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 PTMP0, the time-averaged normal stress σn and the outward force density σout on the shell-phase, and the squared intensity Iee 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, PTMP0, σn and σout at the pole were greater than those in the spherical model, and σout and Iee at the junction increased with the decrease in the junction-radius. The external fields perpendicular to the long axis caused Iee greater than that at the center of the spherical model and negative σout, at the junction. The amplification of PTMP0, σn, σout and Iee 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.