Properties of lipid electropores II: Comparison of continuum-level modeling of pore conductance to molecular dynamics simulations

Electrical conductance of an aqueous pore in the lipid bilayer has an important role in the process of membrane electroporation, i.e., formation of pores induced by electric pulses. In our present study we compare the pore conductance as predicted by a theoretical model based on the continuum Poisson-Nernst-Planck theory to the pore conductance obtained with molecular dynamics simulations (Casciola et al., Bioelectrochemistry 109:108-116, 2016). Our analysis demonstrates that the Poisson-Nernst-Planck model is able to quantitatively predict the dependence of the pore conductance on the pore radius when considering the toroidal shape of the pore. In order to correctly describe the difference in the pore conductance for Cl and Na ions (the pore selectivity), however, it is necessary to take into account the electric double layer next to the lipid-water interface and the electroosmotic flow through the pore. We further show that simplified analytical descriptions of pore conductance can lead to incorrect predictions of the pore size extracted from experimental measurements, and can affect the predictions of electroporation models. Overall, this study demonstrates that continuum modeling can be efficiently used as complementary method to molecular scale models for investigating lipid pores.