Mechanisms of H2O2-induced oxidative stress in endothelial cells

Christian H. Coyle, Luis J. Martinez, Mitchell C. Coleman, Douglas R. Spitz, Neal L. Weintraub, Khalid N. Kader

Research output: Contribution to journalArticle

94 Scopus citations


Hydrogen peroxide, produced by inflammatory and vascular cells, induces oxidative stress that may contribute to endothelial dysfunction. In smooth muscle cells, H2O2 induces production of O2{radical dot}- by activating NADPH oxidase. However, the mechanisms whereby H2O2 induces oxidative stress in endothelial cells are poorly understood. We examined the effects of H2O2 on O2{radical dot}- levels on porcine aortic endothelial cells (PAEC). Treatment with 60 μmol/L H2O2 markedly increased intracellular O2{radical dot}- levels (determined by conversion of dihydroethidium to hydroxyethidium) and produced cytotoxicity (determined by propidium iodide staining) in PAEC. Overexpression of human manganese superoxide dismutase in PAEC reduced O2{radical dot}- levels and attenuated cytotoxicity resulting from treatment with H2O2. L-NAME, an inhibitor of nitric oxide synthase (NOS), and apocynin, an inhibitor of NADPH oxidase, reduced O2{radical dot}- levels in PAEC treated with H2O2, suggesting that both NOS and NADPH oxidase contribute to H2O2-induced O2{radical dot}- in PAEC. Inhibition of NADPH oxidase using apocynin and NOS rescue with L-sepiapterin together reduced O2{radical dot}- levels in PAEC treated with H2O2 to control levels. This suggests interaction-distinct NOS and NADPH oxidase pathways to superoxide. We conclude that H2O2 produces oxidative stress in endothelial cells by increasing intracellular O2{radical dot}- levels through NOS and NADPH oxidase. These findings suggest a complex interaction between H2O2 and oxidant-generating enzymes that may contribute to endothelial dysfunction.

Original languageEnglish (US)
Pages (from-to)2206-2213
Number of pages8
JournalFree Radical Biology and Medicine
Issue number12
StatePublished - Jun 15 2006
Externally publishedYes


  • Hydrogen peroxide
  • NADPH oxidase
  • NOS
  • Superoxide

ASJC Scopus subject areas

  • Biochemistry
  • Physiology (medical)

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