Propylthiouracil attenuates monocrotaline-induced pulmonary arterial hypertension in rats

Background: Propylthiouracil (PTU) enhances nitric oxide production and inhibits smooth muscle cell proliferation, suggesting a possible role in the prevention of pulmonary arterial hypertension (PAH). Methods and Results: The 30 male Sprague-Dawley rats were randomized to receive saline injection only (group 1), monocrotaline (MCT) (70 mg/kg) only (group 2) or MCT+0.1% PTU in drinking water (group 3) given on day 5 after MCT administration. By day 35, western blot showed lower connexin43 (Cx43) and membranous protein kinase C-ε expressions in the right ventricle (RV) of group 2 animals than in the other groups (all P<0.05). Conversely, Cx43 expression in the lung was higher in group 2 than in other groups (all P<0.02). Additionally, mRNA expressions of matrix metalloproteinase-9, tissue necrotic factor-α, and caspase-3 were higher, whereas Bcl-2 and endothelial nitric oxide synthase were lower, in the lungs and RV of group 2 rats than in the other groups (all P<0.05). Moreover, the numbers of alveolar sacs and lung arterioles were also reduced in group 2 than in other groups (all P<0.05), and RV systolic pressure and RV weight were increased in group 2 compared with other groups (all P<0.001). Conclusions: PTU effectively attenuates complications associated with MCT-induced PAH.