高血压大鼠和高血压患者血管平滑肌α肾上腺素受体的反应性增强作用

目的研究高血压状态下血管平滑肌α肾上腺素能受体的反应性增强作用。方法用敏感的离体血管张力描记技术记录大鼠肠系膜动脉和人大网膜动脉的张力，用实时定量的逆转录聚核酶链反应技术测定动脉平滑肌的mRNA水平，用动脉的器官培养方法研究α受体反应性增强的机制。结果自发性高血压大鼠(SHR)的肠系膜动脉环对去甲肾上腺素(NA)的反应性明显强于WKY大鼠，NA对SHR肠系膜动脉平滑肌的最大收缩(E_max)是WKY大鼠E_max的1.82倍；高血压患者大网膜动脉对NA的反应性明显高于非高血压患者，NA的量效曲线显著左移，pD₂值显著高于非高血压患者。SD大鼠肠系膜动脉的器官培养后对NA收缩反应增强，E_max增高，且培养后α₁受体的mRNA水平增高，而α₂受体的mRNA水平无明显变化。结论高血压状态下血管平滑肌α受体的反应性增强，提示α受体上调。

Hypersensitization of α-adrenoreceptor of artery smooth muscle in hypertensive rats and hypertensive patients

AIM: To investigate the hypersensitization of alpha-adrenoreceptor of artery smooth muscle in hypertensive patients and rats and the mechanisms concerned. METHODS: Isometric tension of artery ring segments was recorded by a sensitive myograph system in vitro and the relative amount of alpha-adrenoreceptor mRNA was quantified by a real-time PCR. RESULTS: Noradrenaline (NA)-induced concentration-contraction curve of mesenteric artery segments in spontaneously hypertensive rats (SHR) was more potent than that in Wistar-Kyoto (WKY) rats. The E(max) of NA in SHR was 1.82 times of that of WKY. The concentration-contractile curve induced by NA in great omental arteries of hypertensives significantly shifted toward left and the pD2 value of NA was larger than that of normotensives. After organ culture, the concentration-contractile curves of SD rat mesenteric artery induced by NA shifted toward left with significantly increased E(max). The relative amounts of mRNA for alpha1-adrenoreceptor was increased, but mRNA level for alpha2-adrenoreceptor did not change. CONCLUSION: The sensitivity of alpha1-adrenoreceptor of artery smooth muscle in hypertensive man and rat is enhanced, suggesting alpha1-adrenoreceptor is upregulated.