中文摘要：

本文旨在研究大鼠传导性肺动脉平滑肌细胞（pulmonary artery smooth muscle cells，PASMCs）的电生理特征及对急性低氧的反应。用酶解法急性分离出1-2级分支的PASMCs，通过全细胞膜片钳方法研究常氧及急性低氧状况下细胞钾电流的差异，并在常氧下先后使用iBTX和4-AP阻断大电导钙激活钾离子（large conductance Ca-activated K^＋，BKCa）通道及延迟整流性钾离子（delayed rectifier K^＋，KDR）通道后，观察细胞钾电流特征。根据细胞的大小、形态及电生理特征可将PASMCs分为Ⅰ、Ⅱ、Ⅲ类。iBTX对Ⅰ类细胞几乎无作用，而4-AP几乎完全阻断它的钾电流；Ⅱ类细胞的钾电流在加入iBTX后大部分被抑制，其余的对4．AP敏感；Ⅲ类细胞的钾电流对iBTX及4-AP均敏感。急性低氧对三类细胞的钾电流均有不同程度的抑制，并使Ⅰ类细胞的膜电位显著升高，而Ⅱ、Ⅲ类细胞膜电位升高的程度不如Ⅰ类显著。结果表明，传导性肺动脉有3种形态及电生理特性不同的PASMCs，在急性低氧时其钾电流不同程度地受到抑制，同时静息膜电位也有不同程度去极化，这些可能参与急性低氧时传导性肺动脉舒缩反应的调节。KDR及BKCa通道在3种细胞中的比例不同可能是急性低氧对3种PASMCs影响不同的离子基础。

英文摘要：

The present study was designed to investigate the electrophysiological characteristics of rat conduit pulmonary artery smooth muscle cells （PASMCs） and the response to acute hypoxia. PASMCs of the 1st to 2nd order branches in the conduit pulmonary arteries were obtained by enzymatic isolation. The PASMCs were divided into acute hypoxia preconditioned group and normoxia group. Hypoxia solutions were achieved by bubbling with 5% CO2 plus 95% N2 for at least 30 min before cell perfusion. Potassium currents were compared between these two groups using whole-cell patch clamp technique. The total outward current of PASMCs was measured under normoxia condition when iBTX [specific blocking agent of large conductance Ca-activated K^＋ （BKCa） channel] and 4-AP [specific blocking agent of delayed rectifier K^＋ （KDR） channel] were added consequently into bath solution. PASMCs were classified into three types according to their size, shape and electrophysiological characteristics. Type Ⅰ cells are the smallest with spindle shape, smooth surface and discrete perinuclear bulge. Type Ⅱ cells show the biggest size with banana-like appearance. Type Ⅲ cells have the similar size with type Ⅰ, and present intermediary shape between type Ⅰ and type Ⅱ. iBTX had little effect on the total outward current in type Ⅰ cells, while 4-AP almost completely blocked it. Most of the total outward current in type Ⅱ cells was inhibited by iBTX, and the remaining was sensitive to 4-AP. In type Ⅲ cells, the total outward current was sensitive to both iBTX and 4-AP. Acute hypoxia reduced the current in all three types of cells： （1 614.8±62.5） pA to （892.4±33.6） pA for type Ⅰ cells （P〈0.01）; （438.3±42.8） pA to （277.5±44.7） pA for type Ⅱ cells （P〈0.01）; （1042.0±37.2） pA to （613.6±23.8） pA for type Ⅲ （P〈0.01）, and raised the resting membrane potentials （Em） in all these three types of cells： （-41.6±1.6） mV to （-18.6±1.5） mV （P〈0.01）, （-42.3±3