| Project/Area Number |
17591778
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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 Field |
Otorhinolaryngology
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| Research Institution | The University of Tokyo |
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Principal Investigator |
IWASAKI Shinichi The University of Tokyo, The University of TokyoHospital, Lecturer (10359606)
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| Co-Investigator(Kenkyū-buntansha) |
ITO Ken The University of Tokyo, Hospital, Lecturer (50251286)
佐原 資謹 国立精神神経センター, 神経研究所, 研究員 (40206008)
藤城 芳徳 東京大学, 医学部附属病院, 助手 (50401047)
竹内 直信 東京大学, 医学部附属病院, 講師 (40280945)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,370,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥270,000)
Fiscal Year 2007: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2006: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2005: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | cell & tissue / signal transduction / physiology / pharmacology / brain & nerve / 前庭神経節 / パッチクランプ / ホールセル / K^+チャネル / 培養 / 活動電位 |
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| Research Abstract |
In the present study, we have established the method of culture of primary vestibular ganglions surviving at least 4 days.
We have examined the intrinsic firing properties of isolated rat vestibular ganglion cells (VGCs) and explored contributions of K^+ channels to the discharge regularity. Three classes of VGCs were distinguished on the basis of a degree of spike frequency adaptation observed during sustained membrane depolarization: most neurons exhibited a strong adaptation generating just a single spike or short bursts of spikes, and the others showed moderate adaptation or tonic firing. A degree of spike frequency adaptation in a neuron did not correlate with the cell size. Considerable variation in K^+ currents was present in the class of VGCs. In the presence of 4-aminopyridine or α-dendrotoxin (α-DTX), selective blockers of Kvl α subunits, phasic firing turned into sustained firing, indicating that Kvl channel control the firing characteristic of the pahsic VGCs. In tonic VGCs, tetraethylammonium decreased the frequency of discharges at membrane potentials above threshold while α-DTX lowered the threshold for initiation of discharge in response to depolarizing current steps. Blockade of Ca^<2+> activated K^+ channels and H- currents also had some effects on the firing pattern of the tonic VGCs. Our results indicate that VGCs have heterogeneous intrinsic firing properties, and that low-threshold K^+ channels are critical to determining a pattern of spike discharges that optimize the responsiveness of the vestibular neurons, thereby contributing to the timing of VG inputs.
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