Alterations in plasma nitric oxide during aging in humans.

Nitric oxide (NO) is relatively harmless, but along with superoxide radical becomes precursor of many toxic species, such as peroxy and hydroxyl radicals, hydrogen peroxide, and peroxynitrite. In the present study, we determined plasma NO as a function of human age and correlated NO levels with total antioxidant capacity of the plasma. Results showed significant increase in NO level as a function of human age and plasma NO level positively correlated with total antioxidant potential. Increased NO may contribute to the development of oxidative stress during aging.