The ontogeny of iodothyronine deiodinase systems in liver and intestine of the rat.

@article{Galton1991TheOO,
  title={The ontogeny of iodothyronine deiodinase systems in liver and intestine of the rat.},
  author={Valerie Anne Galton and P. T. Mccarthy and Donald L. St. Germain},
  journal={Endocrinology},
  year={1991},
  volume={128 4},
  pages={
          1717-22
        }
}
The ontogeny of the iodothyronine deiodinase systems has been studied by several investigators in recent years, but our understanding of the subject is far from complete. The present study was conducted to obtain kinetic information concerning 5' deiodinase (5'D) and 5 deiodinase (5D) activities in fetal rat liver and intestine, and to examine reduced glutathione (GSH)-activated 5'D activity in the two tissues. When dithiothreitol (DTT) was used as cofactor in concentrations up to 100 mM, 5'D… 
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TLDR
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Characterization of rat iodothyronine sulfotransferases.
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The responsiveness of the low Km I-5'D's in renal and hepatic microsomes to physiological concentrations of GSH suggests their participation in the metabolism of iodothyronines in vivo.
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TLDR
It is concluded that hepatic iodothyronine metabolism in the immature embryo is directed so as to prevent the accumulation of T3 derived from T4...
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It is suggested that accumulation of T3 generated from T4 in the tadpole is minimal before MD due to the predominance of 5D activity.
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TLDR
It is concluded that the failure to observe T3 generation from T4 in the developing chick until close to hatching, when substrate concentrations are below 5 X 10(-8) M, is due primarily to the presence of an active deiodinase which rapidly converts T4 and T3 to inactive analogs.
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TLDR
An alternative explanation for the failure to observe T4 to T3 conversion before climax is offered; in pre- and prometamorphic tadpoles, any T3 produced from T4 is rapidly converted to 3,3'-diiodothyronine by the 5 D system and thus accumulation is prevented.
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TLDR
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TLDR
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