NOS2 and pulmonary fibrosis: Additionally, previous studies reported the ability of nicorandil to restore the balance between inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) in models of folic acid-induced nephrotoxicity and bleomycin-induced lung fibrosis (Ezzat et al. 2021; Kseibati et al. 2020).