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% O_, 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, 070 ± 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.