Hypertension, Vol 1, 402-409, Copyright © 1979 by American Heart Association
J Conway, R Hatton, J Keddie and P Dawes
Sodium depletion was induced in dogs to raise plasma renin activity (PRA)
from 1.11 to 26.48 ng/ml/hr. Little overall change in blood pressure (BP)
occurred, but cardiac output (CO) and central venous pressure fell, while
total peripheral resistance and heart rate (HR) increased. A nonapeptide
converting enzyme inhibitor (CEI) produced a fall in BP which was linearly
related to log. PRA; the intercept with PRA was at 1.05 ng/ml/hr, close to
the average value for dogs on a normal diet. The fall in BP with this agent
was not accompanied by an increase in HR or CO. When Sar1-Ala8 angiotensin
II was used to antagonize the action of angiotensin, the fall in BP was
also linearly related to log. PRA. However, for a given level of PRA this
fall in BP was less than that achieved with CEI and the intercept of BP
fall with PRA was 2.6 ng/ml/hr. Again with this agent there was little
change in HR or CO as BP was reduced. Thus, both antagonists lowered
peripheral resistance without exciting the homeostatic reflexes indicating
that, as PRA rose above the normal resting level, the angiotensin generated
had both a direct and indirect effect in maintaining BP.
ARTICLES
The role of angiotensin in the control of blood pressure during sodium depletion
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