Moreover, the high levels of PDE-5 in the lung VSMCs provide a strong molecular basis for PDE5 inhibitor treatment for PH (114): in patients with PAH, Tadalafil was well-tolerated and improved exercise capacity and quality of life measures and reduced clinical worsening (115); Sildenafil, in an animal model of hypoxia-induced PH, has been shown to reduce PAP, pulmonary vascular muscularization and prevent induced PH (116). The gene discussed is PDE5A; the disease is pulmonary arterial hypertension.