| Project/Area Number |
04671056
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Otorhinolaryngology
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| Research Institution | KANSAI MEDICAL UNIVERSITY |
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Principal Investigator |
YAMASHITA Toshio Kansai Medical University, Professor, 耳鼻咽喉科, 教授 (10077654)
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| Co-Investigator(Kenkyū-buntansha) |
IWAI Hiroshi Kansai Medical University, Assistant, 耳鼻咽喉科, 助手 (10232638)
KUBO Nobuo Kansai Medical University, Assistant Professor, 耳鼻咽喉科, 講師 (70186435)
天野 一 関西医科大学, 医学部・耳鼻咽喉科, 講師(非常勤) (30159462)
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| Project Period (FY) |
1992 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1993: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1992: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | Cochlear hair cells / vestibular hair cells / spiral ganglion cells / intracellular Ca^<2+> concentration / intracellular Cl- concentration16FA06 : fura-2 / 画像解析法 / 蝸牛有毛細胞 / 細胞内Ca^<2+>濃度 / Ach / ATP / gultamate / 前庭器有毛細胞 / 蝸牛内有毛細胞 / 遠心性神経伝達物質 / 細胞内遊離Ca^<2+>濃度 / 細胞内遊離Cl^-濃度 / 細胞収縮 |
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| Research Abstract |
1) To elucidate efferent inhibitory mechanisms of the cochlear hair cells and vestibular hair cells, the effects of candidate efferent neurotransmitters on intracellular Ca^<2+> concentrations ([Ca^<2+>] i) in these isolated cells of guinea pig were determined. Both Ach and ATP seem to be efferent neurotransmitters, however, CGRP and Enk were thought to be functioning as efferent neuromodulators.
2) Slow shortening of cochlear outer hair cells has been speculated to modify cochlear sensitivity. Tetanic electrical field stimulation of isolated outer hair cells from guinea pigs shortened the cells for 2-3 min. Electrical stimulation reduced cell length and volume and decreased the intracellular Cl-concentration. These findings suggest that these shortening and shrinkage result from Cl- efflux.
3) [Ca^<2+>] i is isolated spiral ganglion cells (SGCs) of the guinea pig cochlear were measured using the Ca^<2+> sensitive fluorescence dye fura-2. L-gultamate increased [Ca^<2+>] i in SGCs with neuritic processes. We thus propose that the excitatory amino acid, probably L-gultamate, may function as a neurotransmitter of the hair cell-afferent nerve synapse in the guinea pig cochlea.
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