Biological cells exchange material with the surrounding environment through the cell membrane. One of the mechanisms for transmembrane transport involves the presence of pores in the lipid bilayer, through which a substantial flow of material can take place. However, pores in lipid bilayers are usually not stable; they shrink due to the highly unfavorable line tension of the pore rim. Even in the presence of charged lipids or certain additives such as detergents or isotropic membrane inclusions, membrane pores are generally not expected to be energetically stabilized. In this seminar, a simple theoretical model [1] that predicts the existence of stable pores in a lipid membrane will be presented. Possible applications of the model will be discussed and the model will be used to explain the observed dependency of the pore size in the membrane of red blood cell ghosts on the ionic strength of the surrounding solution.

[1] M. Fosnaric, V. Kralj-Iglic, K. Bohinc, A. Iglic and S. May, Stabilization of pores in lipid bilayers by anisotropic inclusions, J. Phys. Chem. B 107 12519-12526 (2003).