Xenon attenuated high-mobility group protein-1 (HMGB-1) translocation and nuclear factor κB (NF-κB) activation of A549 cells after oxidative and inflammatory stress. HK-2 cells were given 24 h hypothermia–hypoxia challenge (4°C Soltran preserving solution under 8% O₂) and then followed by 24 h reoxygenation (37°C culture medium in normal cell incubator). The conditioned medium (CM) at the end of reoxygenation was collected. A549 cells were challenged with CM or H₂O₂ or tumor necrosis factor (TNF)-α cells for 24 h. Gas exposure (70% Xe or N₂, and 5% CO₂ balanced with oxygen for 2 h) was given to A549 cells before the challenge, and inhibitor of phosphatidylinositol 3 kinase (PI3K) LY294002 (Ly) or inhibitor of mammalian target of rapamycin (Ra) was given to A549 cells after xenon gas treatment. Small interfering RNA (siRNA) (scrambled or hypoxia-inducible factor [HIF]-1α) was given to A549 6 h before xenon gas treatment. (A) The cytoplasm and nucleus were immunolabeled with anti HMGB-1 (green), HIF-1α (red), and 4',6-diamidino-2-phenylindole (DAPI) nuclear stain (blue). HMGB-1 (green) translocated from nucleus to cytoplasm in nitrogen-treated groups, whereas xenon treatment restricted the translocation through enhanced HIF-1α expression in cytoplasm and nuclear translocation. HIF-1α siRNA abolished these effects. (B) Expression of NF-κB and nuclear translocation. (C) Percentage of cells with HMGB-1 nuclear to cytoplasmic translocation. (D) Fluorescence intensity of NF-κB. Scale bar: 50 μm. Data of fluorescence intensity are expressed as a percentage of basal value in naive control (NC) rats. Data are expressed as median ± interquartile range (n = 8) (*P < 0.05 significantly different from vehicle or scramble siRNA-treated cells). Scale bar: 50 μm. H or H siRNA = HIF-1α siRNA; S or S siRNA = scrambled siRNA; Ve = vehicle; Xe = xenon.