Prothrombic effects of smoking may be directly due to nicotine

A team of researchers from Kyorin University School of Medicine, Tokyo, studied the acute effects of smoking on platelet-dependent thrombin generation, measured as the spontaneous generation of thrombin upon recalcification of platelet-rich plasma in vitro (Eur Heart J 2001, 22: 56–61). Hioki et al report that within a healthy cohort of 10 male smokers and nine non-smokers platelet-dependent thrombin levels measured after overnight abstention was greater in smokers than in non-smokers (121±47 versus 56±5 mIU/ml, p<0.01). This discrepancy increased further when subjects in the smoking group smoked two cigarettes containing 0.9 mg nicotine each. Immediately after smoking there was a transient threefold increase in plasma thrombin levels, which returned to baseline 30 minutes after smoking ceased. In addition, Hioki's group found that 30 minutes after smoking, blood nicotine levels increased (p<0.001) while plasma protein C activity decreased (p<0.05).

When nicotine or cotinine was added to platelet-rich plasma obtained...