Direct quantitative estimation of several iodothyronines in rat bile by radioimmunoassay and basal data on their biliary excretion |
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Authors: | Ondrej Földes Pavel Langer Katarína Straussová Hana Brozmanová Klaudia Gschwendtová |
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Institution: | Institute of xperimental Endocrinology, Center of Physiological Sciences SAV, 833 06 Bratislava, Czechoslovakia |
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Abstract: | A method was developed for the hydrolysis of conjugated iodothyronines in bile with the aid of β-glucuronidase / arylsulfatase and for subsequent direct estimation of total and free iodothyronines with the aid of specific radioimmunoassay. The amount of conjugated fraction could then be calculated from the difference. Thus, basal biliary excretion of several iodothyronines was measured in 31 normal, fed rats in which the bile duct was drained with polyethylene tubing under pentobarbiturate anesthesia and the bile was collected for 2 h. The free fraction of thyroxine, 3,5,3′-triiodothyronine and 3,3′-diiodothyronine was approx. 30% of total content, while that of 3,3′,5′-triiodothyronine and 3,5-diiodothyronine was approx. 20% and that of 3′,5′-diiodothyronine was less than 10%. This suggests some considerable diffrences in the conjugation of individual iodothyronines was about 3–8 times higher than in plasma. This shows close interrelations between the iodothyronine deiodinating pathway in liver cells in vivo and the spectrum of iodothyronine in bile. The average ratio of T3/rT3 as found in bile was about 4. |
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Keywords: | Iodathyronine assay Thyroid hormone Biliary exretion (Rat) |
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