AJP - Regulatory, Integrative and Comparative Physiology, Vol 251, Issue 3 614-R620, Copyright © 1986 by American Physiological Society
Cardiac receptors, vasopressin, and corticosteroid release during arterial hypotension in dogs
M. E. Lee, T. N. Thrasher, L. C. Keil and D. J. Ramsay
The relative roles of cardiopulmonary and sinoaortic baroreceptors in the
regulation of vasopressin and corticosteroid release were evaluated in
conscious dogs. The dogs were prepared with inflatable cuffs around either
the ascending aorta, proximal to the brachiocephalic trunk, or the
pulmonary artery. Inflation of the cuffs was adjusted to cause a reduction
of mean systemic arterial pressure (MAP) of 0, 5, 10, 20, or 30% of control
for 1 h in separate experiments. In spite of the profound systemic
hypotension caused by constriction of the ascending aorta, plasma
vasopressin failed to increase and corticosteroids increased only in
response to a 30% decrease in MAP. In contrast, a 5% reduction in MAP
during pulmonary arterial constriction increased plasma vasopressin and
corticosteroid concentrations significantly. The apparent paradox in these
results is correlated with different effects of the two maneuvers on left
atrial pressure. Left atrial pressure increased dose dependently during
inflation of the ascending aortic cuff but decreased during inflation of
the pulmonary arterial cuff. In contrast, graded inflation of the pulmonary
arterial cuff caused dose-dependent increases in right atrial pressure,
plasma vasopressin, and corticosteroids. Therefore, we conclude that
powerful inhibitory signals, arising from the left heart, can inhibit
vasopressin and hypotension release in response to systemic hypotension.
