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Titolo:
Effects of gentamicin and pH on [Ca2+](i) in apical and basal outer hair cells from guinea pigs
Autore:
Tan, CT; Lee, SY; Yao, CJ; Liu, SH; Lin-Shiau, SY;
Indirizzi:
Natl Taiwan Univ, Coll Med, Inst Toxicol, Taipei 10043, Taiwan Natl TaiwanUniv Taipei Taiwan 10043 Inst Toxicol, Taipei 10043, Taiwan Natl Taiwan Univ Hosp, Dept Otolaryngol, Taipei 10043, Taiwan Natl Taiwan Univ Hosp Taipei Taiwan 10043 laryngol, Taipei 10043, Taiwan
Titolo Testata:
HEARING RESEARCH
fascicolo: 1-2, volume: 154, anno: 2001,
pagine: 81 - 87
SICI:
0378-5955(200104)154:1-2<81:EOGAPO>2.0.ZU;2-B
Fonte:
ISI
Lingua:
ENG
Soggetto:
CALCIUM-CHANNEL CURRENTS; AMINOGLYCOSIDE-INDUCED OTOTOXICITY; INTRACELLULAR CALCIUM; EXTERNAL PH; ANTIBIOTICS; MOTILITY; NEURONS; MECHANISMS; NEOMYCIN; COCHLEA;
Keywords:
outer hair cell; gentamicin; intracellular calcium concentration; fura-2; extracellular pH;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
40
Recensione:
Indirizzi per estratti:
Indirizzo: Lin-Shiau, SY Natl Taiwan Univ, Coll Med, Inst Toxicol, 1 Sect,1 Jen Ai Rd, Taipei 10043, Taiwan Natl Taiwan Univ 1 Sect,1 Jen Ai Rd Taipei Taiwan 10043 wan
Citazione:
C.T. Tan et al., "Effects of gentamicin and pH on [Ca2+](i) in apical and basal outer hair cells from guinea pigs", HEARING RES, 154(1-2), 2001, pp. 81-87

Abstract

Aminoglycosides are widely used antibiotics and frequently produce acute ototoxicity. In this study we attempted to comparatively investigate the effects of gentamicin on Ca2+ influx of apical and basal outer hair cells (OHCs) isolated from guineapig cochlea. Since the solution of gentamicin sulfate salt is acidic (pH 3.1 3.3), we also explored the effect of external acidification on Ca2+ influx. By means of fura-2 microspectrofluorimetry, we measured the intracellular calcium concentration ([Ca2+](i)) of OHCs bathed in Hanks' balanced salt solution (pH 7.40) during either a resting state or high K+-induced depolarization. Our results show that at the resting state,the baseline [Ca2+](i) in apical OHCs (94 +/- 2.0 nM) was slightly lower than that in basal OHCs (101.1 +/- 2.4 nM). By contrast, the increase in [Ca2+](i) evoked by high K+ depolarization in apical OHCs was about two-fold greater than that in basal OHCs. Nifedipine (30 muM) abolished the increased[Ca2+](i) in both types of OHCs, suggesting that Ca2+ influx was mainly through L-type Ca2+ channels of OHCs. While gentamicin and extracellular acidification (pH 7.14) can separately attenuate this increase in [Ca2+](i) in both types of OHCs, their suppressive effects are additive in basal OHCs, but not in apical OHCs. The implications of these findings are that: (1) apical and basal OHCs behave differently in response to depolarization-increased [Ca2+](i), and (2) basal OHCs are more vulnerable to the impairment of Ca2+ entry during depolarization by a combination of gentamicin and extracellular acidification, which is correlated with the clinical observation thatototoxicity of aminoglycosides at the basal coil of OHCs is more severe than that at the apical coils. Moreover, the possibility that extracellular acidification may enhance the acute ototoxic effects of aminoglycosides should be considered especially in topical applications. (C) 2001 Elsevier Science B.V. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 31/05/20 alle ore 13:32:47