正常肠系膜动脉平滑肌细胞钙激活钾通道活性的观察

为了解人体正常肠系膜动脉平滑肌细胞钙激活钾通道的特性 ,取 2 4例人体正常肠系膜动脉小枝节段 ,用酶消化法获取标本细胞 ,以膜片钳制技术检测钙激活钾通道的活性 ,通过Pclamp专用软件实时采样记录其平均开放时间、平均关闭时间及平均开放概率等。结果发现 ,人体肠系膜动脉平滑肌细胞钙激活钾通道开放具有明显电压依赖性 ,在对称性高钾液中 ,电流 -电压关系曲线在 10～ 6 0mV范围内可被直线拟合。在细胞吸附式膜片和内面向外膜片中 ,通道电导分别为 192 .3± 2 9.2Ps和 2 0 2 .5± 5 8.3Ps。开放概率和开放数目随Ca2 + 浓度的增加而增加 ,膜内面应用四乙胺可减少通道开放概率及电流幅值。提示人体肠系膜动脉平滑肌细胞钙激活钾通道与人体其他血管相似 ,主要为大电导钙激活钾通道 ,具有电压和钙浓度双重依赖性。

The Characters of Calcium-Activated Potassium Channels of Artery Smooth Muscle Cell from Normal Human Mesentery

Aim To investigate the characters of Ca2+-activated K+ channels(KCa) of artery smooth muscle cell(SMC) from normal human mesentery. Methods Human normal mesenteric artery branch was digested by enzyme. Patch clamp technique was used to pull cell-attached and inside-out patches on the normal human mesenteric artery SMC respectively. The signal channel open and close times, open probability (P0), open channel number per patch were recorded. Results The channels showed obviously voltage dependent, the amplitude voltagerelation curve can be linearly fitted during the voltage range from 10～60 mV(in symmetrical K+]0 140 mmol/L and Ca2+]free< 10-9 mol/L). The KCa channels have slope conductance of 192.3±29.2 Ps and 202.5±58.3 Ps, in cell-attached and inside-out patches respectively. The channels were Ca2+ sensitive . The single channel P0 and open channel number per patch were increased apparently according to the increase of Ca2+ (10-8～10-6 mol/L) in cytoplasm . TEA in 2×10-4mmol applied in the out side of the channel can reduce the signal channel current amplitude. Conclusion The characters of KCa from normal human mesenteric artery SMC were mainly big conductance KCa, which have voltage and Ca2+ concentration dependent and similar to other artery smooth muscle cell of human．