Journal of Applied Physiology, Vol 56, Issue 6 1541-1549, Copyright © 1984 by American Physiological Society
Central-peripheral chemoreceptor interaction in awake cerebrospinal fluid-perfused goats
C. A. Smith, L. C. Jameson, G. S. Mitchell, T. I. Musch and J. A. Dempsey
We assessed the ventilatory interaction between central [central nervous
system (CNS)] and peripheral chemoreceptor stimuli in five awake goats. CNS
extracellular fluid (ECF) [H+] was altered with cisterna magna perfusion of
mock CSF. Peripheral chemoreceptors were stimulated with three doses of
NaCN given intravenously. The resulting dose-response curves were used to
assess interaction of the central and peripheral stimuli. The observed
interaction was hypoadditive; i.e., the average slope of the NaCN-inspired
minute ventilation dose-response line was significantly greater during
alkaline perfusion than during acidic perfusion. This correlation can be
described by slope = -0.24 (CSF [H+]) + 30.7; r = 0.67 (P less than 0.01).
Increased ventilatory responses were accompanied by increases in mean
inspiratory flow, tidal volume, and breathing frequency and decreases in
expiratory time in response to peripheral chemoreceptor stimulation. Unlike
previous reports in anesthetized and denervated animals, in our awake
intact goats the ventilatory and tidal volume responses showed no
significant dependence on the level of control (pre-NaCN stimulus) inspired
minute ventilation. We conclude that the level of [H+] in cerebral ECF
exerts a significant reflex-mediated hypoadditive effect on the ventilatory
responses to peripheral chemoreceptor stimulation.
