NEW YORK (Reuters Health) - New research reveals that nicotine can damage the insides of arteries and raise the risk of developing heart disease.

According to the report, nicotine taken via a nasal spray or through cigarette smoke reduced blood flow in the arterial inner lining, or endothelium. Damage to the endothelium is an early marker of atherosclerosis, the build-up of plaque inside arteries that can lead to heart attack and stroke, researchers explain in the January issue of the Journal of the American College of Cardiology.

The findings suggest that nicotine is not only addictive but can also contribute directly to the risk of heart disease.

``Cigarette smoking is an established risk factor for cardiovascular disease and the leading preventable cause of (heart disease) and death in most industrialized countries,'' Dr. Thomas Neunteufl from the University of Vienna in Austria and colleagues write. ``However, it remains unclear whether the increased occurrence of atherosclerosis in smokers is caused by nicotine or by other components of tobacco smoke.''

To investigate, the researchers administered 1 milligram of nicotine via a nasal spray or cigarette smoke to 16 healthy long-term smokers, and then used ultrasound to examine the endothelium after 20 minutes. Nicotine-containing nasal spray was less damaging than cigarette smoke but still reduced blood flow inside the artery, the study found.

It is not clear how nicotine damages the endothelium but studies in animals indicate that chronic exposure to the compound leads to oxidative stress, or damage by free radicals. Other compounds in cigarette smoke may contribute to damage, however.

``The findings of this study demonstrate that nicotine causes acute endothelial dysfunction in long-term smokers and suggest that there may be other constituents of cigarette smoke that contribute to this adverse effect,'' Neunteufl and colleagues conclude.

The study also suggests that nicotine-containing nasal spray, which is used as nicotine replacement therapy for smokers trying to quit, could contribute to heart disease risk.

SOURCE: Journal of the American College of Cardiology 2002;39:251-256.

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