| Project/Area Number |
10680767
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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 |
神経・脳内生理学
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| Research Institution | KUMAMOTO UNIVERSITY |
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Principal Investigator |
YAMASHITA Yoshiro KUMAMOTO UNIV., MED.SCH., ASSISTANT, 医学部, 助手 (50128328)
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| Co-Investigator(Kenkyū-buntansha) |
山下 由朗 熊本大学, 医学部, 助手 (50128328)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 1999: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1998: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Keywords | Merkel cell / patch clamp method / Ca-dependent K channel / caffeine / TEA / rat / mechanoreceptor / skin / 遅順応性機械受容器 |
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| Research Abstract |
The CaィイD12+ィエD1-dependent KィイD1+ィエD1 channel currents of Merkel cells freshly dissociated from rat sinus hair follicles or footpad skin were investigated with whole-cell and excised patch configurations of the patch clamp technique. In the whole-cell voltage clamp, application of slow (50 mV/s) voltage ramps from -100 to +100 mV produced an N-shaped current-voltage (I-V) relationship. Maximal current activation occurred at +38.0 ± 10.6 mV (N=14). Replacement of extracellular CaィイD12+ィエD1 by MgィイD12+ィエD1 and addition of 2 mM EGTA abolished the N-shaped I-V relationship. It a holding potential of -30 mV, extracellular application of caffeine (10 mM), which releases CaィイD12+ィエD1 from the intracellular CaィイD12+ィエD1 pool, produced an outward transient current (IィイD2cafィエD2) with an increase of conductance. Its reversal potential was close to the KィイD1+ィエD1 equilibrium potential. The IィイD2cafィエD2 as well as the maximum current in the N-shaped I-V relationship were reduced to less than 40 % by 1 mM TEA. In inside-out patches, using symmetrical 150 mM KCl solutions, channels were observed with a slope conductance of 280 pS and a reversal potential of 0 mV. Reducing [KィイD1+ィエD1] ィイD2oィエD2 to 5 mM shifted the reversal potential as expected for a KィイD1+ィエD1-selective channel. The channel open-state probability (PィイD2oィエD2) was increased by increasing cytosolic [CaィイD12+ィエD1]. PィイD2oィエD2 also increased with depolarization. These data indicate the presence of large-conductance CaィイD12+ィエD1-activated KィイD1+ィエD1 channels in Merkel cells.
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