[Nitric oxide-dependent endogenous and exogenous vasodilators. The mechanism of action of nitrates].

The concept of endothelium-dependent vasodilation was developed after the discovery in 1980 of the endothelium-derived relaxing factor (EDRF) by Furchtgott and Zawadzki. In 1987 Furchgott and Ignarro identified the EDRF with nitric oxide. In the same year Moncada and coworkers demonstrated that the liberation of nitric oxide by endothelial cells was responsible by the biologic activity of EDRF. Nitric oxide is the endogenous mediator responsible by the endothelium-dependent vasodilation and can be considered the endogenous nitrovasodilator. But nitric oxide has a more complex spectrum of action, because it participates in the regulation of platelet activity and preservation of the normal structure of the vessel wall. Nitric oxide is also the terminal product of the biotransformation of therapeutic nitrates responsible by guanylate cyclase activation. Nitrates can be classified as endothelium non dependent vasodilators because some of them release spontaneously nitric oxide from their metabolites, and others are biotransformed to nitric oxide in vascular smooth muscle cells.