Effects of electric pulses on cancer cells: apoptosis induction and decrease of mitochondrial transmembrane potential

In order to investigate the effects of electric pulses on cancer cells, HepG2 and L02 were exposed to electric pulses (1000V/cm, 100 mu s, 1Hz) for different time (8s, 15s, 30s, 60s). Annexin-V-FITC Kit and Flow cytometry were used to study the apoptosis of treated cells. The results showed that the electric pulses of 1000V/cm, 100 mu s, 1Hz for 8s couldn't induce tumor cells apoptosis. Apoptosis was observed when tumor cells were stimulated for 15s and longer, the apoptosis percentage increased with the increase of stimulation time. Furthermore, tumor cells were more sensitive than normal cells in response to electrical pulses. Rhodamine 123 and Laser Scanning Confocal Microscope (LSCM) were used to make a real-time study of mitochondrial transmembrane potential (Delta Psi(m)) when the tumor cells were exposed to electric pulses for 60s. No significant change of Delta Psi(m) was observed within 30s stimulation. After that, the Delta Psi(m) increased sharply and declined later.