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合成的黄酮衍生物EMD_(21388)是T_4与甲状腺素结合前白蛋白(Thyroxine-bindingprealbumin,TBPA)结合的强烈抑制物。对大鼠全身使用EMD_(21388)后,血清TBPA与T_4结合即遭抑制,而白蛋白与T_4结合则增加,因而产生血清总T_4浓度降低,游离T_4百分率(FT_4％)增加以及血清TSH降低。提示在T_4与TBPA结合受抑,并与白蛋白结合增多的同时,由于血清T_4结合蛋白结合容量的减少,血清FT_4有短暂的增加;以及EMD_21388并不能通过血脑屏障。本文也进一步表明血清FT_4的稳定是垂体-甲状腺轴功能正常的十分重要的标志,以及大鼠血清游离甲状腺素的半衰期短于1h。
Synthetic flavone derivative EMD_ (21388) is a strong inhibitor of T_4 binding to Thyroxine-binding prealbumin (TBPA). When EMD_ (21388) was administered to the whole body of rats, serum TBPA was inhibited by binding to T_4 and albumin bound to T_4 increased, resulting in a decrease of serum total T_4 concentration, an increase of free T_4 percentage (FT_4%) and a decrease of serum TSH. It is suggested that there is a transient increase in serum FT_4 due to the inhibition of T_4 binding to TBPA and the increase of albumin binding, and the transient decrease of serum T_4 binding protein binding capacity; and that EMD_21388 does not cross the blood-brain barrier. This article also further shows that the stabilization of serum FT 4 is a very important marker of pituitary-thyroid axis function is normal, and serum half-life of free thyroxine is less than 1 h.