Vagal contributions to respiratory muscle activity during eupnea in the awake dog

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

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

We examined the effects of reversible vagal cooling on respiratory muscle activities in awake chronically instrumented tracheotomized dogs. We specifically analyzed electromyographic (EMG) activity and its ventilatory correlates, end-expiratory lung volume (EELV) and diaphragmatic resting length via sonomicrometry. Elimination of phasic and tonic mechanoreceptor activity by vagal cooling doubled the EMG activity of the costal, crural, and parasternal muscles, with activation occurring sooner relative to the onset of inspiratory flow. Diaphragmatic postinspiration inspiratory activity in the intact dog coincided with a brief mechanical shortening of the diaphragm during early expiration; vagal blockade removed both the electrical activity and the mechanical shortening. Vagal blockade also doubled the EMG activity of a rib cage expiratory muscle, the triangularis sterni, but reduced that of an abdominal expiratory muscle, the transversus abdominis. Within-breath electrical activity of both muscles occurred sooner relative to the onset of expiratory flow during vagal blockage. Vagal cooling was also associated with a 12% increase in EELV and a 5% decrease in end-expiratory resting length of the diaphragm. We conclude that vagal input significantly modulates inspiratory and expiratory muscle activities, which help regulate EELV efficiently and optimize diaphragmatic length during eupneic breathing in the awake dog.

Original languageEnglish (US)
Pages (from-to)1355-1361
Number of pages7
JournalJournal of Applied Physiology
Volume72
Issue number4
StatePublished - 1992
Externally publishedYes

Fingerprint

Respiratory Muscles
Dogs
Abdominal Muscles
Muscles
Diaphragm
Lung
Mechanoreceptors
Leg
Respiration

Keywords

  • end-expiratory lung volume
  • vagal cooling

ASJC Scopus subject areas

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

Cite this

Ainsworth, D. M., Smith, C. A., Johnson, B. D., Eicker, S. W., Henderson, K. S., & Dempsey, J. A. (1992). Vagal contributions to respiratory muscle activity during eupnea in the awake dog. Journal of Applied Physiology, 72(4), 1355-1361.

Vagal contributions to respiratory muscle activity during eupnea in the awake dog. / Ainsworth, D. M.; Smith, C. A.; Johnson, Bruce David; Eicker, S. W.; Henderson, K. S.; Dempsey, J. A.

In: Journal of Applied Physiology, Vol. 72, No. 4, 1992, p. 1355-1361.

Research output: Contribution to journalArticle

Ainsworth, DM, Smith, CA, Johnson, BD, Eicker, SW, Henderson, KS & Dempsey, JA 1992, 'Vagal contributions to respiratory muscle activity during eupnea in the awake dog', Journal of Applied Physiology, vol. 72, no. 4, pp. 1355-1361.
Ainsworth DM, Smith CA, Johnson BD, Eicker SW, Henderson KS, Dempsey JA. Vagal contributions to respiratory muscle activity during eupnea in the awake dog. Journal of Applied Physiology. 1992;72(4):1355-1361.
Ainsworth, D. M. ; Smith, C. A. ; Johnson, Bruce David ; Eicker, S. W. ; Henderson, K. S. ; Dempsey, J. A. / Vagal contributions to respiratory muscle activity during eupnea in the awake dog. In: Journal of Applied Physiology. 1992 ; Vol. 72, No. 4. pp. 1355-1361.
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