Rutgers M, Bonthuis F, de Herder W W, Visser T J
J Clin Invest. 1987 Sep;80(3):758-62. doi: 10.1172/JCI113131.
Triiodothyronine sulfate (T3S) is rapidly deiodinated by the propylthiouracil (PTU)-sensitive type I deiodinase. Here we examined the effects of PTU on plasma T3S levels in rats after intravenous administration of radiolabeled T3 or T3S. Sephadex LH-20 chromatography and high-performance liquid chromatography were used to quantify conjugated and nonconjugated iodothyronines, and iodide was measured as the TCA-soluble radioactivity. In control rats, radioiodide was the main metabolite of both T3 and T3S. Plasma T3S was cleared more rapidly than plasma T3 despite increased binding to plasma proteins. PTU reduced plasma iodide levels by 66 and 78% after T3 and T3S, respectively, and decreased plasma clearance of T3S by 81%. However, PTU had no effect on plasma T3 clearance but increased plasma T3S from injected T3 4.2 times. Biliary excretion of injected T3S was less than 20% in normal rats, in contrast to 70% within 4 h in PTU-treated rats. In conclusion, T3S is an important intermediate in the in vivo metabolism of T3 in rats and accumulates in plasma if type I deiodination is inhibited.
硫酸三碘甲状腺原氨酸（T3S）可被丙硫氧嘧啶（PTU）敏感的I型脱碘酶迅速脱碘。在此，我们研究了静脉注射放射性标记的T3或T3S后，PTU对大鼠血浆T3S水平的影响。采用葡聚糖凝胶LH - 20柱色谱法和高效液相色谱法对结合型和非结合型碘甲状腺原氨酸进行定量分析，并将碘化物作为三氯乙酸可溶性放射性物质进行测定。在对照大鼠中，放射性碘是T3和T3S的主要代谢产物。尽管T3S与血浆蛋白的结合增加，但其从血浆中的清除速度比T3更快。PTU分别使T3和T3S给药后血浆碘水平降低了66%和78%，并使T3S的血浆清除率降低了81%。然而，PTU对血浆T3清除率无影响，但使注射T3后血浆T3S增加了4.2倍。正常大鼠中注射的T3S经胆汁排泄的比例小于20%，相比之下，PTU处理的大鼠在4小时内该比例为70%。总之，T3S是大鼠体内T3代谢的重要中间产物，若I型脱碘作用受到抑制，它会在血浆中蓄积。
