Figure 2. H₂O₂ induces NO consumption, and lipohydroperoxidase turnover depletes endogenously generated NO, in cytokine-treated macrophages.

(A) H₂O₂ (500 μM) was added to 2×10⁶ cells, 1 mM L-NAME and 1 mM CaCl₂ in 1 ml of PBS (n≥3; means±S.D.). Bars represent rates of NO decay for cells in the presence or absence of H₂O₂, as appropriate. ***P<0.05 compared with control (unpaired t test). (B) Representative traces from (A): (i) NO decay in PBS containing 2×10⁶ cytokine-treated J774 cells·ml⁻¹, 1 mM L-NAME and 1 mM CaCl₂; (ii) 500 μM H₂O₂ was added to cytokinetreated cells in (i); (iii) NO decay in 2×10⁶ control J774 cells·ml⁻¹, 1 mM L-NAME and 1 mM CaCl₂; (iv) 500 μM H₂O₂ was added to control cells in (iii). (C) OxyHb (3 μM) (i), 2.4 μM 15(S)-HPETE (ii) or 1 mM L-NAME (iii) was added to 10⁷ cytokine-treated J774 cells·ml⁻¹, 1 mM L-arginine and 1 mM CaCl₂ in PBS.