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

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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.

Original languageEnglish
JournalBiochimica et Biophysica Acta - Biomembranes
Issue number1
Pages (from-to)63-72
Number of pages10
Publication statusPublished - 1988
Externally publishedYes

    Research areas

  • Computer simulation, Density fluctuation, Ion permeability, Lipid bilayer, Phase transition, Reversible electrical breakdown

ID: 238390554