The purpose of this study was to quantify the changes in cell membrane conductance in response to electropermeabilization, which may elucidate the mechanisms of tissue injury resulting from high-voltage electrical shock. A high-speed, space-clamp and voltage-clamp experimental configuration was used. The pulse parameters of an imposed transmembrane potential that are instrumental in membrane properties alteration were precisely controlled. The dynamics of the non-linear electroporation response was characterized.