Figure 7.

The addition of the opposite polarity second phase increases the threshold for cell killing and electroporation. The thresholds were measured by the margins of Pr and YP uptake and are presented at the top and bottom panels, respectively (see Fig. 6 and text for details). The data for unipolar PEF are the same as in Fig. 6. Cells were exposed to trains of 100 or 300 pulses at 10 Hz. For bipolar pulses, the duration of a single phase was used in lieu of the total pulse duration. Note that the difference in thresholds becomes larger for shorter pulses. Differences between uni- and bipolar pulses for Pr uptake thresholds were statistically significant for 12 out of the 14 datapoints. Differences in YP uptake were significant only for the shortest pulses (two-tailed t test at p < 0.05).