Dynamics of membrane sealing in transient electropermeabilization of skeletal muscle membranes

Large supraphysiologic transmembrane electrical potentials are known to alter the molecular organization of the bilayer lipid component of cell membranes, leading to ionic permeabilization or "electroporation". Typically, membrane electroporation is followed by several orders of magnitude increases in electrical conductance and diffusive permeability to low-molecular-weight solutes. Electroporation may be transient or stable depending on whether the membrane eventually seals or remains permeabilized. Factors that control sealing have not been well characterized. This paper describes the kinetics of membrane sealing following electroporation by pulses over a range of supraphysiologic potentials. The increase in membrane conductance is highly nonlinear during a -440-mV, 4-ms pulse and reaches two orders of magnitude greater than baseline. Electroporation and relaxation sealing kinetics are quite different, reflecting a significant hysteresis effect. Thus, it appears that the magnitude and duration of the field pulse are important factors in sealing.