EDN1 and Hypertension: Endothelin (ET) is known as the most potent vasoconstrictor among reported endothelial-derived vasomotor agents.1,2 Among the reported 3 isoforms of ET, endothelin-1 (ET-1) is produced by endothelial cells.3 ET-1 plays a role not only in vasoconstriction but also in vasodilatation through induction of an endothelial cell-derived relaxing factor, nitric oxide.4 These functions of ET-1 correlate to the pathogenesis of atherosclerosis.5 Thus, the association between ET-1 and hypertension- or atherosclerosis-related diseases has been studied.