AJP - Heart and Circulatory Physiology, Vol 250, Issue 1 96-107, Copyright © 1986 by American Physiological Society
Interaction of right and left carotid sinus baroreflexes in the dog
A. S. Greene, M. J. Brunner and A. A. Shoukas
Carotid sinus reflex interactions were studied in 10 dogs anesthetized with
pentobarbital sodium. The right and left carotid sinus regions were
isolated and perfused at controlled pressures. Pressure in the right and
left carotid sinuses were independently varied, and the resulting
steady-state reflex changes in arterial pressure, heart rate, respiratory
frequency, tidal volume, and total ventilation were measured. Reflex
changes when carotid sinus pressure was changed on one side were strongly
influenced by pressure in the contralateral carotid sinus (P less than
0.05). Right carotid sinus gain was found to be 0.628 +/- 0.058 at a left
carotid sinus pressure of 50 mmHg and 0.148 +/- 0.027 when left carotid
sinus pressure was 200 mmHg. Similar results were found for left carotid
sinus gain. Suppression was also found for heart rate, respiratory rate,
tidal volume, and total ventilation. The hypothesis that rapid resetting of
one carotid sinus baroreflex might influence responses from the other side
was also tested. Although ipsilateral resetting was consistently observed,
no contralateral component of the resetting was detected. An additional
inhibitory summation between the right and left carotid sinuses was found
such that simultaneous excitation of both receptors resulted in a smaller
reflex response than did the sum of individual responses. Sympathetic
denervation of the carotid sinus region had no effect.
