INTRACELLULAR CALCIUM-IONS ACTIVATE A LOW-CONDUCTANCE CHLORIDE CHANNEL IN SMOOTH-MUSCLE CELLS ISOLATED FROM HUMAN MESENTERIC-ARTERY
INTRACELLULAR CALCIUM-IONS ACTIVATE A LOW-CONDUCTANCE CHLORIDE CHANNEL IN SMOOTH-MUSCLE CELLS ISOLATED FROM HUMAN MESENTERIC-ARTERY
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DOI：
10.1007/bf00384347
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发表时间：
1993-08-01
影响因子：
4.5
通讯作者：
KLOCKNER, U
中科院分区：
文献类型：
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作者：
KLOCKNER, U
采用膜片钳技术研究了人肠系膜动脉血管平滑肌细胞（VSMC）钙激活的氯离子电流。20 mM的咖啡因溶液通过钙激活的内向电流使细胞膜去极化，该电流峰值为-654 +/- 230 pA（保持电位-50 mV）。细胞附着，同时检测到内向单通道电流，振幅为-0.22 pA。在开放细胞贴片中，将[Ca2+]i升高至10 muM可触发通道活性。在-60 mV时，电流的平均幅值为-0.24 pA，通道的平均打开时间为28 ms。绘制电流与测试电位的幅值，得出单通道电导为2.8 +/- 0.5 pS。当[Cl-]在内外片的细胞质侧从150 mM减少到5 mM时，电流消失，保持电位为-60 mV（计算反转电位-58 mV），表明钙激活电流是氯离子电流。这表明，在人肠系膜VSMC中，[Ca2+]i的升高激活了一个低电导的氯离子通道，这可能介导了激动剂诱导的细胞膜去极化。
Calcium-activated chloride currents were studied by the patch-clamp technique in vascular smooth muscle cells (VSMC) isolated from human mesenteric arteries. Bath application of 20 mM caffeine caused the cell membrane to depolarize by a calcium-activated inward current that peaked to -654 +/- 230 pA (holding potential -50 mV). Cell-attached, at the same time inwardly directed single-channel currents were detected with an amplitude of -0.22 pA. In open-cell-attached patches channel activity was triggered by elevating [Ca2+]i to 10 muM. At -60 mV the mean amplitude of the current was -0.24 pA and the mean open time of the channels was 28 ms. Plotting the amplitude of the current versus the test potential yielded a single-channel conductance of 2.8 +/- 0.5 pS. The currents disappeared when [Cl-] was reduced from 150 mM to 5 mM at the cytosolic side of the inside-out patch at a holding potential of -60 mV (calculated reversal potential -58 mV) suggesting that the calcium-activated current was a chloride current. This suggests that, in human mesenteric VSMC, elevation of [Ca2+]i activates a low-conductance chloride channel, which may mediate the agonist-induced depolarization of the cell membrane.