title: Palmitate increases superoxide production through mitochondrial electron transport chain and NADPH oxidase activity in skeletal muscle cells.
abstract: The effect of unbound palmitic acid (PA) at plasma physiological concentration range on reactive oxygen species (ROS) production by cultured rat skeletal muscle cells was investigated. The participation of the main sites of ROS production was also examined. Production of ROS was evaluated by cytochrome c reduction and dihydroethidium oxidation assays. PA increased ROS production after 1 h incubation. A xanthine oxidase inhibitor did not change PA-induced ROS production. However, the treatment with a mitochondrial uncoupler and mitochondrial complex III inhibitor decreased superoxide production induced by PA. The importance of mitochondria was also evaluated in 1 h incubated rat soleus and extensor digitorum longus (EDL) muscles. Soleus muscle, which has a greater number of mitochondria than EDL, showed a higher superoxide production induced by PA. These results indicate that mitochondrial electron transport chain is an important contributor for superoxide formation induced by PA in skeletal muscle. Results obtained with etomoxir and bromopalmitate treatment indicate that PA has to be oxidized to raise ROS production. A partial inhibition of superoxide formation induced by PA was observed by treatment with diphenylene iodonium, an inhibitor of NADPH oxidase. The participation of this enzyme complex was confirmed through an increase of p47(phox) phosphorylation after treatment with PA.
authors.affiliation: Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil. rhlamber@yahoo.com.br
authors.forename: Rafael Herling
authors.initials: RH
authors.lastname: Lambertucci
authors.forename: Sandro Massao
authors.initials: SM
authors.lastname: Hirabara
authors.forename: Leonardo Dos Reis
authors.initials: Ldos R
authors.lastname: Silveira
authors.forename: Adriana Cristina
authors.initials: AC
authors.lastname: Levada-Pires
authors.forename: Rui
authors.initials: R
authors.lastname: Curi
authors.forename: Tania Cristina
authors.initials: TC
authors.lastname: Pithon-Curi
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D045304:Cytochromes c / Q000378:metabolism; D004579:Electron Transport / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000166:cytology*; D019255:NADPH Oxidases / Q000378:metabolism*; D010084:Oxidation-Reduction; D010168:Palmitates; D019308:Palmitic Acid / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D010168:Palmitates; D017382:Reactive Oxygen Species; D013481:Superoxides; D019308:Palmitic Acid; D045304:Cytochromes c; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1