| Project/Area Number |
10671743
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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 |
Functional basic dentistry
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| Research Institution | NAGASAKI UNIVERSITY |
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Principal Investigator |
OKADA Yukio SCHOOL OF DENTISTRY, NAGASAKI UNIVERSITY, ASSOCIATE PROFESSOR, 歯学部, 助教授 (60136687)
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| Co-Investigator(Kenkyū-buntansha) |
FUJIYAMA Rie SCHOOL OF DENTISTRY, NAGASAKI UNIVERSITY, RESEARCH ASSOCIATE, 歯学部, 助手 (10274664)
MIYAMOTO Takenori SCHOOL OF DENTISTRY, NAGASAKI UNIVERSITY, RESEARCH ASSOCIATE, 歯学部, 助手 (10167679)
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2000: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1999: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1998: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | Taste cell / Saccharin / GTPγS / phospholipase C / patch clamp / bullfrog / ion channel / taste transduction / GTP_γS |
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| Research Abstract |
The taste transduction mechanism of the response elicited by saccharin was analysed in isolated bullfrog taste cells under whole-cell voltage-clamp. Bath application of 30 mM saccharin induced an inward current of -34±12 pA (mean±SEM, n=10) at a membrane potential of -50 mV in 10 (23%) of 44 rod cells. The concentration-response relationship for the saccharin-gated current was consistent with that of the gustatory neural response. The saccharin-induced current was accompanied with a conductance increase under internal low Cl^- condition (E_<Cl>=-56 mV). This suggests that saccharin activated a cation conductance. The reversal potential of the saccharin-induced current was -17±2 mV (n=10). Intracellular dialysis of 0.5 mM GDPβS completely blocked the saccharin-induced response, suggesting the involvement of a G protein in the transduction. The dialysis of heparin (1mg/ml) also inhibited the response almost completely, but the 1 mM 8-Br-cAMP did not affect the response significantly. Intracellular 50μM 1,4,5-InsP_3 also induced the inward current in five (38%) of 13 rod cells, but intracellular Pasteurella multocida toxin (5μg/ml, Gαq-coupled PLC activator) did not elicit any response in the cells. The results suggest that saccharin mainly activates a cation conductance in frog taste cells through the mediation of IP_3 production.
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