Modification of Multidrug Resistance by Magnetic Exposure Indicated from the Point of View of Nuclear Medicine

用~(99m)Tc-MIBI摄取法研究了磁场对肿瘤细胞化疗敏感性的影响，揭示了P-糖蛋白的功能。研究的细胞系是从患者建立的间变性甲状腺癌细胞系；人表皮样细胞KB-31；转导MDR基因KB-G2的KB-31；以及MRP-细胞系CA-500。短时(1小时)强磁场暴露后，部分肿瘤细胞(并非所有细胞)对~(99m)Tcm-MIBI的摄取减少。在弱磁场作用下，所有肿瘤细胞对~(99m)Tc-MIBI的摄取均增加。在抗P-糖蛋白抗体或抑制P-糖蛋白功能的维拉帕米存在时，这些作用不会改变。因此，可以得出结论，不同细胞的磁效应是不同的，并且这些效应不是P-糖蛋白所特有的。磁暴露可能是逆转肿瘤细胞多药耐药性的修饰之一。细胞对TC-99m-MIBI的摄取是评价多药耐药修饰的良好指标。

The effects of magnetic field on the chemosensitivity of tumor cells were investigated by using Tc-99m-MIBI uptake; which indicates the function of P-glycoprotein. The cells lines studies were anaplastic thyroid cancer cell lines established from patients; human epidermoid cell KB-31; KB-31 transfected with mdr gene KB-G2; and MRP-cell line CA-500. By the strong magnetic exposure for a short period (one hour) the Tc-99m-MIBI uptake in some tumor cells (not all cells) was reduced. Under weak magnetic field the Tc-99m-MIBI uptake was increased in all tumor cells studied. These effects were not altered in the presence of anti-P-glycoprotein antibody or verapamil that inhibits the function of P-glycoprotein. It can be, therefore, concluded that the magnetic effects were different from cell to cell, and that these effects were not specific for P-glycoprotein. Magnetic exposure may be one of modifications that reverse multidrug resistance of tumor cells. Tc-99m-MIBI uptake in cells is a good indicator to assess the multidrug resistance modification.