testing the applicability of nernst-planck theory in ion channels comparisons with brownian dynamics simulations测试的适用性nernst-planck理论在离子通道与布朗动力学模拟.pdf

Testing the Applicability of Nernst-Planck Theory in Ion Channels: Comparisons with Brownian Dynamics Simulations 1,2 1 Chen Song , Ben Corry * 1 School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, Perth, Australia, 2 Department of Theoretical and Computational ¨ Biophysics, Max Planck Institute for Biophysical Chemistry, Gottingen, Germany Abstract The macroscopic Nernst-Planck (NP) theory has often been used for predicting ion channel currents in recent years, but the validity of this theory at the microscopic scale has not been tested. In this study we systematically tested the ability of the NP theory to accurately predict channel currents by combining and comparing the results with those of Brownian dynamics (BD) simulations. To thoroughly test the theory in a range of situations, calculations were made in a series of simplified ˚ cylindrical channels with radii ranging from 3 to 15 A, in a more complex ‘catenary’ channel, and in a realistic model of the mechanosensitive channel MscS. The extensive tests indicate that the NP equation is applicable in narrow ion channels provided that accurate concentrations and potentials can be input as the currents obtained from the combination of BD and NP match well with those obtained directly from BD simulations, although some discrepancies are seen when the ion concentrations are not radially uniform. This finding opens a door to utilising the results of microscopic simulations in continuum theory, something that is likely to be useful in the investigation of a range of biophysical and nano-scale