THE INFLUENCE OF HYPOPHYSECTOMY UPON PLASMA IODINE AND THYROXINE CONTENT OF THE THYROID GLAND OF THE RAT1

IN AN EARLIER STUDY (Morton, Perlman, Anderson, and Chaikoff, 1942) radioactive iodine was employed to investigate the turnover of iodine by the thyroid gland of the hypophysectomized rat. The results brought to light an interesting difference in the fate of radioactive inorganic iodine injected into normal and hypophysectomized rats. The normal thyroid gland rapidly converted labeled inorganic iodide to diiodotyrosine, and this conversion was also found to occur readily in the thyroid gland of the rat subjected to hypophysectomy. But the rate of formation of radio-thyroxine by the thyroid gland was greatly depressed by hypophysectomy. For a more complete understanding of the effects of hypophysectomy upon iodine metabolism, it became necessary to provide reliable data on the thyroxine content of the thyroid gland and onvthe protein-bound iodine of plasma of the hypophysectomized rat. This has been done in the present investigation.