Chris D. Meletis, N.D., with Nieske Zabriskie, N.D.
Nitric oxide (NO) is a gas that has significant effects on many physiologic processes in the body. This gas plays a role in inflammation, the immune response, and neurotransmission in the brain, as well as in the functioning of the cardiovascular system. Dysfunction in the NO pathway is associated with many diseases. Conditions such as atherosclerosis, coronary artery disease (CAD), diabetes, hypertension, erectile dysfunction, and stroke are correlated with NO pathology.
Current research suggests that manipulation of NO activity may have profound effects on overall health. Many pharmaceuticals as well as nutrients, supplements, and diet are being investigated and prescribed to modulate NO activity.
The Physiology of NO
NO is most notably produced in endothelial cells, macrophages, and neurons. It is a toxic free-radical gas with a half-life of 6–10 seconds, thus providing only localized effects. NO is synthesized by combining L-arginine with oxygen to form L-citrulline and nitric oxide. The enzyme responsible for this conversion is nitric oxide synthase (NOS), which is found in three forms. 1
One form is found in endothelial cells and platelets and is a calcium calmodulin–dependent enzyme that is made at a constant rate regardless of physiologic demand. The second form is a calcium independent inducible form of the enzyme, and exists in macrophages, neutrophils, cardiac cells, and hepatocytes. 2,3 The third form is found in neural cells.
