Journal of Bioenergetics and Biomembranes

, Volume 29, Issue 1, pp 89–95

Dependence of H2O2 Formation by Rat Heart Mitochondria on Substrate Availability and Donor Age

Authors

  • Richard G. Hansford
    • National Institute on Aging
  • Barbara A. Hogue
    • National Institute on Aging
  • Vida Mildaziene
    • Institute for Biomedical ResearchKaunas Medical Academy
Article

DOI: 10.1023/A:1022420007908

Cite this article as:
Hansford, R.G., Hogue, B.A. & Mildaziene, V. J Bioenerg Biomembr (1997) 29: 89. doi:10.1023/A:1022420007908

Abstract

We have examined the substrate specificity and inhibitor sensitivity of H2O2 formation by rat heart mitochondria. Active H2O2 production requires both a high fractional reduction of Complex I (indexed by NADH/NAD+ + NADH ratio) and a high membrane potential, ΔΨ. These conditions are achieved with supraphysiological concentrations of succinate. With physiological concentrations of NAD-linked substrates, rates of H2O2 formation are much lower (less than 0.1% of respiratory chain electron flux) but may be stimulated by the Complex III inhibitor antimycin A, but not by myxothiazol. Addition of Mn2+ to give 10 nmol/mg of mitochondrial protein enhances H2O2 production with all substrate combinations, possibly by repleting mitochondrial superoxide dismutase with this cation. Contrary to previously published work, no increased activity of H2O2 production was found with heart mitochondria from senescent (24 month) rats, relative to young adults (6 month).

Respiratory chainreactive oxygen species
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Copyright information

© Plenum Publishing Corporation 1997