EDN1 and pulmonary arterial hypertension: As the current most aggressive vasorelaxing therapy for patients with severe PAH is a triple therapy comprising ET-1 antagonist, PDE5 inhibitor and prostacyclin (Humbert et al, 2022) we also compared equal concentrations of FR (10−6 M) with triple therapy (Bos + Sil + Ilo in equal parts, 10−6 M in total, Fig. 4E).