Gianulis Elena C, Casciola Maura, Xiao Shu, Pakhomova Olga N, Pakhomov Andrei G
Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA.
Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA.
Bioelectrochemistry. 2018 Feb;119:10-19. doi: 10.1016/j.bioelechem.2017.08.005. Epub 2017 Aug 25.
Cellular effects caused by nanosecond electric pulses (nsEP) can be reduced by an electric field reversal, a phenomenon known as bipolar cancellation. The reason for this cancellation effect remains unknown. We hypothesized that assisted membrane discharge is the mechanism for bipolar cancellation. CHO-K1 cells bathed in high (16.1mS/cm; HCS) or low (1.8mS/cm; LCS) conductivity solutions were exposed to either one unipolar (300-ns) or two opposite polarity (300+300-ns; bipolar) nsEP (4-40kV/cm) with increasing interpulse intervals (0.1-50μs). Time-lapse YO-PRO-1 (YP) uptake revealed enhanced membrane permeabilization in LCS compared to HCS at all tested voltages. The time-dependence of bipolar cancellation was similar in both solutions, using either identical (22kV/cm) or isoeffective nsEP treatments (12 and 32kV/cm for LCS and HCS, respectively). However, cancellation was significantly stronger in LCS when the bipolar nsEP had no, or very short (<1μs), interpulse intervals. Finally, bipolar cancellation was still present with interpulse intervals as long as 50μs, beyond the time expected for membrane discharge. Our findings do not support assisted membrane discharge as the mechanism for bipolar cancellation. Instead they exemplify the sustained action of nsEP that can be reversed long after the initial stimulus.
纳秒级电脉冲（nsEP）所引起的细胞效应可通过电场反转来减弱，这一现象被称为双相抵消。这种抵消效应的原因尚不清楚。我们推测辅助膜放电是双相抵消的机制。将CHO-K1细胞置于高电导率溶液（16.1mS/cm；HCS）或低电导率溶液（1.8mS/cm；LCS）中，使其暴露于一个单极（300纳秒）或两个相反极性（300 + 300纳秒；双极）的nsEP（4 - 40kV/cm）下，脉冲间隔逐渐增加（0.1 - 50微秒）。延时的YO - PRO - 1（YP）摄取显示，在所有测试电压下，与HCS相比，LCS中的膜通透性增强。在两种溶液中，使用相同的（22kV/cm）或等效的nsEP处理（LCS和HCS分别为12和32kV/cm）时，双相抵消的时间依赖性相似。然而，当双极nsEP的脉冲间隔为零或非常短（<1微秒）时，LCS中的抵消作用明显更强。最后，即使脉冲间隔长达50微秒，超过了膜放电预期的时间，双相抵消仍然存在。我们的研究结果不支持辅助膜放电作为双相抵消的机制。相反，它们例证了nsEP的持续作用，这种作用在初始刺激后很长时间仍可逆转。
