Platelet Spontaneous Aggregation in Platelet-Rich Plasma Is Increased in Habitual Smokers

Cigarette smoking is a well-known risk factor for atherosclerotic disorders. Several authors have suggested that platelet aggregability is important in smoking-induced vascular injury. When platelet-rich plasma is stirred at 37°C in the absence of chemical stimulants, small aggregates of platelets may be formed, but it was difficult to detect small aggregates by conventional aggregometer using optical density. Recent technological advances have made it possible to detect small aggregates by using a newly developed assay system that employs laser light scattering. In the present study, we attempted to measure platelet aggregation by this method, using laser light scattering in 54 nonsmoking healthy males and 51 healthy male habitual smokers who were age matched. In smokers, blood was obtained after 10 hours of smoking abstinence. No significant difference in platelet aggregation was induced by 1 μM or 5 μM of ADP between smokers and nonsmokers. In smokers, plasma fibrinogen levels and the number of small aggregates formed in the absence of chemical stimulants was significantly higher than in nonsmokers. Small aggregates formed in the absence of stimulants correlated positively with the concentrations of von Willebrand factor (vWF) antigen ( r=0.2654 , p