A Study of the Distribution of Iodine between Cells and Colloid in the Thyroid Gland. Iv. the Distribution of Iodine in the Hyperplastic Thy- Roid Gland of the Dog after the Intravenous Injection of Iodine Compounds. by Harry Benjamin

Some years ago Marine and Feiss (1) and Marine and Rogoff (2, 3) first performed experiments which leave little doubt as to the ability of the dog’s thyroid gland, especially when hyperplastic, to bind iodine almost instantaneously. Marine and Feiss (1) carefully perfused the surviving thyroid gland with fluid containing iodine as KI. They found that after 1 hour a considerable amount of iodine was taken up only by a surviving gland. Any evidence of death of the perfused organ was accompanied by a loss of some of the gland’s stored iodine rather than by an absorption of iodine from the circulating medium. However, even a surviving gland, rich in iodine, lost some iodine to a perfusing fluid free of the element. In surviving glands they discovered that the amounts of iodine absorbed were relatively independent of the amounts of iodine in the perfusing fluids. They also pointed out that a similarly rapid absorption of iodine by the intact gland follows the intravenous administration of a solution of KI. From the results of perfusions of spleen and kidney under similar conditions they concluded that these organs were not capable of taking up a significant amount of iodine. Marine and Rogoff (2) on the basis of experiments in which they injected a solution of KI intravenously came to the conclusion that the absorption of iodine by the gland is almost as great 1 hour after the injection as it is 30 hours after the injection. They again found that no significant amount of iodine was taken up by the spleen and liver. The amount of iodine absorbed by the