1993 Fiscal Year Final Research Report Summary
IP_3-Activated Ion Channels in Olfactory Receptor Cell Membrane
| Project/Area Number |
04640647
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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 |
動物発生・生理学
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| Research Institution | Hokkaido University |
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Principal Investigator |
SUZUKI Noriyo Hokkaido University, Faculty of Science, Associate Professor, 理学部, 助教授 (10001851)
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| Co-Investigator(Kenkyū-buntansha) |
NAGAYAMA Toshiki Hokkaido University, Faculty of Science, Associate Professor, 理学部, 助教授 (80218031)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Olfaction / Olfactory Transduction / IP_3 / Olfactory Receptor Cell / Second Messenger / Ion Channels / Patch Clamp / Multiple Transduction Pathways |
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| Research Abstract |
To elucidate their role of IP_3-activated ion channels (IP_3-channels) as the effector ion channels in vertebrate olfactory transduction, we have studied the properties of IP_3-channels in the membrane of olfactory receptor neurons from different vertebrate species, frogs, rats and mice, by means of patchclamp techniques. Results are summarised as follows : (1) IP_3-channels were activated directly by IP_3 in a ligand specific manner, indicating that phosphorlylation of the channel molecule is not associated with its activation. (2) IP_3-channels responded to IP_3 as quickly as cAMP-activated ion channels (cAMP-channels) did. The shortest latency measured with a microflow superfusion chamber was 24 msec for IP_3-channels and 5 msec for cAMP-channels. (3) Most of IP_3-channels did not show a desensitization during the application of IP_3. Only a few channels showed a desensitization to IP_3. (4) The unit conductance of IP_3-channels as determined in Ba^<2+>-external solution was ca. 20pS.(5) IP_3-channels were distributed not only in soma mambrane but also in apical dendrite membrane. The estimation by the success rate for recording of single channel activities suggested that the channel density is higher in apical dendrite membrane, which is thought to be the receptive site for odorants, than in soma membrane. (6) The comparison of success rate for recording of whole-cell responses to IP_3 and cAMP in rat receptor neurons showed that a smaller population of individual receptor neurons responded to IP_3, suggesting that a smaller population of individual receptor neurons utilize the IP_3-rather than the cAMP-pathway for olfactory transduction. Consequently, the properties of these IP_3-channels agree well with the criteria for IP_3-channels to be the effector channels for the IP_3-pathway in vertebrate olfactory transduction.
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[Publications] Suzuki, N.: "IP_3-activated ion channel activities in olfactory receptor neurons from different vertebrate species." In : Olfaction and Taste XI, Kurihara, K., Suzuki, N.and Ogawa, H.(Eds), Springer-Verlag, Berlin, Heidelberg, New York, Hong Kong, Tokyo. 173-177 (1994)
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