| Project/Area Number |
12470009
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Environmental physiology (including Physical medicine and Nutritional physiology)
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
KOBAYSHI Shigeo Graduate School of Informatics, Prof., 情報学研究科, 教授 (40124797)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUMURA Kiyoshi Graduate School of Informatics, Associate prof., 情報学研究科, 助教授 (10157349)
白木 琢磨 京都大学, 情報学研究科, 助手 (10311747)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥13,800,000 (Direct Cost: ¥13,800,000)
Fiscal Year 2002: ¥4,400,000 (Direct Cost: ¥4,400,000)
Fiscal Year 2001: ¥5,700,000 (Direct Cost: ¥5,700,000)
Fiscal Year 2000: ¥3,700,000 (Direct Cost: ¥3,700,000)
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| Keywords | cold receptor / patch-clamp / comparator / transducer / CMR1 / Ca imaging / 冷細胞 / サーモスタット / パッチクランプ / 後根神経節 / 相転移 / 細胞内Caイメージング / カチオンチャンネル / 温度受容器 / 温度調節器 / センサー / イオンチャンネル |
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| Research Abstract |
When temperature (T) of skin decreases stepwise, cold fibers evoke transient efferent discharges, inducing cold sensation and heat-gain responses. Hence we have proposed that cold receptors at distal ends of cold fibers are thermostats to regulate skin T against cold. Here, with patch-clamp techniques, we studied the ionic basis of cold receptors in cultured dorsal root ganglion (DRG) neurons of rats, as a model of nerve endings. Cells that increased cytosolic Ca(2+) level in response to moderate cooling were identified as neurons with cold receptors. In whole-cell current-clamp recordings of these cells, in response to cooling, cold receptors evoked a dynamic receptor potential (RP), eliciting impulses briefly. In voltage-clamp recordings (-60 mV), step cooling induced an inward cold current (I(cold)) with mactivation, underlying the dynamic RP. Ca(2+) ions that entered into cells from extracellular side induced the inactivation. Analysis of the reversal potential implied that I(cold) was nonselective cation current with high Ca(2+) permeability. Threshold temperatures of cooling-induced Ca(2+) response and I(cold) were different primarily among cells. In outside-out patches, when T decreased, single nonselective cation channels became active at a critical T. This implies that a cold receptor is an ion channel and acts as the smallest thermostat. Because these thermal properties were consistent with that in cold fibers, we conclude that the same cold receptors exist at nerve endings and generate afferent impulses for cold sensation and heat-gain behaviors in response to cold.
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