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

我们在实验中对极低频磁场（3 mT）的作用进行了研究。(1)在磁场作用25天期间，30和60 Hz磁场作用组与对照组成骨细胞（MC 3 T3 E-1）的ALP活性和蛋白质含量差异有显著性。观察了60 Hz磁场对成骨细胞蛋白质合成的刺激作用，特别是在培养14天时，胶原和非胶原蛋白在培养物中的积累。(2)在25天期间，由于60 Hz的电流，在暴露组和对照组之间未观察到胶原蛋白和非胶原蛋白积累的显著差异。(3)本研究旨在探讨极低频磁场对成骨细胞生长和分化的影响。1）在含钙和不含钙的培养液中，观察不同浓度缓激肽（BK）对成骨细胞内钙离子浓度（[Ca 2 +]i）的影响。加入BK后，细胞内[Ca ~（2+）]i迅速升高，并在正常Ca ~（2+）培养基中达到最大值。当通过加入EGTA螯合培养基中的游离Ca 2+时，磁场作用24小时后，无钙条件下[Ca ~（2+）] i的增加受到强烈抑制。2）内皮素-1（ET）刺激后，成骨细胞内[Ca ~（2+）]i的增加，随着培养时间的延长，[Ca ~（2+）]i的增加逐渐减少，但随着培养时间的延长，[Ca ~（2+）]i的增加逐渐减少。在有无Ca ~（2+）的培养基中进行了检测。[Ca2 ET使未暴露细胞内[Ca ~（2+）]i迅速升高，而BK则明显抑制暴露细胞内[Ca ~（2+）]i的升高。磁场作用后，内皮素刺激引起的细胞内[Ca ~（2+）]i的增加明显快于生长期细胞。

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.