title: Acute cardiovascular and sympathetic effects of nicotine replacement therapy.
abstract: Sympathetic overactivity is implicated in the increased cardiovascular risk of cigarette smokers. Excitatory nicotinic receptors are present on peripheral chemoreceptor cells. Chemoreceptors located in the carotid and aortic bodies increase ventilation (Ve), blood pressure (BP), heart rate (HR), and sympathetic nerve activity to muscle circulation (MSNA) in response to hypoxia. We tested the hypothesis that nicotine replacement therapy (NRT) increases MSNA and chemoreceptor sensitivity to hypoxia. Sixteen young healthy smokers were included in the study (8 women). After a randomized and blinded sublingual administration of a 4-mg tablet of nicotine or placebo, we measured minute Ve, HR, mean BP, and MSNA during normoxia and 5 minutes of isocapnic hypoxia. Maximal voluntary end-expiratory apneas were performed at baseline and at the end of the fifth minute of hypoxia. Nicotine increased HR by 7+/-3 bpm, mean BP by 5+/-2 mm Hg, and MSNA by 4+/-1 bursts/min, whereas subjects breathed room air (all P<0.05). During hypoxia, nicotine also raised HR by 8+/-2 bpm, mean BP by 2+/-1 mm Hg, and MSNA by 7+/-2 bursts/min (all P<0.05). Nicotine increased MSNA during the apneas performed in normoxia and hypoxia (P<0.05). Nicotine also raised the product of systolic BP and HR, a marker of cardiac oxygen consumption, during normoxia, hypoxia, and the apneas (P<0.05). Ve, apnea duration, and O2 saturation during hypoxia and the apneas remained unaffected. In conclusion, sympathoexcitatory effects of NRT are not because of an increased chemoreflex sensitivity to hypoxia. NRT increases myocardial oxygen consumption in periods of reduced oxygen availability.
authors.affiliation: Department of Cardiology, Erasme Hospital, Brussels, Belgium, bnajem@ulb.ac.be
authors.forename: Boutaïna
authors.initials: B
authors.lastname: Najem
authors.forename: Anne
authors.initials: A
authors.lastname: Houssière
authors.forename: Atul
authors.initials: A
authors.lastname: Pathak
authors.forename: Christophe
authors.initials: C
authors.lastname: Janssen
authors.forename: Daniel
authors.initials: D
authors.lastname: Lemogoum
authors.forename: Olivier
authors.initials: O
authors.lastname: Xhaët
authors.forename: Nicolas
authors.initials: N
authors.lastname: Cuylits
authors.forename: Philippe
authors.initials: P
authors.lastname: van de Borne
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D002319:Cardiovascular System / Q000187:drug effects*; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology; D008297:Male; D018482:Muscle, Skeletal / Q000294:innervation; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology*; D012119:Respiration / Q000187:drug effects; D013564:Sympathetic Nervous System / Q000187:drug effects*
chemical_list: D018722:Nicotinic Agonists; D009538:Nicotine