In the present study we have made use of inhibitors of protein synthesis to obtain information on the relative importance of 2 classes of iodine acceptors in the thyroid: 1) prethyroglobulin, newly or recently synthesized and 2) pre-existing thyroglobulin (already iodinated). Puromycin and cycloheximide depressed iodine uptake in both iodine-sufficient and iodinedeficient rats, but the inhibitory effect was greater in iodine-deficient animals. The changes in thyroid iodine metabolism observed after administration of these drugs did not have the characteristics usually associated with perchlorate- like or thionamide-like antithyroid compounds or with iodide excess. We believe that the observed effects of puromycin and of cycloheximide may be explained in part in relation to their inhibitory action on prethyroglobulin synthesis. Our results suggest that in both iodine-deficient and iodine-sufficient rats newly or recently synthesized prethyroglobulin is more important than stores of pre-existing thyroglobulin in the organification of newly entering iodide.

This content is only available as a PDF.
You do not currently have access to this article.