多巴胺1和多巴胺2受体激动剂对兔冠状动脉和肾动脉cAMP生成量影响的对比研究

目的： 对比研究多巴胺１（ＤＡ１） 和多巴胺２（ＤＡ２） 受体激动剂对兔冠状动脉和肾动脉ｃＡＭＰ生成量的影响。方法： 以ｃＡＭＰ生成量为生化指标，观察了ＤＡ１ 及ＤＡ２ 受体激动剂对兔冠状动脉及肾动脉ＡＣ活性的影响。结果： 发现ＤＡ１ 受体激动剂Ｆｅｎｏｌｄｏｐａｍ（ＦＯＤＡ） 及ＤＡ２ 受体激动剂Ｎ ｎ ｐｒｏｐｙｌ Ｎ ｎ ｂｕｔｙｌｄｏｐａｒｎｉｎｅ（ＰＢＤＡ） 均可剂量依赖性增加冠状动脉及肾动脉ｃＡＭＰ的生成量。然而，肾动脉ｃＡＭＰ的生成量均显著高于冠状动脉ｃＡＭＰ 的生成量，选择性ＤＡ１ 受体阻断剂ＳＣＨ２３３９０ 能够阻断ＦＯＤＡ及ＰＢＤＡ所引起的ｃＡＭＰ生成量的增加，而ＤＡ２ 受体阻断剂ｄｏｍｐｅｒｉｄｏｎｅ 则对ＰＢＤＡ 的这一作用没有影响。心得安阻断β受体后，ＦＯＤＡ仍可显著增加ｃＡＭＰ的生成量，但增加的程度却明显降低。结论： 兔肾动脉及冠状动脉上都存在有刺激ＡＣ活性的ＤＡ１ 受体，但冠状动脉ＤＡ１ 受体的位点数比肾动脉ＤＡ１ 位点数要少得多；冠状动脉ＤＡ１ 受体的作用比肾动脉要弱。

Effects of dopamine 1 and dopamine 2 receptor agonists on the cAMP generating system in rabbit coronary and renal arteries

Objective: The purpose of this study is to reserch the effects of D 1 and D 2 receptor agonists on rabbit coronary and renal arteries.Methods: cAMP content were measured as a biomedical index of DA receptor function. Results: It was found that both the selective D 1 receptor agonist, fenoldopam, and the D 2 receptor agonist, propyl propyl butyl doparnine(PBDA), induced a dose related increases in cAMP formation in coronary and renal arteries; however, the magnitude of increase in the renal artery was remarkably greater than that in the coronary artery. The stimulator effect on AC activity of fenoldopam was significanly more potent than that of PBDA. The selective D 1 receptor antagonist, SCH 23390, blocked fenoldopam and PBDA induced cAMP production, while the selective D 2 receptor antagonist, domperidone, was without effect on the increase of cAMP elicited by PBDA. After β adrenergic blockade with propranolol, fenoldopam still increased the cAMP level significantly but to a much lesser degree.Conclusion: The existence of postsynaptic D 2 receptors associated with stimulation of AC activity in both renal and coronary arteries. However, there are much fewer receptor sites in the coronary artery than in the renal atrery, suggesting less physiological importance of such receptors in the coronary artery than in the renal artery.