Nitric oxide (NO) is a highly reactive free radical synthesized
from the amino acid L-arginine by the reaction of nitric oxide
synthases (NOS) [8]. Despite its essential physiological role in the
regulation of vascular tone, response to vascular injury and
hemostasis under physiological states, NO is also recognized as an
important immunomodulatory and cytotoxic mediator of inflammatory
responses in the lung [9]