Effects of HIF-1α-siRNA on inflammatory cytokines in the presence or absence of TX in OGD/R-treated H9C2 cells. H9C2 cells were transfected with HIF-1α-siRNA or NS-siRNA for 6 h and then treated with TX (10 µM) followed by OGD (6 h)/R (18 h) treatment. The expression levels of (A) IL-1β, (B) IL-6 and (C) TNF-α were determined using reverse transcription-quantitative PCR. The levels of (D) IL-1β, (E) IL-6 and (F) TNF-α in the culture supernatant were analyzed using ELISA kits. Data are presented as the mean ± SD (n=3). *P<0.05, **P<0.01 vs. NS-siRNA + control; #P<0.05, ##P<0.01 vs. NS-siRNA + OGD/R; &P<0.05, &&P<0.01 vs. NS-siRNA + TX + OGD/R group. OGD/R, oxygen-glucose deprivation and reoxygenation; siRNA, small interfering RNA; HIF-1α, hypoxia-inducible factor-1α; NS, non-specific; TX, troxerutin; IL, interleukin; TNF-α, tumor necrosis factor-α.