Plasma protein biosynthesis in different thyroid states

Abstract

[1- 14C]Glycine incorporation into plasma protein fractions and concentrations of albumin, fibrinogen, total globulins, and total plasma proteins have been studied, in vivo, in various thyroid states in rats. Different thyroid states have been induced experimentally by subcutaneous and oral administration of triiodothyronine and thyroidectomy. In a group of rats receiving a high dose ( 10 μg T 3 100 g/day ) subcutaneously, fibrinogen synthesis was significantly elevated compared to controls, without significant change in its plasma concentration. In rats receiving a lower dose of T 3 orally 25 μg 100 ml drinking water) albumin synthesis and concentration were significantly lower while fibrinogen parameters were unaffected. Total plasma protein synthesis and concentration were also reduced. There were characteristic changes in all plasma protein fractions in thyroidectomized rats. Concentration of albumin was reduced, while that of globulins and fibrinogen increased, with the resultant increase in total plasma proteins. However, relative synthesis rates of albumin, total globulins, and total plasma proteins were low. There was no significant change in fibrinogen synthesis. These results have been discussed in relation to thyroid hormones and interplay of other hormones.