Membrane potential, surface potential, and ionic permeabilities.

To clarify contributions to cellular transmembrane potential concentration potentials of phospholipid bilayer membranes and surface potentials of phospholipid monolayers were measured with respect to salt concentrations and various surface charge densities. For highly charged membranes of symmetrical surface charge density, it was found that the observed transmembrnae potentials are due mostly to the difference between the surface potentials on each side of the membrane. For uncharged membranes, it was found that the transmembrane potential is due to the ion diffusion potential across the membrane. Also discussed are ion permeabilities through the membrane in relation to transmembrane potential.