Effect of the cholesterol on electroporation of planar lipid bilayer.

Electroporation threshold depends on the membrane composition, with cholesterol being one of its key components already studied in the past, but the results were inconclusive. The aim of our study was to determine behaviour of planar lipid bilayers with varying cholesterol concentrations under electric field. This would give us a better insight into cholesterol effect on membrane properties during electroporation process, since cholesterol is one of the major components of biological membranes and plays a crucial role in membrane organisation, dynamics, and function. Planar lipid bilayers were prepared from phosphatidylcholine lipids with 0, 20, 30, 50 and 80 mol% cholesterol. Capacitance was measured using the discharge method. Results show no statistical difference of c between the cholesterol concentrations. Breakdown voltage U of planar lipid bilayers was measured by means of linear rising voltage with seven different slopes. Obtained results were fitted to a strength-duration curve, where parameter U represents minimal breakdown voltage, and parameter τ represents the inclination of the strength-duration curve. Adding cholesterol to planar lipid bilayer gradually increased its U until 50 mol% cholesterol concentration. Afterwards at 80 mol% U does not further increase, in fact it reduces by 20% of the U at 50 mol% cholesterol concentration.