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Published on: July 18, 2011
Intracellular calcium and outer hair cell electromotility
1Auditory Physiology Laboratory, Departments of Communication Sciences and Disorders, Frances Searle Building, Northwestern University, 2299 North Campus Drive, Evanston, IL 60208, USA.
Brain Research
|December 4, 2001
Summary
Increased intracellular calcium enhances outer hair cell (OHC) electromotility, a process dependent on calcium and calmodulin. This finding is crucial for understanding OHC function and hearing.
Area of Science:
- Otoacoustic emissions
- Cellular physiology
- Biophysics
Background:
- Outer hair cells (OHCs) are crucial for hearing.
- OHC electromotility is a key mechanism for cochlear amplification.
Purpose of the Study:
- To investigate the influence of intracellular calcium levels on OHC electromotility.
- To determine the role of calcium and calmodulin in OHC electromotility.
Main Methods:
- Transcellular electrical stimulation in a partitioning microchamber.
- Measurement of OHC electromotile activity before and after ionomycin application.
- Assessment of the effect of W7 (calmodulin antagonist) on ionomycin-induced changes.
Main Results:
- Ionomycin increased OHC electromotility, indicating a role for calcium.
- Dimethyl sulfoxide (DMSO), the ionomycin solvent, initially decreased electromotility.
- The DMSO-induced decrease was counteracted and reversed by ionomycin.
- W7 attenuated the ionomycin-induced increase, suggesting partial calmodulin mediation.
Conclusions:
- Increased intracellular calcium enhances OHC electromotility.
- The calcium-induced increase in OHC electromotility is partially dependent on calmodulin.
- These findings elucidate the molecular mechanisms underlying OHC function.
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