An experimental evaluation of the critical potential difference inducing cell membrane electropermeabilization.

When applied on intact cell suspension, electric field pulses are known to induce membrane permeabilization (electropermeabilization) and fusion (electrofusion). These effects are triggered through a modulation of the membrane potential difference. Due to the vectorial character of the electric field effects, this modulation, which is superimposed on the resting membrane potential difference, is position-dependent on the cell surface. This explains the difference between the experimentally observed critical field strengths requested to trigger the processes of permeabilization and fusion. The critical membrane potential difference which induces membrane permeabilization can be calculated from these experimental observations. It is observed that its value is always about 200 mV for many different cell systems as we previously reported in the case of pure lipid vesicles. This is much less than assumed in most previous studies.