Vagal modulation of respiratory muscle activity in awake dogs during exercise and hypercapnia

D. M. Ainsworth, C. A. Smith, B. D. Johnson, S. W. Eicker, K. S. Henderson, J. A. Dempsey

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Using chronically instrumented awake tracheotomized dogs, we examined the contributions of vagal feedback to respiratory muscle activities, both electrical and mechanical, during normoxic hypercapnia (inspired CO2 fraction = 0.03, 0.04, 0.05, and 0.06) and during mild treadmill exercise (3, 4.3, and 6.4 km/h). Cooling exteriorized vagal loops eliminated both phasic and tonic mechanoreceptor input during either of these hyperpneas. At a given chemical or locomotor stimulus, vagal cooling caused a further increase in costal, crural, parasternal, and rib cage expiratory (triangularis sterni) muscles. No further change in abdominal expiratory muscle activity occurred secondary to vagal cooling during these hyperpneas. However, removal of mechanoreceptor input during hypercapnia was not associated with consistent changes in end-expiratory lung volume, as measured by the He-N2 rebreathe technique. We conclude that during these hyperpneas 1) vagal input is not essential for augmentation of expiratory muscle activity and 2) decrements in abdominal expiratory muscle activity may be offset by increments in rib cage expiratory muscle activity and contribute to the regulation of end-expiratory lung volume.

Original languageEnglish (US)
Pages (from-to)1362-1367
Number of pages6
JournalJournal of applied physiology
Issue number4
StatePublished - 1992


  • respiratory muscles
  • vagal cooling

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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