The major findings of this study are that blockade of NOS with L‐NAME (but not with the iNOS inhibitor L‐canavanine) caused marked increases in the already elevated RVSP at 3, 5, and 8 weeks after the initiation of the SU/Hx/Nx‐induced PAH in rats that simulate the human PAH phenotype histologically as well as hemodynamically (Abe et al. This evidence concerns the gene NOS2 and pulmonary arterial hypertension.