Biphasic Binding of ^<125>I-Iodocyanopindolol to β-Adrenergic Receptors in Rat Cerebral Cortical Membranes. I. Assessment by the Use of Agonists(Pharmacological)

概要

論文の詳細を見る
When saturation binding studies of β-adrenoceptors in rat brain with ^<125>I-iodocyanopindolol (^<125>I-ICYP) were carried out by means of radioligand binding assay, the Scatchard plots showed a biphasic character. The addition of guanosine triphosphate (GTP, 3×10^<-4>M) had no effect on the biphasic character. The inhibition constants of various ligands for the high- and low-affinity sites of ^<125>I-ICYP binding were determined from the biphasic Scatchard plots. Competition by the agonists at the high-affinity sites was in the order of I-isoproterenol>I-epinephrine>I-norepinephrine, whereas at the low-affinity sites, the order was I-isoproterenol>I-epinephrine = I-norepinephrme. The specificities of the agonists for the high- and low-affinity sites were high = low (I-isoproterenol), high > low (I-epinephrine), or high < low (I-norepinephrine). These results suggest that two distinct types of β-adrenoceptor sites can be differentiated in rat cerebral cortical membranes.
社団法人日本薬学会の論文
1987-07-25