| Project/Area Number |
05680714
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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 |
神経・脳内生理学
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| Research Institution | Tohoku University |
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Principal Investigator |
KAWA Kazuyoshi Tohoku Univ.School of Medicine, Associate professor, 医学部, 助教授 (70125839)
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| Co-Investigator(Kenkyū-buntansha) |
赤池 紀生 九州大学, 医学部, 教授 (30040182)
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| Project Period (FY) |
1993 – 1994
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| Project Status |
Completed (Fiscal Year 1994)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1994: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1993: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Slice-patch / Hippocampus / Inhibitory neurons / Serotonin / Receptor / Rat / ニューロン / GABA / イオンチャネル / パッチクランプ |
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| Research Abstract |
In dentate gyrus of the rat hippocampal slices, principal neurons (granule cells) and local inhibitory neurons (basket cells) identified under Namarsky microscopy. The effects of serotonin (5-HT) on these neurons were investigated using the whole-cell patch clamp technique and rapid perfusion (Y-tube) method. In granule cells, external application of 5-HT (0.2-100 uM) did not evoke any current but in basket cells definite inward currents at a holding potential of -63mV were induced. The I-V relation for 5-HT response showed a reversal potential around 0 mV accompanying a negative slope conductance at potentials below -60mV.
To compare the functional proparties of these 5-HT receptors, newly identified ADP (adenosine-5'-diphosphate) receptors in the megakaryocytes from the mouse bone marrow were studied. When Cs^+ was used as a major internal cation to block K-currents, external application of ADP (10-100 uM) to dissociated megakaryocytes induced large inward currents (amplitude of 100-500 pA) at a holding potential of -42 mV,which showed a rapid decay with a complete inactivation in 1 sec.
The amplitude of the ADP-induced currents became larger when hyperpolarized, while it became smaller by depolarization and reversed its polarity to outward at aroudn 0 mV.The overall I-V relationship showed an inward rectification. The ADP-induced inward currents are also observed in isotonic Ca2+ or Ba2+ or Mg2+ solution, which indicates that the channels activated by ADP are pormeable to these divalent cations. The channels are also permeable to monovalent cations such as Na+, K+ or Cs+.
These indicate that a certain type of purinergic receptor is specifically involved in generating rapid cationic currents in megakaryocytes, the functional properties of which are very similar to those described for the 5-HT receptors in the brain.
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