Stereospecific transport of triiodothyronine from plasma to cytosol and from cytosol to nucleus in rat liver, kidney, brain, and heart.
Stereospecific transport of triiodothyronine from plasma to cytosol and from cytosol to nucleus in rat liver, kidney, brain, and heart.
复制标题
在大鼠肝、肾、脑和心脏中，三碘甲状腺原氨酸从血浆到细胞质以及从细胞质到细胞核的立体特异性转运。
DOI：
10.1172/jci111667
复制
发表时间：
1985
期刊：
影响因子：
--
通讯作者：
Schwartz,HL
中科院分区：
文献类型：
--
作者：
Oppenheimer,JH;Schwartz,HL
我们研究了L-和D-三碘甲状腺原氨酸（T3）从血浆到细胞质和从细胞质到细胞核的运输，通过估计游离激素的浓度在这些车厢在大鼠肝，肾，脑和心脏。我们通过标准同位素技术评估了T3在各种组织中的分布及其代谢，并通过放射免疫测定法测量了血浆和细胞溶质组织中的T3。此外，我们还测定了单个组织中与细胞溶质相关的放射敏感性T3的分数，并估计了每克组织的细胞溶质体积。平衡透析使我们能够确定细胞质和血浆的结合力，体外饱和技术提供了37 ℃下分离的细胞核在水溶液中对L-和D-T3的亲和力（ka）值。我们计算了游离胞质激素的产品的胞质T3和结合力的胞质T3，和游离的核内T3的ka和先前确定的比率的占用与未占用的结合位点在稳态条件下甲状腺功能正常的动物。我们的结果表明，L-T3和D-T3的游离胞质/游离血浆浓度分别为：肝脏2.8，21.6;肾脏1.17，63.3;心脏1.31，1.58;大脑0.86，0.24。L-T3和D-T3的游离核/游离胞质比值分别为：肝脏58.2，3.70;肾脏55.9，1.54;心脏80.6，24.9;大脑251，108.6。我们的研究结果表明，立体特异性转运既发生在从血浆到胞质溶胶，也发生在从胞质溶胶到细胞核。从细胞质到细胞核的高梯度意味着有一个能量依赖性的过程，并出现在体内和体外确定的核缔合常数的差异占。
We have investigated the transport of L- and D-triiodothyronine (T3) from plasma to cellular cytoplasm and from cytoplasm to nucleus by estimating the concentration of free hormone in these compartments in rat liver, kidney, brain, and heart. We assessed the distribution of T3 in various tissues and its metabolism by standard isotopic techniques and measured plasma and cytosolic tissue T3 by radioimmunoassay. In addition, we determined the fraction of radiosensitive T3 associated with the cytosol in individual tissues and estimated the cytosolic volume per gram of tissue. Equilibrium dialysis allowed us to determine the binding power of cytosols and plasma, and in vitro saturation techniques provided values for the affinity (ka) for L- and D-T3 of isolated nuclei in aqueous solution at 37 degrees C. We calculated the free cytosolic hormone from the product of cytosolic T3 and the binding power of cytosol for T3, and the free intranuclear T3 from the ka and previously determined ratio of occupied-to-unoccupied binding sites under steady state conditions in euthyroid animals. Our results showed that the free cytosolic/free plasma concentrations for L-T3 and D-T3, respectively, were: liver 2.8, 21.6; kidney 1.17, 63.3; heart 1.31, 1.58; brain 0.86, 0.24. The free nuclear/free cytosolic ratios for L-T3 and D-T3, respectively, were: liver 58.2, 3.70; kidney 55.9, 1.54; heart 80.6, 24.9; and brain 251, 108.6. Our findings suggest that stereospecific transport occurs both from plasma to cytosol and from cytosol to nucleus. The high gradients from cytosol to nucleus imply that there is an energy-dependent process and appear to account for the differences in the nuclear association constant determined in vivo and in vitro.