Figure 1

Estrogen stimulates the formation of reactive oxygen species in endothelial cells. Intracellular reactive oxygen species (ROS) production was determined by measuring the intensity of DCF. Human umbilical vein endothelial cells showed a dose dependent increase in oxidant production after 5 min of 17β-estradiol (E2) exposure. Pretreatment with the mitochondrial chemical inhibitor, rotenone (ROT), significantly reduced the level of E2 stimulated oxidant formation. Xanthine oxidase inhibitor, allopurinol (ALP), also showed a significant reduction of oxidant production in E2 treated endothelial cells. Co-treatments with the NADPH oxidase inhibitors, apocynin and DPI, did not decrease the production of oxidants in E2 treated cells. An inhibitor of nitic oxide synthase, L-NAME, also did not show any inhibitory effect on oxidant production in E2 treated endotheial cells. Concentrations of chemical inhibitors were as follows: rotenone (2 μM), allopurinol (50 μM), apocynin (30 μM), DPI (2.5 μM), and L-NAME (50 μM). Data from three independent experiments are presented as ROS production with controls set at 100% (± SD). Values that are significantly different from E2 treatment alone (P < 0.05) are indicated with an asterisk (*).