Cyclooxygenase-1 Mediated Platelet Reactivity in Young Male Smokers

Background: The purpose of this study is to investigate the acute and chronic effects of cigarette smoking on cyclooxygenase- 1(COX-1)-mediated platelet reactivity among cigarette smokers. Methods: The levels of collagen-induced platelet aggregation, platelet COX-1 activity, and expressions were compared between smokers and age-matched nonsmokers. In smokers, the acute effects of cigarette smoking were assessed by repeating these measurements an hour after smoking. Results: Twenty-five smokers and age-matched nonsmokers (all men; mean age, 29 years) were studied. Collagen-induced platelet aggregation and plasma/urinary thromboxane B-2 (TXB2) and 11-dehydroxythromboxane B-2 levels were higher in cigarette smokers compared to nonsmokers. Greater expression of platelet COX-1 was observed in smokers than in nonsmokers. Among smokers, collagen-induced platelet aggregation correlated positively with platelet volume and circulating nicotine and cotinine concentrations. The levels of plasma/urinary TXB2 were significantly increased an hour after cigarette smoking. Conclusion: Cigarette smoking aggravates COX-1-mediated platelet reactivity in young, otherwise healthy, smoking men.