Effects of gap junction uncoupling in the gerbil cochlea.
Laryngoscope
; 112(9): 1635-41, 2002 Sep.
Article
in En
| MEDLINE
| ID: mdl-12352678
ABSTRACT
OBJECTIVE:
To gain insight into molecular and cellular mechanisms regulating cochlear potassium (K+) recycling, including the possible effects of mutations in the gene, which encodes the gap junction protein connexin 26. Intercellular K+ flux was manipulated in vivo by infusion of the gap junction uncoupler proadifen (SKF-525A) into perilymph. Functional and structural alterations induced by gap junction blockade were assessed by electrophysiological and morphologic analysis. STUDYDESIGN:
Laboratory study using an animal model.METHODS:
Physiological effects of acute and chronic uncoupling of gap junctions in the Mongolian gerbil inner ear were evaluated by measurement of compound action potential (CAP) thresholds and input-output (I/O) functions, distortion product otoacoustic emissions (DPOAE), and the endocochlear potential (EP). Morphologic changes were assessed by electron microscopy.RESULTS:
Acute exposures to proadifen resulted in large decreases in EP values, DPOAE magnitudes, and CAP I/O maximum amplitudes and an increase in high-frequency CAP thresholds. These physiological changes were accompanied by vacuolization of type II and type V fibrocytes in the lateral wall of the cochlea. Chronic treatments revealed some recovery in EP values and CAP thresholds, which showed a relatively flat 15- to 20-dB elevation across frequencies.CONCLUSIONS:
Gap junctions play a significant role in normal cochlear function. In particular they appear to be essential for maintaining the EP, an activity that could be related to their participation in K+ recycling. Thus, hearing losses associated with mutations in the gene that alter the expression or function of connexin 26 may result from a diminished capacity to recycle K+ from perilymph back to the stria vascularis and a consequent decline in the EP.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Proadifen
/
Gap Junctions
/
Enzyme Inhibitors
Limits:
Animals
Language:
En
Journal:
Laryngoscope
Journal subject:
OTORRINOLARINGOLOGIA
Year:
2002
Document type:
Article
Affiliation country:
United States