Visualization and functional testing of acetylcholine receptor-like molecules in cochlear outer hair cells.
The efferent nerve endings at outer hair cells (OHCs) have been suggested to regulate active mechanical processes in the cochlea. The discovery of acetylcholine (ACh)-producing and -degrading enzymes in these synapses gave rise to the speculation that ACh might be one of the efferent transmitters. However, there has as yet been no identification and characterization of any corresponding receptor in OHCs which is required for further clarification of this question. In the present paper existence, location and first characterization of acetylcholine receptors (AChRs) in OHCs are reported. Using two anti-AChR monoclonal antibodies, AChR epitopes were found forming a cup at the basal end of the OHCs opposite to the efferent nerve endings. Furthermore, the studied molecules could be shown to extend through the cell membrane. In addition, the denervated OHC AChR-epitopes seem to move by lateral diffusion. Application of Carbachol and ACh to the basal pole of OHCs induced a weak, reversible cell contraction. Pharmacological controls revealed, that hte motile responses were mediated by the AChRs.
Plinkert
P K
PK
Department of Otolaryngology, University of Tübingen, F.R.G.
Gitter
A H
AH
Zimmermann
U
U
Kirchner
T
T
Tzartos
S
S
Zenner
H P
HP
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D000911:Antibodies, Monoclonal; D001285:Atropine / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002465:Cell Movement / Q000187:drug effects; D003051:Cochlea / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D005260:Female; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D007150:Immunohistochemistry; D008297:Male; D009411:Nerve Endings / Q000187:drug effects / Q000378:metabolism*; D011950:Receptors, Cholinergic / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology
D000911:Antibodies, Monoclonal; D011950:Receptors, Cholinergic; D001285:Atropine; D002217:Carbachol; D000109:Acetylcholine