Journal of Applied Physiology, Vol 56, Issue 6 1650-1654, Copyright © 1984 by American Physiological Society
Vagal control of respiratory pattern during hyperpnea in domestic fowl
M. Gleeson and J. H. Brackenbury
Minute volume, tidal volume, and respiratory frequency were measured during
hyperpnea induced by exercise, increased body temperature, and CO2
inhalation. Ventilatory characteristics were compared before and after the
vagus nerve had been blocked. In normal birds exercise produced increases
in both tidal volume and respiratory frequency; hyperthermia produced a
typical thermal polypnea consisting of greatly increased respiratory
frequency and reduced tidal volume; CO2 inhalation produced increases in
tidal volume and respiratory frequency when the birds were euthermic but a
slowing of respiratory rate when the birds were hyperthermic. After vagal
block these pronounced differences in the pattern of ventilatory response
to the various respiratory stimuli were abolished. Instead there was a
uniform ventilatory response to all three stimuli consisting mainly of
increases in tidal volume combined with small increases in respiratory
frequency. It is concluded that in the normal animal control of the varied
pattern of ventilatory response to different respiratory stimuli is
dependent on vagal fiber activity.
