Reversal of severe angioproliferative pulmonary arterial hypertension and right ventricular hypertrophy by combined phosphodiesterase-5 and endothelin receptor inhibition.

Background Patients with pulmonary arterial hypertension (PAH) are treated with vasodilators, including endothelin receptor antagonists (ERAs), phosphodiesterase-5 (PDE-5) inhibitors, soluble guanylyl cyclase activators, and prostacyclin. Despite recent advances in pharmacotherapy for individuals with PAH, morbidity and mortality rates in this patient population remain unacceptably high. Here, we tested the hypothesis that combination therapy with two PAH drugs that target distinct biochemical pathways will provide superior efficacy relative to monotherapy in the rat SU5416 plus hypoxia (SU-Hx) model of severe angioproliferative PAH, which closely mimics the human condition.