A statistical mechanical model of cell membrane ion channels in electric fields: The mean-field approximation

A statistical mechanical model of cell membrane ion channels is proposed wh ich incorporates interactions between ion channels and external electric fi elds. The model provides a physical explanation of trans-membrane ion trans port. Under a mean-field approximation, the maximum fractions of open potas sium and sodium channels are obtained by solving a self-consistent nonlinea r algebraic equation. Using known parameters for the squid giant axon, the model gives excellent agreement with experimental measurements for potassiu m and sodium trans-membrane conductance. The numerical results imply that t he chemical potential of open channels and the interaction energy between c hannels are well above the thermal noise. (C) 1999 Elsevier Science B.V. Al l rights reserved.