Neuronal excitation and permeabilization by 200-ns pulsed electric field: An optical membrane potential study with FluoVolt dye
Neuronal excitation and permeabilization by 200-ns pulsed electric field: An optical membrane potential study with FluoVolt dye
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DOI：
10.1016/j.bbamem.2017.04.016
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发表时间：
2017-07-01
影响因子：
3.4
通讯作者：
Xiao, Shu
中科院分区：
文献类型：
--
作者：
Pakhomov, Andrei G.;Semenov, Iurii;Xiao, Shu
纳秒和皮秒持续时间的电场脉冲是用于神经刺激、激活Ca 2+信号传导和组织消融的新模式。然而，尚不清楚这种短暂的脉冲如何激活电压门控离子通道。我们研究了200 ns脉冲电场（nsPEF）的海马神经元的兴奋和电穿孔，通过延时成像的光学膜电位（OMP）与FluoVolt染料。电穿孔突然将OMP转变到更加去极化的水平，其在10秒内达到，因此细胞保持高于静息OMP水平至少20-30秒。电压门控钠通道（VGSC）的激活增强了电穿孔的去极化效应，导致在nsPEF后4-5 ms内出现额外的河豚毒素敏感性OMP峰。在细胞外溶液中省略Ca 2+并没有减少去极化，表明电压门控钙通道（VGCC）没有贡献。在40%的神经元中，nsPEF触发单个动作电位（AP），中值阈值为3 kV/cm（范围：1.9-4 kV/cm）;低于电穿孔阈值（1.5-1.9 kV/cm）的刺激不能诱发AP。VGSC开放已经可以在nsPEF后0.5 ms内检测到，这太快而不能由电穿孔的去极化效应介导。电穿孔和AP阈值的重叠不一定反映因果关系，但表明与常规电刺激相比，nsPEF对VGSC活化和AP诱导的效力较低。(C)2017爱思唯尔B. V.保留所有权利。
Electric field pulses of nano- and picosecond duration are a novel modality for neurostimulation, activation of Ca2+ signaling, and tissue ablation. However it is not known how such brief pulses activate voltage-gated ion channels. We studied excitation and electroporation of hippocampal neurons by 200-ns pulsed electric field (nsPEF), by means of time-lapse imaging of the optical membrane potential (OMP) with FluoVolt dye. Electroporation abruptly shifted OMP to a more depolarized level, which was reached within 10 s), so cells remained above the resting OMP level for at least 20-30 s. Activation of voltage-gated sodium channels (VGSC) enhanced the depolarizing effect of electroporation, resulting in an additional tetrodotoxin-sensitive OMP peak in 4-5 ms after nsPEF. Omitting Ca2+ in the extracellular solution did not reduce the depolarization, suggesting no contribution of voltage gated calcium channels (VGCC). In 40% of neurons, nsPEF triggered a single action potential (AP), with the median threshold of 3 kV/cm (range: 1.9-4 kV/cm); no APs could be evoked by stimuli below the electroporation threshold (1.5-1.9 kV/cm). VGSC opening could already be detected in 0.5 ms after nsPEF, which is too fast to be mediated by the depolarizing effect of electroporation. The overlap of electroporation and AP thresholds does not necessarily reflect the causal relation, but suggests a low potency of nsPEF, as compared to conventional electrostimulation, for VGSC activation and AP induction. (C) 2017 Elsevier B.V. All rights reserved.