DYNAMICALLY STABILIZED PORES IN BILAYER-MEMBRANES

Zhelev and Needham have recently created large, quasistable pores in a rtificial lipid bilayer vesicles. Initially created by electroporation , the pores remain open for up to several seconds before quickly snapp ing shut. This result is surprising, in light of the large line tensio n for holes in bilayer membranes and the rapid time scale for closure of large pores. We show how pores can be dynamically stabilized via a new feedback mechanism. We also explain quantitatively the observed su dden pore closure as a tangent bifurcation. Finally, we show how Zhele v and Needham's experiment can be used to measure accurately the pore line tension, an important material parameter. For their stearoyloleoy lphosphatidylcholine/cholesterol mixture we obtain a line tension of 2 .6 x 10(-6) dyn.