多药耐药逆转剂与血脑屏蔽上P—糖蛋白ATP酶活性间的相互作用

目的：进一步探讨P－糖蛋白（P-gp)与其多种耐药逆转剂量ATP依赖性相互作用的机制。方法：从牛脑灰质中分离得到微血管内皮细胞（BCEC）,制成细胞膜,定磷法测定BCEC膜上P-gp ATPas活性,结果：维拉帕米（Ver),长春新碱（VCR）,阿霉素（Dox),粉防己碱（Tet),蝙蝠葛碱（DRC）,小檗胺（BBM）以及蝙蝠葛苏林碱（DRS）增加基础P-gp ATPas活性,其Km值分别约为17,5．9,41,2．3,11,23和22μmol/L,小檗碱（BBR）仅有轻微的激活作用,延胡索乙素（dl-THP)和左旋四氢巴马汀（l-THP)不改变基础P-gp ATPas活性。环孢素A（CsA)抑制基因P-gp ATPas活性;竞争性抑制Ver或VCR激活的P-gp ATPas活性;非竞争性抑制Dox或Tet激活的P-gp ATPas活性。Dox非竞争性抑制Tet-激活的P-gp ATPas活性。结论：各种多药耐药逆转剂与P-gp 相互作用的机制及其对P-gp ATPas活性的影响各不相同,CsA,Ver和VCR在血脑屏蔽P-gp 上的结合部位可能是重叠的或者是有相互联系的,而CsA,Dox和Tet与P－gp的结合是相互独立的,并存在各自不同的结合部位。     

多种中草药单体对脑微血管内皮细胞内罗丹明123积累的影响

目的:寻找新型有效的血脑屏障P-糖蛋白逆转剂。方法:通过测定各化合物对牛脑微血管内皮细胞内罗丹明123积累的影响来考查它们对P-糖蛋白的功能性作用,以此筛选血脑屏障上的P-糖蛋白逆转剂。结果:各化合物浓度依赖性地增加胞内Rh123的累积浓度,作用强弱顺序为:环孢素A(CsA)>粉防己碱(Tet)>长春新碱(VCR)≈氟桂利嗪(Flu)>延胡索乙素(dl-THP)>蝙蝠葛碱(DRC)>阿齐霉素(Azi)>维拉帕米(Ver)≈小檗胺(BBM)>蝙蝠葛苏林碱(DRS)>小檗碱(BBR)>阿霉素(Dox)>左旋四氢巴马汀(l-THP)>川芎嗪(TMP)。其中CsA、Tet、Ver、Flu、Azi和dl-THP对胞内罗丹明123的累积的影响是可逆的。结论:多种中药单体,如某些异喹啉类生物碱能逆转血脑屏障上P-糖蛋白的功能,而不使血脑屏障上P-糖蛋白的固有水平发生永久性改变。     

血小板激活因子刺激血小板在脑微血管内皮细胞上粘附及药物的阻断作用(英文)

目的:研究血小板激活因子(PAF)刺激脑微血管内皮细胞导致血小板在内皮细胞上粘附及WEB,DMPP和粉防己碱的抑制作用. 方法:用[~3H]腺嘌呤标记血小板探讨PAF导致血小板在脑微血管内皮细胞上粘附和药物的抑制作用. 结果:PAF 10—100 nmol L~(-1)显著增加血小板与脑微血管内皮细胞的粘附率,WEB,DMPP和粉防己碱抑制由PAF刺激而导致的血小板在脑微血管内皮细胞上的粘附. 结论:DMPP和粉防己碱能够抑制PAF对脑血管的损害作用.     

