Albumin and glucose effects on cell growth parameters, albumin uptake and Na+/H+-exchanger isoform 3 in OK cells
Albumin and glucose effects on cell growth parameters, albumin uptake and Na+/H+-exchanger isoform 3 in OK cells
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DOI：
10.1159/000072422
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发表时间：
2003-01-01
影响因子：
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通讯作者：
Pollock, CA
中科院分区：
文献类型：
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作者：
Drumm, K;Lee, E;Pollock, CA
背景：蛋白尿的程度，依赖钠的高血压的存在以及管状和间质病理学的组织学证据与糖尿病性肾病的进展相关。氢交换器NHE-3在近端肾小管细胞（PTCS）中钠和受体介导的白蛋白内吞作用中起着不可或缺的作用。这项研究的目的是研究高血糖和白蛋白对PTC的体外模型中细胞生长参数，NHE-3蛋白表达和白蛋白摄取的直接影响。方法：在存在或不存在0.1或1.0 g/l牛血清白蛋白（BSA）的情况下，将负粘肾（OK）细胞暴露于5 mmol/L葡萄糖（对照）或25 mmol/L（高）葡萄糖以最多可研究前72小时。 20 mmol/L甘露醇 + 5 mmol/l葡萄糖用作高温性的对照。评估了细胞数，细胞肿胀程度，细胞蛋白含量和NHE-3蛋白表达。细胞白蛋白摄取以及NHE在对照和高葡萄糖条件下的作用均通过FITC-BSA +/- NHE-IN-IN-INYL异丙基（EIPA）确定。结果：高葡萄糖和高摩尔控制诱导的细胞肥大，在白蛋白存在下未经修饰。细胞体积最初增加了1.0 g/L BSA，+/-高葡萄糖，在4872小时内归一化。所有实验条件都诱导NHE-3蛋白表达的早期和持续增加。高葡萄糖增加了白蛋白的摄取，与渗透压的变化无关。 EIPA减少了PTC中的白蛋白摄取，动力学支持NHE-3在此过程中的作用。结论：这些结果表明，PTC暴露于高葡萄糖浓度会促进渗透压介导的细胞肥大，并增加了与NHE-3表达增加有关的肾小管白蛋白重吸收。据推测，由于高葡萄糖暴露而引起的白蛋白摄取的增加可能导致PTC的促炎蛋白质过载，最终损害了管状白蛋白重吸收的补偿性增加。版权（C）2003 S. Karger AG，巴塞尔。
Background: The degree of albuminuria, the presence of sodium-dependent hypertension, and histological evidence of both tubular and interstitial pathology correlate with the progression of diabetic nephropathy. The sodium-hydrogen exchanger NHE-3 plays an integral role in both sodium reabsorption and receptor-mediated albumin endocytosis in proximal tubular cells (PTCs). The aim of this study was to investigate the direct effects of hyperglycemia and albumin on cell growth parameters, NHE-3 protein expression and albumin uptake in an in vitro model of PTCs. Methods: Opossum kidney (OK) cells were exposed to 5 mmol/l glucose (control) or 25 mmol/l (high) glucose in the presence or absence of either 0.1 or 1.0 g/l bovine serum albumin (BSA) for up to 72 hrs prior to study. 20 mmol/l mannitol + 5 mmol/l glucose was used as a control for hyperosmolality. The cell number, the degree of cell swelling, cell protein content and NHE-3 protein expression were assessed. Cellular albumin uptake and the role of NHE in both control and high glucose conditions were determined by FITC-BSA +/- NHE-inhibitor ethyl isopropyl amiloride (EIPA). Results: High glucose and the hyperosmolar control induced cellular hypertrophy, which was not modified in the presence of albumin. Cell volume was initially increased by 1.0 g/l BSA, +/-high glucose, which normalized over 4872 hrs. All experimental conditions induced an early and sustained increase in NHE-3 protein expression. High glucose increased albumin uptake, independent of changes in osmolality. EIPA reduced the albumin uptake in PTCs with kinetics supporting the role of NHE-3 in this process. Conclusion: These results suggest that exposure of PTCs to high glucose concentrations promotes osmolality mediated cell hypertrophy and increased tubular albumin reabsorption linked to an increase in NHE-3 expression. It is postulated that this increase in albumin uptake due to high glucose exposure may lead to proinflammatory protein overload of PTCs, ultimately impairing the compensatory increase in tubular albumin reabsorption. Copyright (C) 2003 S. Karger AG, Basel.