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Titolo:
FLUORESCENCE IMAGING OF NA-CELLS( INFLUX VIA P2X RECEPTORS IN COCHLEAR HAIR)
Autore:
HOUSLEY GD; RAYBOULD NP; THORNE PR;
Indirizzi:
UNIV AUCKLAND,DEPT PHYSIOL,FAC MED & HLTH SCI,MOL PHYSIOL LAB,PRIVATEBAG 92019 AUCKLAND NEW ZEALAND
Titolo Testata:
Hearing research
fascicolo: 1-2, volume: 119, anno: 1998,
pagine: 1 - 13
SICI:
0378-5955(1998)119:1-2<1:FIONIV>2.0.ZU;2-J
Fonte:
ISI
Lingua:
ENG
Soggetto:
GUINEA-PIG COCHLEA; ADENOSINE 5'-TRIPHOSPHATE ATP; EXTRACELLULAR ATP; CALCIUM; RELEASE; ACETYLCHOLINE; LOCALIZATION; RESPONSES; CHANNELS; CURRENTS;
Keywords:
SODIUM GREEN(TM); CAGED-ADENOSINE 5'-TRIPHOSPHATE; ADENOSINE 5'-TRIPHOSPHATE-GATED ION CHANNEL; OUTER HAIR CELL; INNER HAIR CELL; VOLTAGE-CLAMP; CONFOCAL LASER SCANNING MICROSCOPY; PYRIDOXALPHOSPHATE-6-AZOPHENYL-2',4'-DISULFONIC ACID;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
49
Recensione:
Indirizzi per estratti:
Citazione:
G.D. Housley et al., "FLUORESCENCE IMAGING OF NA-CELLS( INFLUX VIA P2X RECEPTORS IN COCHLEAR HAIR)", Hearing research, 119(1-2), 1998, pp. 1-13

Abstract

The adenosine 5'-triphosphate (ATP)-activated membrane conductance, mediated by P2X receptors, was examined in isolated guinea-pig cochlearinner and outer hair cells. Photo-activated release of caged-ATP elicted a 30-ms latency inwardly rectifying nonselective cation conductance, blocked by the P2X receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS; 10-100 mu M), consistent with the direct activation of ATP-gated ion channels. A K-(Ca) conductance in theinner hair cells (IHC), activated by the entry of Ca2+ through the ATP-gated ion channels, was blocked by including 10 mM ,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) in the internal solution. Real-time confocal slit-scanning fluorescence imaging of Na+ influxthrough the ATP-gated ion channels was performed using the dye SodiumGreen(TM) with simultaneous whole-cell recording of membrane currents. The Na+ entry was localized to the endolymphatic surface, with the increase in [Na+](i) detected within approximately 200 ms of the onset of the inward current response. Within 600 ms Na+ had diffused throughout the cell cytoplasm with the exception of the subnuclear region of the outer hair cells. Correlation of voltage-clamp measurements of Naentry with regional increases in Naf-induced fluorescence demonstrated ATP-induced increases in intracellular Na+ in excess of 45 mM within4 s. These data provide direct evidence for the Na+ permeability of the ATP-gated ion channels as well as independent evidence for the localization of P2X receptors at the endolymphatic surface of the sensory hair cells. The localization of the ATP-gated ion channels to the apical surface of the hair cells supports an ATP-mediated modulation of 'silent' K+ current across the cochlear partition which could regulate hearing sensitivity by controlling the transcellular driving force for both mechanoelectrical and electromechanical transduction in hair cells. (C) 1998 Elsevier Science B.V.

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Documento generato il 03/04/20 alle ore 02:53:41