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FOR IMMEDIATE RELEASE
Contact:
Dr. McDonagh, University of Arizona College of Medicine,
(520) 626-2329 or
pmcdonag@u.arizona.edu
SECOND HAND SMOKE EXPOSURE INCREASES NEUTROPHIL-PLATELET
INTERACTIONS
CAUSING DAMAGE IN HEART ATTACKS
Exposure to second hand cigarette smoke has been known to
increase myocardial sensitivity following a heart attack, but the mechanism
by which damage occurs has not been entirely understood. Dr. Paul McDonagh,
University of Arizona, presents a study by Samuel Mendoza,
a graduate student in Dr. McDonagh's laboratory. The study provides at
least one of the reasons smoke exposure can exacerbate heart tissue already
weakened by a heart attack. Even in non-smokers and people without any
exposure to second hand smoke, neutrophils (a component of the immune
system) begin accumulating in small blood vessels of the heart after a heart
attack. Their accumulation can damage the heart because of the associated
production of numbers of free radicals, and studies by other investigators
have found an association between adverse cardiovascular events and when
platelets and neutrophils aggregrate or clump together.
Does exposure to second hand smoke make this worse? Yes.
Mr. Mendoza exposed rats to three hours of second hand smoke daily for a
week. The animals then were anesthetized, given a heart attack, followed by
90 minutes of reperfusion -- a rough model of what happens in human heart
attacks. The rats exposed to second hand smoke had a significantly higher
percent mortality during reperfusion and a significant increase in the
percentage of neutrophil-platelet aggregates compared to rats without smoke
exposure. These findings indicate that exposure to second hand cigarette
smoke may contribute to the severity of heart attacks. The findings appear
to support the
current steps in U.S. culture to limit second hand smoke exposure and
exposure to environmental pollutants, says Dr. McDonagh.
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