Inhaled pharmacotherapies are promising treatment options for patients with pulmonary arterial hypertension (PAH) as they minimize extrapulmonary adverse effects. Recently, we developed a highly specific inhibitor (TPHi) of the serotonin synthesizing enzyme tryptophan hydroxylase 1, TPT-004. We hypothesized that repetitive nose-only inhalation of TPT-004 alleviates PAH and pulmonary vascular remodeling in the Sugen-hypoxia (SuHx) rat model. Male Sprague-Dawley rats were divided into 3 …