Docter R, Krenning E P, Bernard H F, Hennemann G
Department of Internal Medicine III and Clinical Endocrinology, Medical Faculty, Erasmus University, Rotterdam, The Netherlands.
J Clin Endocrinol Metab. 1987 Oct;65(4):624-8. doi: 10.1210/jcem-65-4-624.
Thyroid hormone uptake into human cultured fibroblasts was studied using 2-min incubations with labeled iodothyronines. The results indicate the presence of an active T4 uptake process with two saturable sites with apparent Km values of 1.9 and 141 nM, respectively, and an active T3 uptake process with two saturable sites with Km values of 29 and 650 nM. The uptake of both hormones was energy dependent, i.e. inhibited by KCN or by incubation of the cells in the absence of glucose. By analogy with similar findings in rat hepatocytes we postulate that the high affinity systems represent active transport of thyroid hormone into the cell. Preincubation of the cells with 2 mM ouabain resulted in a decrease in the uptake of both T3 and T4, suggesting that a sodium gradient is necessary for transport. Similar to that in rat hepatocytes, uptake of T3 was inhibited by high concentrations of T4, and uptake of T4 was inhibited by high concentrations of T3. These data indicate that regulation of thyroid hormone uptake at the level of the plasma membrane may be operative in humans.
使用标记的碘甲状腺原氨酸进行2分钟孵育，研究甲状腺激素进入人培养成纤维细胞的情况。结果表明存在一个活跃的T4摄取过程，有两个可饱和位点，其表观Km值分别为1.9和141 nM，以及一个活跃的T3摄取过程，有两个可饱和位点，Km值分别为29和650 nM。两种激素的摄取均依赖能量，即被KCN抑制或在无葡萄糖条件下孵育细胞时被抑制。与大鼠肝细胞中的类似发现相似，我们推测高亲和力系统代表甲状腺激素向细胞内的主动转运。用2 mM哇巴因预孵育细胞导致T3和T4摄取均减少，表明钠梯度对于转运是必需的。与大鼠肝细胞中情况类似，高浓度的T4抑制T3摄取，高浓度的T3抑制T4摄取。这些数据表明在人细胞膜水平对甲状腺激素摄取的调节可能起作用。
