[Comparison of the electrical and isotope characteristics of ionic transport through bilateral phospholipid...

Simultaneous measurements of electrochemical characteristics and tracer fluxes have been made using large spherical bilayer lipid membranes (1-2 cm2 area). The results obtained show the predominant contribution of electrically silent chloride molecules to the fluxes through unmodified membranes. In cases of valinomycin modified (valinomycin concentration=10(-7)M) membranes (in 0.1 M solutions of KCl, RbCl and CsCl) the fluxes are determined exclusively by cations. The membrane permeability for 22Na, in 0.1 NaCl solution, does not depend on the valinomycin concentration. The selectivity sequences obtained by electrochemical and tracer methods are compared and discussed.