We identified the presence of iodothyronine deiodinase in AtT-20 mouse pituitary tumor cells that secrete corticotropin. Iodothyronine deiodinating activity in AtT-20 cells fulfills all the characteristics of type 2 iodothyronine deiodinase (D2), including the inhibition by thyroid hormones, the insensitivity to inhibition by 6-propyl-2-thiouracil, and the low Michaelis-Menten constant value fo...

unoperated rats. At this time (16 days) T, rats were divided into three groups, i.e. given tri-iodothyronine and fed ad libitum, given tri-iodothyronine and fed a restricted amount of food (14 g per day, slightly less than that eaten by the T, rats) or left untreated. In this way the effects of tri-iodothyronine replacement could be measured in rats in which muscle growth was unrestricted or re...

To estimate the relative contribution of l-triiodothyronine (T(3)) and l-thyroxine (T(4)) to thyroidal effects, we have measured the concentration of iodothyronine bound to specific hepatic nuclear receptor sites by three different techniques: (a) specific radioimmunoassay after separation of T(3) and T(4) by preparative paper chromatography; (b) in vivo kinetic approaches as reported previousl...

Selenium, as selenocysteine, is an integral component of two important enzymes — glutathione peroxidase and iodothyronine deiodinase — that are present in many tissues, including the thyroid gland. Glutathione peroxidase catalyzes the breakdown of hydrogen peroxide, thereby protecting against oxidative damage. Iodothyronine deiodinase catalyzes the deiodination of thyroxine to triiodothyronine,...

Sulfation is an important pathway in the metabolism of thyroid hormone because it strongly facilitates the degradation of the hormone by the type I iodothyronine deiodinase. However, little is known about the properties and possible regulation of the sulfotransferase(s) involved in the sulfation of thyroid hormone. We have developed a convenient method for the analysis of iodothyronine sulfotra...

1. This study has evaluated the effect of somatostatin (0.1 or 3 micrograms/ml) on the release of thyroxine, 3,5,3'-tri-iodothyronine and 3,3',5'-tri-iodothyronine from perfused thyroid lobes. 2. Somatostatin did not affect either the total relase of iodothyronines or the ratio between various iodothyronines in thyroid effluent from unstimulated and thyrotrophic hormone stimulated thyroid lobes...