慢性缺氧对大鼠肺动脉平滑肌细胞电压门控钾通道电流的影响

Effects of chronic hypoxia on the current of voltage-gated potassium channel in pulmonary artery smooth muscle cells of rats

目的：研究慢性缺氧对大鼠肺动脉平滑肌细胞电压门控钾通道（Kv）电流的影响。方法：雄性SD大鼠50只随机分为常氧对照组（10只）和慢性缺氧5d、10d、20d及30d组（各10只）。慢性缺氧组大鼠每天在低氧仓中予以缺氧8h，分别取缺氧5d、10d、20d及30d的大鼠进行实验。应用全细胞膜片钳技术记录肺动脉平滑肌细胞电压门控钾通道电流（Ix）。结果：慢性缺氧显著减低大鼠肺动脉平滑肌细胞的Ik峰值及I～V曲线漂移。慢性缺氧5d后肺动脉平滑肌细胞的Ix密度及I～V曲线与常氧组均差异无统计学意义（P〉0．05），而慢性缺氧10d后肺动脉平滑肌细胞的Ix密度及I～V曲线与常氧组均差异有统计学差异（均P〈0．05）；随着缺氧时间延长，Ix密度的峰值进一步降低。结论：慢性缺氧可降低肺动脉平滑肌细胞Kv通道电流密度。

Objective： To observe the influence of chronic hypoxia on the current of voltage-gated potassium channel in pulmonary artery smooth muscle cells of rats. Method：Fifty male Sprague-Dawley rats were randomly allocated into normoxic group （n= 10） and chronic hypoxic groups. The chronic hypoxic groups were randomly allocated into 4 subgroups （n= 10, respectively） according to the chronic hypoxic periods. The chronic hypoxic subgroups were kept in hypoxia environmental chamber eight hours per day for 5 d, 10 d, 20 d and 30 d, respectively. The normoxic group was kept in room air. The current of voltage-gated potassium channel （IK） in pulmonary artery smooth muscle cells using conventional whole cell patch-clamp technique were measured. Result：There was no significant difference in the density of IK （at ＋ 60 mV） and I- V relationship between normoxic group and group exposed to chronically hypoxia for 5 d （P〉0. 05）, whereas difference from chronically hypoxia for 10 d was significant （P〈0.05）. With the exposure to hypoxia for prolonged time, the peak density of IK was decreased gradually at ＋60 mV. Conclusion： Exposure to chronically hypoxia may cause decreased current of voltage-gated potassium channel which leads to hypoxia pulmonary vasoconstriction.