Nissenson R A, Flouret G, Hechter O
Biochim Biophys Acta. 1980 Mar 3;628(2):209-19. doi: 10.1016/0304-4165(80)90368-2.
The present study investigated whether specific [3H]oxytocin binding sites previously demonstrated in estrogen-dominated rabbit uterus have properties expected of physiologic receptors coupled to uterine contraction. Microsomal membranes from estrogen-dominated rabbit uterus were found to contain high-affinity specific oxytocin binding sites with Kd = 2-3 nM. These sites were predominantly myometrial in locus. Specific oxytocin binding exhibited a pH optimum between 7.5 and 8.0. Mg2+ or Mn2+ was necessary for maximal specific [3H]oxytocin binding; in contrast, Ca2+ at submillimolar concentrations inhibited specific binding. Oxytocin binding sites were not detectable in microsomal membranes isolated from progesterone-dominated rabbit uterus. Relative binding and uterotonic activities of 10 synthetic neurohypophyseal hormone analogues were determined in estrogen-dominated rabbit uterus. A qualitative correlation was observed between binding and uterotonic responses. Angiotensin II and insulin did not compete with [3H]oxytocin for uterine binding sites. It is concluded that the specific high affinity [3H]oxytocin binding sites demonstrated in estrogen-dominated rabbit uterus have the selectivity for neurohypophyseal hormone analogues expected for physiologic receptors coupled to uterine contraction.
本研究调查了先前在雌激素占主导的兔子宫中所证实的特异性[3H]催产素结合位点是否具有与子宫收缩相关的生理受体所预期的特性。发现来自雌激素占主导的兔子宫的微粒体膜含有高亲和力的特异性催产素结合位点，解离常数（Kd）为2 - 3 nM。这些位点主要位于子宫肌层。特异性催产素结合在pH值7.5至8.0之间表现出最佳状态。Mg2+或Mn2+是最大特异性[3H]催产素结合所必需的；相反，亚毫摩尔浓度的Ca2+会抑制特异性结合。在从孕激素占主导的兔子宫分离的微粒体膜中未检测到催产素结合位点。测定了10种合成神经垂体激素类似物在雌激素占主导的兔子宫中的相对结合和子宫收缩活性。观察到结合与子宫收缩反应之间存在定性相关性。血管紧张素II和胰岛素不与[3H]催产素竞争子宫结合位点。得出的结论是，在雌激素占主导的兔子宫中所证实的特异性高亲和力[3H]催产素结合位点对神经垂体激素类似物具有与子宫收缩相关的生理受体所预期的选择性。
