AJP - Regulatory, Integrative and Comparative Physiology, Vol 247, Issue 6 953-R959, Copyright © 1984 by American Physiological Society
Elevated cardiac pressure inhibits renin release after arterial hypotension in conscious dogs
M. E. Lee, T. N. Thrasher and D. J. Ramsay
The relative roles of cardiopulmonary, sinoaortic, and renal baroreceptors
in the regulation of plasma renin activity (PRA) were evaluated in dogs
with chronically implanted cuffs around the ascending aorta proximal to the
brachiocephalic artery, the abdominal aorta just proximal to both renal
arteries, or both. Inflation of either cuff was adjusted to cause a
reduction of distal arterial pressure and hence renal perfusion pressure
(RPP) of 0, 5, 10, 20, or 30% of control for 1 h. Reduction of RPP by
inflation of the suprarenal cuff (n = 4) led to a significant (P less than
0.05) increase in PRA throughout the dose range examined. However,
constriction of the ascending aorta (n = 7) to cause identical reductions
in RPP failed to increase PRA. The apparent paradox in these results may be
explained by differential effects of the two maneuvers on left atrial
pressure. Left atrial pressure increased dose dependently during inflation
of the ascending aortic cuff but did not change during inflation of the
suprarenal cuff. To determine if elevated right atrial pressure (RAP) would
inhibit renin release after systemic hypotension, another group of dogs (n
= 4) was prepared with cuffs around the pulmonary artery. Inflation of the
pulmonary cuff to cause similar systemic hypotension led to significant (P
less than 0.05) increases in PRA and RAP. Therefore we conclude that
powerful inhibitory signals, arising from the left heart, can inhibit renin
release in response to systemic hypotension.
