Influence of background vagal c-fiber activity on eupneic breathing pattern in anesthetized dogs

Edward S Schelegle, J. K. Mansoor, J. F. Green

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


In 19 dogs anesthetized with xylazine and α-chloralose, we examined the influence of background vagal C-fiber activity on the breathing pattern using a modified perineural capsaicin treatment. In seven dogs, we tested the efficacy of this treatment by recording compound action potentials before and after capsaicin application. In the remaining 12 dogs, we examined the effect of vagal perineural capsaicin on the Hering-Breuer expiratory facilitatory inflation reflex, pulmonary chemoreflex, and breathing pattern (tidal volume and expiratory and inspiratory times). Neither the peak height nor integral of the A wave of the compound action potential was significantly affected. However, the peak height and integral of the C wave of the compound action potential were significantly reduced. The myelinated fiber-initiated Hering- Breuer reflex remained intact after perineural capsaicin, but the C-fiber- initiated pulmonary chemoreflex was abolished. Perineural capsaicin increased tidal volume (0.399 ± 0.031 to 0.498 ± 0.058 liter; P < 0.05), expiratory time (3.62 ± 0.31 to 4.82 ± 0.68 s; P < 0.05), inspiratory time (1.49 ± 0.12 to 1.72 ± 0.17 s; P < 0.10) and total time per breath (5.11 ± 1.08 to 6.54 ± 0.82 s; P < 0.05). We conclude that background vagal C-fiber activity exerts an inhibitory effect on tidal volume and an excitatory effect on breathing frequency.

Original languageEnglish (US)
Pages (from-to)600-606
Number of pages7
JournalJournal of Applied Physiology
Issue number2
StatePublished - 1995


  • Hering-Breuer expiratory facilitatory reflex
  • lung C fibers
  • pulmonary chemoreflex

ASJC Scopus subject areas

  • Endocrinology
  • Physiology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation


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