Dordal M S, Ho A C, Jackson-Stone M, Fu Y F, Goolsby C L, Winter J N
Clinical Pharmacology Center, Robert H. Lurie Cancer Center, Northwestern Memorial Hospital, Chicago, Illinois, USA.
Cytometry. 1995 Aug 1;20(4):307-14. doi: 10.1002/cyto.990200406.
Development of multidrug resistance (MDR) in cancer cells decrease net doxorubicin uptake as a result of either increased efflux, or decreased intracellular sequestration, or decreased membrane permeability. Kinetic parameters of drug uptake can distinguish among these forms of altered transport. Cellular uptake of fluorescent drugs was monitored by a flow cytometric assay using a rapid-injection system and analyzed with a three-compartment model in which rapid diffusion from extracellular fluid into the cell was followed by uptake into a nonexchangeable pool. In agreement with our recent studies of 14C-doxorubicin distribution (Dordal et al.: J Pharmacol Exp Ther 271:1286-1290, 1994), sequestration of doxorubicin was decreased 2.7-fold in P-glycoprotein-expressing SU-4R lymphoma cells compared to drug-sensitive SU-4 cells (14.0 +/- 4.8 vs. 5.0 +/- 0.9 nl s-1) without a change in membrane permeability or evidence of active efflux. In contrast, sequestration of the highly fluorescent dye rhodamine 123 was decreased 20-fold (17.1 +/- 8.3 vs. 0.9 +/- 0.8 nl s-1). Resistant cells were significantly less permeable to rhodamine than sensitive cells (3.8 +/- 1.2 vs. 10.2 +/- 2.6 x 10(5) cm2 s-1), and rhodamine efflux was increased by 24%. Thus, SU-4R cells exhibit multiple alterations that cause decreased intracellular drug concentrations, of which decreased sequestration is quantitatively the most significant.
癌细胞中多药耐药性（MDR）的产生会导致阿霉素净摄取量减少，这是由于外排增加、细胞内隔离减少或膜通透性降低所致。药物摄取的动力学参数可以区分这些转运改变的形式。使用快速注射系统通过流式细胞术检测荧光药物的细胞摄取，并采用三室模型进行分析，该模型中，药物从细胞外液快速扩散进入细胞后，被摄取到一个不可交换的池。与我们最近对14C-阿霉素分布的研究结果一致（Dordal等人：《药理学与实验治疗学杂志》271:1286 - 1290，1994），与药物敏感的SU - 4细胞相比，表达P - 糖蛋白的SU - 4R淋巴瘤细胞中阿霉素的隔离减少了2.7倍（14.0 +/- 4.8对5.0 +/- 0.9 nl s-1），膜通透性没有变化，也没有主动外排的证据。相比之下，高荧光染料罗丹明123的隔离减少了20倍（17.1 +/- 8.3对0.9 +/- 0.8 nl s-1）。耐药细胞对罗丹明的通透性明显低于敏感细胞（3.8 +/- 1.2对10.2 +/- 2.6 x 10(5) cm2 s-1），罗丹明外排增加了24%。因此，SU - 4R细胞表现出多种导致细胞内药物浓度降低的改变，其中隔离减少在数量上最为显著。
