| Autor: |
Lippe WR; Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology-HNS, Box 357923, University of Washington School of Medicine, Seattle, WA 98195-7923, USA. lippe@u.washington.edu, Zirpel L, Stone JS |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology [J Comp Physiol A Neuroethol Sens Neural Behav Physiol] 2002 Jun; Vol. 188 (5), pp. 381-95. Date of Electronic Publication: 2002 May 04. |
| DOI: |
10.1007/s00359-002-0312-z |
| Abstrakt: |
Nonsensory hyaline cells border the sensory epithelium of the auditory end-organ (basilar papilla) in birds and reptiles. Their innervation by cochlear cholinergic efferent fibers and the presence of contractile proteins suggest that hyaline cells may actively regulate basilar membrane mechanics. The cholinergic pharmacology of hyaline cells was studied by measuring the intracellular calcium concentration ([Ca(2+)](i)) of fura-2-loaded cells in the chicken cochlea in vitro. Superfusion of the cholinergic agonist carbachol produced a dose-dependent increase in hyaline cell [Ca(2+)](i) (EC(50)=1.05 micromol l(-1)) and small responses in short hair cells. Calcium increases in hyaline cells were evoked by the muscarinic agonists oxotremorine (10 micromol l(-1)) and muscarine (100 micromol l(-1)) whereas nicotine (100 micromol l(-1), 200 micromol l(-1)) was without effect. Carbachol-evoked responses were blocked by the muscarinic antagonist atropine (>or=10(-13) mol l(-1)) and were unaffected by the nicotinic antagonists d-tubocurare (100 micromol l(-1), 1 mmol l(-1)) and hexamethonium (100 micromol l(-1)). Responses persisted in the absence of extracellular Ca(2+) and were abolished by thapsigargin (1 micromol l(-1)). These results indicate that the cholinergic-stimulated increase in hyaline cell [Ca(2+)](i) is due to a muscarinic-mediated release of Ca(2+) from intracellular stores. This is the first evidence that hyaline cells possess a muscarinic receptor whose activation causes mobilization of intracellular Ca(2+). |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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