The lipid composition of flight muscle mitochondria isolated from the blowfly, Phormia regina

Guarnieri, Michael; Nair, Padmanabhan P.; Sacktor, Bertram

doi:10.1016/0003-9861(76)90122-3

Cited by 10 publications

(3 citation statements)

References 40 publications

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“…7), more in keeping with a square law. As an explanation of this behaviour, it is proposed that the unusual lipid composition of the flight-muscle mitochondrial membranes (Guarnieri et al, 1976) favours the mobility of a dimeric form of the uncoupler anion (see Finkelstein, 1970), since membrane composition is an important determinant of uncoupler function (Hopfer et al, 1970). Another more trivial explanation of the sigmoid behaviour might be a non-specific binding of uncoupling agent, quantitatively more significant at the lower concentration, decreasing the amount available to act as a proton carrier within the hydrophobic phase of the inner membrane.…”

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confidence: 99%

The nature of controlled respiration and its relationship to protonmotive force and proton conductance in blowfly flight-muscle mitochondria

Johnson

Hansford

1977

Biochemical Journal

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1. To determine whether controlled (State 4) pyruvate oxidation can support a high energy state, measurements of the redox span NAD-cytochrome c, phosphorylation potential and protonmotive force (the gradient in electrochemical activity of protons across the mitochondrial inner membrane) were made as indices of energy status. For comparison, these three measurements were also made with glycerol 3-phosphate, an alternative substrate. The two substrates gave essentially identical values for the redox span NAD-cytochrome c in State 4, and the phosphorylation potential was of sufficient magnitude to be considered in equilibrium with the redox span over the first two phosphorylation sites. The magnitude of the protonmotive force in State 4 was much less and the implications of this finding are discussed. 2. Measurements made during the controlled (State 4) to active (State 3) transition indicated that with glycerol 3-phosphate as substrate, both the redox span NAD-cytochrome c and the protonmotive force were diminished; the State 4 --> State 3 transition with pyruvate as substrate was accompanied by an increase in the redox span but a decrease in protonmotive force. The contrary behaviour of these two energetic parameters in the presence of pyruvate was ascribed to a transient excess in the flux of protons through the adenosine triphosphatase relative to the protonpumping respiratory chain, in spite of the increased dehydrogenase activity. 3. The lower protonmotive force seen in State 3 relative to State 4 with pyruvate as substrate was due to a diminution of both the electrical (DeltaPsi) and the chemical (DeltapH) components; with glycerol 3-phosphate, the magnitude of the decrease in protonmotive force during the State 4 --> State 3 transition was similar to that seen with pyruvate, but was due to a large decrease in the electrical component (DeltaPsi) and a small rise in the chemical component (DeltapH). The reason for the difference seen in the behaviour of the components of the protonmotive force was investigated but not established. 4. In the presence of oligomycin and ADP, oxidation of pyruvate, but not of glycerol 3-phosphate, supported a greater protonmotive force than in State 4, in keeping with the dehydrogenase activation and increased redox span NAD-cytochrome c found under these conditions. 5. Experiments involving the use of uncoupling agent to stimulate respiration are compared with those in which limiting concentrations of ADP were used. Estimates of the proton conductance of the inner membrane indicate a similar non-linear dependence on uncoupler concentration with the two substrates. 6. A model is proposed as an explanation of the high rates of controlled glycerol 3-phosphate oxidation. The model relies on a high permeability of the inner membrane to protons and other ions being induced by glycerol 3-phosphate oxidation in State 4.

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confidence: 99%

The nature of controlled respiration and its relationship to protonmotive force and proton conductance in blowfly flight-muscle mitochondria

Johnson

Hansford

1977

Biochemical Journal

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“…Taking into account the possibility that oleoylanilide could be hydrolysed as a consequence of the metabolic activity of the liver, perfusion experiments were performed with either [1-'4C]oleoylanilide or oleoyl[U-14C]anilide, previously synthesized by the method of Casals et al (1983). After 15 min, the perfusion medium was extracted by a modification of the Folch-Lees procedure (Guarnieri et al, 1976) and the lipid products were separated by t.l.c. on silica-gel G plates.…”

Section: Resultsmentioning

confidence: 99%

“…In some perfusion experiments with labelled oleoylanilides, the recycling media were extracted by a modification of the Folch-Lees method (Guarnieri et al, 1976) and total lipids were fractionated by t.l.c. with as developing solvent hexane/diethyl ether/acetic acid (70: 30: 1, by vol.)…”

Section: Lipid Extractionmentioning

confidence: 99%

The microviscosity of liver plasma membranes of rats fed with oleoylanilide

Pagani¹,

Portolés²,

Gavilanes³

et al. 1984

Biochemical Journal

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Oleoylanilide was administered orally to groups of rats according to different patterns. Oleoylanilide was perfused at different concentrations through rat liver. Oleoylanilide was added to isolated hepatocytes. Oleoylanilide was added to plasma-membrane preparations. Membrane preparations were obtained after experiments performed in vivo and perfusion experiments and, by using 1,6-diphenylhexa-1,3,5-triene as fluorescence probe, the fluorescence polarization parameter was measured, from which the microviscosity (eta) was calculated. In all cases the microviscosity decreased markedly. Addition of oleoylanilide to hepatocyte preparations and to isolated membranes produced the same effect, increasing the fluidity of the membranes. These data suggest that oleoylanilide partitions into the membrane, disordering some lipid interactions.

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The divalent cation requirement of the mitochondrial glycerol-3-phosphate dehydrogenase

Wohlrab

1977

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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The lipid composition of flight muscle mitochondria isolated from the blowfly, Phormia regina

Cited by 10 publications

References 40 publications

The nature of controlled respiration and its relationship to protonmotive force and proton conductance in blowfly flight-muscle mitochondria

The nature of controlled respiration and its relationship to protonmotive force and proton conductance in blowfly flight-muscle mitochondria

The microviscosity of liver plasma membranes of rats fed with oleoylanilide

The divalent cation requirement of the mitochondrial glycerol-3-phosphate dehydrogenase

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