THE BINDING OF THYROIDAL HORMONES BY TRITON WR-1339

The ability of Triton WR-1339 to bind thyroxine was determined by the thyroxine-stabilization technic of Tata. In addition, the effect of Triton treatment on the amount of triiodothyronine bound by guinea pig plasina was measured by the erythrocytic system of Hamolsky et al. and the direct method of Scholer. It was found that Triton was as effective as whole serum protein in its ability to inhibit the drying-induced deiodination of thyroxine occurring on filter paper. Triton treatment resulted in a significantly decreased uptalte of triiodothyronine in the erythrocytic system and, conversely, a significantly increased binding of triiodothyronine by plasma. These results are discussed in terms of a possible competition for available thyroxine in vivo between Triton and thyroxine-binding serum proteins. In previous experiments (I) we described an increase in intravascular disappearance of tracer amounts of exogenous thyroxine in guinea pigs following treatment with Triton WR-1339 (oxyethylated tertiary octyl phenol formaldehyde polyn~er, Winthrop Laboratories). This polymer is known to suppress experimental tuberculosis in the illouse (2,3) and guinea pig (4), and in coinmon with triiodothyronine (5) it is capable of inhibiting the intracellular inultiplication of tubercle bacilli. In view of the fact that thyroxine and triiodothyronii~e are transported in blood by means of protein carriers, it seemed reasoilable that our results could be explained, at least in part, by an interaction of this nonionic detergent and the protein-hormone con~plex. The instability of thyroxine first described by Tata (6), iilvolving the ionization of the phenolic hydroxq~l group, provides a convenient means of determining in vitro whether an interaction occurs with this hormone and Triton. In addition, the procedure of 1-Iamolskq~, Stein, and Freedberg (7), which is essentially the in vitro measurement of the amount of 1,-triiodothyronine bound by the red cells in the presence of the plasma proteins, is suitable for nleasuring changes in the binding capacity of the plasma due to the presence of this nonionic detergent in the blood. The purpose of the present study was to establish the thyroid-horinone binding property of Triton and to measure the effect of this nonionic detergent on the amount of hormonal iodine bound by the plasina of the guinea pig.