Effect of Potassium Iodide and Desiccated Thyroid Substance on Metabolic Rate of Guinea Pigs.

Abstract

A study was made of the changes in the basal metabolism of guinea pigs under the influence of the administration of potassium iodide, thyroid substance, and of a combination of potassium iodide and thyroid. All determinations were made with an apparatus devised by Foster and Sundstroem, and the results are expressed as calories/kilo guinea pig/hr. Our purpose was to correlate the metabolic changes, or their absence, with previous microscopic studies made in our laboratory on the thyroid gland of guinea pigs under the influence of iodine, and of the other substances mentioned. Loeb has found that oral administration of thyroid substance to guinea pigs in which a considerable part of the thyroid gland had been removed, prevents compensatory hypertrophy from taking place, depressed activities in the gland, and mitotic activity is diminished. On the other hand, administration of KI does not prevent hypertrophy, it favors the solution of the colloid, and the hypertrophy is, on the whole, apparently greater in the gland of those animals which have received this drug. In a similar way. Gray and Loeb found KI to increase very markedly the proliferation of the gland and also slightly to increase the size of the epithelium and to soften somewhat the colloid. In view of these structural changes, it was of interest to determine whether there was a corresponding alteration in the basal metabolic rate. It should be expected that alteration of so pronounced a character in a gland which largely controls the metabolic rate of the organism would affect that rate. Thirty-six guinea pigs, weighing between 350 and 500 gm., were used. During the experiment which in the majority of cases extended over a period of thirty days, repeated metabolic studies on each animal were made and a careful record of changes in weight was kept.