Characterization and biological significance of endothelium-derived relaxing factor.

The endothelial cell is a highly metabolically active organ which plays a role in metabolizing vasoactive substances and also generates factors which modulate the interactions between platelets and the vessel wall. In 1976, Moncada and colleagues discovered prostacyclin [ 11, one of the most potent of these factors, which inhibits platelet aggregation and induces vasodilatation by stimulating adenylate cyclase. Recently, another product of vascular endothelium, endothelium-derived relaxing factor ( E D W , [2]), has been shown to account for the vasodilator properties of some pharmacological agents and to inhibit platelet aggregation. The chemical nature of EDRF has now been identified as nitric oxide (NO; [31). In addition to their role as regulators of vascular smooth muscle tone, prostacyclin and NO also synergize to regulate platelet-vessel wall interactions.