一种新四氢异喹啉类化合物H108体外抑制P-糖蛋白功能及对PC12细胞损伤的保护作用

目的 :观察新合成四氢异喹啉衍生物H10 8抑制P 糖蛋白 (P gp)功能及对PC12细胞损伤的保护作用。方法 :测定H10 8对K5 6 2 ADR细胞株及大鼠脑微血管内皮细胞 (RBMECs)内罗丹明 12 3(Rh12 3)积聚的影响 ,考察H10 8逆转P gp介导的多药耐药性及对血脑屏障上P gp药物外排功能的影响。以连二亚硫酸钠 (Na2 S2 O4)建立缺血缺氧损伤模型 ,过氧化氢 (H2 O2 )建立氧化应激损伤模型 ,硝普钠 (SNP)建立NO损伤模型 ,MTT法测定H10 8对三种PC12损伤细胞存活率的影响。结果 :H10 8浓度依赖性地增加K5 6 2 ADR及RBMECs细胞中Rh12 3的累积浓度。并可明显对抗Na2 S2 O4及SNP诱导的PC12细胞损伤 ,增加细胞存活率。结论 :H10 8具有一定的P gp逆转作 ,并可能具有一定的神经保护作用。其有可能成为一种新型、高效 ,特别是用于促进血脑屏障上药物转运的P gp逆转剂     

缺氧对血管内皮生长因子诱导牛冠状动脉内皮细胞脂蛋白通透性升高的调控及丹酚酸B的抑制作用

目的　为了了解缺氧对血管内皮生长因子(VEGF)增强血管内皮细胞通透性作用的影响及其与动脉粥样硬化的关系 ,考察了正常和缺氧状态下VEGF对体外培养牛冠状动脉内皮细胞 (BCEC)脂蛋白通透性的影响及丹酚酸B的抑制作用。方法　正常及缺氧条件下 ,将VEGF及丹酚酸B加入BCEC共孵育 ,用SN 695型液闪计数器测 [12 5I]低密度脂蛋白([12 5I]LDL)通过BCEC的百分率。结果　VEGF可显著增强BCEC对 [12 5I]LDL的通透性 ,这种增加具有浓度依赖性。缺氧 3h可促进VEGF所致的的通透性增加。丹酚酸B在正常和缺氧条件下均显著抑制VEGF诱导的BCEC通透性升高。结论　VEGF可增强血管内皮细胞的通透性 ,可能在动脉粥样硬化的形成和发展过程中起一定作用。丹酚酸B对VEGF诱导的血管内皮通透性升高有显著的抑制作用     

新的四氢异喹啉类化合物CPUE1逆转K562/A02细胞的多药耐药性

目的 :研究新的四氢异喹啉类化合物CPUE1逆转K5 6 2 A0 2细胞多药耐药性的作用及机制。方法 :在CPUE1的作用下 ,用MTT法检测长春新碱(vincristine ,VCR)对K5 6 2 A0 2多药耐药细胞的细胞毒作用的变化 ,使用DNA分析和Annexin Ⅴ PI双染法研究CPUE1对VCR诱导K5 6 2 A0 2细胞凋亡的影响 ,流式细胞仪检测CPUE1对P 糖蛋白 (P glycop rotein ,P gp)外排罗丹明 12 3(rhodamine12 3,Rh12 3)的作用。结果 :CPUE1能明显提高VCR对K5 6 2 A0 2多药耐药细胞的细胞毒作用以及凋亡诱导作用 ,10 μmol·L-1的CPUE1能使K5 6 2 A0 2对VCR的IC50值由 6 0 .5 4μmol·L-1降至 4 .17μmol·L-1。CPUE1还能抑制Rh12 3外排从而增加细胞内Rh12 3的蓄积浓度。结论 :CPUE1通过抑制P gp的活性逆转K5 6 2 A0 2细胞的多药耐药性。     

丁基苯酞对牛脑微动脉及胸主动脉内皮血管活性物质生成的影响(英文)

目的:观察消旋、左旋、右旋丁基苯酞(dl,l,d-NBP)对体外培养的脑血管内皮细胞(BCEC)及主动脉内皮细胞(BAEC)合成一氧化氮(NO),前列环素(epoprostenol,Epo),内皮素-1(ET-1)的影响。方法:自牛大脑灰质及胸主动脉分离培养内皮细胞,并用分光光度法和放免法测定细胞培养液中NO,Epo,ET-1的含量。结果:BCEC及BAEC可持续分泌NO,Epo,ET-1,dl,l-NBP可以剂量依赖性地明显促进BAEC及BCEC中NO的合成,不同浓度的d-NBP均能增加BAEC中NO的产生,而对BCEC无明显作用。低浓度的dl,l-NBP(0.1-10μmol·L~(-1))即可显著升高BCEC中Epo的产生,而对BAEC无明显影响。另外,dl,l,d-NBP对TNFα诱导的BAEC中ET-1增加均无显著影响。结论:1)dl-和l-NBP均可显著增加BAEC及BCEC中NO的释放。2)l-NBP可升高BCEC和BAEC中Epo的释放,且对BCEC具有选择性。dl-NBP选择性增加BCEC中Epo的释放。     

