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 (16.1 mS/cm; HCS) or low (1.8 mS/cm; LCS) conductivity solutions were exposed to either one unipolar (300-ns) or two opposite polarity (300 + 300-ns; bipolar) nsEP (4–40 kV/cm) with increasing interpulse intervals (0.1–50 μs). 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 (22 kV/cm) or isoeffective nsEP treatments (12 and 32 kV/cm for LCS and HCS, respectively). However, cancellation was significantly stronger in LCS when the bipolar nsEP had no, or very short (< 1 μs), interpulse intervals. Finally, bipolar cancellation was still present with interpulse intervals as long as 50 μs, 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.

纳秒电脉冲（nsEP）引起的细胞效应可以通过电场反转来减少，这种现象称为双极消除。这种消除效果的原因仍然未知。我们假设辅助膜放电是双极抵消的机制。在高电导率溶液（16.1 mS / cm; HCS）或低电导率溶液（1.8 mS / cm; LCS）中浸泡的CHO-K1细胞暴露于一种单极性（300 ns）或两种相反极性（300 + 300 ns;双极性）的环境中nsEP（4–40 kV / cm），随着脉冲间隔的增加（0.1–50μs）。在所有测试电压下，与HCS相比，延时YO-PRO-1（YP）的摄取显示LCS中的膜通透性增强。在两种解决方案中，使用相同的（22 kV / cm）或同等有效的nsEP处理（LCS和HCS分别为12和32 kV / cm，分别）。但是，当双极nsEP没有或非常短（<1μs）的脉冲间隔时，LCS中的抵消作用明显增强。最后，双极消除仍然存在，脉冲间断间隔长达50μs，超出了膜放电的预期时间。我们的发现不支持辅助的膜放电作为双极消除的机制。取而代之的是，它们例证了nsEP的持续作用，这种作用可以在初始刺激后很长一段时间内被逆转。我们的发现不支持辅助膜放电作为双极消除的机制。取而代之的是，它们例证了nsEP的持续作用，这种作用可以在初始刺激后很长一段时间内被逆转。我们的发现不支持辅助的膜放电作为双极消除的机制。取而代之的是，它们例证了nsEP的持续作用，这种作用可以在初始刺激后很长一段时间内被逆转。