Pharmacological pleiotropism of the human recombinant alpha(1A)-adrenoceptor: implications for alpha(1)-adrenoceptor classification
Pharmacological pleiotropism of the human recombinant alpha(1A)-adrenoceptor: implications for alpha(1)-adrenoceptor classification
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DOI：
10.1038/sj.bjp.0701207
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发表时间：
1997-07-01
影响因子：
7.3
通讯作者：
Clarke, DE
中科院分区：
文献类型：
--
作者：
Ford, APDW;Daniels, DV;Clarke, DE
1在药理和分子研究中已确定了三个完整的α-肾上腺素能受体(α(1A)、α(1B)和α(1D))。第四种α(1)-肾上腺素能受体，被认为是α(1L)-肾上腺素能受体，已在功能研究中被定义，但没有在分子研究中被定义，并被认为是介导人类下尿路组织的收缩；在本研究中，结合亲和力是通过稳定表达人α(1A)-、α(1B)和α(1D)-受体的中国仓鼠卵巢(CHO-KI)细胞膜匀浆中[H-3]-哌唑嗪的置换来估计的，并与通过测量去甲肾上腺素(NA)刺激的[H-3]-肌醇磷酸蓄积的抑制在相同细胞中获得的亲和力进行了比较。3对于α(1A)-肾上腺素受体，结合研究揭示了经典定义的(1A)-肾上腺素能受体的典型药理学特征。结果表明，哌唑嗪、RS-17053、WE4101、5-甲基乌拉地尔、REC15/2739和S-尼古地平均表现出亚纳摩尔亲和力。在肌醇磷酸蓄积研究中得到了不同的亲和力估计：哌唑嗪、WE4101，5-甲基乌拉地尔、RS-17053和S-尼古地平的亲和力比膜结合时低10-40倍。4相反，在CHO-K1细胞中表达的人的α(1B)和α(1D)肾上腺素受体的结果给出了拮抗剂亲和力的结合和功能分析基本上是相同的。5发现来自CHO-KI细胞的α(1A)-肾上腺素受体的功能研究(肌醇磷酸盐积累)的亲和力估计与最近发表的人类下尿路组织收缩研究(可能的α(1L)-肾上腺素受体)的估计是一致的。这些数据表明，通过功能药理学分析，克隆的α(1A)-肾上腺素能受体显示出与推测的α(1L)-肾上腺素能受体一致的药理识别特性。为什么这个谱不同于在膜结合中获得的谱，以及它是否解释了在许多天然组织中观察到的α(1L)-肾上腺素能受体药理学，需要进一步的研究。
1 Three fully-defined al-adrenoceptors (alpha(1A), alpha(1B) and alpha(1D)) have been established in pharmacological and molecular studies. A fourth alpha(1)-adrenoceptor, the putative alpha(1L)-adrenoceptor, has been defined in functional but not molecular studies, and has been proposed to mediate contraction of human lower urinary tract tissues; its relationship to the three fully characterized alpha(1)-adrenoceptors is not known.2 In the present study, binding affinities were estimated by displacement of [H-3]-prazosin in membrane homogenates of Chinese hamster ovary (CHO-KI) cells stably expressing the human alpha(1A)-, alpha(1B)- and alpha(1D)-adrenoceptors and were compared with affinity estimates obtained functionally in identical cells by measuring inhibition of noradrenaline (NA)-stimulated accumulation of [H-3]-inositol phosphates.3 For the alpha(1A)-adrenoceptor, binding studies revealed a pharmacological profile typical for the classically defined alpha(1A)-adrenoceptor, such that prazosin, RS-17053, WE 4101, 5-methylurapidil, Rec 15/2739 and S-niguldipine all displayed subnanomolar affinity. A different profile of affinity estimates was obtained in inositol phosphates accumulation studies: prazosin, WE 4101, 5-methylurapidil, RS-17053 and S-niguldipine showed 10 to 40 fold lower affinity than in membrane binding. However, affinity estimates were not 'frameshifted', as tamsulosin, indoramin and Rec 15/2739 yielded similar, high affinity estimates in binding and functional assays.4 In contrast, results from human alpha(1B)- and alpha(1D)-adrenoceptors expressed in CHO-K1 cells gave antagonist affinity profiles in binding and functional assays that were essentially identical.5 A concordance of affinity estimates from the functional (inositol phosphates accumulation) studies of the alpha(1A)-adrenoceptor in CHO-KI cells was found with estimates published recently from contractile studies in human lower urinary tract tissues (putative alpha(1L)-adrenoceptor). These data show that upon functional pharmacological analysis, the cloned alpha(1A)-adrenoceptor displays pharmacological recognition properties consistent with those of the putative alpha(1L)-adrenoceptor. Why this profile differs from that obtained in membrane binding, and whether it explains the alpha(1L)-adrenoceptor pharmacology observed in many native tissues, requires further investigation.