USN Alpha Nitrox NO2 is made up of several ingredients that have been selected as they have been associated with increased production of nitric oxide in the muscles. Nitric oxide synthases NOS are enzymes that convert Arginine & citrulline to nitric oxide. n Nitric oxide synthases NOS are enzymes that convert Arginine & citrulline to nitric oxide. Nitric oxide is a key biological messenger playing a role in a variety of biological processes. n It is known as a vasodilator which enhances b