Effects of nicotine on platelet function.

In non-smokers, only high concentrations of nicotine (10 mM) caused platelet aggregation in platelet-rich plasma and release of 5-hydroxytryptamine (5-HT). Both responses to ADP and 5-HT were enhanced at 1 and 10 mM nicotine while they were inhibited to collagen, ristocetin, adrenaline and arachidonic acid. Lower concentrations of nicotine had no effect with any agent other than 5-HT, with which a variable enhancement of 5-HT-induced aggregation was observed. Uptake of 14C-5-HT was inhibited by nicotine at 100 microM or higher while platelet factor 3 availability was unaffected. Thus it is unlikely that direct effects of nicotine on platelets are responsible for smoking-related changes in platelet reactivity.