Acute cardiac effects of nicotine in healthy young adults.
BACKGROUND
Nicotine is known to have many physiologic effects. The influence of nicotine delivered in chewing gum upon cardiac hemodynamics and conduction has not been well-characterized.


METHODS
We studied the effects of nicotine in nonsmoking adults (6 male, 5 female; ages 23-36 years) using a double-blind, randomized, cross-over study. Subjects chewed nicotine gum (4 mg) or placebo. After 20 minutes (approximate time to peak nicotine levels), echocardiograms and signal-averaged electrocardiograms (SAECG) were obtained. After 40 minutes, subjects were again given nicotine gum or placebo in cross-over fashion. Standard echocardiographic measurements were made from two-dimensional images. We then calculated end-systolic wall stress (ESWS), shortening fraction (SF), systemic vascular resistance (SVR), velocity for circumferential fiber shortening corrected for heart rate (Vcfc), stroke volume, and cardiac output. P wave and QRS duration were measured from SAECG.


RESULTS
Significant differences (P < 0.05) from control or placebo were found for ESWS, mean blood pressure, cardiac output, SVR, heart rate, and P wave duration. No significant changes were seen in left ventricular ejection time (LVET), LV dimensions, SF, contractility (Vcfc), or QRS duration.


CONCLUSIONS
These results suggest that nicotine chewing gum increases afterload and cardiac output. Cardiac contractility does not change acutely in response to nicotine gum. Heart rate and P wave duration are increased by chewing nicotine gum.
D000328:Adult; D002638:Chewing Gum; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D005731:Ganglionic Stimulants / Q000008:administration & dosage / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects*; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D008297:Male; D009538:Nicotine / Q000008:administration & dosage / Q000494:pharmacology*
D002638:Chewing Gum; D005731:Ganglionic Stimulants; D009538:Nicotine