TRANSPORT-TOXICITY OF INORGANIC MERCURY IN THE NEPHRON

无机汞在肾单位中的运输毒性

• 批准号: 2154819
• 负责人: DELON W BARFUSS
• 金额: $ 16.7万
• 依托单位: GEORGIA STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-06-01 至 1997-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2154819
• 关键词: basolateral membrane; chemical binding; density gradient ultracentrifugation; endocytosis; high performance liquid chromatography; laboratory rabbit; light microscopy; mathematical model; mercury poisoning; metal metabolism; metallothionein; radionuclides; renal tubular transport; renal tubule; scintillation counter; toxicant interaction

Mercury remains a serious environmental and occupational hazard, ranging from industrial waste to dental amalgams. The kidney is one of the target organs for the toxic effects of mercury, presumably because the kidney of mercury, accumulates more inorganic mercury than any other organ. The kidney also serves as a major route for the excretion of mercury, but very little is known about the mechanisms involved in the renal tubular transport, accumulation and toxicity of inorganic mercury. Thus very little is known about the mechanisms involved in the urinary excretion of the metal. The main thrust of this grant is to characterize the renal transport, accumulation, toxicity, and metabolism of inorganic mercury. The aims of this grant will be carried out using both in vivo and in vitro techniques. One of the principal techniques we will use is the isolated perfused rabbit renal tubule. This technique will allow us to determine simultaneously the renal tubular uptake and transepithelial lumen-to-bath and bath-to-lumen transport of mercury in various isolated segments of the nephron. We will study the transport, accumulation and toxicity of mercury in isolated segments of the proximal tubule (S1, S2, and S3), medullary thick limb of Henle's loop and cortical collecting ducts. These studies will determine if there is axial heterogeneity for transport and accumulation of mercury along the nephron. The studies on the distal segments are important because very little is known about the handling of mercury beyond the proximal tubule. Since inorganic mercury binds avidly to free sulfhydryl groups, we will also examine the effects of compounds that contain sulfhydryl groups on these processes. In order to determine if extracellular cysteine, glutathione and albumin participate in the accumulation and transport of mercury in segments of the nephron, we will use both radiolabelled inorganic mercury (203Hg) and radiolabelled cysteine and glutathione (35S) and albumin (125I) both in vivo and in vitro. The intrarenal localization of mercury and ligand will be determIned for zones of the kidney, while the transport and accumulation of the ligand and mercury will be studied in isolated perfused segments of the nephron. The accumulation and transport of mercury will also be studied when mercury is in an ultrafiltrate of rabbit plasma and when it is complexed with metallothionein. Furthermore, the transport, accumulation and toxicity of mercury will be evaluated when renal intracellular glutathione is depleted and when intracellular synthesis of metallothionein is stimulated. We will also attempt to localize mercury in subcellular fractions of renal tissue from rabbits treated with mercury and the various ligands. In addition, an autometallographic technique will be combined with the isolated perfused tubular technique in an attempt to determine the intracellular localization and accumulated mercury. We will also determine if the metal chelators DMPS and DMSA promote the removal of mercury from various isolated perfused nephron segments when applied to the luminal or basolateral membrane. In summary, from this study we should be able to determine the role of endocytosis and carrier mediated transport in the renal transport and accumulation of free and bound inorganic mercury. Furthermore, this study should provide some insights into the factors influencing the toxicity of mercury in renal epithelia.

汞仍然是一个严重的环境和职业危害， 从工业废物到牙科汞齐。肾是靶子之一 器官对汞的毒性影响，推测是因为肾脏 汞，比任何其他器官积累更多的无机汞。这个 肾脏也是汞排泄的主要途径，但 人们对肾小管的作用机制知之甚少。 无机汞的迁移、积累和毒性。因此非常 关于尿液排泄的机制还知之甚少。 金属。这项资助的主要目的是描述肾脏的特征。 无机汞的运输、积累、毒性和代谢。 这笔赠款的目标将通过体内和体外两种方式实现。 技巧。我们将使用的主要技术之一是孤立的 灌流兔肾小管。这项技术将使我们能够确定 肾小管摄取与跨上皮腔-浴同步 以及汞在不同分离段的从浴槽到管腔的运输 尼龙。我们将研究汞的迁移、积累和毒性。 在近端小管的孤立节段(S1、S2和S3)，髓质 粗大的亨勒氏环和皮质集合管。这些研究 将决定是否存在轴向输送的非均质性 汞沿肾单位积聚。远端节段的研究 数据段非常重要，因为人们对数据段的处理知之甚少 近端小管以外的水银。因为无机汞强烈结合在一起 为了释放巯基，我们还将检查化合物的影响 在这些过程中含有巯基。为了确定 如果细胞外的半胱氨酸、谷胱甘肽和白蛋白参与 汞在肾单位节段的积累和运输，我们将 使用放射性标记无机汞(203汞)和放射性标记无机汞 体内和体内的半胱氨酸、谷胱甘肽(35S)和白蛋白(125I) 体外培养。汞和配体的肾内定位将是 测定为肾区，同时转运和蓄积 配体和汞的含量将在分离的灌流节段中进行研究 肾单位。汞的积累和运输也将是 研究了汞在兔血浆超滤液中的存在以及当它 与金属硫蛋白形成络合物。此外，交通运输， 汞的累积和毒性将在肾移植时进行评估 细胞内谷胱甘肽被耗尽，当细胞内合成 金属硫蛋白受到刺激。我们还将尝试将汞定位在 汞染毒兔肾组织亚细胞组分的研究 以及不同的配体。此外，一种自动金字塔技术将 与隔离灌流小管技术相结合，试图 测定细胞内的定位和汞的累积。我们会 还要确定金属螯合剂DMPS和DMSA是否促进去除 当应用于各种孤立的灌流肾单位节段的汞时 管腔或基底膜。总而言之，从这项研究来看，我们应该 能够确定内吞作用和载体介导的作用 肾转运中的游离态和结合态 无机汞。此外，这项研究应该提供一些见解 探讨汞对肾上皮细胞毒性的影响因素。