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. Author manuscript; available in PMC: 2019 Jul 1.
Published in final edited form as: J Cardiol. 2018 Mar 12;72(1):42–49. doi: 10.1016/j.jjcc.2018.02.003

Figure 4. The classic and alternative pathways for generation of nitric oxide (NO).

Figure 4

The classic pathway involves generation of NO through L-arginine. In the presence of molecular oxygen and several cofactors, nitric oxide synthases (NOS) catalyze the oxidation of the amino acid L-arginine to NO. NO is oxidized to nitrite (NO2-) and nitrate (NO3-) (dashed arrows). The alternative pathway involves generation of NO through reduction of nitrate and nitrite. Endogenously generated nitrate and nitrate from the diet can be reduced to nitrite by oral bacteria. Nitrite is absorbed systemically, and via several enzymatic and non-enzymatic pathways reduced to NO. Adapted from Hezel and Weitzberg with permission [84].