Journal of Applied Physiology, Vol 54, Issue 2 400-407, Copyright © 1983 by American Physiological Society
Sinoaortic contribution to ventilatory control in exercising dogs
P. C. Szlyk, D. R. Pendergast and J. A. Krasney
The role of the sinoaortic reflexes in the regulation of ventilation during
exercise was evaluated in seven awake dogs prepared with chronic
tracheostomies and arterial catheters. Each dog ran on a treadmill at
several work loads before and after sinoaortic denervation and served as
its own control. Minute ventilation in the sinoaortic denervated state was
significantly reduced from intact values by 10-40% at the mild and moderate
levels of exercise [O2 uptake (VO2) = 30-50 ml . kg-1 . min-1] mainly as a
result of a lowering respiratory frequency. At higher work loads (VO2 =
70-80 ml . kg-1 . min-1) minute ventilation was similar in the intact and
denervated states, but the pattern of ventilation was altered with a higher
frequency and a lower tidal volume in the denervated state. The rise in
ventilation toward a stable plateau was slower at all work loads in the
denervated than in the intact state. After sinoaortic denervation, arterial
PCO2(PaCO2) levels were significantly elevated above intact PaCO2 levels
during both the preexercise period and the steady state at all exercise
levels. These results suggest that the sinoaortic reflexes contribute to
both the control of ventilation and the pattern of breathing during mild
and heavy levels of exercise in the conscious dog.
