Aqueous pores in lipid bilayers and red cell membranes

Abstract

There are striking similarities between the properties of the aqueous channels induced in lipid bilayers by the polyene antibiotics nystatin and amphotericin B, and the equivalent pores in human red cell membranes. The equivalent pore radius in the human red cell membrane, calculated from the ratio of the hydraulic conductivity to the water permeability coefficient is 4.5 Å, whereas that for the lipid bilayers, calculated by the same method, is 4.6 Å for the nystatin-treated membrane and 4.3 Å for the amphotericin B-treated membrane. Reflection coefficients for urea, ethylene glycol and glycerol in lipid bilayers are in agreement with those for human red cell membranes. Permeability coefficients for small hydrophilic non-electrolytes are exponentially dependent upon molar volume in both systems and all the data fall on the same curve. The properties of the aqueous channels in these two systems appear to be virtually identical as measured by each of these three independent criteria.