血管内皮对胰岛素介导的血管反应性的作用

Impact of endothelium on insulin mediated vasoconstriction

目的 :探讨在不同浓度胰岛素作用下 ,存在或去除血管内皮后 ,大鼠主动脉对血管紧张素Ⅱ(AngⅡ )和去甲肾上腺素 (NE)的反应 ,及血管平滑肌细胞内钙信号的变化 ,以明确高浓度胰岛素调控血管反应性的可能机制。方法 :应用专用血管槽及生理多导仪测定血管张力 ,及比率荧光倒置显微镜测定培养血管平滑肌细胞内钙的变化。结果 :在存在血管内皮时 ,增加胰岛素浓度能明显抑制AngⅡ引起的缩血管反应 ,而在去除血管内皮后 ,胰岛素的这种抑制作用明显减弱 ,AngⅡ介导的缩血管反应明显增强。高胰岛素抑制AngⅡ作用与其抑制AngⅡ所致细胞内钙信号增加有关。结论 :高浓度胰岛素抑制血管反应性依赖于血管内皮的完整性 。

Objective To investigate the vascular reactivity to the administration of different concentrations of insulin in the presence or absence of endothelium and observe the effects of insulin on the changes of cytosolic free calcium of vascular smooth musclecells （VSMCs）induced by angiotensin Ⅱ （Ang Ⅱ ）and norepinephrine. Methods The thoracic aorta was prepared from male Wistar rat. Vascular reactivity on aortic tings was measured using an isometric force transducer. Aortic VSMCs were cultured and cytosolic free calcium （[ Ca^2＋ ]i） was measured using Fura2/AM fluorescent technique. Results In the presence of endothelium, insulin dose-dependently inhibited Ang Ⅱ induced vasoconstriction. In the absence of endothelium, inhibitory effects of insulin on Ang Ⅱ action was significantly reduced （p 〈 0.01）. Contrary to Ang Ⅱ , insulin had no inhibitory effects on norepinephrine in the either presence or absence of endothelium. Inhibitory effect of insulin was related to decrease the Ang Ⅱ mediated the free calcium increase in VSMCs （p 〈 0.01 ）. Conclusions Vasodilation of insulin was dependent on endothelium status. Endothelium lesion will impair imsulin＇s effect and cause hypertension.