| Project/Area Number |
08680720
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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 |
Biophysics
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| Research Institution | Nagoya University |
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Principal Investigator |
SUZUKI Naoya Nagoya University, School of Science, Research Associate, 大学院・理学研究科, 助手 (50222063)
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| Co-Investigator(Kenkyū-buntansha) |
IIDA Syozo Nagoya University, School of Science, Associate Professor, 大学院・理学研究科, 助教授 (80022664)
KIJIMA Hiromasa Nagoya University, School of Science, Professor, 大学院・理学研究科, 教授 (30012397)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1997: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1996: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | Synapse / Neuro-muscular junction / Calcium sensitive dye / Calcium ion / Confocal microscope / Synaptic terminal / Synaptic plasticity |
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| Research Abstract |
1. Ca^<2+> dynamics in the presynaptic terminal
We loaded Ca^<2+> sensitive dyes into presynaptic nerve-terminals of the frog neuro-muscular junction and measured Ca^<2+> dynamics during and after nerve stimulation. The free Ca^<2+> concentration rose about 1-2 muM during 10 stimulus st 100 Hz in a 1.8mM Ca^<2+> ringer solution. After the end of a tetanus, Ca^<2+> concentration declined quickly with a decay time constant about 50 ms and about 80% of rose Ca^<2+> was cleared within 200 ms. This indicate that rapid and high capacity Ca^<2+> clearance mechanism cxist in the presynaptic terminal. CCCP increased the Ca^<2+> concentration during tetanus and elongated the time constant of Ca^<2+> clearance. This indicates that the uptake of Ca^<2+> into mitochondria largely contributes as this Ca^<2+> clearance mechanism.
2. Visualization of Ca^<2+> microdomain
We succeeded to take images of presynaptic Ca^<2+> dynamics with a time resolution of 2 ms. And we visualized the spatial heterogeneity of Ca^<2+> concentration in the terminal during increses transient phase of Ca^<2+> after a single nerve stimulation.
3. The dependency of the facilitaion of transmitter release on presynaptic Ca^<2+> dynamics
We investigated the effect of BAPTA-AM and EGTA-AM on the Ca^<2+> dynamics at the presynaptic terminal and the fast- and slow-facilitation of transmitter release after 10 tetanus at 100 Hz. BAPTA abolished the rapid Ca^<2+> transient and reduced the amplitade of fast-facilitation significantly. The slow kinetic Ca^<2+> -buffer, EGTA,reduced the amplitude of the rapid Ca^<2+> transient, but did not abolished in contrast to the case applied BAPTA.EGTA had a small effect on the amplitude of the fast-facilitation but shortened its time constant. EGTA reduced both the slow-facilitation and the show Ca^<2+> transient significantly. These results suggest a direct coupling between Ca^<2+> in nerve-terminal and the facilitation of transmitter releaes.
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