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长期以来认为在内脏血管中含有两种亚型的多巴胺受体ＤＡ１和ＤＡ２，而躯体血管中只存在多巴胺受体ＤＡ２亚型。但在实验中偶然发现大鼠尾动脉对ＤＡ１亚型特异性激动剂ｆｅｎｏｌｄｏｐａｍ有明显反应，因此应用离体血管环法和反转录聚合酶链反应方法对大鼠尾动脉平滑肌中多巴胺受体两亚型的分布情况进行了观察。结果显示：亚型选择性多巴胺受体激动剂ｆｅｎｏｌｄｏｐａｍ和ＰＢＤＡ（ＤＡ２亚型激动剂）在尾动脉均产生浓度依赖性舒张反应，该效应分别被亚型特异性拮抗剂部分或完全阻断；来自尾动脉之ＲＮＡ的ＰＣＲ结果可见到预期长度为２４７ｂｐ的特异性阳性扩增条带，而未加反转录酶之结果呈现阴性，说明该产物来自ｃＤＮＡ而非基因组ＤＮＡ。结论：大鼠尾动脉平滑肌中同时存在有多巴胺受体ＤＡ１和ＤＡ２两种亚型
It has long been thought that there are two subtypes of dopamine receptors DA1 and DA2 in the visceral blood vessels, while there are only DA2 subtypes of dopamine receptors in the somatic blood vessels. However, in our experiments, we found that rat caudal artery obviously responded to fenoldopam, a specific agonist of DA1 subtype. Therefore, the in vitro vascularization and reverse transcription polymerase chain reaction The distribution of subtypes was observed. The results showed that both subtype-selective dopamine receptor agonists fenoldopam and PBDA (DA2 subtype agonist) produced a concentration-dependent relaxation response in the tail artery, which was partially or completely blocked by subtype-specific antagonists; PCR results of the tail artery RNA showed a specific positive amplification band of 247 bp in expected length, whereas negative results were obtained with no reverse transcriptase, indicating that the product was from cDNA rather than genomic DNA. Conclusion: There are two subtypes of dopamine receptor DA1 and DA2 in rat tail artery smooth muscle