EFFECT OF CORTISONE ON THE ACTION OF THYROXINE AND TRIIODOTHYRONINE IN HYPOPHYSECTOMIZED RATS1,2

Abstract
The effect of cortisone has been observed on the oxygen consumption of hypophysectomized rats given thyroxine and triiodothyronine. Similarly, the effect of cortisone has been observed on the disappearance of P32 from p32- labeled red cells injected into hypophysectomized rats receiving thyroxine and triiodothyronine. Cortisone inhibited the effect of thyroxine both on oxygen consumption and p32 disappearance but failed to inhibit the stimulating effect of triiodothyronine. The results are consistent with the hypothesis that cortisone inhibits the peripheral degradation of thyroxine to triiodothyronine.