title: Measurement of transmembrane potentials in phospholipid vesicles.
abstract: Phosphatidylcholine vesicles are permeable to tempotartrate, a spin-label derivative of tartaric acid. The inside-outside distribution of tempotartrate is coupled to the inside-outside distribution of H(+), so it must be a measure of the transmembrane electrical potential difference in vesicles permeable to H(+). This prediction is borne out by the finding that the inside-outside distribution of tempotartrate is the reciprocal of the inside-outside distribution of K(+) in vesicles prepared in the presence of valinomycin. The inside-outside distribution of tempotartrate is, by contrast, equal to the inside-outside distribution of Cl(-) in vesicles without valinomycin. This is evidence that an inside-outside Cl(-) concentration gradient induces an H(+) gradient, which must be due to HCl permeation.
mesh_terms: D002462:Cell Membrane / Q000502:physiology*; D002463:Cell Membrane Permeability; D002852:Chromatography, Ion Exchange; D002854:Chromatography, Paper; D004058:Diffusion; D004578:Electron Spin Resonance Spectroscopy; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008564:Membrane Potentials; D008567:Membranes, Artificial; D008722:Methods; D008839:Microelectrodes; D009994:Osmolar Concentration; D010539:Permeability; D010713:Phosphatidylcholines; D010743:Phospholipids; D013644:Tartrates; D014634:Valinomycin
chemical_list: D008567:Membranes, Artificial; D010713:Phosphatidylcholines; D010743:Phospholipids; D013644:Tartrates; D014634:Valinomycin