Effect of angiotensin II and sodium depletion on angiotensinogen production

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Abstract
An in vitro preparation of liver slices was used to study the effect of angiotensin [A] II and Na depletion on the synthesis of angiotensinogen in rats. Two other treatments known to increase plasma angiotensinogen concentration in vivo, i.e., i.p. administration of dexamethasone or ethinylestradiol, resulted in an increase in the rate of release of angiotensinogen by liver slices; this increase was inhibited by adding actinomycin D or vincristine to the incubation medium. I.v. infusion of AII (33 ng/min for 3 days) also produced a marked increase in the release of angiotensinogen concentration and a decrease in plasma renin activity. In contrast, no change in the rate of release of angiotensinogen was observed in rats depleted of Na for 7-14 days, even though these animals exhibited a marked increase in plasma AII concentration. Plasma angiotensinogen concentration decreased by 30%, presumably as a consequence of the accompanying increase in renin secretion. The synthesis of angiotensinogen may be increased by AII, but the circulating level of AII in Na-deficient animals is not sufficiently high to produce this response.