| Project/Area Number |
02044144
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | Asahi University |
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Principal Investigator |
FUNAKOSHI Masaya President of Asahi University, 学長 (10075989)
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| Co-Investigator(Kenkyū-buntansha) |
ELEMER Labos ゼンメルワイス大学, 医学部, 教授
MUSYA Toshimitsu Tokyo Institute Technology, Dept. of Applied Electronics, Prof., 総合理工学研究所, 教授 (70016319)
TAKEUCHI Hiroshi Gifu University, School of Medicine, Prof., 医学部, 教授 (10033333)
TONOSAKI Keiichi Asahi University, School of Dentistry, Assoc. Prof., 歯学部, 講師 (30103485)
LABOS Elemer Semmelweis University, Medical School, Prof.
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| Project Period (FY) |
1990
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| Project Status |
Completed (Fiscal Year 1990)
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| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 1990: ¥3,000,000 (Direct Cost: ¥3,000,000)
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| Keywords | Taste receptor cell / Ionic mechanism / Electrical circuit / Potassium channel / c-GMP / Voltage-clamp / Computer simulation / 蔗糖刺激 |
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| Research Abstract |
Taste receptor cell excitation begins with the absorption of a taste stimulus by taste receptor membrane. The taste receptor cells responded to sucrose with a depolarization accompanied by a membrane resistance increase. The taste receptor cell responded to salt taste stimulus with a depolarization accompanied by a membrane resistance decrease. It is known that the magnitude of sucrose response is smaller than that of salt taste response. Ionic mechanisms responsible for generating sucrose responses may be accounted by an electrical circuit model of the taste cell membrane. The resting stage of membrane conductance is represented the opening of potassium channels and the closing of sodium channels. When sucrose is absorbed to the receptor site, cGMP triggers the closing of potassium channels, depolarizing the membrane and decreasing membrane conductance. This model is supported by the effect of TEA injections into the cell and by the voltage-clamp results. An alternative hypothesis suggests that a salt-related second messenger in the cell triggers the responses, that is, opens Na channels of the cell membrane. We studied the computer simulation of those taste cell activity. It is well known that the electrical circuit of the excitatory cells and nerves can expressed by the Hodgkin-Huxley's equation. We made a Basic program of the modifier H-H equation, E=m^ahg_<Na>V_<Na>+n^bg_kV_K+g_LV_L, and studied what kind of situation can simulate the sucrose or salt response profile. Salt response was mimicked by the usual constant values in the H-H equation, that is, a=4, b=3, m=0.053, h=0.6, n=0.32 and V=-15. If m is smaller and n is larger than those of salt values, then the sucrose response was mimicked. Therefore we don't know what kind of mechanism contributes to change those membrane characteristics, final confirmation of these results are necessary.
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