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K. Kaufmann, W. Hanke and A. Corcia. 1989. BOOK 3: Ion Channel Fluctuations in Pure Lipid Bilayer Membranes: Control by voltage. Caruaru, Brazil.

Abstract: Lipid bilayer membranes are shown to represent a dielectric barrier, which due to the thermodynamic fluctuations in membrane thickness, reversibly breaks down forming ion channels of discrete conductivity. The probability of the phenomenon is controlled by the electrostatic membrane potential (voltage) as well as by pH, pCa, surface pressure and temperature. Ion channel probability increases with the isothermal monolayer compressibilities. The thermodynamics theory is used to explain voltage- as well as surface pressure induced ion channels observed in pure synthetic lipid bilayers in the absence of protein, polypeptide, or detergent. Ion channel localisation in the bilayer is demonstrated by variation of bilayer area and boundary conditions. Patch-clamp and Montal-Mueller techniques gave the same results. Many of the discrete steps in membrane current look indistinguishable from protein induced ion channels. It is concluded that ion channels are hydrophilic defects produced as a consequence of the thermodynamic fluctuations in the two-dimensional bimolecular phospholipid lattice.