Effects of Nimodipine on Quinine Ototoxicity

2003 ◽  
Vol 112 (2) ◽  
pp. 163-168 ◽  
Author(s):  
Kentaro Ochi ◽  
Hirotsugu Kinoshita ◽  
Hirohito Nishino ◽  
Mutsumi Kenmochi ◽  
Toru Ohashi
Keyword(s):  
Action Potential ◽  
Guinea Pigs ◽  
Round Window ◽  
Compound Action Potential ◽  
Simultaneous Administration ◽  
Quinine Hydrochloride ◽  
Click Train ◽  
Compound Action

The compound action potential (CAP) in response to a click train stimulus was recorded at the round window of guinea pigs. Administration of quinine hydrochloride (200 mg/kg) significantly elevated the CAP thresholds by 5 to 25 dB (p < .05), and the CAP waveform elicited by the click train stimulus was abnormal. The amplitude of the CAP elicited by the second click was bigger than that elicited by the first click. These changes may be caused by an abnormally broadened N1 response to the first click in the click train. In contrast, CAP waveforms elicited by the second and subsequent clicks appeared normal. After administration of nimodipine (2 mg/kg), the CAP thresholds and waveforms elicited by the click train stimulus were unchanged. Simultaneous administration of both quinine (200 mg/kg) and nimodipine (2 mg/kg) resulted in the same electrophysiological changes as those induced by quinine alone. These results suggest that nimodipine prevents neither the deterioration in the CAP nor the abnormal properties in the response to a click train stimulus.

Quinine Affects the Response Properties of Compound Action Potentials Elicited by Periodic Click Trains

2002 ◽  
Vol 111 (5) ◽  
pp. 423-429 ◽  
Author(s):  
Kentaro Ochi ◽  
Mutsumi Kenmochi ◽  
Toru Ohashi ◽  
Hitoshi Kikuchi ◽  
Hirotsugu Kinoshita ◽  
...  
Keyword(s):  
Body Weight ◽  
Action Potentials ◽  
Round Window ◽  
Compound Action Potential ◽  
Experimental Session ◽  
Quinine Hydrochloride ◽  
Before And After ◽  
Compound Action Potentials ◽  
Click Train ◽  
Compound Action

The effects of systemically applied quinine on the compound action potential (CAP) were investigated in 5 guinea pigs. A dose of 200 mg/kg body weight of quinine hydrochloride was administered intramuscularly, and CAPs were recorded at the round window before and after administration. The CAP thresholds of the animals were elevated by 5 to 25 dB approximately 30 minutes after administration, and thresholds recovered in some animals during the experimental session. The CAP waveform elicited by the click train stimulus was abnormal after administration of quinine. The amplitude of the CAPs elicited by the second click was larger than that of those elicited by the first click. These changes may be induced by an abnormally broadened N1 response to the first click in the click train following quinine administration. In contrast, the CAP waveforms elicited by the second click and by the following clicks in the click train appeared normal.

Contribution of auditory nerve fibers to compound action potential of the auditory nerve

2014 ◽  
Vol 112 (5) ◽  
pp. 1025-1039 ◽  
Author(s):  
Jérôme Bourien ◽  
Yong Tang ◽  
Charlène Batrel ◽  
Antoine Huet ◽  
Marc Lenoir ◽  
...  
Keyword(s):  
Action Potential ◽  
Auditory Nerve ◽  
Computational Simulation ◽  
Round Window ◽  
Hearing Threshold ◽  
Compound Action Potential ◽  
Nerve Fibers ◽  
Auditory Nerve Fibers ◽  
Round Window Niche ◽  
Compound Action

