Hepatic sequestration and modulation of the canalicular transport of the organic cation, daunorubicin, in the rat
Hepatic sequestration and modulation of the canalicular transport of the organic cation, daunorubicin, in the rat
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DOI：
10.1002/hep.510290216
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发表时间：
1999-02-01
期刊：
影响因子：
13.5
通讯作者：
Boyer, JL
中科院分区：
文献类型：
--
作者：
Hayes, JH;Soroka, CJ;Boyer, JL
与有机阴离子相反，小管mdr 1a和B的底物通常是有机阳离子，并且通常以高浓度螯合在细胞内酸性隔室中。由于这些化合物中有许多是治疗剂，我们研究了它们的螯合是否可以调节。我们使用离体灌注大鼠肝脏（IPRL）、离体大鼠肝细胞偶联（IRHC）和WIF-B细胞研究荧光阳离子柔红霉素（DNR）的细胞定位和胆汁排泄。（在15分钟内）和有效（>90%）的细胞摄取，85分钟后，只有约10%的给药剂量（0.2-20 μ mol）经胆汁排泄。共聚焦显微镜显示荧光主要存在于IPRL、IRHC和WIF-B细胞中小管周围区域的囊泡中。用氯喹和巴夫洛霉素A（破坏囊泡膜pH梯度的试剂）处理这些细胞，导致囊泡荧光丧失，在巴夫洛霉素A的情况下是可逆的。牛磺胆酸盐（TC）和双丁酰cAMP（DBcAMP）是胞内转运的刺激剂，能使DNR在胆汁中的回收率分别增加70%和35%。微管不稳定剂诺考达唑可减少DNR的胆汁排泄，但对mrp 2缺陷的TR（-）突变大鼠的分泌无影响。同时给予维拉帕米（一种mdr 1抑制剂）也可减少柔红霉素的排泄。而TC和DBcAMP不影响IRHC的荧光强度或分布模式，诺考达唑导致DNR重新分布到外周点状结构。这些发现表明，有机阳离子DNR在很大程度上被隔离在细胞（如肝细胞）中，但其排泄仍然可以被调节。
In contrast to organic anions, substrates for the canalicular mdr1a and b are usually organic cations and are often sequestered in high concentrations in intracellular acidic compartments. Because many of these compounds are therapeutic agents, we investigated if their sequestration could be regulated. We used isolated perfused rat liver (IPRL), isolated rat hepatocyte couplets (IRHC), and WIF-B cells to study the cellular localization and biliary excretion of the fluorescent cation, daunorubicin (DNR), Despite rapid (within 15 minutes) and efficient (>90%) cellular uptake in the IPRL, only approximate to 10% of the dose administered (0.2-20 mu mol) was excreted in bile after 85 minutes. Confocal microscopy revealed fluorescence predominantly in vesicles in the pericanalicular region in IPRL, IRHC, and WIF-B cells, Treatment of these cells with chloroquine and bafilomycin A, agents that disrupt the pH gradient across the vesicular membrane, resulted in a loss of vesicular fluorescence, reversible in the case of bafilomycin A. Taurocholate (TC) and dibutyryl cAMP (DBcAMP), stimulators Of transcytotic vesicular transport, increased the biliary recovery of DNR significantly above controls, by 70% and 35%, respectively. The microtubule destabilizer, nocodazole, decreased biliary excretion of DNR, No effect on secretion war noted in TR(-) mutant rats deficient in mrp2. Coadministration of verapamil, an inhibitor of mdr1, also decreased DNR excretion. While TC and DBcAMP did not affect the fluorescent intensity or pattern of distribution in IRHC, nocodazole resulted in redistribution of DNR to peripheral punctuate structures. These findings suggest that the organic cation, DNR, is largely sequestered in cells such as hepatocytes, yet its excretion can still be modulated.