Secondhand smoke triggers a complex inflammatory response and inflammation is linked to heart disease, diabetes and other diseases, U.S. researchers say. Adelheid Kratzer, an investigator at the University of Colorado-Denver working under principal investigator Laima Taraseviciene-Stewart, says to determine how lung tissue may respond to secondhand smoke, the team exposed male Sprague Dawley rats to secondhand smoke in a special chamber five times per week for two months or four months. The exposure was a mixture of 89 percent sidestream smoke, which comes from the end of a lit cigarette and is exposed to the whole body, and 11 percent mainstream smoke -- smoke directly inhaled by the rats. The rats were exposed for two 3-hour shifts twice a day, separated by a 2-hour break. The study, presented at the American Physiological Society conference, finds two months of exposure to secondhand smoke were enough to cause significant changes in the rats' lung tissue. The results were more profound after four months, the United Press International quoted the study as saying. For example, the study finds the numbers of white blood cells -- macrophages lungs exposed to secondhand smoke -- indicates the rats' bodies had developed an immune response, also known as inflammation.
