高肺血流性肺动脉高压大鼠肺动脉平滑肌细胞钙激活氯离子通道的电生理研究

Study of electrophysiology of Ca2 ＋-activated Cl-channels in pulmonary arterial smooth muscle cells of pulmonary hypertension induced by high pulmonary blood flow in rats

目的 观察肺动脉平滑肌细胞（PASMCs）钙激活氯离子通道（ClCa）的电生理特性,探讨其在高肺血流性肺动脉高压（PAH）形成过程中的可能作用.方法 SD大鼠40只,随机分为3组：对照组（10只）、假手术组（10只）、模型组（20只）.建立模型成功后同条件下饲养11周,用右心导管法测定大鼠右心室压力（RVSP）,并检测右心室肥厚指数（RVHI）；急性酶分离法分离出单个PASMC,应用膜片钳全细胞记录模式,测定各组大鼠PASMCs静息膜电位（Em）、ClCa电流（IClCa）及电流密度的改变,比较各组大鼠Ⅰ-Ⅴ曲线的变化,并进行相关性分析.结果 与对照组和假手术组比较,模型组大鼠ClCa内向的尾电流（Itail）的Ⅰ-Ⅴ曲线明显向下移；对照组与假手术组间差异无统计学意义.静息Em与RVSP、RVHI呈正相关（P均＜0.01）；Itail的电流密度与RVSP、RVHI、静息Em均呈负相关（P均＜0.01）.结论 腹主动脉-下腔静脉分流所致高肺血流性PAH大鼠,随着肺动脉压的增高,PASMCs的静息Em升高,ClCa的Itail的绝对值增大,Ⅰ-Ⅴ曲线下移,提示ClCa电流的改变可能在高肺血流性PAH的形成过程中起一定作用.

Objective To investigate the characteristics of different electrophysiology of Ca2＋-activated Cl-channels （ClCa） in pulmonary arterial smooth muscle cells （PASMCs） between pulmonary arterial hypertension （PAH） rats induced by left-to-right shunt and normotensive rats,and to study its possible role in the progress of PAH induced by high pulmanry blood flow.Methods Forty SD rats were randomly divided into 3 groups：control group （n =10）,sham group （n =10）,PAH model group （n =20）.After molding,the rats were raised in the same condition for 11 weeks.Right ventricular systolic pressure （RVSP） of each rat was measured by right cardiac catheterization procedure.Right ventricular hypertrophy index （RVHI） was calculated.Single PASMC was obtained by acute enzyme separation method and the conventional whole-cell patch clamp technique was used to record the resting membrane potential （Em）,ClCa and current density.The Ⅰ-Ⅴ curve between each group were compared.Results Compared with control group and sham group,the Ⅰ-Ⅴ curve about Itail of PAH model group was significantly shift downward; the difference between control group and sham group was not significant.There were positive correlations between Em and RVSP,RVHI （all P ＜ 0.01）,and negative correlations between Itail and RVSP,RVHI and Em（all P ＜ 0.01）.Conclusions During the formation process of left-to-right shunt induced PAH,with the step up of pulmonary arterial pressure,the Em of PASMCs stepping up.The absolute value of current density of inward ClCa currents was increased,and its Ⅰ-Ⅴ curve was shift downward.These suggest that the change of ClCa currents may play a role in the PAH induced by left-to-right shunting.