DA_1受体激动剂对兔肺动脉和肠动脉cAMP产生系统影响的研究

目的　对比分析多巴胺 1(DA1)受体激动剂非诺多泮 (fenoldopam ,FODA)对大鼠肺动脉和肠系膜动脉的影响。 方法　采用cAMP含量放射免疫测定法测定DAl 受体激动剂FODA对肺动脉和肠系膜动脉cAMP的影响。结果　FODA可剂量依赖性增加肠、肺动脉cAMP的生成量 ,然而 ,肠动脉cAMP的生成量显著高于肺动脉cAMP的生成量。选择性多巴胺 (DAl)受体阻断剂SCH - 2 3390能够阻断FODA所引起的肺动脉和肠动脉cAMP生成量增加 ,多巴胺 2 (DA2 )受体阻断剂domperi done则不影响FODA的作用。结论　兔肺动脉和肠动脉均存在有刺激腺苷酸环化酶 (AC)活性的DAl 受体。但肺动脉DAl 受体的位点数明显少于肠动脉DAl 受体位点数 ,从而提示肺动脉DAl 受体的生理作用弱于肠动脉。

Comparison of the effects of fenoldopam on the cAMP generating system in rabbit mesenteric and pulmonary arteries

Objective To evaluate and compare the effects of DA 1 receptor agonist, fenoldopam, on rabbit pulmonary and mesenteric arteries. Methods Radioimmunoassay was used for determining the effects of fenoldopam on the cAMP generating system in rabbit mesenteric and pulmonary arteries. Results The selective DA 1 receptors agonist, fenoldopam, induced a dose related increase of cAMP formation in mesenteric and pulmonary arteries; however, the magnitude of increase in the mesenteric artery was remarkably greater than that in the pulmonary artery. The selective DA 1 receptors antagonist, SCH 23390, blocked fenoldopam induced cAMP production, while the selective DA 2 receptors antagonist, domperidone, was without effect on the increase of cAMP elicited by fenoldopam. Conclusion The presence of DA 1 receptors is associated with stimulation of AC activity in both mesenteric and pulmonary arteries. However, there are much fewer receptor sites in the pulmonary artery than in mesenteric artery, suggesting less physiological importance of such receptors in the pulmonary artery than in the mesenteric artery.