Linked Life Data

9746312

Source:http://linkedlifedata.com/resource/pubmed/id/9746312

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1-2
pubmed:dateCreated
1998-12-3
pubmed:abstractText
Two mechanisms may affect the yield of the oxidative phosphorylation pathway in isolated mitochondria: (i) a decrease in the intrinsic coupling of the proton pumps (H+/2e- or H+/ATP), and (ii) an increase in the inner membrane conductance (proton or cation leak). Hence three kinds of modifications can occur and each of them have been characterized in isolated rat liver mitochondria (see preceding chapter by Rigoulet et al.). In intact isolated hepatocytes, these modifications are linked to specific patterns of bioenergetic parameters, i.e. respiratory flux, mitochondrial redox potential, DY, and phosphate potential. (1) The increase in H+/ATP stoichiometry of the mitochondrial ATP synthase, as induced by almitrine [20], leads to a decrease in mitochondrial and cytosolic ATP/ADP ratios without any change in the protonmotive force nor in the respiratory rate or redox potential. (2) In comparison to carbohydrate, octanoate metabolism by beta-oxidation increases the proportion of electrons supplied at the second coupling site of the respiratory chain. This mimics a redox slipping. Octanoate addition results in an increased respiratory rate and mitochondrial NADH/NAD ratio while protonmotive force and phosphate potential are almost unaffected. The respiratory rate increase is associated with a decrease in the overall apparent thermodynamic driving force (2deltaE'o - ndeltap) which confirms the 'redox-slipping-like' effect. (3) An increase in proton conductance as induced by the protonophoric uncoupler 2,4-dinitrophenol (DNP) leads to a decrease, as expected, in the mitochondrial NADH/NAD and ATP/ ADP ratios and in deltapsi while respiratory rate is increased. Thus, each kind of modification (proton leak, respiratory chain redox slipping or increase in H+/ATP stoichiometry of ATPase) is related to a specific set of bioenergetic parameters in intact cells. Moreover, these patterns are in good agreement with the data found in isolated mitochondria. From this work, we conclude that quantitative analysis of four bioenergetic parameters (respiration rate, mitochondrial NADH/ NAD ratio, protonmotive force and mitochondrial phosphate potential) gives adequate tools to investigate the mechanism by which some alterations may affect the yield of the oxidative phosphorylation pathway in intact cells.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0300-8177
pubmed:author
pubmed:issnType
Print
pubmed:volume
184
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
53-65
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:9746312-2,4-Dinitrophenol, pubmed-meshheading:9746312-Adenosine Triphosphatases, pubmed-meshheading:9746312-Adenosine Triphosphate, pubmed-meshheading:9746312-Almitrine, pubmed-meshheading:9746312-Animals, pubmed-meshheading:9746312-Cells, Cultured, pubmed-meshheading:9746312-Dihydroxyacetone, pubmed-meshheading:9746312-Lactic Acid, pubmed-meshheading:9746312-Male, pubmed-meshheading:9746312-Mitochondria, Liver, pubmed-meshheading:9746312-NAD, pubmed-meshheading:9746312-Octanoic Acids, pubmed-meshheading:9746312-Oxidation-Reduction, pubmed-meshheading:9746312-Oxidative Phosphorylation, pubmed-meshheading:9746312-Proton Pumps, pubmed-meshheading:9746312-Pyruvic Acid, pubmed-meshheading:9746312-Rats, pubmed-meshheading:9746312-Rats, Wistar, pubmed-meshheading:9746312-Thermodynamics
pubmed:year
1998
pubmed:articleTitle
Oxidative phosphorylation in intact hepatocytes: quantitative characterization of the mechanisms of change in efficiency and cellular consequences.
pubmed:affiliation
Laboratoire de Bioénergétique Fondamentale et Appliquée, Université Joseph Fourier, Grenoble, France.
pubmed:publicationType
Journal Article