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 journalArticlepeer-review

99 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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