In-vitro observations of potassium ion effusion and apoptosis with the external DC electric field in the breast cancer cell lines

An apoptosis is induced by various means such as UV-radiation and electrochemical stimulation. In the electrochemical treatment(ECT), the electrochemical resultants such as pH changes, electro-osmosis and depolarization on cell membrane induce the cell death. However, the mechanism of apoptosis by electrolysis has not been made clear in the cellular level, though better known in tissues. We examined the potassium ion effusion and resulting apoptosis by electrolysis in the cell level. Cell cultures grown at 1*10⁶ cells per plate were treated with the direct electric current. The condition of treatment is in the mode of constant current electric charges in 3C/cc and 6C/cc at 1mA including the control specimen and constant voltage electric charges at about 0.05, 0.3, 1.5, 3.0, and 4.8C/cc at 500, 600, 750, 800 and 1000mV, respectively. Changes in intracellular levels of K⁺ were determined using the fluorescent potassium indicator PBFI-AM(Molecular Probes, Eugene, OR). Apoptosis was measured by using the Alexa Fluor 488-conjugated annexin V. The concentration of potassium, after stimulation in both of the modes, becomes lower compared with the control in all of the conditions. After stimulation of 36min, apoptosis was detected and then fluorescent color of apoptosis became brighter after 60min in the condition of stimulation of 600mV in the mode of constant voltage. In conclusion, the ECT led to induction of apoptosis in the mode of constant current and voltage.