Some Further Experiments on Bimolecular Lipid Membranes

In the earlier experiments it was established that a bilayer of pure egg phosphatidyl choline containing less than 50 per cent by volume of n-decane had a capacitance of 0.38 /ff/cm2 , this value being independent of applied voltage up to at least 50 my and independent of frequency between 200 and 5 X 106 cs. It was also unaffected by the nature and concentration of the surrounding electrolyte solution for NaCl, KC1, and CaC12. In an attempt to discover more about the electrical properties of the film at frequencies below 200 cps the time dependence of the response to a sudden change in the D.C. potential across the film was examined. The transients were characterized by a single time constant and, using the measured value of the