芹菜素延缓人脐静脉内皮细胞衰老的体外实验研究

目的：探究芹菜素对人脐静脉内皮细胞衰老的延缓作用及相关机制。方法：将人脐静脉内皮细胞培养至第12代（老年细胞）,且自第4代（幼年细胞）起,与芹菜素（1、3、10μmol·L^-1）共孵育。通过检测细胞β-半乳糖苷酶（sAβ-gal）阳性率,推断细胞衰老程度;通过检测胞内双氢罗丹明氧化产物Rh123的荧光强度,推断胞内活性氧簇（ROS）水平,即氧化应激水平;通过检测培养液中硝酸盐／亚硝酸盐含量,推断胞内一氧化氮（NO）水平。结果：与幼年细胞组相比,老年细胞对照组中内皮细胞SAβ-gal阳性率及ROS水平均明显提高（P〈0．05）,且其培养液中硝酸盐／亚硝酸盐含量明显降低（P〈0．05）;在老年细胞组中,与对照组相比,芹菜素组中内皮细胞sAβ-gal阳性率及ROS水平均明显呈芹菜素剂量依赖性降低（P〈0．05）,而其培养液中硝酸盐／亚硝酸盐含量也明显呈芹菜素剂量依赖性增加（P〈0．05）。结论：芹菜素可延缓人脐静脉内皮细胞的衰老,且该作用与胞内ROS生成减少及NO生成增加有关。     

多药耐药逆转剂与血脑屏障上P-糖蛋白ATP酶活性间的相互作用(英文)

目的:进一步探讨P-糖蛋白(P-gp)与其多种耐药逆转剂间ATP依赖性相互作用的机制.方法:从牛脑灰质中分离得到微血管内皮细胞(BCEC),制成细胞膜,定磷法测定BCEC膜上P-gp ATPase活性.结果:维拉帕米(Ver)、长春新碱(VCR)、阿霉素(Dox)、粉防己碱(Tet)、蝙蝠葛碱(DRC)、小檗胺(BBM)以及蝙蝠葛苏林碱(DRS)增加基础P-gpATPase活性,其Km值分别约为17、5.9、41、2.3、11、23和22μmol/L.小檗碱(BBR)仅有轻微的激活作用,延胡索乙素(dl-THP)和左旋四氢巴马汀(l-THP)不改变基础P-gp ATPase活性.环孢素A(CsA)抑制基础P-gp ATPase活性;竞争性抑制Ver或VCR激活的P-gp ATPase活性;非竞争性抑制Dox或Tet激活的P-gp ATPase活性.Dox非竞争性抑制Tet-激活的P-gp ATPase活性.结论:各种多药耐药逆转剂与P-gp相互作用的机制及其对P-gp ATPase活性的影响各不相同.CsA、Ver和VCR在血脑屏障P-gp上的结合部位可能是重叠的或者是有相互联系的,而CsA、Dox和Tet与P-gp的结合是相互独立的,并存在各自不同的结合部位.     

粉防己碱对培养大鼠心肌细胞胞内游离钙的影响(英文)

目的:研究粉防己碱对心肌的作用。方法:采用Fura-2和AR-CM-MIC阳离子测定系统测定培养大鼠单个心肌细胞胞内游离钙。结果:外钙1.3mmol·L~(-1)时,细胞静息钙为90±12nmol·L~(-1)。粉防己碱不影响静息钙,但可明显抑制CaCl_2,KCl,哇巴因引起的胞内钙增高;对于去甲肾上腺素引起的胞内钙增高,粉防己碱只有在外钙存在时,方对其有抑制作用。结论;粉防己碱抑制钙离子的跨膜运动,但在心肌细胞,它并非是选择性的钙通道阻滞剂。     

P-glycoprotein-mediated transport of morphine in brain capillary endothelial cells.

