Surface dipoles, surface charges and negative steady-state resistance in biological membranes

Abstract

A theoretical expression for the steady-state current-voltage characteristic of biological membranes is given, justifying various assumptions which are usually made in the framework of the electrodiffusion theory, and taking into account the effect of surface charges and surface dipoles. It is shown that the orientation of the dipoles can be treated by a two-state model. But a comparison with the experimental curves of Gilbert and Ehrenstein leads to the conclusion that the observed negative resistances cannot be explained by a reorientation of the dipoles alone. An additional modification of the surface charges could be sufficient. Some features can be well explained by an absorption of divalent cations on the “outside” surface.