( prior study had also shown a significan...)Smoking damages key regulatory enzyme in the lung

MAO A breaks down many compounds that affect blood pressure, and the lung is a major metabolic organ in degrading some of these compounds, Fowler said. So reduced levels of MAO A in smokers' lungs may be a significant factor contributing to some of the physiological effects of smoking, including changes in blood pressure and pulmonary function.

Smokers' lungs also held onto the tracer chemical much longer than nonsmokers, and the delivery of tracer into the arterial blood supply was much lower for smokers, particularly for the first few minutes after being injected, Fowler added. This finding could imply that smokers and nonsmokers respond differently to other substances that enter the body via the bloodstream, including therapeutic drugs, anesthetics, abused substances and environmental agents--even nicotine.

Cigarette smoking, "the most damaging of all addictive substances," remains the leading cause of preventable death and has negative health impacts on people at all stages of life, said Fowler, and has been in the headlines recently with the death of ABC "World News Tonight" anchorman Peter Jennings. Cigarette smoking accounts for 440,000 deaths each year in the United States, or nearly one of every five deaths, according to the Centers for Disease Control and Prevention. Smoking kills more Americans than AIDS, illegal drugs, alcohol, car accidents, suicides and murders combined and increases one's chances of developing lung, bladder, esophageal and throat cancers; chronic lung diseases; and coronary heart and cardiovascular diseases.

Fowler and her colleagues have been studying MAO for more than 30 years. The U.S. Department of Energy (DOE) Office of Biological and Environmental Research and the National Institutes of Health have provided funding for this study, said Fowler. She added, "It's important that the public know about the benefits derived f
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Source:Society of Nuclear Medicine