中文摘要：

目的观察醋柴胡小分子水溶性部位（MHE）对P糖蛋白（Pgp）高表达的HEK293-Pgp细胞中Pgp的影响，分析其可能的分子机制。方法实验分人胚肾细胞HEK293和Pgp高表达的HEK293-Pgp组。M_rr法观察醋柴胡小分子水溶性部位对细胞增殖的影响；细胞分别加入秋水仙碱和罗丹明B作底物，Pgp蛋白摄取活性测定实验分别采用高效液相色谱（HPLC）法和流式细胞术（flowcytometry）检测胞内底物含量，以分析Pgp外排功能；采用Westernblot法检测Pgp蛋白表达水平；实时荧光定量PCR（RT—PCR）检测PgptuRNA水平。结果50g·L^-1MHE作用于细胞48h后，HEK293细胞中的Pgp外排功能略呈上调趋势，但差异无统计学意义（P〉0．05）；而作用于HEK293-Pgp细胞24h后相应的蛋白表达以及mRNA水平分别降低了68．1％和38．8％（P〈0．05），且HEK293-Pgp细胞对罗丹明B的摄取率刀‘商为对照组的3．2倍（P〈0．01），呈下调Pgp外排的功能。结论MHE呈抑制Pgp高表达的细胞中Pgp外排功能的作用，这可能是通过下调PgpmRNA和蛋白表达实现。初步暗示了MHE可能为一种潜在的Pgp抑制剂。

英文摘要：

Aim To determine the effect of MHE on Pgp overexpression in HEK293-Pgp cells, and to ex- plore the potential molecular mechanism. Methods Two groups including HEK293 and HEK293-Pgp cells were set up. Cell proliferation was measured by MTT assay. Pgp substrates eolehicine and Rhodamine B （RB） were added to cells, and then cytoplasmic sub- strates content was detected by HPLC and flow cytome- try respectively. Therefore, Pgp uptake activity and ef- flux function were determined. Pgp protein expression was detected by Western blot, and mRNA level was detected by real-time quantitative PCR （RT-PCR）. Results After treatment with MHE （50 g ·L^- 1 ） for24 h, the uptake of Rhodamine B into HEK293-Pgp cells increased by 3.2 fold （P 〈0. 01 ） compared with the control group and the protein expression and mRNA level of Pgp were down-regulated by 68. 1% （P 〈 0.05） and 38.8% （P 〈0.05） respectively. Mean- while there were no changes in FIEK293 cells. Con- elusion MHE strongly inhibits Pgp efflux function, which might be due to the down-regulation of Pgp pro- tein and mRNA level by MHE. All above indicates MHE is an inhibitor of Pgp.