Voltage-induced formation of alamethicin pores in lecithin bilayer vesicles

The interaction of alamethicin with lecithin bilayer vesicles in the presence of a transmembrane potential difference has been studied by proton magnetic resonance spectroscopy. Asymmetrical vesicles with alamethicin trapped within the intravesicular compartment were prepared and the formation of ion channels, were then triggered by imposing a suitable potassium ion gradient across the bilayer membrane in the presence of valinomycin. These alamethicin channels were found to permit the outward passage of europium ions into the extravesicular medium when the transmembrane potential is more positive for the inner compartment.