title: Effect of TSH on conversion of T4 to T3 in perfused rat kidney.
abstract: This study was undertaken to elucidate the effect of thyrotropin (TSH) on the conversion of thyroxine (T4) to 3,5,3'-triiodothyronine (T3) in the isolated perfused rat kidney. The kidney was perfused with a synthetic medium containing 20 micrograms/dL T4 and the effect of constant infusion of bovine TSH (125 or 250 microU/mL) on the conversion of T4 to T3 was investigated. T4 uptake in the perfused kidney was not changed by the addition of TSH. However, the release of T3 (89 +/- 11 ng/g/30 min, mean +/- SD), tissue T3 (190 +/- 23 ng/g/30 min), net T3 production (227 +/- 37 ng/g/30 min), and the conversion rate of T4 to T3 (9.5 +/- 1.6%) in the kidney perfused with 250 microU/mL TSH were significantly (P less than 0.005) greater than those in controls (63 +/- 9, 143 +/- 15, 152 +/- 36 ng/g/30 min, and 6.3 +/- 1.9%), respectively. Degradation rate of T3 in perfused rat kidney was not changed by the addition of 250 microU/mL TSH. These results suggest that TSH may directly affect renal iodothyronine-monodeiodinating activity in rats in vitro.
mesh_terms: D000818:Animals; D001711:Biotransformation / Q000187:drug effects; D007668:Kidney / Q000378:metabolism*; D008297:Male; D010477:Perfusion; D051381:Rats; D011919:Rats, Inbred Strains; D013972:Thyrotropin / Q000494:pharmacology*; D013974:Thyroxine / Q000378:metabolism*; D014284:Triiodothyronine / Q000096:biosynthesis* / Q000652:urine
chemical_list: D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine