Acute effects of cigarette smoking on platelet-dependent thrombin generation

Aims Thrombin is an important factor in the pathogenesis of thrombotic dise ases. To clarify whether smoking has an effect in platelet-dependent thromb ogenesis, we studied the acute effects of smoking on platelet-dependent thr ombin level in smokers. Methods and Results Subjects consisted of ten smokers and nine non-smokers. Platelet-dependent thrombin level measured after overnight fasting was gre ater in smokers than in non-smokers (smokers vs non-smokers, 121 +/- 47 vs 56 +/- 5 mIU. ml(-1), P<0.01). When subjects in the smokers group smoked tw o cigarettes containing 0.9 mg of nicotine per cigarette, platelet-dependen t thrombin levels showed a transient three-fold increase in blood samples o btained immediately after smoking (365+/-76mIU.ml(-1), P< 0.001). Thrombin levels in the blood samples obtained 10 min and 30 min after smoking were l ess than that in the samples obtained immediately after smoking ceased, but were not significantly different from those in the samples obtained before smoking. Blood nicotine level increased significantly immediately after sm oking (P<0.001), and plasma protein C activity decreased significantly 30 m in after smoking (P<0.05). When nicotine or cotinine was added to the plate let-rich plasma of non-smokers ex vivo, the platelet-dependent thrombin lev el increased significantly (P<0.002). Conclusion Platelet-dependent thrombin level is enhanced in smokers, even w hen not smoking, when compared with non-smokers and increases immediately a fter smoking. Increases in nicotine and cotinine levels caused by smoking i nduced a prothrombotic state in smokers via increased platelet-dependent th rombogenesis. (Eur Heart J 2001; 22: 5-61, doi:10.1053/euhj.1999.1938) (C) 2001 The European Society of Cardiology.