title: Binding of 125I-cyanopindolol to beta-1-adrenoceptors in a high and low affinity state.
abstract: Investigation of binding properties of (+), (-) and (+/-) 125Iodocyanopindolol (ICYP) to beta 1-adrenoceptors of guinea pig left ventricle membranes revealed that these radioligands bind to receptors in a high and low affinity state which is not influenced by guanylnucleotides. The contribution of the (+)enantiomer to the binding of the racemic ligand at low receptor concentrations can be neglected since the dissociation time courses of (+/-) and (-) ICYP are identical. The existence of two affinity states of beta-adrenoceptors interacting with the antagonist ICYP was evident from 1: biphasic dissociation kinetics and 2: from curvilinear Scatchard plots.
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D020120:Iodocyanopindolol; D007700:Kinetics; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism; D010869:Pindolol / Q000031:analogs & derivatives* / Q000378:metabolism; D011941:Receptors, Adrenergic / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*
chemical_list: D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D006165:Guanylyl Imidodiphosphate; D020120:Iodocyanopindolol; D010869:Pindolol