| Project/Area Number |
11834009
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Institution | The University of Tokushima |
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Principal Investigator |
IKEHARA Toshitaka Department of Physiology, School of Medicine, The University of Tokushima, Assistant Professor., 医学部, 講師 (40111033)
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| Co-Investigator(Kenkyū-buntansha) |
AIZAWA Katsuo Tokyo Medical College, Department of Physiology, Professor., 医学部, 教授 (40074645)
KINOUCHI Yohsuke The University of Tokushima, Department of Electrical and Electronic Engineering, Faculty of Engineering, Professor., 工学部, 教授 (80035807)
YAMAGUCHI Hisao Department of Physiology, School of Medicine, The University of Tokushima, Associate Professor., 医学部, 助教授 (90035436)
HOUCHI Hitoshi Department of Pharmacy, School of Medicine, The University of Tokushima, Associate Professor., 医学部・附属病院, 助教授 (00219156)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2000: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1999: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Keywords | time-varying strong magnetic field / extremely-low-frequency magnetic field / intracellular Ca^<2+> / Ca^<2+>-dependent K^+ channel / endoplasmic reticulum / infrared spectroscopy / chromaffin cells / PC12 cells / イノシトール3燐酸 / 誘導電流 / ブラディキニン / アセチルコリン / 変動磁界 / イノシトール3リン酸 / 神経伝達物質 / FT-IRスペクトル |
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| Research Abstract |
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
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