ALPHA-BUNGAROTOXIN INHIBITS OUTER HAIR CELL MOTILITY IN-SITU

Citation
M. Anniko et al., ALPHA-BUNGAROTOXIN INHIBITS OUTER HAIR CELL MOTILITY IN-SITU, ORL, 57(2), 1995, pp. 105-109
Citations number
NO
Categorie Soggetti
Otorhinolaryngology
Journal title
ORLACNP
ISSN journal
03011569
Volume
57
Issue
2
Year of publication
1995
Pages
105 - 109
Database
ISI
SICI code
0301-1569(1995)57:2<105:AIOHCM>2.0.ZU;2-F
Abstract
The effect of two substances (alpha-bungarotoxin, alpha-BGTX, a small protein, and the local anesthetic bupivacaine hydrochloride) with an a ssumed effect on outer hair cell (OHC) motility were analyzed after ex posing the cochlea via the round window membrane. Electrophysiological measurements were performed with a very narrow frequency-specific gat ing(+/- 100 Hz) technique to determine auditory brainstem response (AB R) thresholds, including ABR-based frequency tuning curves. Exposure t o alpha-BGTX gave a minor improvement in thresholds, interpreted as a facilitation of OHCs, i.e. releasing their efferent inhibitory control , whereas exposure to bupivacaine hydrochloride impaired ABR threshold s, possibly due to immobilization of OHC motility via the lateral cell membrane. Our results are consistent with the hypothesis that efferen t influence on the cochlea may be linked with a modulation of the mech anical function of OHCs. We can now postulate that there is in vivo ev idence that acetylcholine exerts its effect at the OHCs via an alpha-B GTX binding acetylcholine receptor.