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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 /Adr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。
Objective To investigate the relationship between pH and drug distribution in drug-resistant LoVo/Adr cells. Methods The expression of P gp was detected by immunohistochemical method. The fluorescence intensity of SNAFL calcein AM in the cells was measured by confocal microscopy. The intensity was proportional to the pH of cytoplasm. The distribution of doxorubicin in cells was observed by fluorescence microscopy. Results The Pgp staining was negative in the sensitive LoVo strain cells, but was strongly positive in the drug-resistant LoVo/Adr cells; the pH in the LoVo/Adr cells was significantly higher than that in the LoVo cells; the LoVo/Adr cells had significantly lower adriamycin content than the LoVo cells. Moreover, the distribution of doxorubicin in the nuclear region was significantly reduced and increased in the cytoplasm. In sensitive LoVo cells, doxorubicin was concentrated in the nuclear region and was rarely found in the cytoplasm. Conclusion Overexpression of Pgp may affect the distribution of drugs in drug-resistant cells by affecting the cytoplasmic pH, which may enhance its tolerance to chemotherapeutic drugs. It is one of the reasons for drug resistance in tumor cells.