ANGIOTENSINOGEN SYNTHESIS IN THE LIVER IS INDEPENDENT OF PHYSIOLOGICAL ESTROGEN-LEVELS

We determined the physiological importance of endogenous estrogen in t he regulation of angiotensinogen synthesis in the liver. The plasma le vels of angiotensinogen and hepatic levels of angiotensinogen mRNA wer e studied in the rat in comparison to those of T-kininogen, a plasma p rotein whose synthesis in the liver is primarily estrogen-dependent. P lasma levels of T-kininogen and hepatic levels of T-kininogen mRNA wer e 3- and 2-fold higher in adult females, respectively, than in adult m ales, whereas there were no sex differences in levels of either plasma angiotensinogen or hepatic angiotensinogen mRNA. Ovariectomy in femal e rats abolished the sex differences in the levels of plasma T-kininog en and hepatic T-kininogen mRNA, but it did not affect those of plasma angiotensinogen and hepatic angiotensinogen mRNA. These results sugge st that, in contrast to T-kininogen, angiotensinogen synthesis in the liver is unlikely to be controlled by endogenous levels of estrogen.