(Na+ + K+)-dependent ATPase activity, heat production and oxygen consumption were increased by 59%, 62% and 75% respectively in hepatocytes from tri-iodothyronine-treated rats. Ouabain at concentrations of 1 and 10 mM decreased oxygen uptake by 2--8% in hepatocytes from euthyroid rats and by 5--15% in hepatocytes from hyperthyroid animals. Heat output was decreased by 4--9% with the glycoside i...

To elucidate the regulatory mechanism of ontogenetic development of iodothyronine-5'-deiodinase in the fetal and neonatal period, fetal mouse liver of the 19th day of gestation, in which no iodothyronine-5'-deiodinating activity was detectable, was cultured in Dulbecco-Vogt medium supplemented with 10% thyroid hormone-depleted fetal calf serum, insulin, hydrocortisone, and thyroid hormones. Iod...

Sulfation appears to be an important pathway for the reversible inactivation of thyroid hormone during fetal development. The rat is an often used animal model to study the regulation of fetal thyroid hormone status. The present study was done to determine which sulfotransferases (SULTs) are important for iodothyronine sulfation in the rat, using radioactive T4, T3, rT3, and 3,3'-T2 as substrat...

The effects of aging on human or animal thyroid function are still not well defined. We evaluated some aspects of thyroid function during aging using an animal model (young and old Dutch-Miranda rats). In old rats of both genders, serum thyroxine (T4) decreased but serum thyrotrophin (TSH) remained unaltered, suggesting a disturbance in the pituitary-thyroid feedback mechanism during aging. Ser...

Tri-iodothyronine (T3) and thyroxine (T4) as well as 3,5-di-iodothyronine (T2) stimulated O2 consumption by isolated perfused livers from hypothyroid rats at a concentration as low as 1 pM by about 30% within 90 min. Application of T2 resulted in a faster stimulation than with application of T3 or T4. Inhibition of iodothyronine monodeiodinase by propylthiouracil, thereby blocking the degradati...

Sulfation is an important pathway of thyroid hormone metabolism that facilitates the degradation of the hormone by the type I iodothyronine deiodinase, but little is known about which human sulfotransferase isoenzymes are involved. We have investigated the sulfation of the prohormone T4, the active hormone T3, and the metabolites rT3 and 3,3'-diiodothyronine (3,3'-T2) by human liver and kidney ...

The acetic acid analogues of thyroxine and tri-iodothyronine, namely tetraiodothyroacetic acid [4-(4'hydroxy-3':5'-di-iodophenoxy)3:5diiodophenylacetic acid] and tri-iodothyroacetic acid [4-(4'hydroxy-3'-iodophenoxy) 3:5 di iodophenylacetic acid] have been synthesized (Harington & PittRivers, 1952; Pitt-Rivers, 1953) and shown to possess considerable biological activity when assayed by the goit...

Type II deiodinase (D2) is important in the regulation of local thyroid hormone bioactivity in certain tissues. D2 in skeletal muscle may also play a role in serum triiodothyronine (T(3)) production. In this study, we identified a polymorphism in the 5'-UTR of the D2 gene (D2-ORFa-Gly3Asp). We investigated the association of D2-ORFa-Gly3Asp, and of the previously identified D2-Thr92Ala polymorp...

(Lillehei et al., 1967). This is attributed to the vasodilator and positive inotropic action of such large doses of hydrocortisone. Similar therapy was successful in our patient. Recent reports recommend that a rapidly acting thyroid hormone should be promptly administered to patients in myxoedema coma or pre-coma. The danger, particularly to the cardio-vascular system, must be balanced against...