Oscillatory phenomena in model membrane: electrical oscillation in lipid-impregnated membrane filter induced by alamethicin and controlled by bacteriorhodopsin

A lipid-impregnated membrane filter was able to show reproducibly of an electrical oscillation under constant current stimulation when alamethicin and protamine were present in the chamber whose salt concentration was higher than the other and the membrane was left for about 12 h. In addition, bacteriorhodopsin, which is a light-activated proton pump, was found to control the oscillation. The oscillatory phenomenon was considered to be driven by the alternating change in the ion-selectivity of the membrane between cation and anion. Impedance measurement indicated the existence of lipid rearrangement which might prepare an environment for both alamethicin and protamine to cause the oscillation.