MECHANISM FOR CHARGED-RELATED NEPHROTOXICITY

带电相关肾毒性的机制

• 批准号: 3243388
• 负责人: Darryl Peterson
• 金额: $ 11.27万
• 依托单位: ROSALIND FRANKLIN UNIV OF MEDICINE & SCI
• 依托单位国家: 美国
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-01-01 至 1993-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3243388
• 关键词: angiotensin II; antiport; autoradiography; calcium; cations; electron microscopy; endocytosis; gentamicins; high density lipoproteins; hydrogen; isolation perfusion; laboratory rabbit; lysosomes; magnesium; membrane permeability; membrane proteins; membrane transport proteins; protein transport; renal toxin; renal tubular transport; sodium

Cationic substances like myeloma proteins, cationized albumin, and gentamicin are nephrotoxic at the level of the proximal tubule. Transport defects may occur rapidly, prior to the appearance of apparent biochemical or morphological damage. An early defect is bicarbonaturia, which is due to a reduction in Na/H antiporter activity in the luminal membrane of proximal tubular cells. The toxic cationic substances mentioned above enter the cells by endocytosis at the luminal membrane. We have recently shown that endosomes containing cationic material fail to fuse with lysosomes during early stages of uptake, and remain sequestered within the cytoplasm of proximal tubular cells. This raises the possibility that membrane transport proteins, including Na/H antiporters, may be taken up during the endocytic process and become trapped in a pool of endosomes that are not able to recycle normally. Preliminary evidence supports this interpretation. Calcium and magnesium have been reported to protect against gentamicin nephrotoxicity, and both inhibit binding of gentamicin to the luminal membrane. The purpose of this proposal is to examine the nature of early transport defects in the kidney due to cationic substances. The following hypothesis will be tested: endocytosis of cationic substances by renal proximal tubular cells causes the internalization of plasmalemmal carriers, which become trapped in a pool of cytoplasmic endosomes; calcium and magnesium protect against these charge-related events. Thus, the following specific aims are proposed: 1) to show that endocytosis of cationized albumin or gentamicin by renal proximal tubular cells inhibits fusion of endosomes to lysosomes, causing an accumulation of endosomal membrane in the cytoplasm during the early phase of toxicity; 2) to show that endocytosis of cationized albumin or gentamicin by renal proximal tubular cells results in the internalization and sequestration of Na/H antiporters in a pool of cytoplasmic endosomes, during the early phase of toxicity; 3) to show that calcium and magnesium reduce endocytosis of cationized albumin and gentamicin, diminish the endosomal-lysosomal fusion defect, and decrease the sequestration of Na/H antiporters observed in renal proximal tubular cells during the early phase of toxicity. The effects of cationized albumin and gentamicin on membrane shuttling and Na/H antiporter activity will be measured in microperfused proximal nephron segments and isolated renal membranes.

阳离子物质，例如骨髓瘤蛋白，阳离子白蛋白和 庆大霉素在近端小管的水平上是肾毒性。运输 在出现明显的生化之前，可能会迅速发生缺陷 或形态损害。早期缺陷是碳尿酸，应得 减少Na/h抗胞菌活性在腔膜中的活性 近端管状细胞。上面提到的有毒阳离子物质进入 细胞通过腔膜的内吞作用。我们最近显示了 含有阳离子材料的内体无法与溶酶体融合 在摄取的早期阶段，并保持在细胞质中 近端管状细胞。这增加了膜的可能性 运输蛋白，包括Na/h抗植物，可以在此期间服用 内吞过程，被困在没有的内体中 能够正常回收。初步证据支持这一点 解释。据报道钙和镁可防止 庆大霉素肾毒性，都抑制庆大霉素与 腔膜。 该提议的目的是检查早期运输的性质 由于阳离子物质而导致的肾脏缺陷。以下假设 将测试：通过肾脏近端对阳离子物质的内吞作用 管状细胞引起浆膜载体的内在化，该载体的内在化 被困在细胞质内体的池中；钙和镁 防止这些与费用相关的事件。因此，以下特定 提出了目的：1）表明阳离子白蛋白的内吞作用或 肾近端管状细胞的庆大霉素抑制内体融合至 溶酶体，导致内体膜在细胞质中的积累 在毒性的早期; 2）表明内吞 肾脏近端管细胞的阳离子白蛋白或庆大霉素结果 在池中Na/h抗植物的内在化和隔离中 在毒性的早期阶段，细胞质内体； 3）表明 钙和镁降低阳离子白蛋白的内吞作用和 庆大霉素，减少内体 - 溶酶体融合缺陷，并减少 在肾近端肾小管中观察到的Na/H抗植物的隔离 毒性早期的细胞。阳离子白蛋白的影响 膜穿梭和Na/H抗胞菌活性的庆大霉素将是 在微源近端肾单位段和孤立的肾脏中测量 膜。