RADIOIODIDE IN THE THYROID AND IN OTHER ORGANS OF RATS TREATED WITH LARGE DOSES OF PERCHLORATE1

Abstract

WE INVESTIGATE]) the hitherto largely unexplored first step of thyroid hormone biogenesis, the diffusion of iodide into the thyroid, by administering radioiodide after complete blocking of the thyroidal iodide pump ("trap") with its most potent inhibitor, sodium perchlorate (Wyngaarden et al., 1952). We correlated the amount of radioiodide that was found in the thyroid under such conditions with the structure of the gland, which was experimentally altered by varying the intensity of thyrotrophic stimulation. It was our hope that such a study may yield information concerning a) the site of the iodide “trap” within the thyroid parenchyma and b) the possible influence of thyrotrophin on the permeability of the thyroid cell to iodide. Levine and Goldstein (1955) have recently emphasized, in discussing the mode of action of insulin, that hormones may regulate metabolic processes by altering the permeability of cell membranes to specific substances.