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Immunodetection of gentamicin (GM) was carried out on surface preparations of the whole organ of Corti from cochleas of guinea pigs treated daily with GM at a dose of 60 mg/kg/day and sacrificed at the end of different treatment periods. Cochlear function was determined just before sacrifice, 24 h after the last injection. Threshold elevations, mainly at(More)
Measures of cochlear selectivity can be obtained from compound responses using tone-on-tone masking procedures [Dallos and Cheatham, J. Acoust. Soc. Am. 59, 591--597 (1976)]. For the normal guinea pig, cochlear fiber tuning is sharper by a factor of 1.8 than AP tuning curves using simultaneous masking (threshold criterion = 25% N1 amplitude reduction).(More)
Guinea pigs (GPs) receiving one intra-muscular injection of gentamicin (GM) (150 mg/kg) in which 2 mg of tritiated GM (2 mCi) were incorporated, followed 1.5 h later by an intra-cardiac injection of ethacrynic acid (EA) (30 mg/kg) were sacrificed 25 min, 1, 4 and 24 h after the EA injection. Other GPs were treated with one injection of GM or EA alone and(More)
In normal adult guinea pigs, evoked potentials recorded at the ipsilateral auditory cortex to monaural high-frequency acoustic stimuli present higher thresholds and lower amplitudes than at the contralateral cortex; in the inferior colliculus, such ipsi-contralateral differences (ICDs) are smaller than in the auditory cortex. Changes in the ICDs were(More)
We have previously shown by chronic implantation of round window electrodes, that after the experimental induction of endolymphatic hydrops by surgical blockade of the endolymphatic canal, in the guinea pig, there is a low/mid-frequency fluctuant hearing loss, followed by a very high frequency loss and after a few months the audiogram is flat. This(More)
In the electrical stimulation (ES) of auditory pathways, the type of stimulus and the electrode/tissue interface are critical parameters for the safety and efficacy of the protocol. In this study the influence of alternate pulses, applied between round window and vertex electrodes in chronically implanted guinea pigs, and maintained during 1 and 25 daily(More)
Measurements were made of the ability of nonsimultaneous, contralaterally presented broadband noise maskers to suppress ipsilaterally-evoked compound action potentials (CAPs) of the auditory nerve to 8-kHz tone pips in guinea pigs. Contralateral acoustic stimuli have been shown to suppress responses to ipsilateral stimuli through the action of the medial(More)
Regional selectivity of gentamicin (GM) ototoxicity was studied in guinea pigs (GPs) using electrophysiological, morphological, autoradiographic and immunohistological observations following combined treatment with GM (150 mg/kg i.m.) and ethacrynic acid (EA) (30 mg/kg i.c. or i.v., 1.5 h after GM injection). The GPs were either continuously stimulated(More)
An experimental study of the electrical stimulation of the guinea pig cochlea is made using an electrode on the round window for both stimulation and recording. The neural response is separated from the electrical artifact with a masking procedure combined with a low amplification, "statistical" averaging method [Charlet de Sauvage et al., Hear. Res. 2,(More)
Free radical generation is increasingly implicated in a variety of pathological processes, including drug toxicity. Recently, a number of studies have demonstrated the ability of gentamicin to facilitate the generation of radical species both in vivo and in vitro, which suggests that this process plays an important role in aminoglycoside-induced(More)