The vascular endothelium itself is responsible for a number of homeostatic functions within normal blood vessels, including the hemostatic function of maintaining vascular tone. The endothelium achieves this in part through the production and release of a variety of relaxing and constricting factors, including the vasoactive peptide endothelin (ET).¹ The normal endothelium also has antithrombotic properties that can turn prothrombotic if the endothelium is perturbed or injured.¹

The delicate balance required for vascular tone is achieved by ET and other endothelium-derived vasoconstrictors counterbalancing the vasodilatory effects of nitric oxide, prostacyclin, and other endothelium-derived relaxing factors.¹