[Effect of phase transition on electric capacitance of plane lipid membranes]

Effect of lipid phase transition on electric capacitance of plane lipid membranes was studied. For this purpose the capacitance of the membranes formed from solutions of saturated synthetic phospholipids in different solvent systems were measured at different temperatures. It was found that the capacitance of the membranes formed from phospholipid solution in dioxane having practically no solvent decreased at phase transition from liquid crystal state to gel. It can be explained by an increased membrane thickness during phase transition due to a change of conformation of phospholipid hydrocarbon chains. At the same time the capacitance of the membranes formed from phospholipid solution in normal hydrocarbons increased at the temperatures below the phase transition one. The latter results agree with the data of other authors. It is explained by the thinning of the membrane at the expense of solvent yield from the membrane phase to microlenses.