NOS3 and pulmonary arterial hypertension: Furthermore, neointimal cells in lungs from patients with idiopathic PAH and in MCT + hypoxia model of PH in rats show positive staining for SMC α-actin and scant caveolin-1 expression but normal eNOS expression [67], which is likely to result in eNOS uncoupling, leading to oxidative and nitrosative stress.