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Titolo:
High calcium permeability and calcium block of the alpha 9 nicotinic acetylcholine receptor
Autore:
Katz, E; Verbitsky, M; Rothlin, CV; Vetter, DE; Heinemann, SF; Elgoyhen, AB;
Indirizzi:
Univ Buenos Aires, Fac Ciencias Exactas & Nat, Consejo Nacl Invest Cient &Tecn, Inst Invest Ingn Genet & Biol Mol, RA-1428 Buenos Aires, DF, Argentina Univ Buenos Aires Buenos Aires DF Argentina RA-1428 Aires, DF, Argentina Univ Buenos Aires, Fac Ciencias Exactas & Nat, Dept Biol, RA-1428 Buenos Aires, DF, Argentina Univ Buenos Aires Buenos Aires DF Argentina RA-1428 Aires, DF, Argentina Salk Inst Biol Studies, Mol Neurobiol Lab, La Jolla, CA 92037 USA Salk Inst Biol Studies La Jolla CA USA 92037 Lab, La Jolla, CA 92037 USA
Titolo Testata:
HEARING RESEARCH
fascicolo: 1-2, volume: 141, anno: 2000,
pagine: 117 - 128
SICI:
0378-5955(200003)141:1-2<117:HCPACB>2.0.ZU;2-I
Fonte:
ISI
Lingua:
ENG
Soggetto:
OUTER HAIR-CELLS; RAT CENTRAL NEURONS; GUINEA-PIG COCHLEA; XENOPUS-OOCYTES; DIVALENT-CATIONS; CHLORIDE CURRENT; GATED CHANNELS; PC12 CELLS; RT-PCR; CONDUCTANCE;
Keywords:
nicotinic receptor; outer hair cell; olivocochlear efferent synapse; Ca2+ permeability; voltage-dependent blockage; neurotransmitter receptor channel; ligand-gated channel;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
61
Recensione:
Indirizzi per estratti:
Indirizzo: Elgoyhen, AB Univ Buenos Aires, Fac Ciencias Exactas & Nat, Consejo Nacl Invest Cient &Tecn, Inst Invest Ingn Genet & Biol Mol, Vuelta Obligado 2490,RA-1428 Buenos Aires, DF, Argentina Univ Buenos Aires Vuelta Obligado 2490Buenos Aires DF Argentina RA-1428
Citazione:
E. Katz et al., "High calcium permeability and calcium block of the alpha 9 nicotinic acetylcholine receptor", HEARING RES, 141(1-2), 2000, pp. 117-128

Abstract

At the synapse between olivocochlear efferent fibers and outer hair cells (OHCs) of the cochlea, a non-classical ionotropic cholinergic receptor allows Ca2+ entry into the hair cell, thus activating a Ca2+-sensitive K+ current which hyperpolarizes the cell's membrane. In the mammalian ear, this leads to a reduction in basilar membrane motion, altering auditory nerve fiberactivity and reducing the dynamic range of hearing. The alpha 9 nicotinic acetylcholine receptor (nAChR) subunit mediates synaptic transmission between cholinergic olivocochlear fibers and OHCs. Given that Ca2+ is a key player at this inhibitory synapse, we evaluated the permeability to Ca2+ of therecombinant a9 receptor expressed in Xenopus laevis oocytes and the modulation of its activity by extracellular Ca2+. Our results show that the a9 receptor is highly permeable to Ca2+ and that this cation potently blocks monovalent currents through this channel (IC50 = 100 mu M, at -70 mV) in a voltage-dependent manner. At a Ca2+ concentration similar to that found in theperilymph bathing the base of the OHCs, approximately 90% of the Na+ current through the alpha 9 receptor is blocked, suggesting that one of the mainfunctions of this channel could be to provide a pathway for Ca2+ influx. (C) 2000 Elsevier Science B.V. All rights reserved.

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Documento generato il 01/04/20 alle ore 16:29:32