Figure 5.

Cellular upregulation of hemoglobin protects against H₂S-induced cytotoxicity. (A) H₂S levels are elevated in the plasma of severe burn and septic patients and in the plasma of mice subjected to burn injury. Data represent mean ± S.E.M.; n = 6–8; *p < 0.05; **p < 0.01. (B) Left panel: Treatment of PBMCs isolated from healthy volunteers with 1 mmol/L NaSH for 1 h induced the expression of hemoglobin mRNA. HEK293T17 cells transfected with a hemoglobin α overexpression construct showed a further increase in the expression of intra-cellular hemoglobin when the transfection was combined with H₂S treatment (7.5 mmol/L). Hb-α expression was quantified by Western blotting at 48 h. Data represent mean ± S.E.M; n = 3; **p < 0.01 (C) Expression of hemoglobin in HEK293T17 cells and uptake of hemoglobin into U937 cells protected against the cytotoxic effect of a high concentration (7.5 mmol/L) of NaSH, as measured by LDH release into the medium. Data represent mean ± S.E.M.; n = 3; *p < 0.05; **p < 0.01.