长期用药在血脑屏障上诱导P-糖蛋白介导的耐药性

的：考察长期用药在血脑屏障上是否引起耐药性及P-糖蛋白(P-gp)表达增强。方法：原代牛脑微血管内皮细胞(BCEC)加入环孢素A(CsA)，长春新碱(VCR)，阿霉素(Dox)，或粉防己碱(Tet)，初始剂量分别为0．0083，0．091，0．34，或0．32μmol/L，培养至传代剂量翻倍。连续作用21，37，51或69d后，用罗丹明123(Rh123)检测P-gp功能。将各药物诱导69天的BCEC制膜，用酶联免疫吸附法(ELISA)测定P-gp表达结果：Dox用药37d使胞内Rh123浓度降低38％连续给药51和69d后，Dox分别使胞内Rh123浓度降低47％和57％，VCR组分别降低36％和40％。而CsA和Tet组一直未见明显变化。维拉帕米(10μmol/L)分别使CsA、Tet、Dox和VCR诱导组BCEC内Rh123的摄取增加92％、85％、143％和186％Dox和VCR连续用药69d使P-gp的表达增强45％和32％结论：长期使用Dox或VCR可在血脑屏障上诱导P-gp介导的耐药性以及P-gp表达增强。

Long-term Administration Induced P-glycoprotein-mediated Drug Resistance at Blood-Brain Barrier

AIM: To study whether long-term administration could induce drug resistance and P-glycoprotein(P-gp) expression at blood-brain barrier(BBB). METHOD: Primary bovine brain capillary endothelial cells(BCECs) were cultured in the presence of cyclosporin A(CsA),vincrinstine(VCR),doxorubicin(Dox),or tetrandrine(Tet) at the original concentration of 0.0083,0.091,0.34,or 0.32 μmol/L,respectively. The drug was maintained until the BCECs approached confluence,at which point the subculture and doubling of drug would be repeated,and the whole process continued through 4-5 cycles. Using rhodamine 123(Rh123) to examine the functional activity of P-gp expressed in drug-treated BCECs after a period of 21,37,51,and 69 d respectively. The plasma membranes of BCECs pretreated with inducing drug for 69 d were isolated and prepared,and the P-gp expression in the plasma membranes was detected by enzyme-linked immunosorbent assay(ELISA). RESULT: No significant change in P-gp function was observed in comparison with the control on d21. Administration of Dox obviously decreased the intracellular Rh123 accumulation by 38% on d37. Administration of Dox and VCR lowered the cellular Rh123 accumulation by 47% and 36% on d51 or by 57% and 40% on d69 respectively. While CsA and Tet didn't induce any significant change at any time. Verapamil(10 μmol/L) increased intracellular Rh123 uptake of BCEC,which was pretreated with CsA,Tet,Dox,or VCR for 69d,by 92%,85%,143%,or 186%,respectively. The P-gp expression in the plasma membranes of BCECs pretreated with Dox or VCR for 69d was increased by 45% and 32% respectively. CONCLUSION: Long-term administration of Dox and VCR could induce the P-gp-mediated drug resistance and enhance P-gp expression at BBB,and verapamil could reverse this kind of resistance obviously.