RADIOACTIVE THYROTROPIC HORMONE PREPARATIONS*†

Abstract

A pituitary prepn. with thyrotropic and gonado-tropic activity has been coupled with S35-labeled diazobenzene sulfonic acid. As detd. by the thyroid wt. of chicks, the biological activity of the labeled prepn. decreased as the number of substituent groups on the protein increased. After the intraven. injn. of the labeled pituitary prepn. to male chicks, concns. of radioactivity were greater in the thyroid, gonads, and liver than with control substances. The latter included serum albumin labeled with S35-labeled diazobenzene sulfonic acid, S35-labeled sulfanilic acid, and S35-labeled sulfate. The biological half-life of the radioactivity in the thyroid and gonads was approx. 18 hrs. when labeled TSH prepns. were admd. Concns. of radioactivity 5 and 3 times greater than blood were realized in the thyroid and gonads resp. There were considerably greater thyroid/blood and gonad/blood ratios of S35 concn. than was obtained with the control substances. Chromatography of the labeled TSH prepn. revealed a heterogeneous prepn. with at least 5 compounds.