Renal cellular transport of exogenous glutathione: heterogeneity at physiological and pharmacological concentrations.
Renal cellular transport of exogenous glutathione: heterogeneity at physiological and pharmacological concentrations.
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DOI：
10.1016/s0006-2952(99)00155-0
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发表时间：
1999-09
影响因子：
5.8
通讯作者：
L. Lash;D. Putt
中科院分区：
文献类型：
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作者：
L. Lash;D. Putt
测定了大鼠肾脏近端肾小管（PT）和远端肾小管（DT）细胞中GSH转运的性质和动力学，以进一步验证细胞处理GSH的差异导致DT细胞对氧化损伤更敏感的假设。PT和DT细胞与广泛的GSH浓度范围一起孵育，包括生理相关（0.001至0.1 mM）至药理学（0.25至5 mM）水平的GSH。谷胱甘肽摄取PT细胞是迅速的，表现出一个最大的过冲在1分钟的孵育。在DT细胞GSH摄取达到最大的细胞内水平在2至5分钟的孵育。PT细胞摄取GSH分为两个不同的动力学过程，Km值分别为41.7和540 μM，Vmax值分别为183和4885 pmol/min/106个细胞。与此相反，DT细胞的GSH摄取最好用一个过程来描述，其K和Vmax值分别为1480 μM和2094 pmol/min/106个细胞。在PT细胞中，从1 mM前体氨基酸合成GSH的速率快约3倍，但在DT细胞中半胱氨酸积累的速率快3.5倍。PT细胞中细胞内GSH的积累与1 mM GSH孵育后比与1 mM前体氨基酸孵育后快8倍。在生理（10 μM）和药理（5 mM）GSH浓度下，摄取均表现出明显的Na+和能量依赖性，对有机阴离子和二羧酸载体的底物敏感性，以及仅对PT细胞中的各种γ-谷氨酰氨基酸敏感性。PT细胞中Na+依赖的GSH摄取完全由有机阴离子和二羧酸载体的活性来解释。这些结果表明，DT细胞具有有限的能力，运输GSH，并建议，外源性GSH可能不会有效地保护其他部分的肾单位除了PT区域从氧化剂或其他药剂，改变GSH状态。
Properties and kinetics of GSH transport into proximal tubular (PT) and distal tubular (DT) cells from rat kidney were determined to validate further the hypothesis that cellular differences in handling of GSH contribute to the greater susceptibility of DT cells to oxidant injury. PT and DT cells were incubated with a broad range of GSH concentrations, encompassing physiologically relevant (0.001 to 0.1 mM) to pharmacological (0.25 to 5 mM) levels of GSH. GSH uptake in PT cells was rapid, exhibiting an overshoot with a maximum at 1-min incubation. GSH uptake in DT cells reached maximal intracellular levels at 2- to 5-min incubations. GSH uptake in PT cells was resolved into two kinetically distinct processes, with Kmvalues of 41.7 and 540 μM and Vmaxvalues of 183 and 4885 pmol/min per 106cells. In contrast, GSH uptake in DT cells was best described by one process, with Kmand Vmaxvalues of 1480 μM and 2094 pmol/min per 106cells, respectively. Rates of GSH synthesis from 1 mM precursor amino acids were approximately 3-fold faster in PT cells, but rates of cysteine accumulation were 3.5-fold faster in DT cells. Accumulation of intracellular GSH in PT cells was 8-fold faster after incubation with 1 mM GSH than after incubation with 1 mM precursor amino acids. At both a physiological (10 μM) and a pharmacological (5 mM) GSH concentration, uptake exhibited marked Na+and energy dependence, sensitivity to substrates for the organic anion and dicarboxylate carriers, and sensitivity to various γ-glutamyl amino acids in PT cells only. Na+-dependent GSH uptake in PT cells was accounted for completely by activity of the organic anion and dicarboxylate carriers. These results indicate that DT cells possess limited capacity to transport GSH and suggest that exogenous GSH may not be effective in protecting other segments of the nephron besides the PT region from oxidants or other agents that alter GSH status.