Distinct mechanisms of block of Kv1.5 channels by tertiary and quaternary amine clofilium compounds.
Distinct mechanisms of block of Kv1.5 channels by tertiary and quaternary amine clofilium compounds.
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DOI：
10.1016/s0006-3495(01)75904-8
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发表时间：
2001-11
影响因子：
3.4
通讯作者：
J. Steidl;A. Yool
中科院分区：
文献类型：
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作者：
J. Steidl;A. Yool
使用季铵化合物氯非铵及其叔胺衍生物LY 97241来分析电压门控钾通道中的阻断机制。用双电极电压钳记录野生型和突变型Kv1.5通道。50μM Clofilium或200μM LY 97241可逆地诱导了20%对照电流幅度的开放通道阻滞，并被视为宏观电流衰减的加速。虽然阻滞剂仍然存在应用程序后，通道恢复从块在每个脉冲间隔。在通道激活阈值时恢复的最佳电压（pH7.3时为-45mV）表明氯非铵阻断和恢复主要通过开放通道状态发生。相反，LY 97241似乎从关闭状态和打开状态退出。在耐酸Kv1.5突变体通道（H452 Q）中，使用外部pH滴定LY 97241。在使LY 97241胺基团质子化的低pH下，从超极化电位下的阻滞中恢复受损，其方式与氯非铵相似。在与pH值无关的负电位下，氯菲铵阻滞的恢复率会降低，这一效应归因于封闭通道内永久带电化合物的捕获。
The quaternary ammonium compound clofilium and its tertiary amine derivative LY97241 were used to analyze mechanisms of block in a voltage-gated potassium channel. Wild-type and mutant Kv1.5 channels expressed inXenopusoocytes were recorded by two-electrode voltage clamp. Open-channel block to 20% of the control current amplitude was induced reversibly by 50μM clofilium or 200μM LY97241, and was seen as an acceleration of the macroscopic current decay. Although blockers remained present after application, channels recovered from block during each interpulse interval. The optimum voltage for recovery (−45mV at pH 7.3) at the threshold for channel activation indicated that clofilium block and recovery occurred principally through the open channel state. In contrast, LY97241 appeared to exit from the closed state and the open state. In an acid-tolerant Kv1.5 mutant channel (H452Q), external pH was used to titrate LY97241. At low pH, which protonates the LY97241 amine group, recovery from block at hyperpolarized potentials was impaired in a manner similar to that seen with clofilium. Recovery from clofilium block was reduced at negative potentials independent of pH, an effect attributed to trapping of the permanently charged compound within the closed channels.