Figure 2
From: Bench-to-bedside review: Nitric oxide in critical illness – update 2008
Reaction of nitric oxide with oxidative radicals is dependent on concentration and distance. When local nitric oxide (NO) levels exceed concentrations of reactant oxidant species, NO tends to reduce oxidative stress. When oxidant species exceed NO concentrations, they reduce the amount of bioavailable NO. When local NO and superoxide (O2-) levels are roughly equimolar, however, the highly reactive and toxic radical peroxynitrite (ONOO-) is formed.