To investigate the effects of vinegar-procssed Chaihu（Radix Bupleuri）and its differentextraction parts on the uptake of cisplatin（DDP）by cells with high expression of organic cation transporter 2（OCT）（hOCT2-HEK293）and cells with high expression ofmultidrug resistance associated protein 2（MRP2）（hMRP2-HEK293）and to preliminarily explore their mechanisms so as to provide data support for the exploration of the mechanism of using vinegar-procssed Chaihu（Radix Bupleuri）to assist in reversing DDPmultidrug resistance in tumor cells in clinical practice.

The hOCT2-HEK293 and hMRP2-HEK293 cells were co-incubated with vinegar-procssed Chaihu（Radix Bupleuri）and its different parts for 24 hours，and then DDP was added to continue incubation for 4 hours.The intracellular DDP content of the two types of cells was measured by HPLC.Western Blot and real-time quantitative PCR（RT-PCR）were used tomeasure the protein and gene expressions of OCT2 and MRP2 in two types of cells，respectively.

In hOCT2-HEK293 cells，the total extract，polysaccharide fraction and small molecule water-soluble fraction of vinegar-procssed Chaihu（Radix Bupleuri）can significantly promote the uptake of DDP，and all promote the protein and gene expressions of OCT2.In hMRP2-HEK293 cells，the total extract，polysaccharide fraction and small molecule water-soluble fraction of vinegar-procssed Chaihu（Radix Bupleuri）also significantly promoted the uptake of DDP，but only the total extract could significantly reduce the expression of MRP2 protein.

In tumor cells，the reversal of multidrug resistance to anti-tumor drugs by vinegar-procssed Chaihu（Radix Bupleuri）may be related to the up-regulation of OCT2 protein and mRNA expressions in polysaccharide and small molecule water-soluble sites，or the down-regulation ofMRP2 protein expression in vinegar-procssed Chaihu（Radix Bupleuri）total extract.Preliminary speculation suggests that affecting the functions of OCT2 and MRP2 is one of the mechanisms by which vinegar-procssed Chaihu（Radix Bupleuri）enhances the meridian stimulation.