The bilayer lipid membrane (BLM) under electrical fields

Transmembrane voltage pulses are known to create transient "pores" in the lipid bilayer. This phenomenon, termed electroporation (EP), has been extensively investigated. EP occurs following electric field pulses of up to 10/sup 6/ V/cm with duration between (mu)s and ms to membranes in close contact and is believed to initiate primarily in the lipid bilayer. This paper begins with a brief summary of the origin of lipid bilayer research. One of practical applications of EP is cell transfection for gene expression. Other applications include encapsulation of drugs in controlled-release and insertion of proteins in living cells. It seems likely that the presence of membrane proteins affect the EP of the lipid bilayer by changing its mechanical properties. Transport of ions such as Na/sup +/, K/sup +/, Cl/sup -/ through membrane channels discharge the membrane potential, and at times an external pulse of sufficient amplitude and duration tends to cause dielectric breakdown of the lipid bilayer. Molecular transport through primary pores and pores enlarged by secondary processes provides the basis for transporting molecules into and out of cells. Some recent relevant papers on BLM under electric fields are referenced.