Biochimica et Biophysica Acta 940 (1988) 275-287

Reversible electrical breakdown of lipid bilayers: formation and evolution of pores

Ralf W. Glasera,b, Sergei L. Leikinb, Leonid V. Chernomordikb, Vasili F. Pastushenkob and Artjom I. Sokirkob

aHumboldr- University of Berlin. Department of Biology, Berlin (G. D. R.)

bFrumkijn Institute of Electrochemisrty of the Academy of Sciences of the USSR, Moscow (U.S.S.R.)

(Received 23 November 1987)

Key words: Lipid bilayer; Electrical breakdown; Hydrophobic pore; Hydrophilic pore; Pore formation

The mechanism of reversible electric breakdown of lipid membranes is studied. The following stages of the process of pore development are substantiated. hydrophobic pores are formed in the lipid bilayer by spontaneous fluctuations. If these water-filled defects extend to a radius of 0.3 to 0.5 nm, a hydrophilic pore is formed by reorientation of the lipid molecules. This process is favoured by a potential difference across the membrane. The conductivity of the pores depends on membrane voltage, and the type of this dependence changes with the radius of the pore. Hydrophilic pores of an effective radius of 0.6 up to more than 1 nm are formed, which account for the membrane conductivity increase observed. The characteristic times of changes in average radius and number of pores during the voltage pulse and after it are investigated.