Caco-2细胞对酸枣仁皂苷A的跨膜转运

目的研究酸枣仁皂苷A（Jujuboside A,JuA）在Caco-2细胞的跨膜转运特性。方法采用体外培养的Caco-2细胞单层模型,考察时间、介质pH值、药物浓度、抑制剂对JuA在Caco-2细胞上转运的影响。结果 Caco-2细胞转运JuA呈时间及浓度依赖性;在pH为5.0～8.0范围内,Caco-2细胞对JuA的转运不受pH值的影响;P-糖蛋白（P-glycoprotein,P-gp）抑制剂维拉帕米（Verapamil,Ver）对Caco-2细胞转运JuA无影响;线粒体呼吸链复合体Ⅳ抑制剂叠氮化钠（Sodium azide）对Caco-2细胞转运JuA有抑制作用;JuA的AP-BL侧的Papp与BL-AP侧的Papp的两组均数比较无统计学意义。结论 JuA不是P-gp的底物,其跨膜转运是被动转运与主动转运共同参与的过程。     

抗肿瘤药物西美替尼在Caco-2细胞模型中的吸收转运

目的研究抗肿瘤药物西美替尼在Caco-2细胞模型中的吸收转运。方法建立Caco-2细胞转运模型,采用HPLC法测定药物浓度,计算表观渗透系数(P_app),研究西美替尼的Caco-2细胞跨膜转运情况。结果西美替尼在转运过程中没有明显的浓度依赖性。在低浓度范围内,药物的转运速率随着浓度的增加而增加;在较高浓度时达到饱和。西美替尼不同浓度的P_app值(3.91×10^-5、3.29×10^-5、1.90×10^-5和0.95×10^-5cm·s^-1)基本都大于难吸收药物的临界值(1×10^-5cm·s^-1)。西美替尼在Caco-2细胞中的转运呈现较强的方向性,从肠腔面到基底面的P_app值显著大于从基底面到肠腔面的P_app值（2.36～7.58倍）。ATP抑制剂叠氮化钠能显著降低西美替尼的正向转运程度,并升高其反向转运程度。当加入葡萄糖后,从肠腔面到基底面的跨膜转运程度显著降低。结论西美替尼主要是以转运载体介导的主动转运方式被吸收,其小肠吸收情况较好。     

白术内酯类在人源Caco-2细胞单层模型中的肠吸收研究(英文)

采用人源Caco-2细胞单层模型,研究了倍半萜内酯类的白术内酯Ⅰ、Ⅱ和Ⅲ的肠渗透性。研究了它们从顶端到基底侧以及从基底侧到顶端的双向渗透性。HPLC法测定其浓度。白术内酯Ⅰ、Ⅱ、Ⅲ的P_app值皆在10^-5cm/s水平,表明其具有高肠渗透率和良好吸收的特性。它们的双向转运具有时间和浓度依赖性,提示其吸收转运的主要机制为被动扩散。此外,白术内酯Ⅰ的吸收转运可能部分存在主动转运机制。     

坎地沙坦与坎地沙坦酯在Caco-2细胞模型中的转运特性

目的 研究坎地沙坦(Cand)与坎地沙坦酯(Cil)在Caco-2细胞中的跨膜转运特征.方法 采用Caco-2细胞单层膜模型来考察药物的浓度、介质pH与P-gp抑制剂维拉帕米对Cand与Cil跨膜转运的影响,并比较两者双向跨膜转运的差异.结果 两者的吸收转运具有pH依赖性,分泌转运具有浓度依赖性,其分泌(BL-AP)方向转运均快于吸收(AP-BL)方向转运,且Cil的AP-BL方向转运比Cand快;在P-gp抑制剂维拉帕米存在下,两者的转运外排率显著下降(P<0.01).结论 Cil容易通过Caco-2细胞的单层膜,且外排蛋白参与了Cand与Cil的跨膜转运.     

