States of lipid pores in bilayer lipid membranes at a phase transition in a LiCl solution with addition of molecules of polyethylene glycol

Statistics of times of open and closed states of lipid pores in planar lipid bilayer membranes that consisted of dipalmitoylphosphatidyl choline were experimentally studied at a temperature of a phase transition in the 1 M solution of LiCl after the addition of water-soluble molecules of polyethylene glycol of different molecular masses. Transmembrane current impulses were measured in a voltage-clamp regime (50 mV). Histograms of the impulse duration and impulse intervals had a non-exponential shape and a pronounced characteristic maximum. Therefore, the sequence of impulses of the transmembrane current under the conditions of phase transition was dependent. New impulses appeared depending on the time of antecedent impulses, and the moment of the impulse completion depended on the moment of its start. The proposed Erlang model quite accurately approximated the experimental histograms. According to this model, a lipid pore had several open and closed states.