BINDING OF I-125-LABELED CYANOPINDOLOL TO BETA-1-ADRENOCEPTORS IN A HIGH AND LOW AFFINITY STATE
D HOYER, G ENGEL
JOURNAL OF RECEPTOR RESEARCH | MARCEL DEKKER INC | Published : 1983
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.