黄连素对P-糖蛋白底物在Caco-2和L-MDR1细胞跨膜转运的影响

目的研究黄连素(berberine,Ber)对P-糖蛋白底物环孢素(cyclosporine A,CsA)和地高辛在Caco-2和L-MDR1细胞跨膜转运的影响。方法以Caco-2、L-MDR1细胞为模型,在50μmol·L-1～5mmol·L-1Ber作用后,测定地高辛和CsA跨膜转运的转运率和表观渗透系数。结果Ber在50μmol·L-1～5mmol·L-1范围内可剂量依赖性地降低地高辛在Caco-2和L-MDR1细胞单层底端(B侧)至顶端(A侧)的转运。对于CsA在Caco-2细胞的转运,50μmol·L-1～5mmol·L-1的Ber不但剂量依赖性地降低CsA从B→A方向的转运,而且也明显增加其在A→B方向的转运。在Caco-2和L-MDR1细胞,Ber抑制地高辛B→A方向转运的IC50值分别为1.44mmol·L-1和1.24mmol·L-1。Ber抑制CsA在Caco-2细胞转运的IC50值为607μmol·L-1。结论Ber和CsA相互作用的机制可能涉及P-gp功能的抑制和饱和。     

新抗癌活性物AG337在Caco-2细胞模型中经p-糖蛋白介导的跨细胞转运

目的研究AG337在Caco-2细胞模型中的转运机制.方法改变药物浓度和实验温度以及他用合适抑制剂,测定AG337的跨细胞转运速率及其在细胞内的累积量.结果AG337的跨细胞转运显示强烈的有向性,B→A转运(细胞绒毛而Apical→基底面Basolateral)大于A→B10倍以上,P-糖蛋白的专属抑制剂维拉帕米(Ver)可以消除这种有向性温度从37℃至4℃时B→A的转运速率下降50倍,而A→B下降不大.结论AG337在Caco-2模型中的跨细胞转运.受到P-糖蛋白强烈的外排作用.     

根皮苷和3-羟基根皮苷在Caco-2细胞单层模型中的转运与吸收研究

目的:研究根皮苷和3-羟基根皮苷在人克隆结肠腺癌细胞(Caco-2细胞)单层模型中的转运与吸收。方法:采用高效液相色谱法,以表观渗透系数(Papp)为指标,分别考察50、100、200μmol/L的根皮苷和3-羟基根皮苷在Caco-2细胞单层模型中的双向(AP→BL、BL→AP)转运;并通过两药配伍同时混合转运与两药单独转运比较,考察两药转运的相互作用。结果:随着浓度的增加,根皮苷AP→BL和BL→AP的Papp均有一定的上升趋势;3-羟基根皮苷AP→BL的Papp有下降趋势,BL→AP的Papp却略有上升趋势。与单独转运比较,混合转运中根皮苷和3-羟基根皮苷的转运量和Papp均明显下降(P<0.05)。结论:根皮苷和3-羟基根皮苷在Caco-2细胞单层模型的吸收状况良好,两药配伍转运时存在竞争性抑制。     

HPLC考察小檗碱和黄连提取物中小檗碱在Caco-2细胞模型的转运

目的同时考察小檗碱和黄连提取物中小檗碱在Ca-co-2细胞模型的转运。方法以Caco-2细胞单层模型研究药物的双向转运,首先系统考察时间、药物浓度、抑制剂、pH、温度对小檗碱单体吸收转运的影响,然后比较相同浓度的小檗碱单体与黄连提取物中的小檗碱在Caco-2细胞模型的转运差异。运用高效液相色谱法检测药物浓度,计算其表观渗透系数。结果相同浓度的小檗碱从底端(BL)到顶端(AP)的转运量大于顶端(AP)到底端(BL)的转运量,在AP→BP和BP→AP方向,其转运量随时间呈增长趋势。维拉帕米可以明显降低其在BL→AP方向的转运量;在AP→BL方向,其在pH=5的HBSS中的转运量最大;在BL→AP方向的转运对温度有较高的依赖性。在AP→BL和BL→AP方向,提取物中的小檗碱比单一的小檗碱的转运量要低。结论小檗碱在AP→BL方向以被动转运为主,在BL→AP方向以主动转运为主;同时还受到P-gp糖蛋白的调节。提取物中的小檗碱在Caco-2模型中转运的影响因素呈多样化。     

