Luiza A. Rabêlo et al. Valéria Nunes de Souza Lucas José Sá da Fonseca Walkyria O. Sampaio
Several studies refer to reactive oxygen and nitrogen species (RONS) as important agents in the pathogenesis of a number of heart diseases, including high blood pressure, arteriosclerosis and heart failure. Such species are highly bioactive molecules and a short life due chiefly to reduction of molecular oxygen. The enzyme complex of NADPH oxidase is the main source of these reactive species in vascular system. Under physiological conditions, formation and elimination of these substances seem balanced in vascular wall. During redox Unbalance, nonetheless, there is increase in NADPH oxidase activity and predominance of pro-oxidizing agents, surpassing the anti-oxidant capacity of the organism self-defense. Besides this, such enzyme hyperactivity reduces the bioavailability of nitric oxide, capital for vasodilation and maintenance of normal vascular function. In spite of NADPH oxidase being directly connected to the endothelial dysfunction, it was firstly described as for its expression in phagocytes, where its activity determines efficiency of organism defense mechanisms against pathogens. Slight differences between structural units of NADPH oxidases, depending on the type of cell which expresses it, may create therapeutic implications, allowing to selectively inhibiting redox unbalance triggered by NADPH oxidase, without compromising, however, its participation in physiological cellular signaling which make sure protection against micro-organisms.