RADIOACTIVE IODINE AS AN INDICATOR IN THYROID PHYSIOLOGY III. IODINE COLLECTION AS A CRITERION OF THYROID FUNCTION IN RABBITS INJECTED WITH THYROTROPIC HORMONE1

Abstract

Using radioactive I as an indicator, we have compared the following criteria of thyroid function in rabbits injected with thyrotrophic hormone: thyroid I collection, acinar cell height, relative thyroid size, and B.M.R. rate. An approx. parallel variation of cell height, basal metabolic rate, and thyroid size takes place. The thyroid I collection varies with the other criteria, but not in a parallel fashion. The B.M.R., cell height, and thyroid size show initial rises to a maximum with subsequent decline, which is accelerated by the adm. of I. All except thyroid size reach final values below normal when I is administered. Thus the result of thyrotrophic hormone injs. may be regarded as an initial stimulation followed by (a) involution if I is administered, (b) functional depression after prolonged thyrotrophic stimulation.