Molecular action of lidocaine on the voltage sensors of sodium channels.
Molecular action of lidocaine on the voltage sensors of sodium channels.
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DOI：
10.1085/jgp.20028651
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发表时间：
2003-02
期刊：
影响因子：
--
通讯作者：
Hanck DA
中科院分区：
文献类型：
--
作者：
Sheets MF;Hanck DA
利多卡因阻断钠离子电流与门控电荷-电压（Q-V）关系的改变有关，其特征为最大门控电荷（Qmax）降低38%，以及在负测试电位下出现额外的门控电荷。我们研究了利多卡因诱导的心脏钠通道门控电荷减少的分子基础，通过依次中和人心脏钠通道（hH 1a）的四个域中每个电压传感器（S4段）中的碱性残基。通过测定经利多卡因修饰的每个突变通道的Qmax的相对降低，我们鉴定了有助于门控电荷降低的那些S4片段。没有发现利多卡因与域I或II中的电压传感器的相互作用。发现结构域III的S4对电荷移动的最大抑制与利多卡因完全抑制其移动一致。在Na通道中用胞内MTSET（带电巯基试剂）进行的保护实验（结构域III的S4中第四个最外精氨酸突变为半胱氨酸）表明，利多卡因使结构域III中的S4稳定在去极化构型中。利多卡因也部分抑制了结构域IV中S4的运动，但利多卡因最显著的作用是改变了结构域IV中S4的电压依赖性电荷运动，从而导致在接近−100 mV的电位下出现额外的门控电荷。这些发现表明，利多卡因对Na通道门控电荷的作用是由利多卡因结合位点与结构域III和IV中S4片段形成的电压传感器的变构偶联引起的。
Block of sodium ionic current by lidocaine is associated with alteration of the gating charge-voltage (Q-V) relationship characterized by a 38% reduction in maximal gating charge (Qmax) and by the appearance of additional gating charge at negative test potentials. We investigated the molecular basis of the lidocaine-induced reduction in cardiac Na channel–gating charge by sequentially neutralizing basic residues in each of the voltage sensors (S4 segments) in the four domains of the human heart Na channel (hH1a). By determining the relative reduction in the Qmax of each mutant channel modified by lidocaine we identified those S4 segments that contributed to a reduction in gating charge. No interaction of lidocaine was found with the voltage sensors in domains I or II. The largest inhibition of charge movement was found for the S4 of domain III consistent with lidocaine completely inhibiting its movement. Protection experiments with intracellular MTSET (a charged sulfhydryl reagent) in a Na channel with the fourth outermost arginine in the S4 of domain III mutated to a cysteine demonstrated that lidocaine stabilized the S4 in domain III in a depolarized configuration. Lidocaine also partially inhibited movement of the S4 in domain IV, but lidocaine's most dramatic effect was to alter the voltage-dependent charge movement of the S4 in domain IV such that it accounted for the appearance of additional gating charge at potentials near −100 mV. These findings suggest that lidocaine's actions on Na channel gating charge result from allosteric coupling of the binding site(s) of lidocaine to the voltage sensors formed by the S4 segments in domains III and IV.
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影响因子：
16.2
作者：
Aggarwal, SK;MacKinnon, R
通讯作者：
MacKinnon, R
影响因子：
56.9
作者：
Doyle, DA;Cabral, JM;MacKinnon, R
通讯作者：
MacKinnon, R
影响因子：
16.2
作者：
CHAHINE, M;GEORGE, AL;HORN, R
通讯作者：
HORN, R
影响因子：
5.5
作者：
BEKKERS, JM;GREEFF, NG;NEUMCKE, B
通讯作者：
NEUMCKE, B
影响因子：
3.8
作者：
BEAN, BP;COHEN, CJ;TSIEN, RW
通讯作者：
TSIEN, RW