NOS2 and pulmonary arterial hypertension: Considering the correlations between inducible and constitutive NOS isoforms, PAH associated with congenital heart disease (CHD) showed elevated levels of both iNOS and eNOS in pulmonary vascular endothelial cells, but not in other cell types, i.e., pulmonary macrophages, airway epithelium, and alveolar lining cells [194].