Boundary-element calculations for amplification of effects of low-frequency electric fields in a doublet-shaped biological cell.

To examine the amplification of the effects of low-frequency electric fields due to the junction between the cells, the amplitude of transmembrane potential P(TMP0), the time-averaged normal stress sigma(n) and the outward force density sigma(out) on the shell-phase, and the squared intensity I(ee) of electric fields in the inner and the outer phases induced by uniform external ac fields were calculated with the boundary-element method for doublet-shaped cell models consisting of two spheres of the same size connected by the junction; the results were compared with those in a spherical model. When the external fields were parallel to the long axis of the doublet-shaped models, P(TMP0), sigma(n) and sigma(out) at the pole were greater than those in the spherical model, and sigma(out) and I(ee) at the junction increased with the decrease in the junction-radius. The external fields perpendicular to the long axis caused I(ee) greater than that at the center of the spherical model and negative sigma(out), at the junction. The amplification of P(TMP0), sigma(n), sigma(out) and I(ee) took place within restricted frequency-regions that could be specified by the characteristic frequencies for the frequency-dependence of the polarization factor of the models.