Jin X H, Wang W Z, Zhao R R
Department of Physiology, Shanxi Medical College, Taiyuan, Peoples Republic of China.
Methods Find Exp Clin Pharmacol. 1995 Sep;17(7):455-61.
By using radioreceptor binding techniques and [3H]SCH23390 as a ligand, a comparative study was performed on the pharmacological properties and the density of dopamine-1 (D1) receptors in different vascular systems. [3H]SCH23390 was specifically bound to membranes from rabbit renal, mesenteric and pulmonary, but not femoral, arteries. The binding was saturable and in a manner consistent with the labeling of D1 receptors. The Kd value and Hill coefficient (nH) were similar in all three arteries with no statistically significant differences (p > 0.05) among them, indicating a homogenous binding site with a single class of high affinity. In competitive binding tests, the selective D1 antagonist and agonist inhibited the binding much more potently than the D2 antagonist, indicating a pharmacological characteristic of D1 receptors. The Bmax values, however, differed considerably among these arteries, with the value being the largest in the renal artery and smallest in the pulmonary artery. These findings are indicative of the existence of D1 receptor sites with identical properties but diverse density in different vascular beds, which underlies the relative functional importance of the receptors in regulating local blood flow in distinct vessels.
利用放射受体结合技术，以[3H]SCH23390作为配体，对不同血管系统中多巴胺-1（D1）受体的药理学特性和密度进行了比较研究。[3H]SCH23390特异性结合于兔肾动脉、肠系膜动脉和肺动脉的膜，但不结合股动脉的膜。这种结合是可饱和的，并且与D1受体的标记方式一致。在所有三条动脉中，Kd值和希尔系数（nH）相似，它们之间无统计学显著差异（p>0.05），表明存在具有单一高亲和力类别的同质结合位点。在竞争性结合试验中，选择性D1拮抗剂和激动剂比D2拮抗剂更有效地抑制结合，表明具有D1受体的药理学特征。然而，这些动脉之间的Bmax值差异很大，肾动脉中的值最大，肺动脉中的值最小。这些发现表明，在不同血管床中存在性质相同但密度不同的D1受体位点，这是受体在调节不同血管局部血流中相对功能重要性的基础。