Cell accumulation, transendothelial permeability, and efflux studies were conducted in bovine brain capillary endothelial cells (BBCECs) to assess the role of P-glycoprotein (P-gp) in the blood-brain barrier (BBB) transport of morphine in the presence and absence of P-gp inhibitors. Cellular accumulation of morphine and rhodamine 123 was enhanced by the addition of the P-gp inhibitors N-{4-[2-(1,2,3,4-tetrahydro-6,7dimethoxy-2-isoquinolinyl)-ethyl]-phenyl}-9,10-dihydro-5-methoxy-9- carboxamide (GF120918), verapamil, and cyclosporin A. Positive (rhodamine 123) and negative (sucrose and propranolol) controls for P-gp transport also were assessed. Morphine glucuronidation was not detected, and no alterations in the accumulation of propranolol or sucrose were observed. Transendothelial permeability studies of morphine and rhodamine 123 demonstrated vectorial transport. The basolateral to apical (B:A) fluxes of morphine (50 microM) and rhodamine (1 microM) were approximately 50 and 100% higher than the fluxes from the apical to the basolateral direction (A:B), respectively. Decreasing the extracellular concentration of morphine to 0.1 microM resulted in a 120% difference between the B:A and A:B permeabilities. The addition of GF120918 abolished any significant directionality in transport rates across the endothelial cells. Efflux studies showed that the loss of morphine from BBCECs was temperature- and energy-dependent and was reduced in the presence of P-gp inhibitors. These observations indicate that morphine is transported by P-gp out of the brain capillary endothelium and that the BBB permeability of morphine may be altered in the presence of P-gp inhibitors.     

Effect of p-glycoprotein inhibitor combinations on drug efflux from rat brain microvessel endothelial cells

In an effort to develop a clinically useful approach to inhibit the drug efflux across the blood brain barrier (BBB) mediated by P-glycoprotein (P-gp), the combined inhibitory effect of four P-gp inhibitors: cyclosporin A (CsA), verapamil (Ver), tetrandrine (Tet) and doxorubicin (Dox), was evaluated by determining the intracellular concentration of rhodamine 123 in in vitro cultured rat brain microvessel endothelial cells (BMEC). The results showed that CsA combined with Ver or Tet synergistically inhibited P-gp mediated efflux of Rh123 from rat BMEC, suggesting that the combined application of P-gp inhibitors would possibly be a useful approach to increase drug concentration in brain tissues, enhance the therapeutic effect and reduce the toxicity of drugs.     

Induction of P-glycoprotein expression and activity by ritonavir in bovine brain microvessel endothelial cells

Extended treatment with human immunodeficiency virus (HIV) protease inhibitors (HPIs) is standard in HIV/AIDS therapy. While these drugs have helped decrease the overall incidence of AIDS defining illnesses, the relative prevalence of HIV/AIDS dementia has increased. HPIs may cause induction of blood-brain barrier (BBB) drug transporters (P-glycoprotein; P-gp) and thereby limit entry of HPIs into brain tissue, increasing the probability that the brain could become an HIV sanctuary site. Using bovine brain microvessel endothelial cells (BMEC) as an in-vitro model of the BBB, the potential for the HIV protease inhibitor ritonavir to cause induction of P-gp activity and expression was examined. BMEC were isolated from fresh cow brain by enzymatic digest and density centrifugation. Primary culture BMEC were co-incubated with ritonavir or vehicle control for 120 h. Quantitative drug accumulation of rhodamine 123 (Rh123) and fluorescence microscopy were used as measures of P-gp activity. P-gp expression was assessed using quantitative Western blotting. Ritonavir decreased Rh123 cell accumulation and increased P-gp immunoreactive protein in a concentration-dependent manner. Fluorescent microscopy mirrored Rh123 quantitative studies. In BMEC pretreated with 30 microM ritonavir, Rh123 accumulation was decreased 40% and immunoreactive P-gp protein increased 2-fold. Collectively, a strong correlation between decreased Rh123 BMEC accumulation and increased P-gp immunoreactive protein was observed (Spearman r2 = 0.77, P < 0.0001). Thus extended exposure of BMEC to ritonavir caused a concentration-dependent increase in P-gp activity and expression. Similar findings may occur at the clinical level with prolonged HIV protease inhibitor use, giving insight into the central nervous system as an HIV sanctuary site and eventual development of HIV dementia.     

