T3/T4Ratios and α-Glycerophosphate Activity in Intact Rats Exposed to a Cold Environment
- 1 January 1975
- journal article
- research article
- Published by Georg Thieme Verlag KG in Hormone and Metabolic Research
- Vol. 7 (03) , 222-227
- https://doi.org/10.1055/s-0028-1093743
Abstract
The quantitative distribution of I-containing compounds has been studied in the thyroid and different tissues of intact rats, equilibrated isotopically with I125 and exposed to 4-10°C for two weeks. It was found that the T3/T4 ratio was increased in extrathyroidal samples. The T3/T4 ratio in the intrathyroidal pool of "free" iodothyronines also tended to increase. In the liver, but not in the kidney, of cold-exposed rats, the concentrations of T3 was higher, and the concentration of T4 the same, or lower. The α-GPD activity increased in the liver, but not in the kidney of similarly treated animals. A positive correlation was found between α-GPD activity and T3 concentration, but not between α-GPD and the concentration of T4. These and previous findings support the idea that conversion of T4 to T3 plays an important role in the expression of a biological effect of T4.Keywords
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