Effects of Magnetic field on Nerve Transmission and Analyses of Efficiency and Safety for Human on Application of Magnetic Field.

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1. The time-varying magnetic fields (MF) partly suppressed K^+ uptake through Ca^<2+>-dependent K^+ channels. When the cells were placed in the high K^+ medium, [Ca^<2+>]c increased to about 1.4 times the original level, but exposure to the magnetic fields completely suppressed the increase. Addition of ionomycin to the high K^+ medium increased [Ca^<2+>]c to the level of control cells, regardless of exposure to the magnetic field. But the inhibition of K^+ uptake by the magnetic field was not restored by addition of ionomycin. The suppression of K^+ influx could relate to a change in electric properties of cell surface.2. The time-varying MF inhibited the transient increase in [Ca^<2+>]c stimulated by acetylcholine, bradykinin, caffeine, ionomycin and thapsigargin in chromaffin cells. Also, [Ca^<2+>]c was markedly increased in inositol 1,4,5-trisphosphate-loaded cells, and this increase was inhibited by exposure. Inhibition of bradykinin-induced increase in [Ca^<2+>]c by exposure for … More 0.5 hr was mostly recovered after placing the cells for 1 hr outside the magnetic field. Our results indicate that the MF-exposure inhibits Ca^<2+> release from intracellular Ca^<2+> stores, but that bradykinin binding to bradykinin receptors of the cell membrane and inositol 1,4,5-trisphosphate production are not influenced.3. The effects of exposure to 50 Hz extremely-low-frequency (ELF) MF (maximally 41.7-43.6 mT) on structures of membrane protein of living HeLa cells were studied by the attenuated total reflection infrared spectroscopy. The exposure for 1 min shifted the peak absorbance of amide I band to a smaller wave number, strongly reduced the absorbance of amide II band and increased the absorbance at around 1600 cm^<-1>. These results suggest that exposure to the ELF magnetic field reversibly influences N-H inplane bendings and C-N stretching vibrations of peptide linkages, and changes secondary structures of alpha-helix and beta-sheet in proteins of the cell membrane.4. Exposure to ELF MF to 60 Hz MF (maximally 3 mT) further increased the differentiation of PC12 cells stimulated by addition of nerve growth factor. Less