title: Role of Fe(III) in Fe(II)citrate-mediated peroxidation of mitochondrial membrane lipids.
abstract: In this report we study the effect of Fe(III) on lipid peroxidation induced by Fe(II)citrate in mitochondrial membranes, as assessed by the production of thiobarbituric acid-reactive substances and antimycin A-insensitive oxygen uptake. The presence of Fe(III) stimulates initiation of lipid peroxidation when low citrate:Fe(II) ratios are used (< or = 4:1). For a citrate:total iron ratio of 1:1 the maximal stimulation of lipid peroxidation by Fe(III) was observed when the Fe(II):Fe(III) ratio was in the range of 1:1 to 1:2. The lag phase that accompanies oxygen uptake was greatly diminished by increasing concentrations of Fe(III) when the citrate:total iron ratio was 1:1, but not when this ratio was higher. It is concluded that the increase of lipid peroxidation by Fe(III) is observed only when low citrate:Fe(II) ratios were used. Similar results were obtained using ATP as a ligand of iron. Monitoring the rate of spontaneous Fe(II) oxidation by measuring oxygen uptake in buffered medium, in the absence of mitochondria, Fe(III)-stimulated oxygen consumption was observed only when a low citrate:Fe(II) ratio was used. This result suggests that Fe(III) may facilitate the initiation and/or propagation of lipid peroxidation by increasing the rate of Fe(II)citrate-generated reactive oxygen species.
authors.affiliation: Departamento de Patologia Clínica, Universidade Estadual de Campinas, Brazil.
authors.forename: R F
authors.initials: RF
authors.lastname: Castilho
authors.forename: A R
authors.initials: AR
authors.lastname: Meinicke
authors.forename: A E
authors.initials: AE
authors.lastname: Vercesi
authors.forename: M
authors.initials: M
authors.lastname: Hermes-Lima
mesh_terms: D000818:Animals; D019343:Citric Acid; D005290:Ferric Compounds / Q000378:metabolism*; D005296:Ferrous Compounds / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism; D015227:Lipid Peroxidation; D008563:Membrane Lipids / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D010101:Oxygen Consumption; D051381:Rats; D017208:Rats, Wistar
chemical_list: D005290:Ferric Compounds; D005296:Ferrous Compounds; D008563:Membrane Lipids; D019343:Citric Acid; C016600:ferrous citrate