Electric field effects on lipid membrane structure

Multiple bilayers of dimyristoyl phosphatidylcholine and potassium oleate were macroscopically oriented between silver-coated glass slides. These model membranes were subjected to an electric field of up to 10(5) V . cm-1. The influence of the field on the molecular structure was monitored by ESR of cholestane and stearic acid spin labels and by NMR of the phosphorus atom in the phosphatidylcholine headgroup. It is concluded that the conformation of the headgroup is greatly affected while no influence on the structure and dynamics of the hydrocarbon chains can be detected. At electric fields above 10(4) V . cm-1, where structural effects are still reversible, spontaneous current fluctuations are observed. At fields above 10(5) V . cm-1, irreversible breakdown of the bilayer structure occurs.