Hegmann E J, Bauer H C, Kerbel R S
Cancer Research Division, Sunnybrook Health Science Centre, Toronto, Ontario, Canada.
Cancer Res. 1992 Dec 15;52(24):6969-75.
Analysis of a panel of endothelial cells passaged between 5 and 25 times and derived from various organs and species demonstrated that murine and porcine cerebral capillary endothelial cells actively excluded the fluorescent dye rhodamine 123, a substrate of P-glycoprotein. In addition, rhodamine 123 accumulation could be enhanced by the multidrug resistance chemosensitizer verapamil, known to reduce P-glycoprotein-mediated drug efflux. Cloned murine and porcine cerebral capillary endothelial cells were immunoreactive with the C219 monoclonal antibody to P-glycoprotein, and a C219 epitope-specific blocking peptide could abolish staining. The antiproliferative and cytotoxic effects of vincristine, but not cis-platinum(II) diamminedichloride, were increased by the addition of either verapamil or cyclosporin A to brain endothelial cell cultures in a 72-h assay, as determined by [3H]thymidine incorporation and total protein measurement. Cyclosporin A was a more effective reversal agent than verapamil. Thus, a P-glycoprotein isoform may be constitutively expressed in brain endothelial cells in vitro and supports the available data on in situ immunohistochemical staining of P-glycoprotein at the blood-brain barrier. In addition, these findings may indicate that one function of P-glycoprotein in vivo at the blood-brain barrier is the exclusion of xenobiotics from central nervous system tissues.
对传代5至25次、来源于不同器官和物种的一组内皮细胞进行分析，结果表明，小鼠和猪的脑毛细血管内皮细胞能有效排斥荧光染料罗丹明123（一种P-糖蛋白的底物）。此外，多药耐药性化学增敏剂维拉帕米可增强罗丹明123的蓄积，已知该药物可减少P-糖蛋白介导的药物外排。克隆的小鼠和猪脑毛细血管内皮细胞与抗P-糖蛋白的C219单克隆抗体发生免疫反应，且C219表位特异性阻断肽可消除染色。在一项72小时的试验中，通过[3H]胸腺嘧啶核苷掺入和总蛋白测量发现，向脑内皮细胞培养物中添加维拉帕米或环孢素A可增强长春新碱（而非顺铂）的抗增殖和细胞毒性作用。环孢素A作为一种逆转剂比维拉帕米更有效。因此，P-糖蛋白同工型可能在体外脑内皮细胞中组成性表达，这支持了血脑屏障处P-糖蛋白原位免疫组化染色的现有数据。此外，这些发现可能表明，P-糖蛋白在血脑屏障处的体内功能之一是将外源性物质排除在中枢神经系统组织之外。
