Conversion Of T3 And RT3 To T2 PH Dependent

Drareg

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Defending plasma T3 is a biological priority

This text gives an overview about how T3 is regulated. A few of the references might be interesting.

"Furthermore, D3 expression can be enhanced in multiple other tissues in disease states, including the liver, lungs, heart and brain, particularly during ischaemic or hypoxic states."

.....

I found this one by chance. Don't know if it helps.

Conversion of T3 and rT3 to 3,3'-T2: pH dependency. - PubMed - NCBI

You should put the last study in the studies as an individual post,it's interesting PH will do this,where does that leave CO2 in this!
 

tara

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I've just read the abstract. Not sure if I'm reading it right. Is it saying that T3 (which drives metabolism) accumulates more (is broken down to T2 more slowly) in a more acidic environment, while rT3 (which slows metabolism) accumulates more (is broken down more slowly to T2) in a more alkaline environment?
I didn't understand how this:
"The pH activity profile shows a peak at 8.4."
related to the above - 8.4 being quite an alkaline environment.
Is the relevant environment in the body about the blood pH (7.35-7.45) or about the tissue pH (intercellular fluid pH), which can vary much more, or about the intracellular pH?
I'll understand if someone says I should read the study properly myself, and I may get a round to that, but others' thoughts are interesting.
 
OP
Giraffe

Giraffe

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Is the relevant environment in the body about the blood pH (7.35-7.45) or about the tissue pH (intercellular fluid pH), which can vary much more, or about the intracellular pH?
This is from the text I linked in the other thread (see link in OP):

T3 production via deiodination is an intracellular event. T4 enters cells via specific transmembrane transporters and can then be converted to T3.26 D1 is located in the plasma membrane and thus T3 produced via the D1 pathway exits the cells promptly and rapidly equilibrates with the plasma pool of T3.27,28 In fact, kinetics studies indicate that T3 molecules generated via the D1 pathway stay inside the cell for just about 30 min before exiting to plasma. In contrast, D2 is an endoplasmic reticulum (ER)-resident protein, and thus, T4 to T3 conversion through this pathway occurs in a cellular compartment that is physically associated with the cell nucleus, where the TRs are located.27,29 Thus, D2-originated T3 also diffuses to the nucleus and perhaps for this reason remains in the target cell for a longer period time, approximately 8 h.28,30

D3 is located in the plasma membrane and thus has easy access to incoming thyroid hormone molecules.31,32 Furthermore, under hypoxic or ischaemic conditions, D3 is preferentially inserted into the nuclear membrane where it inactivates thyroid hormone, thereby decreasing thyroid hormone signalling.33
 

tara

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Interesting. This is a stretch for me - my understanding of cell anatomy and physiology leaves a lot to be desired. :)
Thanks.
 

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