PROTEIN-BOUND IODINE IN VARIOUS TISSUES AFTER INJECTION OF ELEMENTAL IODINE¹

Abstract

In iodine returned toward normal the depressed growth rate of young thyroidectomized rats and lowered the cell height of the thyroid epithelium of thiouracil-treated animals. Both of these effects were interpreted as being due to the formation of thyroxine, but no demonstration of organic iodine formation was made. Nelson and Wheeler (1948) found that the disturbances of the estrous cycle produced in rats by thyroidectomy could be reversed by elemental iodine injections. Barker and Lipner (1948) showed an elevation of metabolic rate in thyroidectomized or thiouracil-treated rats injected with 16 mg. I2 per kilogram body weight per day and in thyroidectomized injected with 4; normal animals showed no effects at either dose level. The protein-bound iodine (PBI) of the blood plasma increased remarkably in all groups of animals to a greater extent than would be expected from the metabolic changes. The present work was undertaken to inquire further into the PBI changes in various tissues.