Ethinylestradiol and estradiol have different effects on oxidative stress and nitric oxide synthesis in human endothelial cell cultures

Study objectiveTo compare the effects of ethinylestradiol (EE) and 17β-estradiol (E2) on nitric oxide (NO) production and protection against oxidative stress in human endothelial cell cultures.DesignExperimental study.SettingsResearch laboratory.MaterialHuman ECV304 endothelial cell cultures.Intervention(s)The NO synthesis was determined by flow cytometry, and oxidative stress was determined by a cell viability assay, after exposure to hydrogen peroxide (H2O2) and stimulation of endothelial cells with EE at concentrations similar to those of a contraceptive containing 30 μg EE.Main Outcome Measure(s)The effects of EE were compared with those of E2 at concentrations similar to those occurring during the follicular phase.Result(s)Ethinylestradiol did not increase NO synthesis and did not protect cells against oxidative stress. The viability of the cells incubated with E2 in combination with H2O2 was greater than the viability obtained with H2O2 only or with H2O2 in combination with EE. The cells stimulated with E2 presented a significant increase in NO production compared with control.Conclusion(s)In contrast to the effects of E2, EE did not protect human ECV304 endothelial cells against oxidative stress and did not increase their production of NO.