阴茎海绵体α1-肾上腺素受体亚型的实验研究

目的研究兔阴茎海绵体α１肾上腺素受体（α１ＡＲ）三种亚型的分布及其介导的收缩效应。方法采用放射配基结合实验和离体组织收缩功能实验。结果在放射配基结合实验中,标本经氯乙基可乐定（ＣＥＣ）预处理后,１２５ＩＢＥ与α１ＡＲ最大结合容量（Ｂｍａｘ）由７４６±２３６ｆｍｏｌ／ｍｇ蛋白下降至２１４±７１ｆｍｏｌ／ｍｇ蛋白（Ｐ＜００１）。α１ＡＲ选择性拮抗剂竞争抑制曲线经两位点分析显示,α１Ａ、α１ＤＡＲ和α１ＢＡＲ分别约占２０％、２５％、５５％。在收缩功能实验中,标本经用ＣＥＣ预处理后,去甲肾上腺素（ＮＥ）介导的最大收缩无明显下降,α１ＡＲ亚型选择性拮抗剂５ＭＵ和ＢＭＹ７３７８抑制ＮＥ介导阴茎海绵体收缩的拮抗指数（ｐＡ２）值与克隆α１ＡＡＲ亚型的解离常数（ＫＩ）值相符合。结论在兔阴茎海绵体中α１ＡＲ三种亚型均有分布,但功能性α１ＡＲ则以α１ＡＡＲ为主。

Alpha1-adrenoceptor subtypes in rabbit penile corpus cavernosum

OBJECTIVE: To study alpha(1)- adrenoceptor (alpha(1)- AR) subtypes with the functional role and the distribution of its subtypes in rabbit penile corpus cavernosum. METHOD: The rabbit penile corpus cavernosum was studied by using functional experiment and radioligand binding assay. RESULT: In the radioligand binding assay, the maximal binding capacity (Bmax of (125)IBE and alpha(1)-AR) decreased obviously after pretreatment with chloroethylclonidine (CEC), which were 746 +/- 236 fmol/mg protein and 214 +/- 71 fmol/mg protein, respectively. Alpha(1A)-, alpha(1D)-and alpha(1B)-AR took about 20%, 25% and 55%, respectively. In the functional experiments, the maximal contraction induced by norepinephrine (NE) was not decreased significantly after pretreatment with CEC. The pA(2) values of two alpha(1)-AR selective antagonists, 5-MU, BMY7378, for antagonizing NE-induced penile corpus cavernosum contraction had a high correlative association with the pK(I) values for cloned alpha(1A)-AR. CONCLUSION: The functional alpha(1)-AR subtype is alpha(1A)-AR although there are three subtypes in the penile corpus cavernosum.