Electrophoretic and Salt Fractionation of the Serum Proteins of Normal and Hypothyroid Rats*

In a previous communication (1) we reported that the sera of intact, -normal rats of the Long-Evans strain, when examined electrophoretically in saline-sodium phosphate buffer at pH 7.4, contained little or none of the protein component usually designated as a-globulin. In contrast, sera taken from rats 21 days after hypophysectomy uniformly showed the presence of this component. Earlier experiments (2) depending on salt fractionation methods had ,shown that the concentration of total serum globulin increased after thyroidect,omy as well as after hypophysectomy and that such globulin elevation might be prevented by thyroid replacement therapy. It was therefore of interest to ascertain whether the sera of thyroidectomized rats showed the presence of a-globulin and whether this component accounted for at least a portion of the increase in total serum globulin. Likewise, it seemed probable that the sera of rats made hypothyroid (3) by thiouracil administration would show the presence of a-globulin. The data reported in this paper, obtained from the sera of eight thyroidectomized, eleven thiouracil-fed, and eight additional untreated control rats, show that oc-globulin does indeed appear in the serum of hypothyroid rats.