RESUMO
STUDY OBJECTIVE: To compare the effects of ethinylestradiol (EE) and 17ß-estradiol (E(2)) on nitric oxide (NO) production and protection against oxidative stress in human endothelial cell cultures. DESIGN: Experimental study. SETTINGS: Research laboratory. MATERIAL: Human 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 (H(2)O(2)) 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 E(2) 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 E(2) in combination with H(2)O(2) was greater than the viability obtained with H(2)O(2) only or with H(2)O(2) in combination with EE. The cells stimulated with E(2) presented a significant increase in NO production compared with control. CONCLUSION(S): In contrast to the effects of E(2), EE did not protect human ECV304 endothelial cells against oxidative stress and did not increase their production of NO.