Fig. 4.

Dose-dependent effects of Sulfide and DATS on xanthine oxidation and NO₂^-reduction. Purified XO (20 mU, dissolved in HBSS) was exposed to Sulfide (0–50 μM), and both XOR-dependent oxidation of xanthine to UA (λ = 295 nm) and XOR-dependent NO₂^- reduction to NO were assessed (A). Total NOx was determined in hypoxic HUVECs treated with or without xanthine (100 μM) and Sulfide or DATS (1–100 μM) (B). Average rate of NO formation induced by 10 μM or 100 μM sulfide (C) and DATS in the presence or absence of Zinc acetate and/or DTPA (D). For panel A, *p<0.0001, #p<0.05, n = 4, compared to group with 0 μM of Sulfide; for B-D *p = 0.006, **p = 0.0014, ***p = 0.0170; #p = 0.04; n = 4.