THE DISTRIBUTION OF I131 LABELLED CORTICOTROPHIN PREPARATIONS AND PROTEINS IN RATS AFTER INTRAVENOUS INJECTION)

Abstract

The fate of labeled heterologous corticotrophin in rats was similar to that previously reported for homologous corticotrophin. Although the combined weight of both kidneys of the rats used in these experiments was about 1.2, 10 to 15% of the dose given was localized in 1 g of kidney tissue 20 minutes after the administration. The finding of this much as 15% of injected corticotrophin in the kidneys, which together account for only about 0.7% of the total body weight, was not explained. No differences in uptake by the kidney were observed for labeled corticotrophin, an inactive hypophyseal protein, and placental protein. Hormonal activity is probably not the deciding factor. Labeled serum, liver, and muscle 40722-40730 proteins were not so highly concentrated in the liver. No reasons can be given at this stage.