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Additional pharmacological evidence that endogenous ATP modulates cochlear mechanics
C Chen1, R A Skellett, M Fallon
1Kresge Hearing Research Laboratory of the South, Department of Otorhinolaryngology and Biocommunication, Louisiana State University Medical Center, New Orleans 70112-2234, USA.
Hearing Research
|May 30, 1998
Summary
Endogenous adenosine triphosphate (ATP) influences cochlear mechanics by acting on cells within the organ of Corti. Blocking ATP receptors with PPADS affects outer hair cells and alters sound-evoked potentials and emissions.
Area of Science:
- Auditory Neuroscience
- Cell Physiology
- Molecular Biology
Background:
- Outer hair cells (OHCs) are crucial for active cochlear mechanics.
- Supporting cells like Deiters' and Hensen's cells may also influence cochlear mechanics.
- The presence of adenosine triphosphate (ATP) receptors on these cells suggests a role for endogenous ATP.
Purpose of the Study:
- To investigate the role of endogenous ATP in cochlear mechanics.
- To examine the effects of the ATP antagonist pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS) on cochlear function.
Main Methods:
- In vitro whole-cell patch-clamp recordings on isolated cochlear cells (OHCs, Deiters', Hensen's, pillar cells).
- In vivo perilymphatic perfusion in guinea pigs to assess sound-evoked potentials (CM, SP, CAP) and distortion product otoacoustic emissions (DPOAEs).
Main Results:
- PPADS reduced ATP-evoked currents in isolated cochlear cells.
- In vivo, PPADS application decreased CAP and SP, and increased N1 latency.
- PPADS reversibly suppressed DPOAEs and reversed their slow decline during continuous stimulation.
Conclusions:
- Endogenous ATP, acting on cells in the organ of Corti, appears to modulate cochlear mechanics.
- These findings support a functional role for ATP in auditory processing and cochlear function.