Different PI uptake signatures were associated with different degrees of membrane disruption.

Representative images of PI fluorescence at the end of a 1400-second experiment (A) and TB inclusion/exclusion for those same cells immediately subsequent to TB addition 30 minutes after PEF administration (B). These images highlight the correlation between the relative intensity of PI fluorescence and TB inclusion verses exclusion. That is, NEP cells (cells 12, 15, 20, and 21) do not fluoresce at detectible levels and do not internalize TB. TEP cells (1, 4, 5, 9, 10, 11, and 18) moderately fluoresce and do not internalize TB. IEP cells (2, 3, 6, 7, 8, 13, 14, 16, 17, and 19) fluoresce brightly and do internalize TB. C: NEP, TEP, and IEP cells fluoresce at discernibly different fluorescence levels as shown by a fluorescence pixel intensity histogram. D: These fluorescence values differ in a statistically significant manner. In C–D, fluorescence data was obtained from 41 separate experiments involving the use of PEFs ranging in intensity from 0 to 6.7 kV/cm, wherein 974 individual cells were analyzed. In D, *** indicates statistical significance of p<0.001. The data represent pixel counts of N = 1765, 2701, and 4022 for the NEP, TEP, and IEP cases, respectively.