The stimulatory effect of nicotine on vagal pulmonary C-fibers in dogs

Y. R. Kou, D. T. Frazier, L. Y. Lee

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


Our recent studies suggested that a nicotine-induced stimulation of afferent vagal C-fibers in the lungs was involved in eliciting the immediate cardiorespiratory responses to inhaling cigarette smoke. To examine this possibility, afferent impulses were recorded from vagal pulmonary C-fibers in 16 anesthetized, open-chest and artificially ventilated dogs, before and after four separate doses of nicotine (2.5, 5, 10 and 20 μg/kg) were injected into the right atrium. The base-line activity did not change after injection of isotonic saline. In contrast, nicotine stimulated 24 of 29 C-fibers: a burst of discharge was evoked immediately (1-2 sec) after the injection and usually lasted 3-8 sec. The peak responses of these pulmonary C-fibers to nicotine injections showed a dose-dependent relationship. In 17 C-fibers tested, the responses evoked by right atrial injection of 10 μg/kg of nicotine were similar to those evoked by delivery into the lungs of a single breath of smoke generated from cigarette with a high-nicotine content. Based upon these results, we conclude that nicotine alone stimulates vagal pulmonary C-fibers in a dose-dependent manner and this stimulant action of nicotine may play a part in eliciting the immediate reflex cardiorespiratory responses to inhalation of cigarette smoke.

Original languageEnglish
Pages (from-to)347-356
Number of pages10
JournalRespiration Physiology
Issue number3
StatePublished - Jun 1989

Bibliographical note

Funding Information:
Acknowledgements, The authors are grateful to Cecil Woolfoik for surgical assistance and John Turbek for statistical analysis of data. The study was supported by University of Kentucky tobacco and Health Research Institute grant 41066 and by USPHS NIH Program Project grant HL-40369.


  • Apnea
  • Bronchoconstriction
  • Capsaicin
  • Cigarette smoke
  • Nicotinic receptors
  • Pulmonary chemoreflexes

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine


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