Nitric Oxide: Definition and Overview

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What is nitric oxide and what does it do

What is nitric oxide?

Nitric oxide is a clear, colorless gas that performs a number of important functions in the body. Nitric oxide is considered such an important chemical in the body that the journal Science named it the “Molecule of the Year” in 1992, and in 1998 three scientists won the Nobel Prize in Medicine for researching its role in the body.

What does nitric oxide do for the body?

People with diabetes have a reduced ability to produce nitric oxide, which may be one reason they have an increased risk of heart disease. Abnormalities in the body’s production of nitric oxide have been implicated in high blood pressure, atherosclerosis (narrowing of the arteries) and stroke.

Normally, cells lining the inner wall of blood vessels secrete nitric oxide, which travels to the muscle cells around the blood vessels and causes them to widen, allowing easier blood flow. Impaired nitric oxide production may contribute to constricted blood vessels, high blood pressure and atherosclerosis. Scientists now know that nitroglycerin and similar drugs dilate blood vessels and help alleviate angina — temporary chest pain resulting from insufficient oxygen to the heart — because these drugs stimulate the release of nitric oxide. Nitric oxide also keeps blood platelets from clumping together and sticking to the inner walls of arteries, protecting the body from blood clots and atherosclerosis

Nitric oxide also helps to initiate penile erections. During sexual stimulation, nerves in the penis release nitric oxide, which causes the corpora cavernosa — the rods of spongy tissue within the penis — to fill with blood and become erect. The discovery of nitric oxide’s role in erections has led to the development of the popular impotence drugs sildenafil (brand name Viagra), vardenafil (Levitra, Staxyn), tadalafil (Adcirca, Cialis) and avanafil (Stendra). Taking these drugs can be potentially dangerous for people who also take nitrate drugs, such as nitroglycerine, because they can raise nitric oxide levels too high. Always let your doctor know if you are taking nitrate drugs.

Want to learn more about diabetes and sexual health? Read “When Viagra Doesn’t Work: Treating Erectile Dysfunction,” “When Diabetes Affects Your Sex Life,” and “Sex and Diabetes.”

Originally published May 2, 2006.

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