二氯醋酸钠对模拟高原肺动脉高压大鼠肺动脉平滑肌细胞Kv1.5亚型的作用研究

Effects of Dichloroacetate on the Kv1.5 of Pulmonary Arterial Smooth Muscle Cells in Simulated High Altitude Pulmonary Hypertension Rats

目的研究电压门控性钾通道亚型(Kv1.5)在高原低压低氧性肺动脉高压中的作用,观察二氯醋酸钠(DCA)对高原低压低氧性肺动脉高压大鼠肺小动脉平滑肌细胞(PASMCs)电压门控性钾通道Kv1.5亚型基因表达的影响和肺动脉高压的降压作用。方法24只雄性SD大鼠随机分为正常对照组(N组,8只)、高原低压低氧组(HA组,8只)及DCA干预组(DCA组,8只)。N组置于平原处室内喂养,HA组和DCA组均同时置于模拟的海拔5000m高原环境,DCA组大鼠予以DCA70mg·kg-1·d-1灌胃。21d后测量三组大鼠平均肺动脉压(mPAP)、肺小动脉平滑肌和心脏壁厚度,用荧光定量PCR法检测三组大鼠PASMCs Kv1.5 mRNA,免疫组织化学和免疫印迹法观察大鼠PASMCsKv1.5蛋白的表达。结果模拟高原5000m21d后,HA组大鼠mPAP明显高于N组(P<0.01),其肺小动脉管壁增厚,管腔狭窄,表现为管壁厚度占外径的百分比(WT%)、管壁面积占总面积的百分比(WA%)和右心室与左心室加室间隔之比(RV/LV+S)较N组明显升高(P均<0.01)。与HA组相比,DCA组mPAP则明显降低(P<0.01),表现血管重构减弱,WT%和WA%明显下降(P<0.01),RV/LV+S下降(P<0.01)。HA组Kv1.5 mRNA明显低于N组(P<0.01),DCA组Kv1.5 mRNA则明显恢复表达(P<0.01)。HA组肺小动脉壁Kv1.5平均光密度低于N组(P<0.01),DCA组则明显高于HA组(P<0.01)。蛋白表达呈现相似结果。结论高原低压低氧性大鼠PASMCs Kv1.5表达明显受到抑制,DCA具有恢复Kv1.5表达、阻止肺小动脉重塑及降低肺动脉压的作用。

Objective To investigate the role of Kv1. 5 in the pathogenesis of pulmonary hypertension simulated by hypobaria and hypoxia, and the effects of dichloroacetate （DCA） on the Kv1. 5 expression in pulmonary arterial smooth muscle ceils （PASMCs） and mean pulmonary arterial pressure （mPAP）. Methods Twenty-four SD rats were randomly divided into a normal group （N group）, a high altitude group （HA group）, and a DCA treated group （DCA group）. The N group were fed in normal conditions ,the HA group and DCA group were fed in a hypobaria and hypoxia chamber simulated to an altitude of 5000 meters. In addition, the DCA group rats were gastric gavaged with DCA （70 mg · kg^-1 · d^- 1 ）. Twenty-one days later, percentage of wall thickness （ WT% ） and percentage of wall area （ WA% ） of the pulmonary arteriole, mPAP, and the ratio of right ventricle/left ventricle and septum （ RV/LV ＋ S） were evaluated. Real-time PCR, immunohistochemistry and Western blot were carried out to detect the Kvl. 5 expression in PASMCs. Results In the HA group, WT% , and WA% of pulmonary arteriole, mPAP and RV/（ LV ＋ S） all increased significantly compared with the N group （ P 〈 0. 01 ）. These changes in the DCA group were significantly lower than those in the HA group （P 〈 0. 01 ）. Furthermore, the protein and mRNA expression of Kvl. 5 in the PASMCs deceased significantly in the HA group compared with the N group（ P 〈0. 01 ）, but recovered in the DCA group （ P 〈 0. 01 ）. Conclusions The expression of Kv1. 5 in PASMCs is tremendously inhibited in rats fed in high altitude, which might be a important role of pulmonary hypertension. DCA can inhibit the remodeling of pulmonary arterials probably by recovering Kvl. 5 expression.