Contribution of aqueous interphases to the permeability barrier of lipid bilayer for non-electrolytes

E.A. DISALVO ; J. DE GIER

CHEMISTRY AND PHYSICS OF LIPIDS

ELSEVIER IRELAND LTD

Lugar: Amsterdam; Año: 1983 vol. 32 p. 39 - 47

0009-3084

Equilibrium dialysis experiments are used to measure excluded volumes for the non-electrolyte permeant [U-14C] erythritol in lipidbilayer systems. The data indicate amounts of water associated with the lipid membranes which correspond with amounts calculated from calorimetric measurements. The membrane systems can be described as composite elements consisting of the lipid bilayers and adjacent water layers on both sides. The finding that the permeant is excluded indicates that the water layers contribute to the permeabilitybarrier. The mean thickness of the water layers is about 6 Å for planar bilayers in multilayered liposomes and 10 Å for curved bilayers in sonicated vesicles. Next to the difference in thickness of the water layers differences in interfacial adsorption between the two systems are apparent. Keywords non-solvent water; non-electrolytepermeability; lipid bilayers; sonicated vesicles