AJP - Heart and Circulatory Physiology, Vol 253, Issue 3 598-H603, Copyright © 1987 by American Physiological Society
Aortic arch reflex control of total systemic vascular capacity
A. A. Shoukas, M. J. Brunner, A. S. Greene and C. L. MacAnespie
The ability of the aortic arch baroreceptors to change vascular capacity
was measured and, in the same animal, compared with carotid sinus reflex
changes in capacity. Seven dogs were anesthetized with pentobarbital sodium
and perfused with constant flow. Changes in external reservoir volume
reflected reciprocal changes in total systemic vascular capacity and
changes in arterial pressure parallel changes in total peripheral
resistance. The aortic arch and carotid sinus baroreceptor areas were
isolated, and the pressures were controlled separately. With carotid sinus
pressure held constant at 125 mmHg, aortic arch pressure was increased and
decreased between 225 and 50 mmHg, and the changes in reservoir volume and
systemic arterial pressure were measured. Results from increasing and
decreasing aortic arch or carotid sinus pressure were not significantly
different and were averaged. The mean change in reservoir volume was 1.9
+/- 0.2 ml/kg and the change in mean arterial pressure was 18.7 +/- 3.7
mmHg. The changes in reservoir volume and arterial pressure caused by the
aortic arch reflex were not influenced by the level of carotid sinus
pressure. Carotid sinus pressure changes between 200 and 50 mmHg at a
constant aortic arch pressure caused reservoir volume and arterial pressure
to change by 7.2 +/- 0.9 ml/kg and 45.1 +/- 4.1 mmHg, respectively. The
level of aortic arch pressure did not modify these responses.
