TRANSPORT-TOXICITY OF INORGANIC MERCURY IN THE NEPHRON

无机汞在肾单位中的运输毒性

• 批准号: 3254304
• 负责人: DELON W BARFUSS
• 金额: $ 16.51万
• 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/3254304
• 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.

汞仍然是一种严重的环境和职业危害，范围广泛 从工业废物到牙科汞合金。肾脏是目标之一 汞毒性作用的器官，大概是因为肾脏 汞，比任何其他器官积累更多的无机汞。这 肾脏也是汞排泄的主要途径，但非常重要 对于肾小管的相关机制知之甚少 无机汞的迁移、积累和毒性。因此非常 对于尿排泄的机制知之甚少 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。 这笔赠款的目的将利用体内和体外进行 技术。我们将使用的主要技术之一是隔离 灌注兔肾小管。这项技术将使我们能够确定 同时进行肾小管摄取和跨上皮腔浴 以及汞在各个隔离部分中的浴到管腔的传输 肾单位。我们将研究汞的迁移、积累和毒性 在近端小管（S1、S2 和 S3）的孤立部分中，髓质 亨利氏环和皮质集合管的粗肢。这些研究 将确定运输是否存在轴向异质性 汞沿着肾单位累积。远端研究 段很重要，因为我们对如何处理知之甚少 汞超出近端小管。由于无机汞会强烈结合 对于游离的巯基，我们还将检查化合物的影响 这些过程中含有巯基。为了确定 如果细胞外半胱氨酸、谷胱甘肽和白蛋白参与 汞在肾单位部分的积累和运输，我们将 使用放射性标记无机汞 (203Hg) 和放射性标记 体内和体内的半胱氨酸和谷胱甘肽 (35S) 以及白蛋白 (125I) 体外。汞和配体的肾内定位将是 确定肾脏区域，同时运输和积累 配体和汞的结合将在隔离的灌注片段中进行研究 肾单位。汞的积累和迁移也将 研究了汞何时存在于兔血浆的超滤液中以及何时 与金属硫蛋白络合。此外，交通、 汞的蓄积和毒性将在肾脏检查时进行评估 细胞内谷胱甘肽耗尽，当细胞内合成谷胱甘肽时 金属硫蛋白受到刺激。我们还将尝试将汞本地化 用汞处理的兔子肾组织的亚细胞部分 和各种配体。此外，自动金相技术将 与孤立灌注管状技术相结合，试图 确定细胞内定位和累积的汞。我们将 还确定金属螯合剂 DMPS 和 DMSA 是否促进去除 当应用于时，来自各种分离的灌注肾单位段的汞 腔膜或基底外侧膜。综上所述，从这项研究中我们应该 能够确定内吞作用和载体介导的作用 肾脏中的转运以及游离和结合的转运和积累 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。