Chang B K, Huang A T, Joines W T
Cancer Res. 1980 Apr;40(4):1002-5.
We have studied the effects of low-power-density microwave (MW) radiation (continuous and pulsed wave with average power density of 10 milliwatts/sq cm and range of 5 to 50 milliwatts/sq cm; frequency, 1.0 GHz) on the uptake and action of methotrexate (MTX), the inhibition of DNA synthesis in L1210 murine leukemia cells in vitro, and the MTX treatment of mice bearing this leukemia. Using short-term tissue culture techniques, MTX concentrations of 0.2 microM, and MW exposure times of 20 min, we have found that continuous-wave low-power-density MW irradiation enhances the uptake of [3H]MTX as compared to nonirradiated controls. The enhancement is observed in only a small range of power densities (5 to 25 milliwatts/sq cm) and is in an inverted-U-shaped relationship. MW irradiation alone has an inhibitory effect on the [3H]deoxyuridine incorporation into DNA. Compared to cell suspensions treated with MTX alone, groups treated with MW irradiation followed by MTX exhibit an augmentation of inhibition of DNA synthesis as measured by [3H]deoxyuridine incorporation. Combined treatment of L1210-bearing mice with MW irradiation and MTX in vivo prolonged the duration of survival over that of animals treated with MTX alone, indicating a greater killing of leukemia cells. These results suggest that the therapeutic index of MTX may be improved by the use of MW irradiation at low power densities.
我们研究了低功率密度微波（MW）辐射（连续波和脉冲波，平均功率密度为10毫瓦/平方厘米，范围为5至50毫瓦/平方厘米；频率为1.0吉赫兹）对甲氨蝶呤（MTX）摄取和作用、体外L1210小鼠白血病细胞DNA合成抑制以及荷有该白血病小鼠的MTX治疗效果的影响。采用短期组织培养技术、0.2微摩尔的MTX浓度以及20分钟的MW暴露时间，我们发现与未辐照的对照组相比，连续波低功率密度MW辐照可增强[3H]MTX的摄取。这种增强仅在小范围的功率密度（5至25毫瓦/平方厘米）内观察到，且呈倒U形关系。单独的MW辐照对[3H]脱氧尿苷掺入DNA有抑制作用。与仅用MTX处理的细胞悬液相比，先用MW辐照再用MTX处理的组，通过[3H]脱氧尿苷掺入测量的DNA合成抑制作用增强。在体内，对荷有L1210的小鼠联合进行MW辐照和MTX治疗，其存活时间比仅用MTX治疗的动物延长，表明对白血病细胞的杀伤作用更大。这些结果表明，使用低功率密度的MW辐照可能会提高MTX的治疗指数。
