Weinreich P, Chiu A, Warsh J, Seeman P
Can J Physiol Pharmacol. 1981 Nov;59(11):1170-7. doi: 10.1139/y81-180.
Binding of the alpha-adrenergic agonist [3H]clonidine and the alpha-adrenergic antagonist [3H]WB-4101 exhibited multiple binding site characteristics in both rat frontal cortex and cerebellum. Kinetic analysis of the dissociation of both radioligands in rat frontal cortex suggests two high affinity sites for each ligand. Competition of various noradrenergic agonists and antagonists for [3H]WB-4101 binding yielded shallow competition curves, with Hill coefficients ranging from 0.45 to 0.7. This further suggests multiplicity in [3H]WB-4101 binding. In the rat cerebellum, competition of various noradrenergic drugs for [3H]clonidine binding yielded biphasic competition curves. Furthermore Scatchard analysis of [3H]clonidine binding in rat cerebellum showed two high affinity sites with KD = 0.5 nM and 1.9 nM, respectively. Competition of various noradrenergic drugs for [3H]WB-4101 binding in the rat cerebellum yielded biphasic competition curves. Lesioning of the dorsal bundle with 6-hydroxydopamine did not significantly affect the binding of either [3H]clonidine or [3H]WB-4101. These findings for both [3H]clonidine and [3H]WB-4101 binding in rat frontal cortex and cerebellum can be explained by the existence of postsynaptic binding sites for both 3H ligands.
α-肾上腺素能激动剂[³H]可乐定和α-肾上腺素能拮抗剂[³H]WB-4101在大鼠额叶皮质和小脑中均表现出多个结合位点特征。对大鼠额叶皮质中两种放射性配体解离的动力学分析表明，每种配体都有两个高亲和力位点。各种去甲肾上腺素能激动剂和拮抗剂对[³H]WB-4101结合的竞争产生了浅竞争曲线，希尔系数范围为0.45至0.7。这进一步表明[³H]WB-4101结合存在多样性。在大鼠小脑中，各种去甲肾上腺素能药物对[³H]可乐定结合的竞争产生了双相竞争曲线。此外，对大鼠小脑[³H]可乐定结合的Scatchard分析显示有两个高亲和力位点，KD分别为0.5 nM和1.9 nM。各种去甲肾上腺素能药物对大鼠小脑[³H]WB-4101结合的竞争产生了双相竞争曲线。用6-羟基多巴胺损毁背束对[³H]可乐定或[³H]WB-4101的结合均无显著影响。大鼠额叶皮质和小脑中[³H]可乐定和[³H]WB-4101结合的这些发现可以通过两种³H配体的突触后结合位点的存在来解释。