坤复康片中芍药内酯苷在Caco-2细胞模型中的吸收特征研究

目的 研究坤复康片中的芍药内酯苷在Caco-2细胞模型中的跨膜吸收特征,探讨人小肠对芍药内酯苷的吸收和转运。方法 研究了不同药物浓度、pH值、温度和抑制剂对芍药内酯苷在Transwell细胞培养板中从顶膜(apical,AP)到基底(basolateral,BL)的双向渗透吸收的影响。结果 芍药内酯苷以3种测试浓度给药时(5,20和100 μmol·L^-1),从AP到BL方向的表观渗透系数(P_app)值范围为(3.27~5.37)×10^-7 cm·s^-1。相反,从BL到AP,P_app值范围为(6.64~9.63)×10^-7 cm·s^-1。数据表明,芍药内酯苷转运具有pH和温度依赖性。芍药内酯苷的细胞通透性受多种抑制剂影响,包含Na⁺/K⁺离子通道抑制剂钒酸钠,多耐药蛋白抑制剂MK571和吲哚美辛及乳腺癌耐药蛋白抑制剂芹菜素。当坤复康溶液加入后,芍药内酯苷从AP到BL方向的P_app值显著增加。结论 芍药内酯苷在Caco-2细胞模型中的肠道吸收较差,其吸收机制可能涉及多种蛋白介导的主动转运。     

千层纸素A在Caco-2细胞模型中的吸收机制研究

目的研究千层纸素A在Caco-2细胞模型中的吸收机制。方法 MTT实验考察千层纸素A在Caco-2细胞中的安全浓度范围,再利用Caco-2细胞单层模型研究千层纸素A的双向转运机制,以转运量及表观渗透系数(Papp)为指标,考察时间、浓度、pH和P-gp抑制药维拉帕米对其吸收的影响。结果千层纸素A在Caco-2细胞模型中的转运与时间和浓度呈正相关;并受pH值影响,P-gp抑制药维拉帕米对其转运无影响,从单层细胞层顶端(AP)到基底端(BL)的转运与基底端到顶端的转运大致相同。结论千层纸素A在Caco-2细胞模型中的吸收是被动转运。     

9-硝基喜树碱在Caco-2细胞模型中的体外摄取、转运及外排动力学

目的研究9-硝基喜树碱(9-NC)的细胞摄取、转运及外排特性。方法一种体外培养的人小肠上皮细胞模型Caco-2应用于9-NC的小肠上皮细胞的摄取、跨膜转运及外排动力学研究。评价了时间、温度、pH,P-糖蛋白(P-glycoprotein, P-gp)抑制剂对细胞摄取的影响。采用HPLC测定药物含量。结果9-硝基喜树碱以被动扩散为主要方式被细胞摄取和转运。药物的摄取与时间呈正相关，与温度、pH呈负相关。P-gp抑制剂环孢菌素和维拉帕米增加9-NC细胞摄取(P<0.05)。药物从Basolateral(B,基底面)到Apical(A,肠腔面)的渗透系数P_app大于A到B(2.6-6.9倍)。9-NC外排符合二级外排动力学过程，A侧m₀［(148.0±2.2) pmol·cm^-2］和外排速率(41.1 pmol·cm²·min^-1)高于B侧的m₀［(121±7) pmol·cm^-2(P<0.05)和外排速率(29.2 pmol·cm²·min^-1)(P<0.01)。结论 9-NC是以被动扩散方式为主要方式被小肠上皮细胞摄取和转运，并受到P-糖蛋白强烈的外排作用。     

