Pulmonary C-fiber activation attenuates respiratory-related tongue movements

Kun Ze Lee*, David D. Fuller, Ji Chuu Hwang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


The functional impact of pulmonary C-fiber activation on upper airway biomechanics has not been evaluated. Here, we tested the hypothesis that pulmonary C-fiber activation alters the respiratory-related control of tongue movements. The force produced by tongue movements was quantified in spontaneously breathing, anesthetized adult rats before and after stimulation of pulmonary C fibers via intrajugular delivery of capsaicin (0.625 and 1.25 μg/kg). Brief occlusion of the trachea was used to increase the respiratory drive to the tongue muscles, and hypoglossal (XII) nerve branches were selectively sectioned to denervate the protrusive and retrusive tongue musculature. Tracheal occlusion triggered inspiratory- related tongue retrusion in rats with XII nerves intact or following section of the medial XII nerve branch, which innervates the genioglossus muscle. Inspiratory-related tongue protrusion was only observed after section of the lateral XII branch, which innervates the primary tongue retrusor muscles. The tension produced by inspiratory- related tongue movement was significantly attenuated by capsaicin, but tongue movements remained retrusive, unless the medial XII branch was sectioned. Capsaicin also significantly delayed the onset of tongue movements such that tongue forces could not be detected until after onset of the inspiratory diaphragm activity. We conclude that altered neural drive to the tongue muscles following pulmonary C-fiber activation has a functionally significant effect on tongue movements. The diminished tongue force and delay in the onset of tongue movements following pulmonary C-fiber activation are potentially unfavorable for upper airway patency.

Original languageEnglish
Pages (from-to)1369-1376
Number of pages8
JournalJournal of Applied Physiology
Issue number9
Publication statusPublished - 2012 Nov 1


  • Hypoglossal
  • Pharyngeal
  • Upper airway patency

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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