title: Interrelated influence of superoxides and free fatty acids over mitochondrial uncoupling in skeletal muscle.
abstract: Mitochondrial uncoupling protein 3 (UCP(3))-mediated uncoupling has been postulated to depend on several factors, including superoxides, free fatty acids (FFAs), and fatty acid hydroperoxides and/or their derivatives. We investigated whether there is an interrelation between endogenous mitochondrial superoxides and fatty acids in inducing skeletal muscle mitochondrial uncoupling, and we speculated on the possible involvement of UCP(3) in this process. In the absence of FFAs, no differences in proton-leak kinetic were detected between succinate-energized mitochondria respiring in the absence or presence of rotenone, despite a large difference in complex I superoxide production. The addition of either arachidic acid or arachidonic acid induced an increase in proton-leak kinetic, with arachidonic acid having the more marked effect. The uncoupling effect of arachidic acid was independent of the presence of GDP, rotenone and vitamin E, while that of arachidonic acid was dependent on these factors. These data demonstrate that FFA and O(2-) play interrelated roles in inducing mitochondrial uncoupling, and we hypothesize that a likely formation of mitochondrial fatty acid hydroperoxides is a key event in the arachidonic acid-induced GDP-dependent inhibition of mitochondrial uncoupling.
authors.affiliation: Dipartimento delle Scienze Biologiche, Sezione Fisiologia, Università degli Studi di Napoli Federico II, Via Mezzocannone 8, 80134 Napoli, Italy.
authors.forename: Assunta
authors.initials: A
authors.lastname: Lombardi
authors.forename: Paola
authors.initials: P
authors.lastname: Grasso
authors.forename: Maria
authors.initials: M
authors.lastname: Moreno
authors.forename: Pieter
authors.initials: P
authors.lastname: de Lange
authors.forename: Elena
authors.initials: E
authors.lastname: Silvestri
authors.forename: Antonia
authors.initials: A
authors.lastname: Lanni
authors.forename: Fernando
authors.initials: F
authors.lastname: Goglia
mesh_terms: D000818:Animals; D005230:Fatty Acids, Nonesterified / Q000378:metabolism / Q000494:pharmacology*; D006861:Hydrogen Peroxide / Q000378:metabolism; D007473:Ion Channels / Q000502:physiology*; D007700:Kinetics; D008297:Male; D008931:Mitochondria, Muscle / Q000187:drug effects / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D010101:Oxygen Consumption; D011522:Protons; D051381:Rats; D017208:Rats, Wistar; D013481:Superoxides / Q000494:pharmacology*; D014475:Uncoupling Agents / Q000494:pharmacology*; D000071256:Uncoupling Protein 1
chemical_list: D005230:Fatty Acids, Nonesterified; D007473:Ion Channels; D024101:Mitochondrial Proteins; D011522:Protons; D014475:Uncoupling Agents; D000071256:Uncoupling Protein 1; D013481:Superoxides; D006861:Hydrogen Peroxide