左旋紫草素肠道转运及Caco-2细胞转运特性

目的研究左旋紫草素肠道及Caco-2细胞转运特征及其机制。方法应用翻转肠囊法和Caco-2细胞模型考察时间、浓度对左旋紫草素转运吸收特性的影响,应用P-糖蛋白抑制剂维拉帕米对左旋紫草素转运吸收机制进行研究,采用HPLC法测定左旋紫草素的浓度,计算其表观渗透系数(Papp)。结果在Caco-2细胞模型,随浓度增加和时间延长,左旋紫草素的累积转运量逐渐增加;加用维拉帕米后,使AP侧到BL侧的表观渗透系数Papp(AP→BL)显著增加,而从BL侧到AP侧的表观渗透系数Papp(BL→AP)显著降低。在翻转肠囊模型,100μmol·L-1左旋紫草素中加入维拉帕米后Papp显著增加。结论左旋紫草素的转运存在被动转运和主动转运2种形式,P糖蛋白参与主动转运过程;该药经肠道吸收中等,加入维拉帕米可能促进吸收。     

Transport characteristics of 9-nitrocamptothecin in the human intestinal cell line Caco-2 and everted gut sacs

The intestinal absorptive characteristics and the efflux mechanisms of 9-nitrocamptothecin (9-NC), a novel water-insoluble camptothecin (CPT) derivative, were investigated. The Caco-2 cells and the everted gut sacs were used as models of the intestinal mucosa to assess transepithelial transport of 9-NC. The determination of 9-NC was performed by HPLC. In the Caco-2 cells, the absorptive transport of 9-NC was pH dependent and the transport was enhanced at weakly acidic pH on the apical side. No concentration dependence and saturation were observed for the absorptive transport of 9-NC at concentrations up to 250 microM, while secretory transport were concentration dependent and saturable process (K(m) was 49.8 +/- 1.2 microM, V(max) was 38.28 +/- 0.8 ng/cm(2)/min). In the presence of verapamil (100 microM) and CsA (10 microM), potent inhibitors of P-glyprotein (P-gp)/MRP2 (cMOAT), the P(appBL-AP)/P(appAP-BL) ratio was decreased from 3.4 to 1.4 and 1.3, respectively, and permeation of apical to basolateral was enhanced approximately two-fold. In the everted gut sacs, the absorption of 9-NC was passive diffusion and had no significant difference in different gut regions. Adding verapamil in the everted gut sacs over a concentration ranging from 10 to 100 microM, the absorption of 9-NC was significantly enhanced, especially more markedly in lower small intestine (P < 0.05). Overall, the current study suggests that pH and efflux transporters are capable of mediating the absorption and efflux of 9-NC, and they may play significant roles in limiting the oral absorption of 9-NC.     

Transport characteristics of zolmitriptan in a human intestinal epithelial cell line Caco-2

The intestinal absorption characteristics and the efflux mechanisms of zolmitriptan, a new generation and highly selective 5-HT(1B/1D) receptor agonist used in the acute oral treatment of migraine, were investigated. A human intestinal cell line, Caco-2, was used as an in-vitro model of the intestinal mucosa to assess transepithelial transport of zolmitriptan. In the Caco-2 cells, the absorptive transport of zolmitriptan was pH dependent and the transport was enhanced at weakly alkali pH on the apical side. No concentration dependence and saturation were observed for the apical-to-basolateral and basolateral-to-apical transport of zolmitriptan at a concentration of 0.1-10 mM. The permeability ratio value was about 1.5-2.6 at a concentration of 0.1-2.0 mM. Inhibition experiments using verapamil, nifedipine and nimodipine as inhibitors were studied and indicated that P-glycoprotein participated in the transport of zolmitriptan. Inhibition of the Na+-H+ exchanger with amiloride resulted in a significant increase in absorption and a slight inhibition in secretion. This suggests that the Na+-H+ exchanger may be involved in the transport of zolmitriptan. The results indicated that the transport of zolmitriptan was mediated by both passive diffusion and active transport. A series of drug-drug interaction experiments were carried out between zolmitriptan and some drugs that may be co-administrated with zolmitriptan in the clinic. The results indicated that flunarizine, cetirizine, propranolol and atenolol potently decreased both the apical-to-basolateral and basolateral-to-apical transport rate of zolmitriptan. Cimetidine and aspirin slightly inhibited the apical-to-basolateral transport of zolmitriptan, but significantly decreased the basolateral-to-apical transport of zolmitriptan. Thus, the absorption drug-drug interactions should be considered when these drugs are co-administrated with zolmitriptan in the clinic.     

