Effect of vitamin E on hydrogen peroxide production by human vascular endothelial cells after hypoxia/reoxygenation

Changes in oxidative stress status play an important role in tissue injury associated with ischemia-reperfusion events such as those that occur during stroke and myocardial infarction. Endothelial cells (EC) from human saphenous vein and aorta were incubated for 22 h and found to take up vitamin E from media containing 0–60 mM vitamin E in a dose-dependent manner. EC supplemented with 23 or 28 mM vitamin E in the media for 22 h were maintained at normoxia (20% O2, 5% CO2, and balance N2) or exposed to hypoxic conditions (3% O2, 5% CO2, and balance N2) for 12 h, followed by reoxygenation (20% O2) for 30 min. Saphenous EC supplemented with 23 mM vitamin E produced less (p < 0.05) H2O2 than unsupplemented controls, both at normoxic condition (supplemented: 4.9 ± 0.05 vs. control: 10.9 ± 1.3 pmol/min/106 cells) and following hypoxia/reoxygenation (supplemented: 6.4 ± 0.78 vs. control: 17.0 ± 2.7 nmol/min/106 cells). In contrast, aortic EC, which were found to have higher superoxide dismutase and catalase activity than EC from saphenous vein, did not produce any detectable levels of H2O2. Following hypoxia/reoxygenation, the concentration of vitamin E in supplemented saphenous EC was 62% lower than cells maintained at normoxia (0.19 ± 0.03 vs. 0.5 ± 0.12 nmoles/106 cells, p < 0.001); in aortic EC vitamin E content was reduced by 18% following reoxygenation (0.86 ± 0.16 vs. 0.70 ± 0.09 nmoles/106 cells, p < 0.05). Therefore, enrichment of vitamin E in EC decreases H2O2 production and thus may reduce the injury associated with ischemia-reperfusion events.