Sound-evoked compound action potential (CAP), which captures the synchronous activation of the auditory nerve fibers (ANFs), is commonly used to probe deafness in experimental and clinical settings. All ANFs are believed to contribute to CAP threshold and amplitude: low sound pressure levels activate the high-spontaneous rate (SR) fibers, and increasing levels gradually recruit medium- and then low-SR fibers. In this study, we quantitatively analyze the contribution of the ANFs to CAP 6 days after 30-min infusion of ouabain into the round window niche. Anatomic examination showed a progressive ablation of ANFs following increasing concentration of ouabain. CAP amplitude and threshold plotted against loss of ANFs revealed three ANF pools: 1) a highly ouabain-sensitive pool, which does not participate in either CAP threshold or amplitude, 2) a less sensitive pool, which only encoded CAP amplitude, and 3) a ouabain-resistant pool, required for CAP threshold and amplitude. Remarkably, distribution of the three pools was similar to the SR-based ANF distribution (low-, medium-, and high-SR fibers), suggesting that the low-SR fiber loss leaves the CAP unaffected. Single-unit recordings from the auditory nerve confirmed this hypothesis and further showed that it is due to the delayed and broad first spike latency distribution of low-SR fibers. In addition to unraveling the neural mechanisms that encode CAP, our computational simulation of an assembly of guinea pig ANFs generalizes and extends our experimental findings to different species of mammals. Altogether, our data demonstrate that substantial ANF loss can coexist with normal hearing threshold and even unchanged CAP amplitude.

Influence of argon laser stapedotomy on inner ear function and temperature

1983 ◽  
Vol 91 (5) ◽  
pp. 521-526 ◽  
Author(s):  
Michael Vollrath ◽  
Christoph Schreiner
Keyword(s):  
Action Potential ◽  
Inner Ear ◽  
Guinea Pigs ◽  
Time Course ◽  
Argon Laser ◽  
Compound Action Potential ◽  
Clinical Use ◽  
Cochlear Microphonics ◽  
Temperature Changes ◽  
Compound Action

The influence of argon laser stapedotomy on inner ear function was investigated in guinea pigs. The cochlear microphonics (CM) and the compound action potential (CAP) served as parameters for the functional status of the cochlear. Transitory depression of both potentials was found during and after laser stapedotomy. The time course of CM and CAP depression and recovery is compared to endocochlear temperature changes. Possible implications for clinical use are discussed.

Effects of Nimodipine on Salicylate Ototoxicity

2002 ◽  
Vol 111 (12) ◽  
pp. 1092-1096 ◽  
Author(s):  
Kentaro Ochi ◽  
Hirotsugu Kinoshita ◽  
Hirohito Nishino ◽  
Mutsumi Kenmochi ◽  
Toru Ohashi
Keyword(s):  
Round Window ◽  
Compound Action Potential ◽  
Lateral Wall ◽  
Systemic Blood Pressure ◽  
Simultaneous Administration ◽  
Significant Elevation ◽  
Systemic Blood ◽  
Cochlear Blood Flow ◽  
Doppler Flowmetry ◽  
Compound Action

The purpose of this study was to examine the effects of nimodipine on salicylate ototoxicity in guinea pigs. The compound action potential (CAP) was recorded at the round window, and the cochlear blood flow (CBF) was measured simultaneously from the lateral wall of the basal turn of the cochlea by laser Doppler flowmetry. After administration of salicylate (100 mg/kg), the CAP thresholds were significantly elevated, by 5 to 20 dB (p < .05), and the CBF was significantly decreased (p < .05). After administration of nimodipine (2 mg/kg), the CAP thresholds were unchanged, but the CBF had increased significantly (p < .05), while systemic blood pressure had decreased significantly (p < .05). Simultaneous administration of both salicylate (100 mg/kg) and nimodipine (2 mg/kg) resulted in significant elevation of the CAP thresholds (p < .05), while the CBF did not decrease. These results suggest that nimodipine prevents the decrease in CBF induced by salicylate, but that nimodipine does not prevent the deterioration in the CAP.

Stimulation parameters differ between current anti-modiolar and peri-modiolar electrode arrays implanted within the same child

2016 ◽  
Vol 130 (11) ◽  
pp. 1007-1021 ◽  
Author(s):  
M J Polonenko ◽  
S L Cushing ◽  
K A Gordon ◽  
B Allemang ◽  
S Jewell ◽  
...  
Keyword(s):  
Action Potential ◽  
Round Window ◽  
Compound Action Potential ◽  
Surgical Approaches ◽  
Electrode Arrays ◽  
Time Points ◽  
Stimulation Parameters ◽  
Evoked Compound Action Potential ◽  
Stapedial Reflex ◽  
Compound Action

