title: Nicotine increases chemoreflex sensitivity to hypoxia in non-smokers.
abstract: BACKGROUND
  The peripheral chemoreflex contributes to cardiovascular regulation and represents the first line of defence against hypoxia. The effects of nicotine on chemoreflex regulation in non-smoking humans are unknown.
  
  
  METHODS
  We conducted a prospective, randomized, crossover, and placebo-controlled study in 20 male non-smokers to test the hypothesis that nicotine increases chemoreflex sensitivity. The effects of two intakes of 2 mg nicotine tabs and placebo on sympathetic nerve activity to muscle circulation (muscle sympathetic nerve activity; MSNA), minute ventilation (Ve), blood pressure and heart rate were assessed during normoxia, moderate isocapnic hypoxia, hyperoxic hypercapnia and an isometric handgrip in 10 subjects. Maximal end-expiratory apnoeas were performed at baseline and at the end of the fifth minute of hypoxia. In a second experimental setting, we studied the ventilatory response to a more marked isocapnic hypoxia in 10 other volunteers.
  
  
  RESULTS
  Mean MSNA and Ve were not modified by nicotine during the 5 min of normoxia or moderate hypoxia. In the presence of nicotine MSNA was related to oxygen desaturation (P < 0.01). The sympathoexcitatory effects of nicotine became especially evident when apnoeas achieved oxygen saturations less than 85% (511 +/- 44% increase in MSNA after the first intake, and 436 +/- 43% increase after the second intake versus 387 +/- 56% and 338 +/- 31% with placebo, respectively, P < 0.05). Nicotine also increased the ventilatory response compared with placebo when oxygen saturation decreased to less than 85% (P < 0.05).
  
  
  CONCLUSIONS
  This is the first study to demonstrate that nicotine increases peripheral chemoreflex sensitivity to large reductions in arterial oxygen content in healthy non-smokers.
authors.affiliation: Department of Cardiology, CUB Erasme, Brussels, Belgium. jfxa@skynet.be
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Argacha
authors.forename: Olivier
authors.initials: O
authors.lastname: Xhaët
authors.forename: Marko
authors.initials: M
authors.lastname: Gujic
authors.forename: Dionysios
authors.initials: D
authors.lastname: Adamopoulos
authors.forename: Sofia
authors.initials: S
authors.lastname: Beloka
authors.forename: Celine
authors.initials: C
authors.lastname: Dreyfuss
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Degaute
authors.forename: Philippe
authors.initials: P
authors.lastname: van de Borne
mesh_terms: D000328:Adult; D001049:Apnea / Q000503:physiopathology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002344:Carotid Body / Q000187:drug effects; D002628:Chemoreceptor Cells / Q000187:drug effects*; D018592:Cross-Over Studies; D004562:Electrocardiography / Q000187:drug effects; D005731:Ganglionic Stimulants / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D009538:Nicotine / Q000494:pharmacology*; D011446:Prospective Studies; D012119:Respiration / Q000187:drug effects*
chemical_list: D005731:Ganglionic Stimulants; D009538:Nicotine