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Acetylcholine activates two currents in guinea-pig outer hair cells
1Department of Physiology, School of Medical Sciences, Bristol, UK.
The Journal of Physiology
|March 1, 1996
Summary
Acetylcholine activates distinct cation and potassium currents in outer hair cells. Calcium influx triggers the potassium current, while the cation current is directly gated by nicotinic receptors.
Area of Science:
- Auditory Neuroscience
- Cellular Electrophysiology
- Sensory Biology
Background:
- Outer hair cells (OHCs) play a critical role in hearing by amplifying sound vibrations.
- Understanding the ionic mechanisms underlying OHC function is crucial for deciphering auditory processing.
Purpose of the Study:
- To investigate the ionic currents activated by acetylcholine (ACh) in OHCs.
- To elucidate the properties and dependencies of these ACh-sensitive currents.
Main Methods:
- Whole-cell voltage clamp recordings from isolated OHCs.
- Application of acetylcholine (ACh) to the basal pole of OHCs.
- Voltage-dependent current measurements and analysis of tail currents.
Main Results:
- ACh activated a rapid early inward cation current and a voltage-dependent late outward K+ current.
- The K+ current was dependent on extracellular Ca2+ influx.
- Both currents were blocked by alpha-bungarotoxin and curare, suggesting nicotinic receptor involvement.
Conclusions:
- ACh directly gates an early cation current via nicotinic receptors.
- Calcium influx through this cation current activates a subsequent Ca2+-dependent K+ current.
- These findings reveal a novel signaling pathway in OHCs involving ACh and calcium-mediated potassium efflux.