Figure 2: Regulation of nitric oxide by inducing various transcriptional factors and role of Vitamin E: Nitric oxide (NO) generation induced by either endothelial NO synthases (e-NOS) or inducible NOS (i-NOS) pathways. It also shows how excessive NO produce due to either Lead (Pb) or hypoxia exposure by stimulating i-NOS pathway. Hypoxia may induce either e-NOS or i-NOS activities. Lead (Pb) usually activates i-NOS via Nuclear factor kappa B (NF-κB) pathways. However, hypoxia if it takes NF-κB pathway it will induce more i-NOS activities than e-NOS. Vitamin E actually block i-NOS pathway