心肌肥大大鼠心肌尾加压素II受体的变化

目的:观察心肌浆膜上新发现的强缩血管活性肽尾加压素II(UII)的受体在压力超荷性心肌肥大中的变化及意义。方法:在腹主动脉缩窄复制的大鼠压力超荷性心肌肥大模型上,采用放射性配基结合技术,测定术后1d(早期组)和30d(晚期组)大鼠心肌浆膜上UII受体的结合位点。结果:早期组血压较正常对照组和假手术组分别高54%和43%(P＜0.01),心重/体重比值无明显差异,受体数目(Bmax)分别上调184%和159%(P＜0.01),亲和力下降(Kd值分别高224%和206%,P＜0.01)。晚期组血压较对照组和假手术组分别高85%和67%(P＜0.01),心重/体重比值分别高18%和22%(P＜0.05),受体数目分别下调35%和41%(P＜0.05),亲和力增强(Kd值分别低30%和33%,P＜0.05)。结论:压力负荷引起心肌浆膜UII受体先增加后减少的双相变化,其变化可能参与心肌肥大的发病过程。

Alteration of functional receptors in heart for human urotensin II in pressure overload- induced cardiac hypertrophy of rats

AIM: To investigate alteration of functional receptors for urotensin II in pressure overload-induced cardiac hypertrophy of rats. METHODS: In the rat cardiac hypertrophy model produced by constriction of the abdominal aorta, urotensin II binding sites in myocardial sarcolemma were determined with radioligand assay first day (early group) and 30th day (late group) after operation. RESULTS: Compared with control and sham group, in the early group,the blood pressure increased 54% and 43% respectively(P<0.01),and heart/body weight ratio unchanged(P>0.05),UII receptors were up-regulated by 184% and 159%(P<0.01)respectively, While the affinity to UII was decreased (Kd increased 224% and 206 respectively,P<0.01).In the late group, the blood pressure increased 85% and 67% (P<0.01), and heart/body weight ratio increased 18% and 22% (P<0.05) respectively,than that of control and sham group. UII receptors were down-regulated by 35% and 41%(P<0.05) respectively while the affinity to UII was increased (Kd decreased 30% and 33% respectively, P<0.05). CONCLUSION: The biphasic changes of UII receptor in myocardial sarcolemma induced by pressure-overload were observed,increasing in early stage, while decreasing in late stage, and these changes were involved in the development of cardiac hypertrophy.