Electric fields within cells as a function of membrane resistivity-a model study

Externally applied electric fields play an important role in many therapeutic modalities, but the fields they produce inside cells remain largely unknown. This study makes use of a three-dimensional model to determine the electric field that exists in the intracellular domain of a 10-μm spherical cell exposed to an applied field of 100 V/cm. The transmembrane potential resulting from the applied field was also determined and its change was compared to those of the intracellular field. The intracellular field increased as the membrane resistance decreased over a wide range of values. The results showed that the intracellular electric field was about 1.1 mV/cm for R_m of 10 000 Ω·cm², increasing to about 111 mV/cm as R_m decreased to 100 Ω·cm². Over this range of R_m the transmembrane potential was nearly constant. The transmembrane potential declined only as R_m decreased below 1 Ω·cm². The simulation results suggest that intracellular electric field depends on R_m in its physiologic range, and may not be negligible in understanding some mechanisms of electric field-mediated therapies.