(Ivanhoe Newswire) -- An antioxidant contained in nutritional supplements often used by body builders has been linked to a serious respiratory disorder called pulmonary arterial hypertension (PAH).

Essentially, the disease causes high blood pressure in the arteries carrying blood to the lungs, leading to significant breathing and other problems. The antioxidant, known as N-acetylcysteine (NAC), promotes the development of a substance that causes the detrimental changes.

"NAC fools the body into thinking that it has an oxygen shortage," study author Ben Gaston, M.D., from the University of Virginia Children's Hospital, was quoted as saying. "We found that an NAC product formed by red blood cells, know as a nitrosothiol, bypasses the normal regulation of oxygen sensing. It tells the arteries in the lung to 'remodel'; they become narrow, increasing the blood pressure in the lungs and causing the right side of the heart to swell."
 

The researchers uncovered the mechanism in a study involving mice. In normal animals receiving both NAC and nitrosothiols for three weeks, NAC was converted into the nitrosothiol -- S-nitroso-N-acetylcysteine (SNOAC) -- by the red blood cells. These mice went on to develop PAH. Mice missing an enzyme needed to convert NAC into SNOAC did not develop the condition, leading the authors to conclude NAC must first be converted to SNOAC for the disease to develop.

The researchers admit they have yet to determine whether regular use of supplements containing NAC could be a danger to people, but report these findings suggest the need for more study to determine the risk, especially because NAC is currently being tested as a treatment for people with cystic fibrosis, and other research using nitrosothiols is in the works.

SOURCE: Journal of Clinical Investigation, published online Sept. 4, 2007