AJP - Endocrinology and Metabolism, Vol 239, Issue 6 442-E446, Copyright © 1980 by American Physiological Society
Stimulation of angiotensinogen production: a dose-related effect of angiotensin II in the conscious dog
C. Sernia and I. A. Reid
The hypothesis that angiotensin II (AII) provides a positive feedback
stimulus for production of angiotensinogen was examined in conscious dogs.
AII was infused intravenously for 24 h at 5, 20, and 50 ng x kg-1 x min-1
and blood pressure, plasma renin activity (PRA), and the concentrations of
AII, angiotensinogen, corticosteroids, and total protein in plasma were
measured 0, 2, 4, and 24 h after the start of infusion. In addition, the
liver content of angiotensinogen and the release of angiotensinogen by
liver slices in vitro were measured after the 24-h sampling period. AII
infusion increased blood pressure in a dose-related manner. PRA was
markedly decreased by all doses of AII. Plasma corticosteroids were
increased only at the highest dose of AII and did not bear any relationship
to changes in the concentration of angiotensinogen. Plasma protein
concentration and hematocrit were unchanged. Plasma angiotensinogen
concentration was unchanged at 2 and 4 h but was increased significantly at
24 h by the two highest doses of AII. A linear relationship was found
between the dose of AII and plasma angiotensinogen concentration, the liver
content of angiotensinogen, and the release from liver slices during a 2-h
incubation. These results provide further evidence that AII has a role in
angiotensinogen production but suggest that it is of minor importance in
physiological conditions.
