Pulmonary hypertension is rare in chronic respiratory diseases but has a strong impact on the prognosis and is partly underlined by factors other than hypoxaemia. The aim of the present study was to assess the potential role of endothelin-1 (ET-1) and nuclear factor (NF)-κB vasoconstrictive pathways in pulmonary hypertension.The effects of ET-1 receptors blockers (BQ 123 and 788) and of genistein were assessed on response to acetylcholine of pulmonary vascular rings from cystic fibrosis (CF) lung transplant recipients (n = 23). NF-κB and ET-1 receptor expression was immunodetected in pulmonary arteries and quantitated using Western blotting. ET-1 vascular content was quantitated using ELISA.In total, 14 out of 23 subjects exhibited strongly impaired pulmonary vasodilation (p<0.01versusnine out of 23 subjects with a normal response) associated with an activation of ET-1 receptors A and NF-κB pathways. Genistein restored vasodilation in subjects with an abnormal response.Pulmonary vascular dysfunction is frequent in end-stage CF, involving the NF-κB pathway and that of ET-1 through ET-1 receptor A (ETAR). These data leave a conceptual place for ETAR blockers and isoflavones in the management of the devastating vascular complication of chronic obstructive respiratory diseases such as CF.