| Budget Amount *help |
¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1998: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1997: ¥900,000 (Direct Cost: ¥900,000)
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| Research Abstract |
Recent finding that purinergic receptor, which is known as specific receptor to extra-cellular ATP, existed in cells of organ of Corti of guinea pig cochlea, introduces a new concept that extra-cellular ATP acts as a bio-modulator in the cochlea. In order to explicate of the physiological functions of ATP in cochlea, by using patchclamp whole cell configuration and simultaneous Ca^<2+> fluorometry, the ATP evoked cellular responses are measured.
Extra-cellular ATP evoked an inward current and a simultaneous increase of intracellular free Ca^<2+> in all cells (inner hair cell, outer hair cell, Deiters cell, Hensen cell and Piller cell) of organ of Cord. Those responses were coupled to the activations of P2x and P2y receptor, respectively. Interestingly, in inner hair cells Ca^<2+> responses secondary activated Ca^<2+>-dependent potassium channel and in Hensen cells also secondary activated Ca^<2+> dependent Chloride channel.
All cells except Deiters cells ; P2x receptor was located endlymphatic side of the cells. Location of P2y receptor was identified only in inner hair cells. It was placed in the base of inner hair cells.
There were different patterns of purinergic response in each cells of organ of Cord suggesting that ATP act as a bio-modulator in organ of Cord in different manners.
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