title: The current-voltage relationships of liposomes and mitochondria.
abstract: Current-voltage relationships were determined for various membrane systems. We show that phospholipid and mitochondrial membranes exhibit linear relations between H+ flux and pH gradients. These membranes, however, exhibited non-linear relationships when the applied voltage was a membrane potential. The current-voltage relationship approximated to an exponential function. This relationship was found to be linearized when the membranes were treated with an electrogenic proton ionophore. The incorporation of cytochrome c oxidase (EC 1.9.3.1) was found to have no effect on the current-voltage characteristics of the phospholipid membranes. When a membrane potential of more than 140 mV was imposed across vesicular and mitochondrial membranes, they exhibited reversible di-electric breakdown. This phenomenon was correlated with the requirement of a permeant ion for the experimental demonstration of proton translocation by so-called 'proton pumps'.
mesh_terms: D000818:Animals; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002463:Cell Membrane Permeability; D003576:Electron Transport Complex IV / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000502:physiology; D008081:Liposomes / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D008565:Membrane Proteins / Q000378:metabolism; D008930:Mitochondria, Liver / Q000187:drug effects / Q000502:physiology*; D010743:Phospholipids / Q000378:metabolism; D051381:Rats
chemical_list: D008081:Liposomes; D008565:Membrane Proteins; D010743:Phospholipids; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D003576:Electron Transport Complex IV