SENSITIVITY OF TRANSMEMBRANE VOLTAGE INDUCED BY APPLIED ELECTRIC-FIELDS - A THEORETICAL-ANALYSIS

The sensitivity of induced transmembrane voltage to extracellular cond uctivity, membrane conductivity, cytoplasmic conductivity, cell radius and electric pulse duration has been studied. The study showed that v ariations of membrane conductivity, cytoplasmic conductivity and cell radius within the ranges of their physiological values do not influenc e induced transmembrane voltage substantially, provided that extracell ular conductivity also corresponds to the physiological conditions, an d duration of the electric pulse is in range of 10 mu s or longer. How ever, when extracellular conductivity is reduced to the values typical for a ''low conductivity'' medium, the induced transmembrane voltage decreases considerably, while the charging time of the membrane increa ses up to the range of 1 ms. This increases the necessary amplitude an d duration of electric pulses used for electroporation. In a ''low con ductivity'' medium, the induced transmembrane voltage is also much mor e sensitive to variations in cell radius, membrane conductivity, and c ytoplasmic conductivity. Such a medium is used in many in vitro studie s of the effects of an electric field upon single cells. Our study sho ws that in these cases, in order to evaluate the induced transmembrane voltage, it is important to consider the values of conductivities and radii of cells used in the experiment, as well as the duration of the electric pulses used. (C) 1997 Elsevier Science S.A.