耐药株LoVo/Adr细胞pH与药物分布的关系研究

目的：探讨耐药株LoVo/Adr细胞pH与药物分布的关系。方法：采用免疫组化法检测P－gp的表达；在共聚焦显微镜下测细胞内SNAFL－calcein-AM荧光强度，其强度与胞浆的pH成正比；利用荧光显微镜观察阿霉素在细胞内的分布。结果：敏感LoVo株细胞P-gp染色为阴性，而耐药株LoVo/Adrk细胞呈强阳性；LoVo/Adr细胞内pH显著高于LoVo细胞；LoVo/Adr细胞内阿霉素含量显著低于LoVo细胞，且阿霉素在核区分布明显减少，相对在胞浆中增多；而在敏感LoVo细胞中，阿霉素集中分布在核区，胞浆中很少。结论：P-gp过度表达可能通过影响胞浆的pH而导致药物在耐药细胞中异常分布，可增进其对化疗药物的耐受性，是肿瘤细胞发生耐药的原因之一。

Study on relationship between pH in the multidrug resistant LoVo/Adr cell line and distribution of drug

Objective To investigate relationship between pH in the multidrug resistant LoVo /Adr cell line and distribution of drug. Methods The expression of P-gp was detected by immunohistochemistry. The fluorescence density of SNAFL-calcein-AM which is direct proportional with pH in the cytoplasm was observed by confocal microscope. ADR subcellular distribution was examed by fluorescent microscope. Results P-gp was positive in LoVo /Adr cells, while negative in LoVo cells. The level of pH in the cytoplasm in MDR LoVo /Adr cells was significantly higher than sensitive LoVo cells. The concentration of ADR in LoVo /Adr cells was significantly lower than that in LoVo cells and the distribution of ADR in LoVo /Adr cells significantly decreased in the nucleus and relatively increased in the cytoplasm. The fluorescence of ADR in the drug-sensitive LoVo cells mainly distributed in the nucleus, while a little in the cytoplasm. Conclusion Over expression of P-gp may lead to abnormal distribution of ADR in resistant cells by changing pH level in the cytoplasm. It is one of the mechanisms of multidrug resistance.