Journal of Applied Physiology, Vol 39, Issue 1 129-134, Copyright © 1975 by American Physiological Society
Avian ventilatory responses to dynamic CO2 signals
D. A. Miller and A. L. Kunz
This study uses an awake unidirectionally ventilated avian preparation to
examine the effects of dynamic CO2 signals on the respiratory drive.
Results show that minute ventilation is affected by both 1) mean CO2 level
and 2) amplitude of CO2 oscillations at the frequency of breathing. An
increase in mean CO2 level increased minute ventilation. Comparisons of the
effects of CO2 oscillations at the same mean CO2 level, however, showed
minute ventilation to be less with the larger amplitudes of oscillations
than with smaller ones. Graphs of minute ventilation (V) versus mean CO2
for families of oscillation sizes (0.5%, 1% and 2%) showed that the
ventilatory sensitivity (slop) was least for the 2% oscillations and
greatest for the 0.5% oscillations. Therefore, a static model for the
respiratory regulator is not adequate. However, the apneic level of CO2 (V
= O intercept) was independent of the size of the CO2 oscillations.
