烟雾暴露对大鼠肺动脉平滑肌电压依赖性钾通道蛋白mRNA表达的影响及其与肺动脉压力的关系

Cigarette smoke exposure induced pulmonary artery pressure increase through inhibiting Kvl. 5 and Kv2. 1 mRNA expression in rat pulmonary artery smooth muscles

目的研究烟草烟雾暴露和尼古丁刺激对大鼠肺动脉平滑肌电压依赖性钾通道蛋白Kv1．5和Kv2．1的mRNA表达的影响，探讨吸烟参与肺动脉高压疾病发生发展的机制。方法采用随机数字表法将36只雄性SD大鼠分为6组，每组6只：（1）对照1个月组；（2）对照3个月组；（3）对照6个月组；（4）烟雾暴露1个月组；（5）烟雾暴露3个月组；（6）烟雾暴露6个月组。采用直接右心测压法、HE染色及实时荧光定量PCR分别检测烟雾暴露1个月、3个月及6个月对大鼠右心室收缩压（RVSP）及平均压（mPAP）、右心室肥厚指数[RV／（LV＋s）]及肺动脉平滑肌组织Kv1．5和Kv2．1的mRNA表达的影响。采用原代细胞培养，胶原酶消化法分离、培养大鼠肺动脉平滑肌细胞（PASMC），尼古丁（终浓度100nmol／L）处理48h后，应用实时荧光定量PCR法检测Kv1．5和Kv2．1的mRNA表达，并与对照组进行比较。结果烟雾暴露6个月组大鼠右心室平均血压和右心室收缩压分别为（13．1±0．6）mmHg（1mmHg=0．133kPa）、（29．7±0．8）mmHg，略高于对照6个月组[（10．2±0．4）mmHg、（22．6±0．6）mmHg（P〈0．01）]。烟雾暴露各组与其各自对照组相比大鼠PASMC的Kv1．5mRNA相对表达量分别为（52±11）％、（64±19）％和（75±11）％（均P〈0．05）；烟雾暴露各组与其各自对照组相比大鼠PASMC的Kv2．1mRNA的相对表达量分别为（51．0±18．6）％、（78．7±10．1）％和（71．4±2．3）％（P〈0．01）。浓度为100nmol／L尼古丁刺激大鼠PASMC48h后Kv1．5和Kv2．1mRNA的相对表达量降低，对照组Kv1．5和Kv2．1mRNA的相对表达量分别为[（67±14）％，P〈0．05]和[（72±15）％，P〈0．01]。结论烟草烟雾暴露可能通过尼古丁抑制大鼠肺动脉平滑肌Kv1．5、Kv2．1mRNA的表达参与肺动脉高压的发生发展。

Objective To investigate the effect of cigarette smoke exposure on Kvl. 5 and Kv2. 1 mRNA expression in rat pulmonary arterial smooth muscle cells （ PASMCs ）, and further to clarify the possible mechanism of cigarette smoking induced pulmonary arterial hypertension. Methods Primary cell culture and animal experiments were used in this study. Rat distal PASMCs were isolated and cultured by collagenase digestion. PASMCs were treated by nicotine 100 nmol/L. After 48 h, Kvl. 5 and Kv2. 1 mRNA expression were detected by real-time quantitative PCR and compared with the control group. Rat model of chronic exposure to cigarette smoke was established. Thirty-six male SD rats were randomly divided equally into 6 groups ： （ 1 ） 1 month control group ; （2） 1 month cigarette exposure group ; （ 3 ） 3 month control group ; （4） 3 month cigarette exposure group ; （5） 6 month control group ; （6） 6 month cigarette exposuregroup. Direct right heart manometry, HE staining and real-time quantitative PCR were used to detect the effect of smoke exposure on rat right ventricular systolic pressure （ RVSP）, mean pressure （ mPAP）, right ventricular hypertrophy index [ RV/（ LV ＋ S ）] as well as Kvl. 5 and Kv2. 1 mRNA expression on pulmonary artery smooth muscle at different time points（ 1 month, 3 months and 6 months） . Results The mPAP and RVSP in cigarette smoke exposure 6 month group were （13.08 ± 0. 64）mm Hg and （29.73 ± 0. 83） mm Hg, slightly higher than those in the control 6 month group [ （10. 16 ± 0.44） mm Hg and （22.56 ±0. 64） mm Hg] （P 〈0. 01 ）. The ratio of Kvl. 5 mRNA expression in distal pulmonary arteries in 1 month, 3 month, 6 month cigarette exposure group to that in control groups was （52 ± 11 ）%, （64 ± 19） % and （75 ±11 ） % （ P 〈 0. 05 ）. The ratio of Kv2. 1 mRNA expression in distal pulmonary arteries in 1 month, 3 month, 6 month cigarette exposure groups to that in control groups was （51.0 ±18.6） % , （78.7 ± 10. 1 ）%and（71.4 ± 2. 3 ）% （P 〈 0. 01 ）; Chronic exposure to cigarette smoke significantly decreased Kvl. 5 and Kv2. 1 mRNA expression in rat pulmonary arterial smooth muscle at each time point. The ratio of Kvl. 5 and Kv2. 1 mRNA expression in rat distal PASMCs treated with nicotine （100 nmol/L,48 h） to control group were （ 62± 14 ） % （ P 〈 0. 05 ） and （ 72 ±15 ） % （ P 〈 0. 01 ）, respectively. Nicotine inhibited Kvl. 5 and Kv2. 1 mRNA expression in rat distal PASMCs. Conclusion Cigarette smoke exposure may be involved in pulmonary hypertension by downregulating potassium channels Kvl. 5 and Kv2. 1 mRNA expression in rat pulmonary artery smooth muscles.