AJP - Heart and Circulatory Physiology, Vol 242, Issue 6 1050-H1055, Copyright © 1982 by American Physiological Society
Response of large hindlimb veins of dog to aortic arch chemoreceptor stimulation
S. L. Britton and D. E. Donald
Experiments were performed in chloralose-anesthetized dogs to examine the
reflex effects on tone in the saphenous vein of stimulating the aortic arch
chemoreceptors. The saphenous vein was perfused with cooled (30 degrees C)
aortic blood at constant flow, and perfusion pressure was measured. In 13
animals the aortic arch chemoreceptors were stimulated by injection of
cyanide (0.1 mg/kg) into the root of the aorta. Cyanide caused a decrease
(20 +/- 2 mmHg) in saphenous vein perfusion pressure and an increase (44
+/- 4) in aortic pressure. These changes that occurred subsequent to aortic
root cyanide injections were abolished by vagotomy or section of the aortic
nerves (afferent pathway); section of the lumbar sympathetic chain at L4
and L5 abolished the dilator response of the vein (efferent pathway) but
did not alter the increase in aortic pressure. Four dogs were prepared for
cardiopulmonary bypass and separate perfusion of the systemic circulation
and the isolated aortic arch. Delivery of hypoxic-hypercapnic blood to the
isolated aortic arch caused a dilation of the saphenous vein and an
increase in systemic arterial perfusion pressure. From these results we
conclude that cutaneous venomotor tone can be reflexly reduced through the
aortic chemoreflex.
