Role of Fe(III) in Fe(II)citrate-mediated peroxidation of mitochondrial membrane lipids |
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Authors: | Castilho Roger F. Meinicke André R Vercesi Anibal E. Hermes-Lima Marcelo |
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Affiliation: | (1) Departamento de Patologia Clínica, NMCE, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, Brazil;(2) Oxyradical Research Group, Departamento de Biologia Celular, Universidade de Brasília, Brasília, Brazil |
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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 ( 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. |
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Keywords: | Fe(II)citrate free radicals iron lipid peroxidation mitochondria reactive oxygen species |
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