Effects of miR-126 on oxidative stress in HUVECs exposed to OGD/R in the presence or absence of SIRT1 siRNA or Con-siRNA. HUVECs were pre-transfected with SIRT1-siRNA or Con-siRNA for 30 min, and then transfected with miR-126 m or miR-NC prior to OGD (4 h)/R (24 h) exposure. (A) Intracellular ROS generation was assayed by dichlorohydrofluorescein diacetate staining followed by flow cytometry. (B) Quantitative analysis of ROS level. (C) MDA content was measured using a Lipid Peroxidation MDA assay kit. (D) SOD activity was determined by a Superoxide Dismutase assay kit. (E) GSH-PX activity was detected using a Cellular Glutathione Peroxidase assay kit. Data are presented as the mean ± SD of at least three independent experiments. *P<0.05 and **P<0.01 vs. control group; #P<0.05 and ##P<0.01 vs. miR-NC + OGD/R group; &P<0.05 and &&P<0.01 vs. miR-126 m + OGD/R + Con-siRNA group. miR-126 m, miR-126 mimics; miR-NC, miR-negative control; miR, microRNA; OGD, oxygen-glucose deprivation; R, reoxygenation; HUVEC, human umbilical vein endothelial cell; SIRT1, NAD-dependent protein deacetylase sirtuin-1; siRNA, small interfering RNA; Con-siRNA, negative control siRNA; ROS, reactive oxygen species; MDA, cell malondialdehyde; SOD, superoxide dismutase; GSH-Px, glutathione peroxidase.