title: The effect of adrenaline pretreatment on the in vitro generation of 3,5,3'-triiodothyronine and 3,3',5'-triiodothyronine (reverse T3) in rat liver preparation.
abstract: The effects of adrenaline (A) on liver T3 and rT3 neogenesis from T4 were studied in Wistar rats. The animals were implanted subcutaneously either with A or placebo (P) especially coated tablets which linearly released the hormone. The serum A values 6 hrs after implantation of 7.5, 15.0 and 45.0 mg tablets were 6.5 +/- 1.31, 6.8 +/- 1.8 and 16.4 +/- 1.9 ng/ml, respectively vs 4.4 +/- 2.5 ng/ml seen in P pretreated group. The output rates of A were 0.11 (7.5 mg), 0.18 (15 mg) and 0.52 microgram/ml (45 mg). The pretreatment with A led to hyperglycemia and the "low T3 syndrome". Neogenesis of T3 from T4 in medium containing liver microsomes of P pretreated rats was 5.49 +/- 0.25 pmol of T3/mg protein/min and decreased in A pretreated rats to 3.82 +/- 0.17, 3.12 +/- 0.27 and 3.06 +/- 0.11 pmol of T3/mg of protein/min. Neogenesis of rT3 from T4 in microsomes from P group was 1.52 +/- 0.09 pmol rT3/mg protein/min and increased after A to 2.71 +/- 0.11, 2.60 +/- 0.21 and 2.21 +/- 0.34 pmol of rT3/mg protein/min thus showing no dose dependency. Enrichment of microsomes medium with cytosol either from P or A pretreated rats had no effect on T3 generation thus excluding effect of A on cytosolic cofactor. Although cytosol further increased rT3 neogenesis this was seen regardless of whether cytosol was obtained from A or P implanted rats. It is concluded that A decreases the activity of T4-5'-deiodinase in liver, and possibly increases the activity of T4-5-deiodinase.
mesh_terms: D000818:Animals; D003067:Coenzymes / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology; D004837:Epinephrine / Q000494:pharmacology*; D066298:In Vitro Techniques; D007453:Iodide Peroxidase / Q000378:metabolism; D008099:Liver / Q000201:enzymology*; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology; D051381:Rats; D011919:Rats, Inbred Strains; D013974:Thyroxine / Q000378:metabolism*; D014284:Triiodothyronine / Q000096:biosynthesis*; D014285:Triiodothyronine, Reverse / Q000096:biosynthesis*
chemical_list: D003067:Coenzymes; D014284:Triiodothyronine; D014285:Triiodothyronine, Reverse; D007453:Iodide Peroxidase; D013974:Thyroxine; D004837:Epinephrine