Acetylcholine-evoked calcium increases in Deiters' cells of the guinea pig cochlea suggest alpha9-like receptors.
The medial efferent system innervates outer hair cells in the organ of Corti. Neurotransmission at this synapse is mediated by acetylcholine (ACh) acting on nicotinic ACh receptors containing the alpha9 subunit. In addition to the sensory cells, the supporting cells of the mammalian cochlea also receive efferent innervation but the neurotransmitter(s) at these synapses are not known. We show slow transient increases of intracellular calcium evoked by ACh in isolated Deiters' cells of the guinea pig cochlea. The antagonists atropine, d-tubocurarine and strychnine blocked the ACh-effect. Nicotine was an ineffective agonist. The pharmacologic profile and the kinetics of the calcium response suggest an alpha9-like ACh receptor on Deiters' cells similar but not identical to that on the outer hair cells.
Matsunobu
T
T
Kresge Hearing Research Institute, University of Michigan, Ann Arbor, Michigan 49109-0506, USA.
Chung
J W
JW
Schacht
J
J
D000109:Acetylcholine / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D018680:Cholinergic Antagonists / Q000494:pharmacology; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism; D018722:Nicotinic Agonists / Q000494:pharmacology; D011978:Receptors, Nicotinic / Q000187:drug effects* / Q000378:metabolism; D013569:Synapses / Q000187:drug effects* / Q000378:metabolism
D018680:Cholinergic Antagonists; D018722:Nicotinic Agonists; D011978:Receptors, Nicotinic; D000109:Acetylcholine; D002118:Calcium