Journal of Applied Physiology, Vol 45, Issue 3 339-344, Copyright © 1978 by American Physiological Society
Lack of effect of vagal afferent input on central neural respiratory afterdischarge
F. L. Eldridge and P. Gill-Kumar
The effect of respiratory inhibition caused by vagal stimulation or lung
inflation on the central neural mechanism that maintains respiration after
cessation of a facilitatory stimulus was studied in anesthetized cats.
Phrenic activity was increased by carotid sinus nerve stimulation or by
squeezing or stretching calf muscle. On cessation of stimulation there was
an immediate decrease in respiratory output followed by a slow decrease
(afterdischarge) over a period of 5 min. Vagal stimulation or lung
inflation, which caused marked inhibition of inspiration, had no effect on
the development of the afterdischarge or on the course of the subsequent
recovery process. The mechanism causing afterdischarge is probably a
buildup of activity in a neural network in the medulla and pons. Since its
activity is unaffected by vagal inhibition of respiration, it can be
concluded that the network is separate from inspiratory output neurons and
those involved in phase switching and that it is not dependent on increased
central inspiratory neuron activity.
