Surface Charges on Nerve Membranes and Artificial Lipid Bilayers

Abstract

The determination of membrane surface charges is described for membranes of unmyelinated and myelinated nerves and for artificial lipid bilayer membranes. In nerve membranes negative surface charges are found. Their density is larger at the external than at the internal interface. This result is discussed in terms of “flip‐flop” transfer of charges between both surfaces across the membrane which is controlled by the electric field. Surface charge densities at lipid bilayer membranes formed from lipids with charged polar groups are higher than the corresponding densities at nerve membranes. The importance of discreteness of charge effects on the determination of membrane surface charges is estimated for nerve membranes and lipid bilayers and is illustrated by several examples.