Existence of nicotinic receptors in a subset of type I vestibular hair cells of guinea pigs
Autor: | Chang-Kai Guo |
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Rok vydání: | 2017 |
Předmět: |
0301 basic medicine
Guinea Pigs Pharmacology Cholinergic Agonists Receptors Nicotinic Apamin Efferent nerve Cholinergic Antagonists Membrane Potentials 03 medical and health sciences chemistry.chemical_compound Hair Cells Vestibular 0302 clinical medicine Mecamylamine medicine Animals Patch clamp Molecular Biology Chemistry General Neuroscience Iberiotoxin 030104 developmental biology Nicotinic agonist Cholinergic Neurology (clinical) 030217 neurology & neurosurgery Acetylcholine Developmental Biology medicine.drug |
Zdroj: | Brain research. 1681 |
ISSN: | 1872-6240 |
Popis: | In mammals, vestibular hair cells (VHCs) are classified as type I and II according to morphological criteria. Acetylcholine (ACh) is identified as the primary efferent neurotransmitter. To date, cholinergic activities have been reported in mammalian type II VHCs, but similar activities in type I VHCs have not been pursued presumably because the body of type I VHCs were suggested to be totally surrounded by afferent nerve calyces. A few reports showed that part of type I VHCs were incompletely surrounded by calyces and received contact from the efferent nerve endings in the mammals studied. The possibility of the expression of cholinergic receptors, their subunit composition, and their function in mammals’ type I VHCs are still unclear. In this study, nicotinic responses were investigated by the whole-cell patch clamp technique in isolated type I VHCs of guinea pigs. Of the cells, 7.3% were sensitive to cholinergic agonists and showed an excitatory current at −40 mV which was not sensitive to nifedipine, iberiotoxin (IBTX), and apamin. The main carriers of this current were Na+ and K+. The rank order of activation potency was nicotine > 1,1-dimethyl-4-phenyl-piperazinium (DMPP) > ACh. These nicotinic ACh receptors (nAChRs) were not blocked by strychnine and α-bungarotoxin (α-BTX), but sensitive to d-tubocurarine (dTC) and mecamylamine (Mec). The findings provide physiological evidence that some subtypes of nAChRs may be located in a subset of type I VHCs, which were different from α9α10 nAChRs. |
Databáze: | OpenAIRE |
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