Synthesis of angiotensinogen by isolated rat liver cells and its regulation in comparison to serum albumin

Angiotensinogen (renin substrate) and albumin are synthesized by isolated hepatocytes almost linearly for 5 hr. The incorporation of radioactive leucine into total protein proceeded linearly for 3 hr. Without addition of amino acids to the incubation medium the synthesis of both proteins was still linear but fell off to 40% compared to the synthesis rate obtained by incubation with amino acids in serum concentrations. Higher amino acid concentrations could not further stimulate the synthesis. Addition or withdrawal of tryptophan had no effect on the synthesis rate of both proteins. After 5 hr incubation hydrocortisone had stimulated the incorporation of radioactive leucine into total protein by 13%, the albumin synthesis by 43%, and the angiotensinogen synthesis by 142%.