Intra- and extra-cellular sources of T3 binding to putative thyroid hormone receptors in liver, kidney, and gill nuclei of immature rainbow trout, Oncorhynchus mykiss.
The sources of extracellular and intracellular 3,5,3'-triiodo-L-thyronine (T3) binding to putative thyroid hormone receptors in liver, kidney, and gill nuclei were determined in vivo for immature rainbow trout at 12 degrees C. Both [131I]T3 and [125I]T4 were injected intraperitoneally, the plasma and tissues were examined at isotopic equilibrium at 20 h, and the proportions of intracellular [125I]T3 and extracellular [131I]T3 saturably bound in the nucleus were determined. Comparable total amounts of T3 were saturably bound in the nuclei of liver (7.2), kidney (8.0), and gill (9.7 moles x 10(-13) .mg DNA-1), but the percentage of nuclear T3 generated within the target cell was greater for gill (76%) than for liver (50%) and kidney (28%). Both gill and liver possess a low Km T4 5'monodeiodinase which could be responsible for the high proportion of the nuclear T3 generated within those tissues.
MacLatchy
D L
DL
Department of Zoology, University of Manitoba, Winnipeg, Canada.
Eales
J G
JG
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D005880:Gills / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D011988:Receptors, Thyroid Hormone / Q000378:metabolism*; D012474:Salmon; D014284:Triiodothyronine / Q000097:blood / Q000378:metabolism*
D011988:Receptors, Thyroid Hormone; D014284:Triiodothyronine