Interaction of Clonidine and Clonidine Analogues with α‐Adrenergic Receptors of Neuroblastoma × Glioma Hybrid Cells and Rat Brain
Interaction of Clonidine and Clonidine Analogues with α‐Adrenergic Receptors of Neuroblastoma × Glioma Hybrid Cells and Rat Brain
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可乐定和可乐定类似物与神经母细胞瘤×胶质瘤杂交细胞和大鼠脑的α-肾上腺素能受体的相互作用
DOI：
10.1111/j.1432-1033.1981.tb05094.x
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发表时间：
1981
期刊：
影响因子：
5.4
通讯作者：
S. Sabol
中科院分区：
文献类型：
--
作者：
D. Atlas;S. Sabol
可乐定和几种可乐定类似物在配体结合和腺苷酸环化酶抑制的比较研究中被证明是α2-肾上腺素能受体的有用探针。本文报道了一种新的α-肾上腺素能探针N-（4-羟基苯乙酰基）-4-氨基可乐定盐酸盐的性质。[3 H]可乐定与NG 108 -15神经母细胞瘤×神经胶质瘤杂交细胞膜的α受体结合，推定的高亲和力和低亲和力位点的Kd值分别为1.7和33 nM。p-氨基可乐定和羟基苯乙酰氨基可乐定取代[3 H]可乐定从高亲和力网站的Kd值分别为2.3和5.8 nM。大鼠脑α2-受体对可乐定、对氨基可乐定和羟苯乙酰氨基可乐定也表现出高亲和力，这通过特异性结合的[3 H]可乐定的置换来确定。可乐定、对氨基可乐定和羟苯乙酰氨基可乐定通过与α2-受体相互作用（Kd，app分别为300、50和130 nM）对NG 108 -15腺苷酸环化酶产生适度抑制（高达24%）;这些化合物还部分逆转了（-）-去甲肾上腺素引起的抑制。
腺苷酸环化酶试验混合物的组分，特别是ATP、GTP、钠离子和核苷三磷酸再生系统，可降低[3 H]可乐定与NG 108 -15膜的高亲和力结合;在存在这些组分的情况下，α受体对[3 H]可乐定仅具有低亲和力（Kd 43 nM）。这些结果与受体介导的腺苷酸环化酶抑制所需的某些组分将α2受体从高亲和力非活性状态转化为低亲和力活性状态的概念一致。
Clonidine and several analogues of clonidine are shown to be useful probes for α2-adrenergic receptors in a comparative study of ligand binding and inhibition of adenylate cyclase. The α-adrenergic properties of a new potential probe, N-(4-hydroxyphenacetyl)-4-aminoclonidine hydrochloride, are described. [3H]Clonidine binds to α-receptors of NG108-15 neuroblastoma × glioma hybrid cell membranes with Kd values of 1.7 and 33 nM for putative high-affinity and low-affinity sites, respectively. p-Aminoclonidine and hydroxyphenacetyl aminoclonidine displace [3H]clonidine from the high-affinity sites with Kd values of 2.3 and 5.8 nM, respectively. Rat brain α2-receptors also exhibit high affinity toward clonidine, p-aminoclonidine, and hydroxyphenacetyl aminoclonidine, as determined by displacement of specifically bound [3H]clonidine. Clonidine, p-aminoclonidine, and hydroxyphenacetylaminoclonidine elicit modest inhibition (up to 24%) of NG108-15 adenylate cyclase by interaction with α2-receptors (Kd,app 300, 50, and 130 nM, respectively); these compounds also partially reverse the inhibition elicited by (–)-norepinephrine.
Components of the adenylate cyclase assay mixture, particularly ATP, GTP, sodium ions, and a nucleoside-triphosphate-regenerating system, decrease the high-affinity [3H)clonidine binding to NG108-15 membranes; in the presence of these components, α-receptors possess only low affinity (Kd 43 nM) for [3H]clonidine. These results are consistent with the concept that certain components required for the receptor-mediated inhibition of adenylate cyclase convert α2-receptors from a high-affinity inactive state to a low-affinity active state.