Figure 2

Sources of vascular reactive oxygen species and potential protective effects of H ₂ S. Schema showing the major vascular sources of superoxide, the parent reactive oxygen species. H₂S has been shown to inhibit A. NADPH oxidase activity and expression [39, 40], B. mitochondrial ROS production [43], and possibly C. xanthine oxidase activity [74]. Additionally, H₂S has been reported to scavenge ROS [35–38] and also promote the actions of D. SOD [43] and E. GSH [41]. SOD: superoxide dismutase, MPO: myeloperoxidase, CAT: catalase, GPx: glutathione peroxidase, GSH: reduced glutathione, GSSG, oxidised glutathione.