Impact of Extracellular Protein Binding on Passive and Active Drug Transport Across Caco-2 Cells

Aim The objective of the study is to evaluate the mechanism behind alterations in passive and active transport of drugs in the presence of basolaterally applied extracellular protein using the Caco-2 cell model. Methods The permeation across Caco-2 monolayers of two groups of compounds, transported either solely by passive diffusion or partly also by active transport in the secretory direction, was studied at two donor concentrations in the absence or presence of bovine serum albumin (BSA, 0–4%). Each group contained compounds with high or low protein binding (PB) capabilities and high or low absorption in humans (fraction absorbed, f_a). The unbound fraction (f_u) of each compound was determined by ultrafiltration. Results The transport rate of the passively permeating compounds was the same in both apical-to-basolateral (absorptive) and basolateral-to-apical (secretory) directions in the absence of BSA. Basolaterally applied BSA increased the transport rate in the absorptive direction and decreased it in the secretory direction for all compounds, in direct proportion to the extent of PB. The efflux ratios for the actively transported compounds were reduced in the presence of BSA. Conclusions Basolaterally applied BSA, which mimics in vivo PB, alters both passive and active drug transport in the Caco-2 cell model. Using C_u in the calculations of transport rate allowed elucidation of the different mechanisms behind these alterations. Our data also suggest that active secretory transport for highly protein-bound compounds might have less effect in vivo than predicted from traditional Caco-2 cell models (without BSA).     

Combined application of parallel artificial membrane permeability assay and Caco-2 permeability assays in drug discovery

Data from permeability profiling using the parallel artificial membrane permeability assay (PAMPA) and cell monolayer (Caco-2 and MDR1-MDCKII) methods were compared for two published compound sets and one in-house set. A majority of compounds in each set correlated (R(2) = 0.76-0.92), indicating the predominance of passive diffusion in the permeation of these compounds. Compounds that did not correlate grouped into two subsets. One subset had higher PAMPA permeability than cell monolayer permeability and consisted of compounds that are subject to secretory mechanisms: efflux or reduced passive diffusion of bases under Caco-2 when run under a pH gradient. The other subset had higher cell monolayer permeability than PAMPA permeability and consisted of compounds that are subject to absorptive mechanisms: paracellular, active transport, or increased passive diffusion of acids under Caco-2 when run under a pH gradient. Given the characteristics of the two methods, these studies suggest how PAMPA and Caco-2 can be synergistically applied for efficient and rapid investigation of permeation mechanisms in drug discovery. During early discovery, all compounds can be rapidly screened using PAMPA at low pH and neutral pH to assess passive diffusion permeability to indicate potential for gastrointestinal and cell assay permeation. During intermediate discovery, selected compounds can be additionally assayed by apical-to-basolateral Caco-2, which, in combination with PAMPA data, indicates susceptibility to additional permeation mechanisms (secretory and absorptive). During mid-to-late discovery, selected candidates can be examined in detail via multiple directional Caco-2 experiments and with transporter inhibitors for complete characterization of permeation mechanisms.     

