BETHESDA, MARYLAND. Nitrogen oxide (NO) is generated by the lining (endothelium) of blood vessels. A dysfunction of the endothelium involving a reduced NO availability is an early event in the development of atherosclerosis. A lack of NO tends to constrict blood vessels (reduce their diameter), increase platelet adhesion, and raise the risk of the formation of blood clots. Researchers at the National Institutes of Health now report that N- acetylcysteine (NAC) is quite effective in counteracting the effects of endothelial dysfunction and decreased NO availability.
Their clinical trial involved sixteen people, seven with coronary atherosclerosis and nine without. The researchers measured the blood flow in a coronary artery as well as its diameter and also measured the diameter of coronary arteries in the epicardium (outermost layer of the heart wall). All the participants were given an infusion of acetylcholine in order to establish baseline data. They were then given a 10-minute intracoronary infusion of NAC (48 mg/min). A 36 per cent increase in coronary blood flow was observed after the NAC infusion. The researchers also noted that the epicardial blood vessel diameter went from a 1.2 per cent constriction to a 4.7 per cent dilation after the NAC infusion. The response was similar in patients with and without atherosclerosis.
The researchers speculate that NAC either enhances the bioavailability of NO or
prevents it from being prematurely inactivated through its antioxidant
properties. NAC is a common supplement available in health food stores.
However, the researchers make no comment as to whether oral supplementation
would have effects similar to those obtained by infusion directly into the