期刊
JOURNAL OF COMPARATIVE PHYSIOLOGY A-NEUROETHOLOGY SENSORY NEURAL AND BEHAVIORAL PHYSIOLOGY
卷 191, 期 6, 页码 491-503出版社
SPRINGER HEIDELBERG
DOI: 10.1007/s00359-005-0601-4
关键词
chicken; efferent inhibition; hair cells; patch-clamp techniques; small-conductance calcium-sensitive potassium channels
资金
- NIDCD NIH HHS [DC01508, T 32 DC00023, P30 DCO5188, P30 DC05211, P30 DC005188] Funding Source: Medline
In the inner ear of birds, as in mammals, reptiles and amphibians, acetylcholine released from efferent neurons inhibits hair cells via activation of an apamin-sensitive, calcium-dependent potassium current. The particular potassium channel involved in avian hair cell inhibition is unknown. In this study, we cloned a small-conductance, calcium-sensitive potassium channel (gSK2) from a chicken cochlear library. Using RT-PCR, we demonstrated the presence of gSK2 RNA in cochlear hair cells. Electrophysiological studies on transfected HEK293 cells showed that gSK2 channels have a conductance of approximately 16 pS and a half-maximal calcium activation concentration of 0.74 +/- 0.17 mu M. The expressed channels were blocked by apamin (IC50=73.3 +/- 5.0 pM) and d-tubocurarine (IC50=7.6 +/- 1.0 mu M), but were insensitive to charybdotoxin. These characteristics are consistent with those reported for acetylcholine-induced potassium currents of isolated chicken hair cells, suggesting that gSK2 is involved in efferent inhibition of chicken inner ear. These findings imply that the molecular mechanisms of inhibition are conserved in hair cells of all vertebrates.
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