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为研究多巴胺对肾素—血管紧张素系统的调节作用，本研究利用离体血管收缩实验观察了服用左旋多巴后大鼠主动脉平滑肌中血管紧张素ＡＴ１受体的变化情况。结果表明在服用左旋多巴１周、２周、４周后主动脉对血管紧张素Ⅱ（ＡｎｇⅡ）的反应性下降，最大收缩反应分别为４７２．７９ｍｇ±７４．５９ｍｇ、４９２．３９ｍｇ±６９．６１ｍｇ和３０２．２６ｍｇ±６１．６０ｍｇ，较对照组（６０３．８３ｍｇ±５６．２１ｍｇ）明显为低。用药组主动脉对ＡｎｇⅡ之累积浓度收缩曲线比对照组显著下移，且以４周组最为显著，但ｐＤ２值在各组间无明显差异（Ｐ＞０．０５），表明血管本身的反应性未发生显著改变。上述结果表明多巴胺能引起主动脉中ＡＴ１受体水平下调，提示多巴胺在治疗高血压中除作用于多巴胺系统外，使ＡＴ１受体水平发生改变可能也是其发挥作用的重要途径
In order to study the regulatory effect of dopamine on the renin-angiotensin system, we examined the changes of angiotensin AT1 receptor in the aortic smooth muscle of rats after administration of levodopa. The results showed that the aorta reactivity to angiotensin Ⅱ (Ang Ⅱ) decreased after 1, 2 and 4 weeks of administration of levodopa. The maximum systolic responses were 472.79 mg ± 74.59 mg and 492.39 mg ± 69, respectively. 61 mg and 302.26 mg ± 61.60 mg, which were significantly lower than the control group (603.83 mg ± 56.21 mg). The contraction curve of cumulative concentration of Ang Ⅱ in the aorta of the treated group was significantly lower than that of the control group, and was the most significant in the 4-week group, but there was no significant difference in the pD2 value among the groups (P> 0.05), indicating that the vascular reactivity No significant changes occurred. These results suggest that dopamine can cause AT1 receptor in the aorta downregulation, suggesting that dopamine in the treatment of hypertension in addition to the role of the dopamine system, the AT1 receptor levels may also be an important way to play a role