Aim To investigate whether genistein protects paraoxon-induced vascular endothelial dysfunction through down-regulating p22phox and Nox4 expressions as well as inhibiting the generation of ROS. Methods In this study, thoracic aortas were isolated from the male Sprague-Dawley(SD) rats and were divided into the following groups: (1) control group, the thoracic aortas were incubated with dimethyl sulfoxide (DMSO, 0.1 %) for 30 min; (2) genistein group, the thoracic aortas were incubated with genistein (100 μmol • L-1) for 30 min; (3) paraoxon gr...