Biochemical, demographic, and self-reported tobacco-related predictors of the acute heart rate response to nicotine in smokers.

Understanding the stimulatory effects of nicotine on cardiovascular function in humans is of great interest given the wide-spread use of different forms of combustible and smokeless products that deliver nicotine. An intravenous nicotine infusion procedure was used to evaluate factors associated with the acute heart rate (HR) response to nicotine (0.5 mg per 70 kg bodyweight) in a sample of 213 smokers. We tested for differential response to nicotine based on demographic characteristics (race [European American vs African America], sex, body mass index and age); a set of blood-based biomarkers (baseline nicotine, cotinine and cortisol levels and nicotine metabolite ratio); and a set of self-reported measures related to tobacco use. Nicotine infusion was first noted to increase HR approximately 10 beats per minute (95% CI: 7.8-12.3) one minute post-infusion, and 13 beats per minute (95% CI: 11.0-15.2) two minutes post-infusion. Higher cortisol, lower nicotine levels, higher nicotine metabolite ratio, being female and greater withdrawal symptoms were independently associated with a potentiated increase in HR 1 or 2 min after nicotine infusion. Factors associated with the acute HR effects of nicotine warrant further investigation given their potential to inform the development of nicotine delivery systems as tobacco harm reduction approaches for smokers.