The deiodination of L-thyroxine to triiodothyronine has been observed in vitro using surviving rat kidney slices (1, 2). Surveys of other rat tissues have not shown consistent deiodination of tlhyroxine, but occasional appearances of trace quantities of triiodothyronine in surviving heart slices and diaphragm (3) have led to the belief that other tissues in the rat convert thyroxine to triiodot...

In this research study, the effect of baclofen (GABAB receptor agonist) on mean concentration of growth hormone, thyroxine, and triiodothyronine was examined. For this purpose, twelve Holstein Cows were divided into four groups. Then, each cow received daily injection of 25, 50, 75, and l00 mg/kg of baclofen for a period of four days. Blood samples were daily collected at one time point for eig...

In the course of a search for compounds which might prove to be competitive inhibitors of thyroxine in its action on the peripheral tissues, we have initiated a study of the relationship between chemical structure and thyroxine-like activity of a number of thyroxine analogues. Early attempts to relate chemical constitution to physiological activity have been summarized by Harington (1, 2) who c...

Thyroxine has been shown to accelerate the synthesis of carbamyl phosphate synthetase in the liver of Rana catesbdana. Stimulation of carbamyl phosphate synthetase synthesis by thyroxine appears to be relatively specific because of the following observations: (I) succinoxidase activity decreased during the time that carbamyl phosphate synthetase increased; (2) liver catalase responded more slow...

The effect of temperature on the binding of thyroxine and triiodothyronine to thyroxine-binding globulin has been studied by equilibrium dialysis. Inclusion of ovalbumin in the dialysis mixture stabilized thyroxine-binding globulin against losses in binding activity which had been found to occur during equilibrium dialysis. Ovalbumin by itself bound the thyroid hormones very weakly and its bind...

The rate of appearance of labeled thyroxine (T4) and albumin in lymph from various areas after simultaneous i.v. injection of the labeled substances in conscious ambulatory sheep has been used to estimate the relative rates of transcapillary movement of stable T4 and albumin. Labeled T4 appeared in hepatic lymph at the same rate as albumin. In intestinal and leg lymph, labeled T4 appeared eight...