Figure 2. The pathophysiologic hypothesis of nitric oxide-mediated cardiac diseases. NOS, nitric oxide synthases (e, endothelial; i, inducible; n, neuronal); NO, nitric oxide radical; ONOO^–, peroxynitrite anion; O₂^–·, superoxide anion; NO₂, nitrogen dioxide; OH·, hydroxyl radical; H₂O₂, hydrogen peroxide.