AbstractObjective:To compare stimulation parameters of peri-modiolar and anti-modiolar electrode arrays using two surgical approaches.Methods:Impedance, stimulation thresholds, comfortably loud current levels, electrically evoked compound action potential thresholds and electrically evoked stapedial reflex thresholds were compared between 2 arrays implanted in the same child at 5 time points: surgery, activation/day 1, week 1, and months 1 and 3. The peri-modiolar array was implanted via cochleostomy in all children (n = 64), while the anti-modiolar array was inserted via a cochleostomy in 43 children and via the round window in 21 children.Results:The anti-modiolar array had significantly lower impedance, but required higher current levels to elicit thresholds, comfort, electrically evoked compound action potential thresholds and electrically evoked stapedial reflex thresholds than the peri-modiolar array across all time points, particularly in basal electrodes (p < 0.05). The prevalence of open electrodes was similar in anti-modiolar (n = 5) and peri-modiolar (n = 3) arrays.Conclusion:Significant but clinically acceptable differences in stimulation parameters between peri-modiolar and anti-modiolar arrays persisted four months after surgery in children using bilateral cochlear implants. The surgical approach used to insert the anti-modiolar array had no overall effect on outcomes.

scholarly journals Changes over time in the electrically evoked compound action potential (ECAP) interphase gap (IPG) effect following cochlear implantation in Guinea pigs

2019 ◽  
Vol 383 ◽  
pp. 107809 ◽  
Author(s):  
Kara C. Schvartz-Leyzac ◽  
Deborah J. Colesa ◽  
Christopher J. Buswinka ◽  
Donald L. Swiderski ◽  
Yehoash Raphael ◽  
...  
Keyword(s):  
Action Potential ◽  
Cochlear Implantation ◽  
Guinea Pigs ◽  
Compound Action Potential ◽  
Evoked Compound Action Potential ◽  
Changes Over Time ◽  
Over Time ◽  
Compound Action

scholarly journals Comparative Studies on Distortion Product Otoacoustic Emissions and Compound Action Potential in Cisplatin Treated Guinea Pigs.

1997 ◽  
Vol 40 (6) ◽  
pp. 719-723
Author(s):  
Narihisa Tachihara ◽  
Hideki Okubo ◽  
Shigenori Satoh ◽  
Kazuhiko Takahashi ◽  
Tetsurou Wada ◽  
...  
Keyword(s):  
Action Potential ◽  
Comparative Studies ◽  
Guinea Pigs ◽  
Otoacoustic Emissions ◽  
Compound Action Potential ◽  
Distortion Product Otoacoustic Emissions ◽  
Distortion Product ◽  
Compound Action

The antidromic compound action potential of the auditory nerve

1994 ◽  
Vol 71 (5) ◽  
pp. 1826-1834 ◽  
Author(s):  
M. C. Brown
Keyword(s):  
Action Potential ◽  
Auditory Nerve ◽  
Refractory Period ◽  
Round Window ◽  
Compound Action Potential ◽  
Nerve Fibers ◽  
Negative Peak ◽  
Positive Peak ◽  
Auditory Nerve Fibers ◽  
Compound Action

1. The antidromic compound action potential (ACAP) of the auditory nerve was evoked by shocks to the auditory nerve root and recorded at the round window of the cochlea in anesthetized guinea pigs. The goal of this study was to determine the characteristics of the ACAP and compare these characteristics with those of the orthodromic, sound-evoked compound action potential (CAP). 2. The ACAP consists of an initial complex of a positive peak (p1) followed by a negative peak (n1). In contrast, the CAP consists of a negative peak (N1) followed by a positive peak (P1). These differences in waveform are likely due to the differences in conduction direction, antidromic for the ACAP vs. orthodromic for the CAP. 3. After the initial complex, the ACAP has a second complex of peaks (p2, n2) at a latency of approximately 1 ms; this complex is much smaller in amplitude than the initial complex (p1, n1). It is likely that the initial ACAP complex reflects firing of auditory-nerve fibers whereas the second complex reflects firing of neurons further centrally, perhaps in the cochlear nucleus, that are activated by orthodromic firing of auditory-nerve fibers. 4. Experiments with shock pairs are consistent with the idea that for auditory nerve fibers, the absolute refractory period is < 0.5 ms, and the relative refractory period is between 0.5 and at least 5 ms. 5. Experiments with click-shock pairs indicate that a shock interferes with the response to a click when the click and shock are given at about the same time.(ABSTRACT TRUNCATED AT 250 WORDS)

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