The Effect of Acetylcholine on the Potassium Currents and Length of Outer Hair Cell.
- Author:
Hyong Ho CHO
1
;
Joon Kyue LEE
;
Jae Hong LEE
;
Myung Joo JANG
;
Mei HUANG
;
Han Seong JEONG
;
Yong Bum CHO
;
Jong Seong PARK
Author Information
1. Department of Phisiology, Chonnam National University Medical School, Gwangju, Korea. parkjs@chonnam.ac.kr
- Publication Type:Original Article
- Keywords:
Outer hair cell;
Potassium channels;
Calcium;
Acetylcholine
- MeSH:
Acetylcholine*;
Animals;
Auditory Cortex;
Basilar Membrane;
Calcium;
Guinea Pigs;
Hair*;
Membrane Potentials;
Mesencephalon;
Nerve Fibers;
Neurotransmitter Agents;
Olivary Nucleus;
Organ of Corti;
Potassium Channels;
Potassium*
- From:Korean Journal of Otolaryngology - Head and Neck Surgery
2005;48(2):153-157
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
BACKGROUND AND OBJECTIVES: Inner hair cells (IHCs) of the organ of Corti change the external sound stimulus into the electrical signal and transmit this signal to the auditory cortex through afferent nerve fibers. Outer hair cells (OHCs) control the sound transmission function of IHC. OHCs respond with a somatic shape change to alterations in their membrane potential and this electromotile response is believed to provide mechanical feedback to the basilar membrane. Efferent nerve fibers which arise from the superior olivary nucleus in the midbrain and transmit to OHCs through medial olivocochlear bundle use acetylcholine (ACh) as a neurotransmitter. The cholinergic response of OHCs' alpha-9 nicotinic ACh receptor increase the Ca2+ influx, which control OHCs' electromotility by changing a membrane potential. In this research, the effect of ACh on the K+ current in OHC of guinea pig was studied, and the change of OHC length by ACh was studied. MATERIALS AND METHODS: Using the extracted OHC from a guinea pig potassium currents induced by ACh were recorded using the whole-cell patch clamp technique. The change of OHC length when ACh was applied was observed. RESULTS: 1) ACh increases voltage-dependent K+ current in OHC. 2) In the condition, which Ca2+-dependent K+ current is blocked by removing Ca2+ from intra-cellular fluid, ACh has no effect on K+ current in OHC. 3) ACh increases OHC length. CONCLUSION: These experimental results show that ACh from the medial olivocochlear efferent system regulates mobility of OHC, increases the Ca2+-dependent K+ currents in OHC.