Mechanistic studies of the effect of bile salts on rhodamine 123 uptake into RBE4 cells

To examine the ability of bile salts (BS) to act as permeation enhancers at the blood brain barrier, the effect of four BS (cholate, deoxycholate, monoketocholate and taurocholate) on accumulation of rhodamine 123 (R123) in rat brain endothelial (RBE4) cells was investigated. Experiments were performed using BS concentrations shown to be noncytotoxic to RBE4 cells. Uptake and efflux of R123 in the absence and presence of BS were studied by fluorescence spectroscopy and confocal microscopy. Changes in RBE4 cell membrane fluidity in the presence of BS were evaluated using fluorescence anisotropy. The direct interaction between BS and R123 (ion pairing) and the effect of BS on distribution of R123 into liposomes were studied by capillary electrophoresis. All BS influenced R123 uptake in a concentration-dependent manner and increased cell membrane fluidity. Monoketocholate produced the greatest increase in uptake and also significantly reduced R123 efflux probably by inhibition of P-glycoprotein (P-gp). Direct interaction of BS and R123 was weak, but distribution of R123 into liposomes was increased by BS. The results suggest that BS increase R123 uptake by increasing cell membrane fluidity and, in the case of MKC, by inhibiting P-gp.     

Quantitative Assessment of HIV-1 Protease Inhibitor Interactions with Drug Efflux Transporters in the Blood–Brain Barrier

Purpose To quantitatively characterize the drug efflux interactions of various HIV-1 protease inhibitors in an in vitro model of the blood–brain barrier (BBB) and to compare that with HIV-1 protease inhibitor stimulated P-glycoprotein (P-gp)-ATPase activity.Methods Cellular accumulation of the P-gp sensitive probe, rhodamine 123 (R123), and the mixed P-gp/multidrug resistance–associated protein (MRP) probe, 2′,7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF), were evaluated in primary cultured bovine brain microvessel endothelial cells (BBMEC) in the presence of various concentrations of HIV-1 protease inhibitors. The potency (IC₅₀) and efficacy (I_max) of the drugs in the cell accumulation assays for P-gp and/or MRP was determined and compared to activity in a P-gp ATPase assay.Results For R123 (P-gp probe), the rank order potency for inhibiting R123 accumulation in the BBMEC was saquinavir = nelfinavir > ritonavir = amprenavir > indinavir. This correlated well with the rank order affinity in the P-gp ATPase assay. The rank order potency for MRP-related drug efflux transporters, was nelfinavir > ritonavir > saquinavir > amprenavir > indinavir.Conclusions HIV-1 protease inhibitors potently interact with both P-gp and MRP-related transporters in BBMEC. Characterization of the interactions between the HIV-1 protease inhibitors and drug efflux transporters in brain microvessel endothelial cells will provide insight into potential drug–drug interactions and permeability issues in the BBB.     

P-糖蛋白限制经血脑屏障的尼莫地平转运(英文)

目的:研究P-糖蛋白(P-gp)是否限制尼莫地平(NMD)从血液循环进入脑内。方法:当原代培养的鼠脑微血管内皮细胞(BCEC)长至互相连接成片时,加入含有NMD 10mg/L的Hanks’液37℃温孵,记录细胞摄取NMD的时间过程,将含有NMD和各种不同受试药物的Hanks’液分别加入到不同培养孔中,检测90min时细胞对NMD的摄取量,在细胞摄取NMD 90min后,分别加入红霉素,克拉霉素和环孢素A以检测P-糖蛋白抑制剂对原代培养的脑微血管内皮细胞外排NMD的影响。结果:细胞对NMD的摄取呈时间依赖性,P-gp抑制剂或代谢抑制剂的加入会增加稳态时NMD在细胞内的浓度,P-gp抑制剂的加入也使NMD的外排受到了抑制。结论:P-gp限制NMD进入脑内,P-gp抑制剂的加入可增加NMD的进入。     

