电压门控性钾通道亚型Kv2.1在低氧性肺动脉高压形成和恢复中的作用

目的 研究电压门控性钾通道亚型Kv2.1基因表达变化在大鼠低氧性肺动脉高压形成以及恢复中的作用.方法 32只雄性SD大鼠均分为正常对照组、高原慢性低压低氧组(CH组)、二氯醋酸钠(DCA)治疗组(CH+DCA组)和高原低氧返回平原恢复7 d组(CHR7组).正常对照组在常压常氧平原条件下喂养,其余各组在模拟高原5 000 m低压氧舱内喂养21 d,动物模型建成后用闭式胸腔法测平均肺动脉压(mPAP),荧光定量PCR法检测4组大鼠肺动脉平滑肌细胞(pulmonary arterial smooth muscle cells,PASMCs)的Kv2.1 mRNA表达;免疫组织化学方法检测大鼠PASMCs Kv2.1的表达;图像分析技术检测肺小动脉形态改变及Kv2.1表达强度变化;Western blot法检测肺动脉平滑肌细胞Kv2.1蛋白表达.结果 模拟高原5 000 m缺氧21 d后,与正常对照组相比,CH组Kv2.1 mRNA和蛋白表达明显下降,免疫组化显示PASMCs Kv2.1表达的平均光密度值(mIOD)减少,而mPAP明显增高,肺小动脉管壁增厚,管腔狭窄,肺血管重构明显.与CH组相比,DCA+CH组和CHR,组Kv2.1 mRNA和蛋白则明显恢复表达,PASMCs Kv2.1表达的mIOD增加,mPAP下降,血管重构减弱.结论 Kv2.1基因表达变化与高原低氧性肺动脉高压变化存在负相关性,表明Kv2.1在低氧性肺动脉高压的形成和恢复中可能起着一定的作用.

Role of voltage-gated K~+ channel Kv2.1 in development and regression of hypoxic pulmonary artery hypertension in rats

Objective To investigate the effect of the expression of voltage-gated K~+ channel Kv2. 1 in the development and regression of pulmonary arterial hypertension ( PAH) in hypobaria and hypoxia rats. Methods Totally 32 adult male Sprague-Dawley rats (200 to 250 g) were randomly and equally divided into 4 groups, normal group (N group) , chronic hypoxia group (CH group) , Dichloroacetate (DCA, 70 mg·kg~(-1)·d~(-1), introgastrically) treated group ( CH+DCA group) , and chronic hypoxia return to normal conditions for 7 d group (CHR_7 group). For the rats of the CH, CH + DCA and CHR_7 groups, 5 000 meter high altitude circum-stance was simulated by exposure rats in a hypobaric and hypoxia chamber for 21 d. Rats in N group were fed in normal air pressure and PO_2 conditions. The animals of N, CH and CH + DCA groups were sacrificed for mPAP measurement and tissue harvest at day 21. The mPAP measurement and tissue harvest of CHR_7 group were per-formed after the rats returned to normal conditions for 7 d. Real time PCR, immunohistochemical staining and Western blot analysis were carried out to detect the Kv2. 1 expression in pulmonary arterial smooth muscle cells ( PASMCs). Results Compared with the rats in N group, the mRNA and protein expressions of Kv2.1 in the PASMCs in CH rats were deceased but mPAP were increased significantly, and the pulmonary artery wall were thickened significantly. However, compared with the CH rats, the Kv2. 1 mRNA and protein expressions of the CH + DCA group and CHR_7 group were restored and mPAP were decreased, and the pulmonary artery wall thicken was slightly. Conclusion The expression of Kv2. 1 is negatively correlated with the chronic hypoxia hypertension, suggesting that Kv2. 1 may play an important role in the development and regression of PAH.