EDN1 and portal hypertension: Portal hypertension complicating liver cirrhosis is associated with vascular resistance possibly attributed to the overexpression of humoral vasoconstrictors such as norepinephrine, endothelin (ET), and angiotensin-II.7 Endothelin-1 (ET-1) binds to both ET-A receptors found on vascular smooth muscle cells, where they mediate vasoconstriction, and ET-B receptors on endothelial cells, where they lead to NO release through stimulation of endothelial NO synthase (eNOS).