Tseng Pang-Yen, Bennetts Brett, Chen Tsung-Yu
Center foor Neuroscience and Department of Neurology, University of California, Davis, CA 95616, USA.
J Gen Physiol. 2007 Aug;130(2):217-21. doi: 10.1085/jgp.200709817.
The CLC-1 Cl(-) channel is abundantly expressed on the plasma membrane of muscle cells, and the membrane potential of muscle cells is largely controlled by the activity of this Cl(-) channel. Previous studies showed that low intracellular pH increases the overall open probability of recombinant CLC-1 channels in various expression systems. Low intracellular pH, however, is known to inhibit the Cl(-) conductance on the native muscle membrane, contradicting the findings from the recombinant CLC-1 channels in expressed systems. Here we show that in the presence of physiological concentrations of ATP, reduction of the intracellular pH indeed inhibits the expressed CLC-1, mostly by decreasing the open probability of the common gate of the channel.
CLC-1氯离子通道在肌肉细胞质膜上大量表达，肌肉细胞的膜电位在很大程度上受该氯离子通道活性的控制。先前的研究表明，在各种表达系统中，细胞内低pH值会增加重组CLC-1通道的总体开放概率。然而，已知细胞内低pH值会抑制天然肌膜上的氯离子电导，这与表达系统中重组CLC-1通道的研究结果相矛盾。在此我们表明，在生理浓度ATP存在的情况下，细胞内pH值降低确实会抑制表达的CLC-1，主要是通过降低通道共同门控的开放概率来实现的。
