceptors in rat liver and human platelets.
abstract: 1--Displacement of tritiated prazosin binding to rat liver plasma membranes and tritiated yohimbine human platelet membranes shows that (+)-yohimbine, alloyohimbine and alpha-yohimbine (rauwolscine) are selective alpha 2-adrenoceptor antagonists (KD alpha 1/KD alpha 2:635, 46.6 and 112 respectively) whereas corynanthine is more alpha 1-selective (KD alpha 1/KD alpha 2:0.036). 2--11-Methoxy derivatives of alpha-yohimbine and epi-alpha-yohimbine are very weak alpha-adrenoceptor blockers. 3--It is concluded that the aromatic A ring, the Nb atom, and the carboxymethyl moiety are important for the binding of yohimbine to the alpha-adrenoceptor, the carboxymethyl group being important for the alpha 1/alpha 2 specificity of the molecule.
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D005260:Female; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D011224:Prazosin / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000378:metabolism*; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D015016:Yohimbine / Q000097:blood / Q000378:metabolism*
chemical_list: D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D015016:Yohimbine; D011224:Prazosin