EDN1 and pulmonary arterial hypertension: Current evidence strongly suggests that vascular endothelial dysregulation plays acrucial role in the initiation and progression of pulmonary hypertension.Moreover, alterations in endothelium-derived mediators such as NO, ET-1, andprostanoids as well as reactive oxygen species have been established asimportant mechanisms in the development of vascular remodeling leading topulmonary hypertension.