Schepers Marieke S J, van Ballegooijen Eddy S, Bangma Chris H, Verkoelen Carl F
Department of Urology, Erasmus Medical Center Rotterdam, Rotterdam, The Netherlands.
Kidney Int. 2005 Oct;68(4):1660-9. doi: 10.1111/j.1523-1755.2005.00576.x.
Oxalate-induced tissue damage may play an initiating role in the pathophysiology of calcium oxalate nephrolithiasis. The concentration of oxalate is higher in the renal collecting ducts ( approximately 0.1 to 0.5 mmol/L) than in the proximal tubule ( approximately 0.002 to 0.1 mmol/L). In the present investigation, we studied the damaging effect of oxalate to renal proximal and collecting tubule cells in culture.
Studies were performed with the renal proximal tubular cell lines, LLC-PK1 and Madin Darby canine kidney II (MDCK-II), and the renal collecting duct cell lines, rat renal cortical collecting duct (RCCD1) and MDCK-I. Confluent monolayers cultured on permeable growth substrates in a two-compartment culture system were apically exposed for 24 hours to relatively low (0.2, 0.5, and 1.0 mmol/L) and high (5 and 10 mmol/L) oxalate concentrations, after which several cellular responses were studied, including monolayer morphology (confocal microscopy), transepithelial electrical resistances (TER), prostaglandin E(2) (PGE(2)) secretion, lactate dehydrogenase (LDH) release, DNA synthesis ([(3)H]-thymidine incorporation), total cell numbers, reactive oxygen species (H(2)O(2)) generation, apoptotic (annexin V and DNA fragmentation), and necrotic (propidium iodide influx) cell death.
Visible morphologic alterations were observed only at high oxalate concentrations. TER was concentration-dependently decreased by high, but not by low, oxalate. Elevated levels of PGE(2), LDH, and H(2)O(2) were measured in both cell types after exposure to high, but not to low oxalate. Exposure to high oxalate resulted in elevated levels of DNA synthesis with decreasing total cell numbers. High, but not low, oxalate induced necrotic cell death without signs of programmed cell death.
This study shows that oxalate is toxic to renal tubular cells, but only at supraphysiologic concentrations.
草酸盐诱导的组织损伤可能在草酸钙肾结石的病理生理学中起起始作用。肾集合管中的草酸盐浓度（约0.1至0.5毫摩尔/升）高于近端小管（约0.002至0.1毫摩尔/升）。在本研究中，我们研究了草酸盐对培养的肾近端和集合小管细胞的损伤作用。
使用肾近端小管细胞系LLC-PK1和犬肾Madin Darby II（MDCK-II）以及肾集合管细胞系大鼠肾皮质集合管（RCCD1）和MDCK-I进行研究。将在两室培养系统中可渗透生长底物上培养的汇合单层细胞顶端暴露于相对低浓度（0.2、0.5和1.0毫摩尔/升）和高浓度（5和10毫摩尔/升）的草酸盐中24小时，之后研究几种细胞反应，包括单层形态（共聚焦显微镜检查）、跨上皮电阻（TER）、前列腺素E2（PGE2）分泌、乳酸脱氢酶（LDH）释放、DNA合成（[3H] - 胸腺嘧啶核苷掺入）、总细胞数、活性氧（H2O2）生成、凋亡（膜联蛋白V和DNA片段化）以及坏死（碘化丙啶内流）性细胞死亡。
仅在高草酸盐浓度下观察到明显的形态学改变。高浓度而非低浓度的草酸盐使TER呈浓度依赖性降低。暴露于高浓度而非低浓度草酸盐后，两种细胞类型中PGE2、LDH和H2O2的水平均升高。暴露于高浓度草酸盐导致DNA合成水平升高，同时总细胞数减少。高浓度而非低浓度的草酸盐诱导坏死性细胞死亡，无程序性细胞死亡迹象。
本研究表明草酸盐对肾小管细胞有毒性，但仅在超生理浓度时如此。
