SIMULTANEOUS BIOASSAY OF EXOPHTHALMOS-PRODUCING AND THYROTROPHIC SUBSTANCES

Abstract

ABSTRACT Two methods of thyrotrophin assay based on the crucian carp, Carassius carassius L., are described. One method used the 72-h combined thyroid region radioiodine uptake as response, the other, which makes possible the continuous study of response evolution, was based on the induced excretion of labeled thyroid iodine. The endogenous TSH release was suppressed by hypophysectomy or thyroxine administration. The optimal time intervals between injections, samplings and sacrifice were determined. Linear log dose-response regressions were obtained in the intervals of 0.35–110 mIU and 0.6–180 mIU, respectively. The most favourable designs produced mean indices of precision of 0.46 and 0.58, respectively, with single hormone injections. Two strains of the same species were compared. A preliminary study of heavily y-irradiated bovine thyrotrophin disclosed a radiosensitive molecular weight of 2.7 × 104.