Interaction of living cells with electric pulses: Parameters and possible applications

Abstract

Remarkable improvements have been seen recently towards the applications of pulsed electric fields in permeabilizing the cell membranes. Under the normal functional activities of a living cell, the transmembrane potential is about -30 to -90 millivolts. External electric fields can induce on a living cell an extra component of transmembrane voltage. The magnitude of the added component is proportional to the strength of the external field. Both the resting and the induced component are superimposed during the incidence of the external field. The induced component will be dependent on the position, shape, and orientation of the cells with respect to the electric field. In suspensions, it also depends on the volume fraction occupied by the cells. The latent period between exposure and induction is in the order of microseconds but it can last longer if cells are in low conductivity medium. It should be also mentioned that as a consequence of this latent period, pulsed electric fields with frequencies more than 1 MHz or pulse durations shorter than 1 μs the induced transmembrane potential is inversely proportional to the frequency of the applied field and directly proportional to the pulse duration. In gigahertz range, or pulses in nanosecond range, induced voltage inside the cell become comparable or even greater than that induced on the plasma membrane. Low intensity and long duration electric pulses increase the electrophoretic lateral mobility of charged molecules in the membrane. In this review, principles and some applications of pulsed electric fields with their biological end points are discussed.

Keywords: Pulsed electric fields, testing potential, transmembrane potential, electrochemotherapy, bleomycin, electroendocytosis.