Lash L H, Tokarz J J
Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan 48201.
Am J Physiol. 1990 Aug;259(2 Pt 2):F338-47. doi: 10.1152/ajprenal.1990.259.2.F338.
Suspensions of purified proximal tubular (PT) and distal tubular (DT) cells were isolated from rat kidney cortical cells by Percoll density-gradient centrifugation and were used to investigate susceptibility of these regions of the nephron to oxidative injury. Exposure to tert-butyl hydroperoxide (tBH), menadione (MD), or H2O2 produced significantly greater cytotoxicity, as assessed by leakage of lactate dehydrogenase, in DT cells than in PT cells. The order of cytotoxic potency in both cell types was MD greater than tBH greater than H2O2. Preincubation of PT and DT cells with 5 mM glutathione (GSH) or 5 mM dithiothreitol delayed tBH-induced cytotoxicity, indicating a protective role of GSH. Addition of buthionine sulfoximine and acivicin with GSH, to inhibit GSH synthesis and degradation, eliminated the protective effect of GSH, indicating that protection by GSH in DT cells is not dependent on uptake of the intact tripeptide. Incubation of both PT and DT cells with tBH resulted in oxidation of GSH to glutathione disulfide. Activities of five detoxication enzymes were significantly higher in PT cells, indicating that a diminished ability to detoxify reactive metabolites may contribute to the higher intrinsic susceptibility of DT cells to oxidative injury.
通过Percoll密度梯度离心从大鼠肾皮质细胞中分离出纯化的近端肾小管（PT）和远端肾小管（DT）细胞悬液，用于研究肾单位这些区域对氧化损伤的易感性。用乳酸脱氢酶泄漏评估，暴露于叔丁基过氧化氢（tBH）、甲萘醌（MD）或H2O2时，DT细胞产生的细胞毒性明显大于PT细胞。两种细胞类型中细胞毒性强度的顺序为MD大于tBH大于H2O2。用5 mM谷胱甘肽（GSH）或5 mM二硫苏糖醇对PT和DT细胞进行预孵育可延迟tBH诱导的细胞毒性，表明GSH具有保护作用。将丁硫氨酸亚砜胺和阿西维辛与GSH一起添加以抑制GSH的合成和降解，消除了GSH的保护作用，表明DT细胞中GSH的保护作用不依赖于完整三肽的摄取。用tBH孵育PT和DT细胞均导致GSH氧化为谷胱甘肽二硫化物。PT细胞中五种解毒酶的活性明显更高，表明解毒活性代谢物的能力降低可能导致DT细胞对氧化损伤的内在易感性更高。
