Ahmad S, Allescher H D, Jang E, Rausa J, Daniel E E
Department of Biomedical Sciences, McMaster University, Hamilton, Ont., Canada.
Can J Physiol Pharmacol. 1991 Jun;69(6):837-40. doi: 10.1139/y91-126.
We have studied the distribution and properties of alpha 2-adrenergic receptors in the circular muscle layer (containing deep muscular plexus) of canine small intestine. Using radioactivity labelled rauwolscine, we located the binding sites to the neuronal membranes supporting the prejunctional action of alpha 2-adrenergic agents in the gut. Moreover, although the functional data to suggest the existence of postjunctional alpha 2-adrenergic receptors coupled to contraction are not available so far, we measured a substantial number of rauwolscine binding sites on the smooth muscle plasma membranes. Scatchard and Hill analyses of the saturation data were indicative of the presence of a single high affinity site (Hill coefficient 0.996) with a KD value of 8.8 nM and the maximum number of binding sites (Bmax) of 313 fmol/mg of protein. Competition studies suggested the presence of multiple subtypes of alpha 2-adrenoceptors.
我们研究了犬小肠环形肌层（含深部肌丛）中α2-肾上腺素能受体的分布及特性。我们使用放射性标记的育亨宾，将结合位点定位到支持肠道中α2-肾上腺素能药物节前作用的神经细胞膜上。此外，虽然目前尚无功能数据表明存在与收缩相关的节后α2-肾上腺素能受体，但我们在平滑肌质膜上检测到大量育亨宾结合位点。对饱和数据进行的Scatchard和Hill分析表明存在一个单一的高亲和力位点（Hill系数0.996），解离常数（KD）值为8.8 nM，最大结合位点数（Bmax）为313 fmol/mg蛋白质。竞争研究提示存在多种α2-肾上腺素能受体亚型。
