TY - JOUR

T1 - Passive ion permeability of lipid membranes modelled via lipid-domain interfacial area

AU - Cruzeiro-Hansson, Leonor

AU - Mouritsen, Ole G.

PY - 1988

Y1 - 1988

N2 - A microscopic interaction model of the gel-to-fluid chain-melting phase transition of fully hydrated lipid bilayer membranes is used as a basis for modelling the temperature dependence of passive transmembrane permeability of small ions, e.g. Na+. Computer simulation of the model shows that the phase transition is accompanied by strong lateral density fluctuations which manifest themselves in the formation of inhomogeneous equilibrium structures of coexisting gel and fluid domains. The interfaces of these domains are found to be dominated by intermediate lipid-chain conformations. The interfacial area is shown to have a pronounced peak at the phase transition. By imposing a simple model for ion diffusion through membranes which assigns a high relative permeation rate to the domain interfaces, the interfacial area is then identified as a membrane property which has the proper temperature variation to account for the peculiar experimental observation of a strongly enhanced passive ion permeability at the phase transition. The excellent agreement with the experimental data for Na+-permeation, taken together with recent experimental results for the phase transition kinetics, provides new insight into the microphysical mechanism of reversibel electric breakdown. This insight indicates that there is no need for aqueous pore-formation to explain the experimental observation of a dramatic increase in ion conductance subsequent to electric pulses.

AB - A microscopic interaction model of the gel-to-fluid chain-melting phase transition of fully hydrated lipid bilayer membranes is used as a basis for modelling the temperature dependence of passive transmembrane permeability of small ions, e.g. Na+. Computer simulation of the model shows that the phase transition is accompanied by strong lateral density fluctuations which manifest themselves in the formation of inhomogeneous equilibrium structures of coexisting gel and fluid domains. The interfaces of these domains are found to be dominated by intermediate lipid-chain conformations. The interfacial area is shown to have a pronounced peak at the phase transition. By imposing a simple model for ion diffusion through membranes which assigns a high relative permeation rate to the domain interfaces, the interfacial area is then identified as a membrane property which has the proper temperature variation to account for the peculiar experimental observation of a strongly enhanced passive ion permeability at the phase transition. The excellent agreement with the experimental data for Na+-permeation, taken together with recent experimental results for the phase transition kinetics, provides new insight into the microphysical mechanism of reversibel electric breakdown. This insight indicates that there is no need for aqueous pore-formation to explain the experimental observation of a dramatic increase in ion conductance subsequent to electric pulses.

KW - Computer simulation

KW - Density fluctuation

KW - Ion permeability

KW - Lipid bilayer

KW - Phase transition

KW - Reversible electrical breakdown

U2 - 10.1016/0005-2736(88)90316-1

DO - 10.1016/0005-2736(88)90316-1

M3 - Journal article

C2 - 3415999

AN - SCOPUS:0023722226

VL - 944

SP - 63

EP - 72

JO - B B A - Biomembranes

JF - B B A - Biomembranes

SN - 0005-2736

IS - 1

ER -