Journal of Applied Physiology, Vol 51, Issue 3 665-670, Copyright © 1981 by American Physiological Society
Responses of aortic chemoreceptors before and after pneumothorax in the cat
M. Pokorski, A. Mokashi, E. Mulligan, T. Nishino and S. Lahiri
That the response of aortic chemoreceptors to hypercapnia is considerably
smaller than that of carotid chemoreceptors is well accepted, but the
mechanism for the difference is not known. It has been suggested that
surgical exposure of the carotid body may contribute to the difference.
Accordingly, the response of aortic body chemoreceptors to CO2 would be
expected to resemble quantitatively that of carotid chemoreceptors after
exposure of the aortic bodies by pneumothorax. The effect of opening the
chest on aortic and carotid chemoreceptor responses to several levels of
arterial CO2 and O2 tension and arterial blood pressure were studied in
anesthetized cats. The activity of aortic chemoreceptors increased in spite
of a decreased stimulus level in the thoracic cavity after pneumothorax.
The activity remained higher than the control at all levels of arterial CO2
and O2 tension and arterial blood pressure. However, the slopes of CO2
response curves, which were initially small, did not change after
pneumothorax. Thus a change in the normal environment of the aortic bodies
by experimental manipulation did not cause the aortic chemoreceptor
responses to resemble those of carotid chemoreceptors.
