Thyroxine and 3,3',5-triiodothyronine are glucuronidated in rat liver by different uridine diphosphate-glucuronyltransferases.
Endocrinology
; 128(2): 741-6, 1991 Feb.
Article
em En
| MEDLINE
| ID: mdl-1899220
ABSTRACT
Male Wistar rats were treated with 50 mg 3,3',4,4'-tetrachlorobiphenyl (TCB)/kg BW or vehicle. After 4 days, the livers were isolated and perfused for 90 min with 2 nM [125I]T3 or 10 nM [125I]T4 in Krebs-Ringer medium containing 1% albumin. Deiodination and conjugation products and remaining substrates were determined in bile and medium samples by Sephadex LH-20 chromatography and HPLC. TCB treatment did not affect hepatic uptake and metabolism of T3. However, biliary excretion of T4 glucuronide was strongly increased by TCB, resulting in an augmented T4 disappearance from the medium, although initial hepatic uptake of T4 was not altered. Measurement of the microsomal UDP-glucuronyltransferase (UDPGT) activities confirmed that T4 UDPGT was induced by TCB, whereas T3 glucuronidation was unaffected. T3 UDPGT activity showed a discontinuous variation, which completely matched the genetic heterogeneity in androsterone glucuronidation in Wistar rats. These results indicate that different isozymes catalyze the glucuronidation of T3 and T4.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Tiroxina
/
Tri-Iodotironina
/
Glucuronosiltransferase
/
Glucuronatos
/
Isoenzimas
/
Fígado
Limite:
Animals
Idioma:
En
Revista:
Endocrinology
Ano de publicação:
1991
Tipo de documento:
Article
País de afiliação:
Holanda