CJZ3, a lomerizine derivative, modulates P-glycoprotein function in rat brain microvessel endothelial cells

AIM: To investigate the modulatory effect of CJZ3, a lomerizine derivative, on P-glycoprotein (P-gp) function in rat brain microvessel endothelial cells (RBMEC). METHODS: RBMEC were isolated and cultured in Dulbecco modified Eagle medium/F12 (1:1) medium, and the amount of intracellular rhodamine 123 (Rh123) was determined using a fluorescence spectrophotometer to evaluate the modulatory effect of CJZ3 on P-gp function. RESULTS: The accumulation of Rh123 was potentiated in a concentration-dependent manner after incubation with CJZ3 for RBMEC, but not for human umbilical vein endothelial cells (HUVEC). CJZ3 caused the accumulation of intracellular Rh123 in a time-dependent manner and significantly decreased the efflux of Rh123 from the cells. The inhibitory effect of CJZ3 on P-gp function was reversible and remained for 120 min after CJZ3 (2.5 micromol/L) was removed from the medium. CONCLUSION: CJZ3 has a potent in vitro effect on the inhibition of P-gp function.     

枸杞多糖对Caco-2细胞P-糖蛋白作用的影响

目的 研究枸杞多糖(LBP)对Caco-2细胞P-糖蛋白(P-gp)功能和表达的影响.方法 采用MTT法确定药物实验剂量;采用Rh-123摄取法评价P-gp的功能;利用流式细胞术与免疫荧光抗体检测P-gp的表达;采用经典的Caco-2细胞单层模型,研究P-gp外向转运这一动态过程受枸杞多糖作用后的变化.结果 由MTT法得到枸杞多糖＜100μg·mL-1时,细胞的存活率＞90％;枸杞多糖使细胞内Rh-123累积增加,对功能表现为抑制作用;高浓度组(100μg·mL-1)枸杞多糖对P-gp表达有诱导作用;高浓度组(100μg ·mL-1)枸杞多糖使Caco-2细胞单层模型外排率(ER)降低,对P-gp有抑制作用.结论 枸杞多糖对P-gp功能表现为抑制作用,而对P-gp表达表现为诱导作用.     

Persistent reversal of P-glycoprotein-mediated daunorubicin resistance by tetrandrine in multidrug-resistant human T lymphoblastoid leukemia MOLT-4 cells

Multidrug resistance (MDR) represents a major problem in cancer chemotherapy. P-glycoprotein (P-gp), the drug efflux pump that mediates this resistance, can be inhibited by compounds with a variety of pharmacological functions, thus circumventing the MDR phenotype. The present study was performed to evaluate a unique MDR-reversal feature of a bisbenzylisoquinoline alkaloid tetrandrine (TET) in a P-gp expressing MOLT-4 MDR line (MOLT-4/DNR) established in our laboratory. Cell viability was determined by an MTT assay. P-gp function was characterized by determining the Rh123 accumulation/efflux capacity. P-gp overexpression in resistant MOLT-4/DNR cells was confirmed by flow cytometry analysis after staining with phycoerythrin-conjugated anti-P-gp monoclonal antibody 17F9. Compared to ciclosporin A (CsA), TET exhibited stronger activity to reverse drug resistance to daunorubicin (DNR), vinblastine (VLB) and doxorubicin (DOX) in MOLT-4/DNR cells. TET showed no cytotoxic effects on parental MOLT-4 cells lacking P-gp expression or on the resistant MOLT-4/DNR cells. TET modulated DNR cytotoxicity even after it was washed with the medium for 24 h, while CsA almost completely lost its reversal capability 24 h after washing. TET and CsA similarly increased the accumulation of Rh123 in resistant MOLT-4/DNR cells. However, TET inhibited Rh123 efflux from resistant cells even after washing with the medium, while CsA rapidly lost its ability to inhibit Rh123 efflux after washing. The current study suggests that TET enhances the cytotoxicity of anticancer drugs in the P-gp expressing MDR cell line by modulating P-gp in a different manner to the well-known P-gp inhibitor CsA.