EDN1 and pulmonary arterial hypertension: Consistent with this, we found that ET-1 levels were higher in the supernatants of PASMCs from PAH patients with known BMPR2 mutations, than in the supernatants of PASMCs from healthy controls, and that these were reduced following supplementation of the growth medium with iron (+FAC) or exogenous HAMP peptide (Fig. 4L).