REGULATION OF RENAL THYROID HORMONE UPTAKE & METABOLISM

这项建议的长期目标是研究 调节外周组织对甲状腺激素(T4)的摄取和代谢， 甲状腺的主要分泌产物，以及3，5，3‘- 三碘甲腺原氨酸(T3)，最有效的甲状腺激素以及其他 碘甲腺原氨酸代谢物。这些研究将检验肾脏的作用。 三碘甲腺原氨酸和四碘甲状腺原氨酸的产生和组织分区与循环。 与甲状腺激素摄取有关的三个普遍现象是 在拟议的研究中检查1)血管，2)细胞膜3) 胞质或胞质。灌流的肾脏系统，建立在这个 实验室，为研究其他生物的甲状腺效应提供了机会 纸巾。使用单次通过和再循环肾脏灌流， 调节细胞甲状腺激素流入和流出的机制将是 探索过了。胞浆和灌流液中的游离甲状腺激素组分 将通过平衡透析法测定。潜在的机制 将寻求广泛的单程肾摄取甲状腺激素。 并与稳态组织甲状腺激素浓度和 代谢率。有了这些信息，动态吸收过程将 进行数学建模，以帮助区分简单的 自由荷尔蒙的扩散和促进或主动的运输。建模 在这个系统中大大简化了转运过程，因为 激素载体蛋白类型和浓度、配体等参数 浓度、组织通过时间以及排泄物和 代谢途径是可以控制的。这些技术将被采用 鉴别肾血流量的变化和稳态分布 与甲状腺激素竞争的药物存在时的碘甲状腺原氨酸 与循环蛋白或细胞蛋白结合。光镜 将进行放射自显影以识别组织和细胞 肾脏甲状腺激素交换的基因座。 一项研究将探索组织/灌流液分区的差异 由T4的局部5‘-脱碘生成的T3与由 从发行量来看。体外5‘-脱碘酶抑制剂的作用， 与细胞激素结合竞争的药物和改变的甲状腺状态 将会被检查。非脱碘代谢途径，如结合作用 并通过对HIGH代谢物的分析来检查去卷曲 高效液相色谱。 使用纯化的近端小管细胞，新陈代谢需求 将对肾脏甲状腺激素摄取进行研究，并将使用该系统 解决甲状腺激素摄取和稳态的假设 分布可能受到细胞内等因素的强烈调节 钙、pH和氧化还原电位。

The long term objective of this proposal is to study the mechanisms which regulate the peripheral tissue uptake and metabolism of thyroxine (T4), the main secretory product of the thyroid gland, and 3,5,3'- triiodothyronine, (T3), the most potent thyroid hormone as well as other iodothyronine metabolites. These studies will examine the role of renal production and tissue compartmentation of T3 and T4 with the circulation. Three general phenomena relating to thyroid hormone uptake will be examined in the proposed studies 1) vascular, 2) cell membrane 3) cellular or cytosolic. The perfused kidney system, established in this laboratory, provides the opportunity to study thyroid effect of other tissues. Using single-pass and recirculating kidney perfusion, the mechanisms regulating cellular thyroid hormone influx, and efflux will be explored. Free thyroid hormone fractions in cytosol and perfusate medium will be determined by equilibrium dialysis. The mechanisms underlying the extensive single-pass renal uptake of thyroid hormone will be sought and related to steady-state tissue thyroid hormone concentrations and metabolic rates. With this information, the dynamic uptake process will be mathematically modeled to aid the distinction between uptake by simple diffusion of free hormone and facilitated or active transport. Modeling of the translocation process is considerably simplified in this system as parameters such as hormone carrier protein type and concentration, ligand concentration, tissue transit time, and the significance of excretory and metabolic pathways can be controlled. These techniques will be employed to distinguish alterations in renal flux and steady-state distribution of iodothyronines in the presence of drugs competing with thyroid hormone binding to circulating or cellular proteins. Light microscopic autoradiography will be performed to identify the tissue and cellular loci of renal thyroid hormone exchange. A study will probe for differences in tissue/perfusate compartmentation of T3 generated by local 5'-deiodination of T4 compared to T3 derived from the circulation. THe effects of in vitro 5 '-deiodinase inhibitors, drugs competing with cellular hormone binding, and altered thyroid status will be examined. Nondeiodinative metabolic pathways such as conjugation and deconjugation will be examined by analysis of metabolites by high performance liquid chromatography. Using purified proximal tubular cells, the metabolic requirements of renal thyroid hormone uptake will be studies and this system will be used to address the hypothesis that thyroid hormone uptake and steady-state distribution may be acutely regulated by factors such as intracellular calcium, pH and redox potential.