title: Intrinsic uncoupling of mitochondrial proton pumps. 1. Non-ohmic conductance cannot account for the nonlinear dependence of static head respiration on delta microH.
abstract: The passive membrane conductance LH1 of rat liver mitochondria has been measured and compared with the quantity nJesh/delta microHsh (n = H+/e stoichiometry; Jesh = rate of electron transfer in static head) over a delta microH range. The two curves approach each other only in the lower part of the range, while they sharply diverge at large values of delta microH. Thus nJesh/delta microHsh cannot be considered to be a measure of LH1 in the upper delta microH region. Only a fraction of the static head electron flow is accounted for by futile proton cycling via leaks. Contaminating open membrane fragments or completely leaky mitochondria can be responsible for only a small part of the residual rate of oxygen consumption. We conclude that a large part of static head respiration must have yet another cause and propose it to be intrinsic uncoupling of the respiratory chain enzymes.
authors.forename: M
authors.initials: M
authors.lastname: Zoratti
authors.forename: M
authors.initials: M
authors.lastname: Favaron
authors.forename: D
authors.initials: D
authors.lastname: Pietrobon
authors.forename: G F
authors.initials: GF
authors.lastname: Azzone
mesh_terms: D000818:Animals; D004553:Electric Conductivity; D004579:Electron Transport; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008564:Membrane Potentials; D008930:Mitochondria, Liver / Q000378:metabolism* / Q000502:physiology; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D051381:Rats
chemical_list: D006180:Proton-Translocating ATPases