Nitric oxide, NO, is a very simple gas with just one nitrogen and one oxygen molecule, and is a free radical with a half-life in the body of only seconds. This unassuming little compound is of profound physiological importance in life forms from bacteria to elephants.
In 1998, the Nobel Peace Prize in Medicine/Physiology was awarded to Louis Ignarro and Ferid Murad for their discovery of the role of nitric oxide as a signaling molecule in the cardiovascular system. Since its discovery there have been over 170,000 scientific publications on nitric oxide and in a mere 20 years it has its own journals: Nitric Oxide – the journal of the Nitric Oxide Society; the Open Nitric Oxide Journal; and Nitric Oxide Biology and Chemistry. Nitric oxide is a super star. In 1992 it was named “Molecule of the Year”.
With good reason too. Unlike other discoveries that hold the spotlight for just a short time, interest in NO has not let up. There have been around 1000 professional publications referencing NO already cataloged for 2020 on PubMed, the National Institute of Health database of refereed medical publication.
There are two inducable enzyme systems producing nitric oxide on as as-needed basis only – iNOS and nNOS – serving the immune and nervous systems, as well as an eNOS enzyme, endogenous nitric oxide synthase, which works 24/7 to maintain key function such as keeping blood vessels open, dilating airways and triggering cellular healing, growth of new blood vessels and other responses of tissues to stress and exercise.
Inhaled nitric oxide is used to assist the management of people with pulmonary hypertension or babies with premature lung issues. Inhaled nitric oxide also improves oxygenation in horses undergoing surgery and general anesthesia. Note: This is not the same thing as the anesthetic nitrous oxide, aka laughing gas.
Nitric oxide is of particular importance in hoof health. Imbalances between endogenous nitric oxide from eNOS causing dilation and effects of the potent vasoconstrictor endothelin-1 can restrict blood flow to the foot. Carbohydrate sensitive horses can have such imbalances. Restoring homeostasis between the two allows for optimal health and growth. Cold weather also causes a reflex constriction of the blood vessels in the leg and hoof.
The amino acid L-arginine and its byproduct L-citrulline are needed for nitric oxide production but play no significant role in actually promoting it. Several herbs and natural substances are known to support NO production, including Hawthorn which is a popular human supplement, but the most effective is Gynostemma pentaphyllum, aka Jiaogulan.
Jiaogulan is a vine indigenous to a remote area of China where it often is used as a tea or vegetable. The leaves are helpful for endogenous nitric oxide support. At the same time it supports homeostatic regulation of inflammatory nitric oxide production. It has a mild, pleasant odor and horses seem to enjoy the taste.
Eleanor Kellon, VMD