Drug specificity and intestinal membrane localization of human organic cation transporters (OCT)
Drug specificity and intestinal membrane localization of human organic cation transporters (OCT)
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DOI：
10.1016/j.bcp.2005.09.011
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发表时间：
2005-12-05
影响因子：
5.8
通讯作者：
Brandsch, M
中科院分区：
文献类型：
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作者：
Müller, J;Lips, KS;Brandsch, M
本研究旨在探讨人有机阳离子转运体hOCT1、hOCT2或hOCT3在口服阳离子药物肠道吸收中的阳离子专一性和膜定位。比较了不同化合物对Caco-2细胞和稳定表达hOCT1、hOCT2或hOCT3的HEK-293或CHO细胞摄取N-[甲基-H-3]-4-苯基吡啶([H-3]MPP+)的抑制作用。阿托品、丁基东莨菪碱、可乐定、苯海拉明、黄藤碱、奎宁和雷尼替丁可抑制Caco-2细胞对[H-3]MPP+的摄取，IC50值在6 mM~4 mM之间。这些化合物对Caco-2细胞单层从顶端到基底端的[H-3]MPP+跨上皮通量也有强烈的抑制作用。阳离子药物和典型有机阳离子对Caco-2细胞的抑制作用与CHO-hOCT3细胞的抑制作用有很好的相关性，而与HEK-hOCT1和-hOCT2细胞的抑制作用较差。这是hOCT3主要作用的功能证据。通过hOCT3将阿托品和阿托品特异性地转运到CHO细胞中。在Caco-2细胞中，检测到三种hOCT及其蛋白hOCT2和hOCT3的表达。更重要的是，免疫细胞化学分析首次发现hOCT3定位于肠细胞刷状缘膜，而hOCT1免疫标记主要定位于肠细胞的侧膜。(C)2005 Elsevier Inc.保留所有权利。
This study was performed to investigate which human organic cation transporter, hOCT1, hOCT2 or hOCT3, participates with regard to cation specificity and membrane localization in the intestinal absorption of orally available cationic drugs. Inhibition of N-[methyl-H-3]4-phenylpyridinium ([H-3]MPP+) uptake by various compounds into Caco-2 cells and into cells (HEK-293 or CHO) that were stably transfected with hOCT1, hOCT2 or hOCT3 was compared. The uptake of [H-3]MPP+ into Caco-2 cells was inhibited by atropine, butylscopolamine, clonidine, diphenhydramine, etilefrine, quinine and ranitidine with IC50 values between 6 mu M and 4 mM. Transepithelial, apical to basal flux of [H-3]MPP+ across Caco-2 cell monolayers was also strongly inhibited by these compounds. The inhibitory potency of the cationic drugs and prototypical organic cations at Caco-2 cells correlated well with the inhibitory potency measured at CHO-hOCT3 cells but much less with that at HEK-hOCT1 and -hOCT2 cells. This is functional evidence for the predominant role of hOCT3. Etilefrine and atropine were specifically transported into CHO cells by hOCT3. In Caco-2 cells, the mRNA of all three hOCT and the proteins hOCT2 and hOCT3 were detected. More importantly, immunocytochemical analyses of human jejunum revealed for the first time that hOCT3 is localized to the brush border membrane whereas hOCT1 immunolabeling was mainly observed at the lateral membranes of the enterocytes. (c) 2005 Elsevier Inc. All rights reserved.