ELECTRIC BREAKDOWN OF BILAYER LIPID-MEMBRANES .3. ANALYSIS OF POSSIBLE MECHANISMS OF DEFECT ORIGINATION

Different mechanisms of the defect formation are analyzed. A cylindrical hole was taken as an example of a defect caused by thermal motion. It follows from the analysis of such a defect's energy dependence on its sizes that the most probable way of the through-going pore origination is the formation of narrow and deep holes. It is shown by an estimate that the membrane breakdown due to van der waals forces is possible only when an appreciable area of the membrane surface becomes free of phospholipid molecules, and therefore when a pure organic solvent layer is formed. Thus the Van der waals mechanism is shown to be improbable. The effect of local electric field caused by a single ion is analysed. Approximate calculations have shown that the so called image forces can be significant only on late stages of membrane breakdown, i.e. for relatively wide pores. This result constitutes the basis for further theoretical description of the processes taking place during membrane breakdown. © 1979.