Moderate dependence of ROS formation on ΔΨm in isolated brain mitochondria supported by NADH-linked substrates

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Abstract

The membrane potential (ΔΨm) dependence of the generation of reactive oxygen species (ROS) in isolated guinea-pig brain mitochondria respiring on NADH-linked substrates (glutamate plus malate) was addressed. Depolarization by FCCP was without effect on H2O2 formation in the absence of bovine serum albumin (BSA). Addition of BSA (0.025%) to the assay medium hyperpolarized mitochondria by 6.1 ± 0.9 mV (from 169 ± 3 to 175.1 ± 2.1 mV) and increased the rate of H 2O2 formation from 207 ± 4.5 to 312 ± 12 pmol/min/mg protein. Depolarization by FCCP (5-250 nM) in the presence of BSA decreased H2O2 formation but only to the level observed in the absence of BSA. Rotenone stimulated the formation of H2O 2 both in the absence and presence of BSA. It is suggested that H2O2 formation in mitochondria supported by NADH-linked substrates is sensitive to changes in ΔΨm only when mitochondria are highly polarized and even then, 60% of ROS generation is independent of ΔΨm. This is in contrast to earlier reports on the highly ΔΨm sensitive ROS formation related to reverse electron flow observed in well-coupled succinate-supported mitochondria.

Original languageEnglish
Pages (from-to)569-575
Number of pages7
JournalNeurochemical research
Volume32
Issue number4-5
DOIs
Publication statusPublished - Apr 1 2007

Keywords

  • Amplex red
  • Bovine serum albumin
  • Brain
  • Complex I
  • Glutamate-malate
  • Guinea pig
  • Hydrogen peroxide
  • Membrane potential
  • Mitochondria
  • NADH
  • Reactive oxygen species
  • Respiratory chain
  • Superoxide

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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