Vectorial transport of fexofenadine across Caco-2 cells: involvement of apical uptake and basolateral efflux transporters

Fexofenadine is a nonsedative antihistamine that exhibits good oral bioavailability despite its zwitterionic chemical structure and efflux by P-gp. Evidence exists that multiple uptake and efflux transporters play a role in hepatic disposition of fexofenadine. However, the roles of specific transporters and their interrelationship in intestinal absorption of this drug are unclear. This study was designed to elucidate vectorial absorptive transport of fexofenadine across Caco-2 cells involving specific apical uptake and efflux transporters as well as basolateral efflux transporters. Studies with cellular models expressing single transporters showed that OATP2B1 expression stimulated uptake of fexofenadine at pH 6.0. Apical uptake of fexofenadine into Caco-2 cells was decreased by 45% by pretreatment with estrone 3-sulfate, an OATP inhibitor, at pH 6.0 but not at pH 7.4, indicating that OATP2B1 mediates apical uptake of fexofenadine into these cells. Examination of fexofenadine efflux from preloaded Caco-2 cells in the presence or absence of (i) the MRP inhibitor MK-571 and (ii) the P-gp inhibitor GW918 showed that apical efflux is predominantly mediated by P-gp, with a small contribution by MRP2, whereas basolateral efflux is predominantly mediated by MRP3. These results also showed that while OSTαβ is functionally active in the basolateral membrane of Caco-2 cells, it does not play a role in the export of fexofenadine. MK-571 decreased the absorptive transport of fexofenadine by 17%. However, the decrease in absorptive transport by MK-571 was 42% when P-gp was inhibited by GW918. The results provide a novel insight into a vectorial transport system mainly consisting of apical OATP2B1 and basolateral MRP3 that may play an important role in delivering hydrophilic anionic and zwitterionic drugs such as pravastatin and fexofenadine into systemic circulation upon oral administration.     

Relevance of p-glycoprotein for the enteral absorption of cyclosporin A: in vitro-in vivo correlation.

1. The interaction of cyclosporin A (CyA) with p-glycoprotein during intestinal uptake was investigated by a combination of in vitro experiments with human Caco-2 cells and an intubation study in healthy volunteers. 2. CyA uptake into the cells was not saturable and exhibited only a low temperature sensitivity, suggesting passive diffusion. When the permeation of CyA across Caco-2 monolayers from the apical to the basolateral side was determined, overall transport had an apparently saturable component up to a concentration of 1 microM. At higher concentrations permeation increased over-proportionally. Calculation of the kinetic parameters of apical to basolateral permeation suggested a diffusional process with a KD of 0.5 microliter min-1 per filter, which was overlayed by an active system in basolateral to apical direction with a KM of 3.8 microM and a Jmax of 6.5 picomol min-1 per filter. 3. CyA permeation was significantly higher when the drug was given from the basolateral side as compared to the permeation from the apical side. Apical to basolateral transport of CyA was increased in the presence of vinblastine, daunomycin and a non-immunosuppressive CyA-derivative. All compounds inhibit p-glycoprotein-mediated transport processes. Basolateral to apical permeation of CyA showed a dose-dependent decrease in the presence of vinblastine. Permeation of daunomycin across Caco-2 cell monolayers was also higher from the basolateral to the apical side than vice versa. Basolateral to apical permeation was decreased in the presence of SDZ PSC 833 and cyclosporin A. 4. Western blot analysis of Caco-2 cells with the monoclonal antibody C219 confirmed the presence of p-glycoprotein in the used cell system. 5. When the absorption of CyA in the gastrointestinal (GI)-tract of healthy volunteers was determined, a remarkable decrease of the plasma AUC could be observed dependent on the location of absorption in the rank order stomach > jejunum/ileum > colon. The decrease in absorption exhibited a marked correlation (r = 0.994) to the expression of mRNA for p-glycoprotein over the GI-tract (stomach < jejunum < colon). 6. All data provide evidence that CyA is a substrate of p-glycoprotein in the GI-tract, which might explain the local differences and the high variability in cyclosporin absorption found in vivo.