Journal of Applied Physiology, Vol 54, Issue 2 562-570, Copyright © 1983 by American Physiological Society
Reflex control of breathing following inhalation of cigarette smoke in conscious dogs
L. Y. Lee, R. F. Morton, A. H. Hord and D. T. Frazier
The acute ventilatory response to spontaneously inhaled cigarette smoke
(750 ml, 10% concentration) was studied in 92 experiments on 6 awake
resting dogs. Upon the first or second breath of smoke inhalation, either
an apnea or an augmented breath was elicited consistently in each dog, and
a hyperpnea occurred subsequently. Minute ventilation (VE) increased from a
base line of 3.2 to a peak of 23.9 l/min at 8.3 s (mean values) after the
smoke was completely inhaled and returned toward base line in 1-3 min. Cold
blocking of both vagi (exteriorized in skin loops) eliminated the initial
change in breathing pattern but did not significantly reduce the delayed
hyperpnea. Denervation of carotid body chemoreceptors alone abolished 71.5%
of the increase in VE induced by cigarette smoke. These results suggest
that the apnea or augmented breath immediately following the smoke
inhalation is mediated through vagal afferents, whereas the delayed
hyperpnea results primarily from the stimulation of carotid body
chemoreceptors, presumably by the absorbed nicotine.
