Effects of ELF magnetic field and induced currents on cell growth or differentiation of cultured osteoblasts.

我们从暴露在极低频磁场（3mT）下的实验中得到了一些研究结果如下：(1)培养成骨细胞（MC3T3 E-1）在30 Hz和60 Hz磁场作用25 d时，细胞ALP活性和蛋白质含量与对照组存在显著差异。观察了60hz磁场对成骨细胞蛋白质合成的刺激作用，特别是对培养物中胶原蛋白和非胶原蛋白的积累。(2)暴露组与对照组在25天内60hz电流下胶原蛋白和非胶原蛋白的积累无显著差异。(3)短时间暴露极低频磁场对成骨细胞生长或分化的影响。1)观察在有或不含Ca2+的培养基中添加缓激蛋白（BK）后成骨细胞细胞内Ca2+浓度（[Ca2+]i）的变化。在添加BK后，[Ca2+]i立即从静息水平增加，在正常Ca2+培养基中达到最大值。当在培养基中添加EGTA螯合游离Ca2+时，BK刺激后的峰值仅为正常培养基的一半，在没有Ca2+的情况下，暴露于磁场24小时，强烈抑制了[Ca2+]i的增加。2)观察内皮素-1（ET）对生长成骨细胞细胞内Ca2+浓度[Ca2+]i的影响。未暴露细胞的[Ca2+]i在ET的作用下立即升高，而BK处理明显抑制了试剂暴露细胞[Ca2+]i的升高。当分化细胞暴露于磁场时，ET刺激的[Ca2+]i的增加明显加快，而不是生长细胞。

We have obtained some research results from the experiments for the effects of exposure to ELF magnetic fields(3mT) as following.(1) Significant differencies existed between the exposure and control groups of cultured osteoblasts(MC3T3 E-1) as to cellular ALP activities and protein contents at 30 and 60 Hz during the application of magnet for 25 days, respectively. The stimulatory effects of 60 Hz magnetic fields for protein synthesis of osteoblasts were observed concerning the accumulation of collagen and non-collagen protein in the cultures for 14 days in particularly.(2) No significant differences were observed between the exposure and control groups on the accumulation of collagen and non-collagen protein due to the electric currents at 60 Hz during 25 days.(3) The effects of exposure to ELF magnetic field for short time on growing or differentiated osteoblasts.1) The intracellular Ca2+ concentration ([Ca2+]i) of growing osteoblasts after addition of bradyknin(BK) in the culture media with or without of Ca2+ were examined. The [Ca2+]i increased instantly from the resting level on addition of BK, reaching a maxmal value in normal medium with Ca2+. When the free Ca2+ was chelated in the culture medium by addition of EGTA, the peak value was only half of that in normal medium after the stimulation of BK. Exposure to magnetic field for 24 hours 4t the absence of Ca2+ strongly inhibited the increase in [Ca2+]i.2) The intracellular Ca2+ concentration [Ca2+]i of growing osteoblasts after addition of endothelin-1(ET) in the culture media with or without of Ca2+ were examined. [Ca2+]i of unexposed cells increased instantly by addition of ET, but the increasing of [Ca2+]i in exposed cells by reagent was inhibited significantly as BK treatment. When the differetiated cells were exposed to magnetic field, the increasing of [Ca2+]i by ET stimulation was accelerated significantly in contrast to the growing cells.