Theory of the Effect of Surface Active Agent on the Electric Conductance of Lipid Membrane. I

Abstract

A theoretical analysis of the ionic transport across the lipid membrane is given on the basis of the thin symmetric membrane model with electric change on central plane and compared with the experimental result. The condition of the electric neutrality in the membrane does not stand since the thickness of the lipid membrane, 40–60Å, is too thin to neglect the effect of the ionic atmosphere.
The distributions of the electric potential and ions in the membrane which satisfy Poisson’s equation and the ionic flux equation are taken into consideration.
The increase in the electric conductance of the membrane on addition of the surface active agent can be interpreted as follows.
The added agent to the electrolyte solution is adsorbed on charged plane due to physical adsorption. The charge density of the charged plane changes by this adsorption, and subsequently this charge may affect the electric conductance of the membrane.