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Electroporation-stochastic model for electric field-induced membrane pores*
Bioelectroehemistry and Bioenergetics, 11 (1983) 479 A section of J. Electroanal. Chem., and constituting Vol. 156 (1983) Elsevier Sequoia .%A., Lausanne - Printed in The Netherlands
677-ELECTROPORATION-STOCHASTIC FIELD-INDUCED MEMBRANE PORES
479
MODEL FOR ELECTRIC l
1. SUGAR Institute of Biophysics, Semmelweis E. NEUMANN Max
l
Medical University, Budapest (Hungary)
*
- Planck - Institut ftir Biochemie, Martinsried, Miinchen (F. R.G.)
Electric impulses (l-20 kV cm- ‘; l-5 I.LS)cause transient structural changes in biological membranes and lipid bilayers, leading to apparently reversible pore formation (electroporation) with cross-membrane material flow and, if two membranes are in contact, to irreversible membrane fusion (electrofusion). The fundamental process operative in electroporation and electrofusion is treated in terms of a lipid block model, a block being the nearest neighbour pair of lipid molecules in either of two states: (i) the polar head group in the bilayer plane or (ii) facing the centre of a pore or defect site. The number of blocks in the pore wall is the stochastic variable of the model describing pore size and stability. The Gibbs free energy function characterizing the transition probabilities of the various pore states contains the surface energies of the pore wall and the planar bilayer and, if an electric field is present, also a dielectric polarization term (dominated by the polarization of the water layer adjacent to the pore wall). Assuming a Poisson process, the average number of blocks in a pore wall is given by the solution of a non-linear differential equation. At subcritical electric fields, the average pore size is stationary and very small. At supercritical field strengths, the pore radius increases and, reaching a critical pore size, the membrane ruptures (dielectric breakdown). If, however, the electric field is switched off before the critical pore radius is reached, the pore apparently completely reseals to the closed bilayer configuration (reversible electroporation).
Presented at the 7th International Symposium on Bioekectrochemistry, Stuttgart (F.R.G.), 18-22 July 1983. This abstract was sent to, and distributed by, the Organizing Committee of the Symposium. A final manuscript was not sent by the authors. l * Present address: University Bielefeld, Sektion Biophysical Chemistry. l
677-ELECTROPORATION-STOCHASTIC FIELD-INDUCED MEMBRANE PORES
479
MODEL FOR ELECTRIC l
1. SUGAR Institute of Biophysics, Semmelweis E. NEUMANN Max
l
Medical University, Budapest (Hungary)
*
- Planck - Institut ftir Biochemie, Martinsried, Miinchen (F. R.G.)
Electric impulses (l-20 kV cm- ‘; l-5 I.LS)cause transient structural changes in biological membranes and lipid bilayers, leading to apparently reversible pore formation (electroporation) with cross-membrane material flow and, if two membranes are in contact, to irreversible membrane fusion (electrofusion). The fundamental process operative in electroporation and electrofusion is treated in terms of a lipid block model, a block being the nearest neighbour pair of lipid molecules in either of two states: (i) the polar head group in the bilayer plane or (ii) facing the centre of a pore or defect site. The number of blocks in the pore wall is the stochastic variable of the model describing pore size and stability. The Gibbs free energy function characterizing the transition probabilities of the various pore states contains the surface energies of the pore wall and the planar bilayer and, if an electric field is present, also a dielectric polarization term (dominated by the polarization of the water layer adjacent to the pore wall). Assuming a Poisson process, the average number of blocks in a pore wall is given by the solution of a non-linear differential equation. At subcritical electric fields, the average pore size is stationary and very small. At supercritical field strengths, the pore radius increases and, reaching a critical pore size, the membrane ruptures (dielectric breakdown). If, however, the electric field is switched off before the critical pore radius is reached, the pore apparently completely reseals to the closed bilayer configuration (reversible electroporation).
Presented at the 7th International Symposium on Bioekectrochemistry, Stuttgart (F.R.G.), 18-22 July 1983. This abstract was sent to, and distributed by, the Organizing Committee of the Symposium. A final manuscript was not sent by the authors. l * Present address: University Bielefeld, Sektion Biophysical Chemistry. l