TY - JOUR
T1 - Vagal modulation of respiratory muscle activity in awake dogs during exercise and hypercapnia
AU - Ainsworth, D. M.
AU - Smith, C. A.
AU - Johnson, B. D.
AU - Eicker, S. W.
AU - Henderson, K. S.
AU - Dempsey, J. A.
PY - 1992
Y1 - 1992
N2 - 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.
AB - 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.
KW - respiratory muscles
KW - vagal cooling
UR - http://www.scopus.com/inward/record.url?scp=0026552505&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0026552505&partnerID=8YFLogxK
U2 - 10.1152/jappl.1992.72.4.1362
DO - 10.1152/jappl.1992.72.4.1362
M3 - Article
C2 - 1592727
AN - SCOPUS:0026552505
SN - 0161-7567
VL - 72
SP - 1362
EP - 1367
JO - Journal of applied physiology
JF - Journal of applied physiology
IS - 4
ER -