阴茎海绵体α_1-肾上腺素受体亚型的实验研究

α1adrenoceptor subtypes in rabbit penile corpus cavernosum

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。

Objective To study α1 adrenoceptor ( α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 α1AR) decreased obviously after pretreatment with chloroethylclonidine (CEC), which were 746±236 fmol/mg protein and 214±71 fmol/mg protein , respectively. α1A,α1Dand α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 α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 α1AAR. Conclusion The functional α1 AR subtype is α1AAR although there are three subtypes in the penile corpus cavernosum.