Electrophysiological study of existence and regulation of chloride current in endothelial cells

本文报道了体外培养的人主动脉、人脐静脉和牛肺动脉内皮细胞（ETC）中存在C1通道。C1电流的产生可以被认为是内皮细胞的共同特性。我们主要使用培养的人主动脉ETC，用膜片钳技术测量膜电流，用Fura-2荧光法测量细胞内Ca浓度[Ca]i。主要结果如下：（1）1-10 μ M ATP可诱发外向整流性Cl-电流，随后是Ca激活的K+电流。（2）用pCa 6和pCa 5的移液器溶液，C1电流在膜片破裂后延迟几分钟出现。（3）Ca激活的C1电流可被钙调素拮抗剂三氟拉嗪和W7阻断。（4）外源性10 μ M ATP使[Ca]i呈双相增加，5）[Cl]o从146降至20 mM可抑制ATP诱导的[Ca]i升高的紧张相。应用膜片钳技术，由[K]o、[Cl]o的变化和ATP的作用产生的ETC的静息电位比K+离子的反转电位高出20-40 mV。这表明C1电流的功能作用是稳定静息膜电位到去极化范围

The present study has disclosed the existence of C1- channels in cultured endothelial cells (ETC) from human aorta, human umbilical vein as well as bovine pulmonary artery. The generation of C1- current can be regarded as a common property of the endothelial cells. We used mainly cultured human aortic ETC and measured membrane currents by patch clamp technique and intracellular Ca concentration [Ca]i by fura-2 fluorometry. Major results were : 1) External application of 1-10 uM ATP induced outward-rectifying Cl- currents succeeding to Ca-activated K+ current, 2) With pipette solution of pCa 6 and pCa 5, C1 currents developed with a delay of a few minuts after breaking the patch membrane, 3) The Ca-activated C1- currents were blocked by trifluoperazine and W7, calmodulin antagonists, 4) [Ca]i increased in a bipasic manner by external application of 10 uM ATP, 5) The tonic phase of the ATP- induced [Ca]i increase was suppressed by decreasing [Cl]o from 146 to 20 mM.6) From the change of the leakage current and single channel currents recorded by cell-attached patch clamp technique produced by the change in [K]o, [C1]o and an application of ATP, the resting potential of ETC is at 20-40 mV more depolarized potentials from the reversal potential of K+ ions. It suggests that the functional role of the C1- currents is the stabilization of the resting membrane potential to the depolarized range