Functional characterisation of the active ascorbic acid transport into cerebrospinal fluid using primary cultured choroid plexus cells
Functional characterisation of the active ascorbic acid transport into cerebrospinal fluid using primary cultured choroid plexus cells
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DOI：
10.1016/s0006-8993(03)03350-x
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发表时间：
2003-10-24
期刊：
影响因子：
2.9
通讯作者：
Galla, HJ
中科院分区：
文献类型：
--
作者：
Angelow, S;Haselbach, M;Galla, HJ
穿过血脑脊液屏障是某些营养物质进入中枢神经系统的重要途径。培养的脉络丛上皮细胞是研究该组织体外主动运输特性的有效模型系统。在本研究中，该体外模型用于分析抗坏血酸跨血脑脊液屏障的转运，该转运被认为是由 Na+ 依赖性转运蛋白 SVCT2 介导的。 RT-PCR证实培养细胞中SVCT2的表达。跨细胞单层的主动运输导致抗坏血酸在脑脊液模拟侧富集。在 200 μM 根皮素存在下，抗坏血酸转运和吸收分别降低至 13% 和 27%。在无 Na+ 的培养基中观察到跨上皮底物转运（至 7.5%）和细胞质摄取（至 20%）的抑制，表明位于基底外侧且依赖 Na+ 的转运蛋白介导抗坏血酸摄取。用碘化物或 D-葡萄糖酸盐替代 Cl- 可使抗坏血酸的摄取量分别增加 3.7 或 2.5 倍。当分析 Na-除以依赖性肌醇转运时，也得到了类似的观察结果。此外，在存在100μM布美他尼的情况下，观察到Na+-Cl-共转运抑制剂间接增加了抗坏血酸和肌醇转运速率，表明抗坏血酸-Na+-共转运可能平衡细胞内低Na+浓度。 (C) 2003 Elsevier B.V. 保留所有权利。
Crossing the blood-CSF barrier is an important pathway for certain nutrients to enter the CNS. Cultured choroid plexus epithelial cells are a potent model system to study active transport properties of this tissue in vitro. In the present study this in vitro model was used to analyse ascorbic acid transport across the blood-CSF barrier that is supposedly mediated by the Na+-dependent transporter SVCT2. The expression of SVCT2 in the cultured cells was proven by RT-PCR. Active transport across the cell monolayer resulted in ascorbic acid enrichment at the CSF mimicking side. Ascorbic acid transport and uptake were decreased to 13 and 27%, respectively, in the presence of 200 muM phloretin. Inhibition of both transepithelial substrate transport (to 7.5%) and cytoplasmatic uptake (to 20%) was observed in Na+-free medium indicating that a basolaterally located and Na+-dependent transporter mediates ascorbic acid uptake. Substituting Cl- by either iodide or D-gluconate increased ascorbic acid uptake by factors of 3.7 or 2.5, respectively. Similar observations were made when Na-divided by dependent myo-inositol transport was analysed. Additionally, in presence of 100 muM bumetanide, an inhibitor of Na+-Cl- cotransport indirectly increased ascorbic acid and myo-inositol transport rates were observed showing that ascorbic acid-Na+-cotransport might balance low intracellular Na+ concentration. (C) 2003 Elsevier B.V. All rights reserved.