Electroporation in cells and tissues - A biophysical phenomenon due to electromagnetic-fields
Weaver JC Radio Science 30: (1) 205-221 JAN-FEB 1995
The effect of ''strong'' electromagnetic fields on cells and tissue
can be dramatic but not necessarily harmful. The essentially universal
biophysical phenomenon of ''electroporation'' occurs if an applied
field causes the cell transmembrane voltage to reach about 0.5-1 V in a
time of microseconds to milliseconds. Ordinarily the cell membrane is
a formidable barrier to the transport of ions and charged molecules.
However, electroporation results in a large increase in transmembrane
conductance, which is believed to be caused by ion transport through
temporary membrane openings (''pores''). This high-conductance state
limits the transmembrane voltage and thereby protects the membrane.
A large increase in molecular transport generally occurs for the same
conditions and allows polar molecules to be introduced into cells.
Similar enhanced molecular transport can be caused in living tissues.
Not only cell membranes, but also cell layers or even the stratum
corneum of human skin can be temporarily altered by the electrical
creation of aqueous pathways. The mechanism of electroporation is
partially understood, in that the electrical and mechanical behavior
of artificial planar bilayer membranes can be described quantitatively
by a theoretical model based on transient aqueous pores. More complex
behavior in cell membranes may be due to both the complicated shapes of
cell membranes and the additional participation of metastable pores
and interactions with cell structures. In the case of tissues the
situation is even more complex and has only recently begun to be
studied but has the prospect of providing a new approach to transporting
polar molecules across tissue barriers.