[3H]p-Aminoclonidine binding to multiple alpha 2-adrenoceptor sites in homogenates of cat frontal cortex and cat spinal cord.
[3H]p-Aminoclonidine binding to multiple alpha 2-adrenoceptor sites in homogenates of cat frontal cortex and cat spinal cord.
复制标题
[3H]p-氨基可乐定与猫额叶皮质和猫脊髓匀浆中的多个 α2-肾上腺素受体位点结合。
DOI：
10.1016/0014-2999(84)90058-x
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发表时间：
1984
影响因子：
5
通讯作者：
Yaksh,TL
中科院分区：
文献类型：
--
作者：
Howe,JR;Yaksh,TL
我们研究了[~ 3 H] p-氨基可乐定与猫额叶皮质和猫脊髓匀浆结合的特性。在37°C下，可饱和的[3 H]对氨基可乐定结合显示出快速缔合和解离动力学。从任一组织获得的数据的Scatchard图始终是双相的。采用基于单配体/双结合位点模型的计算机辅助非线性最小二乘回归分析将这些图解析为两个线性分量。该分析的结果表明，对于任一组织的匀浆，[3 H] p-氨基可乐定与高亲和力结合位点和低亲和力结合位点结合的KD分别约为0.5 nM和9 nM。平均Bmax值（fmol/mg蛋白质），分别为28和149的猫额叶皮质匀浆和7.1和56的猫脊髓匀浆的高和低亲和力结合位点。使用0.13 nM [3 H] p-氨基可乐定的竞争性抑制实验结果表明，儿茶酚胺以立体选择性方式竞争[3 H] p-氨基可乐定结合位点，这些位点具有α2-肾上腺素受体的药理学特征。竞争数据的Hill分析结果表明，α2肾上腺素受体激动剂和α2肾上腺素受体拮抗剂对这两个结合位点具有选择性亲和力。这两个可饱和的[3 H] p-氨基可乐定结合位点群似乎与α2-肾上腺素受体的“超高”和“高”亲和力状态的α 2-肾上腺素受体配体结合位点相对应。
We have investigated the characteristics of [3H]p-aminoclonidine binding to homogenates of cat frontal cortex and of cat spinal cord. At 37°C, saturable [3H]p-aminoclonidine binding displayed rapid association and dissociation kinetics. Scatchard plots of data obtained from either tissue were consistently biphasic. Computer-assisted nonlinear least squares regression analysis based upon a one ligand/two binding site model was employed to resolve these plots into two linear components. The results of this analysis indicate that, for homogenates of either tissue, the KDof [3H]p-aminoclonidine binding, to the high and low affinity binding sites respectively, is approximately 0.5 nM and 9 nM. Mean Bmaxvalues (fmol/mg protein), for the high and low affinity binding sites respectively, of 28 and 149 for homogenates of cat frontal cortex and 7.1 and 56 for homogenates of cat spinal cord were obtained. The results of competitive inhibition experiments, where 0.13 nM [3H]p-aminoclonidine was used, indicate that catecholamines compete for [3H]p-aminoclonidine binding sites in a stereoselective fashion, and that these sites possess a pharmacology characteristic ofα2-adrenoceptors. The results of Hill analysis of the competition data suggest thatα2-adrenoceptor agonistsandα2-adrenoceptor antagonists possess selective affinity for these twoα2-adrenoceptor binding sites. The two populations of saturable [3H]p-aminoclonidine binding sites appear to correspond to thoseα2-adrenoceptor ligand binding sites that have been referred to as the ‘super high’ and ‘high’ affinity state of theα2-adrenoceptors.