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Wright A, Forge A, Jagger DJ. Structural Changes in the Human Stria Vascularis Induced by Aminoglycosides and Loop Diuretics. Hear Res 2022. [DOI: 10.1016/j.heares.2022.108626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 09/05/2022] [Accepted: 09/30/2022] [Indexed: 11/20/2022]
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Tanyeli TT, Karadaş H, Akyıldız İ, Gökdoğan O, Sönmez Ç, Çavuş ME, Kaptan Z, Uzunkulaoğlu H, Arslan N, Zeybek ND. Effect of Folic Acid on Cisplatin-Induced Ototoxicity: A Functional and Morphological Study. J Int Adv Otol 2020; 15:237-246. [PMID: 31347504 DOI: 10.5152/iao.2019.6208] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
OBJECTIVES The aim of our study was to investigate the effects of folic acid on cisplatin-induced ototoxicity. MATERIALS AND METHODS Thirty Wistar albino rats were divided into five groups. Group I received intraperitoneal cisplatin (IP) 10 mg/kg/day and IP folic acid 10 mg/kg/day; Group II received IP cisplatin 10 mg/kg/day and IP physiological saline; Group III received IP cisplatin 10 mg/kg/day and intratympanic (IT) folic acid 0.15 mL/day; Group IV received IP cisplatin 10 mg/kg/day and IT physiological saline; and Group V received IT folic acid 0.15 mL/day. Before and after drug administration, plasma homocysteine, folic acid levels, and auditory brainstem evoked responses (ABR) were measured. The rats were then sacrificed, and the inner ears were processed for electron microscopy. RESULTS The differences of ABR thresholds in Group I compared to Group II were significantly smaller at 4 kHz, 8 kHz, and 16 kHz, whereas they were smaller but not statistically significant at 12 kHz in ABR. The differences of ABR thresholds in Group III compared to Group IV were significantly smaller at 12 kHz, and smaller but not statistically significant at 4 kHz, 8 kHz, and 16 kHz. Cisplatin treatment resulted in the degeneration of the cells of the organ of Corti, stria vascularis, and spiral ganglion. The cells of the organ of Corti, stria vascularis, and spiral ganglion showed a partially preserved morphology in both Group I and Group III. CONCLUSION Our study results suggests that folic acid is a potential agent in preventing cisplatin-induced ototoxicity.
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Affiliation(s)
- Talip Talha Tanyeli
- Clinic of Otorhinolaryngology, Head and Neck Surgery, Ankara Polatli State Hospital, Ankara, Turkey
| | - Hatice Karadaş
- Department of Otorhinolaryngology, Head and Neck Surgery, Ankara Training and Research Hospital, Ankara, Turkey
| | - İlker Akyıldız
- Department of Otorhinolaryngology, Head and Neck Surgery, Ankara Diskapi Training and Research Hospital, Ankara, Turkey
| | - Ozan Gökdoğan
- Clinic of Otorhinolaryngology, Memorial Health Group Ankara Hospital, Ankara, Turkey
| | - Çiğdem Sönmez
- Department of Biochemistry, Abdurrahman Yurtaslan Ankara Oncology Training and Research Hospital, Ankara, Turkey
| | - Mehmet Emin Çavuş
- Clinic of Otorhinolaryngology, Head and Neck Surgery, Ankara Polatli State Hospital, Ankara, Turkey
| | - Zeynep Kaptan
- Department of Otorhinolaryngology, Head and Neck Surgery, Ankara Training and Research Hospital, Ankara, Turkey
| | - Hakkı Uzunkulaoğlu
- Department of Otorhinolaryngology, Head and Neck Surgery, Meclis State Hospital, Ankara, Turkey
| | - Necmi Arslan
- Department of Otorhinolaryngology, Head and Neck Surgery, Ankara Training and Research Hospital, Ankara, Turkey
| | - Naciye Dilara Zeybek
- Department of Histology and Embryology, Hacettepe University School of Medicine, Ankara, Turkey
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Abstract
This is a reference chart that identifies 16 aminoglycoside antibiotics and platinum based drugs that could be cochleotoxic, vestibulotoxic or both. Using the most currently available data from published research from the National Library of Medicine's PubMed data base, incidence figures and risk factors are included in the chart along with the potential of permanence of reversibility of the impairment.
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Affiliation(s)
- Robert M DiSogra
- School of Communication Disorders and Deafness, Kean University, Union, New Jersey
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Lee C, Jones TA. Acute blockade of inner ear marginal and dark cell K + secretion: Effects on gravity receptor function. Hear Res 2018; 361:152-156. [PMID: 29459166 DOI: 10.1016/j.heares.2018.02.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 12/13/2017] [Accepted: 02/09/2018] [Indexed: 11/18/2022]
Abstract
Specific pharmacological blockade of KCNQ (Kv7) channels with XE991 rapidly (within 20 min) and profoundly alters inner ear gravity receptor responses to head motion (Lee et al., 2017). We hypothesized that these effects were attributable to the suppression of K+ secretion following blockade of KCNQ1-KCNE1 channels in vestibular dark cells and marginal cells. To test this hypothesis, K+ secretion was independently inhibited by blocking the Na+-K+-2Cl- cotransporter (NKCC1, Slc12a2) rather than KCNQ1-KCNE1 channels. Acute blockade of NKCC1 with ethacrynic acid (40 mg/kg) eliminated auditory responses (ABRs) within approximately 70 min of injection, but had no effect on vestibular gravity receptor function (VsEPs) over a period of 2 h in the same animals. These findings show that, vestibular gravity receptors are highly resistant to acute disruption of endolymph secretion unlike the auditory system. Based on this we argue that acute suppression of K+ secretion alone does not likely account for the rapid profound effects of XE991 on gravity receptors. Instead the effects of XE991 likely require additional action at KCNQ channels located within the sensory epithelium itself.
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Affiliation(s)
- Choongheon Lee
- University of Nebraska-Lincoln, Department of Special Education and Communication Disorders, Lincoln, NE 68583-0738, USA.
| | - Timothy A Jones
- University of Nebraska-Lincoln, Department of Special Education and Communication Disorders, Lincoln, NE 68583-0738, USA.
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Abstract
OBJECTIVES To describe the human temporal bone pathology in two patients who incurred furosemide induced ototoxicity. PATIENTS 1) A 46-year-old woman in acute liver and renal failure treated with high doses of furosemide for anasarca who developed a rapidly progressive severe-to-profound asymmetric sensorineural hearing loss. 2) A 65-year-old woman with undifferentiated small cell carcinoma of the lung who received intravenous furosemide 1 day prior to death for pulmonary edema. INTERVENTIONS Removal of temporal bones, histologic processing, and light microscopy of temporal bones. MAIN OUTCOME MEASURES Temporal bone histopathology and correlation with clinical and audiometric data. RESULTS All three temporal bones demonstrated edema and cystic changes in the stria vascularis. In the first case the furosemide exposure was associated with hearing loss and the pathological changes were more extensive including cystic changes in the Hensen's cells, collapse of Reissner's membrane and the tectorial membrane and diffuse loss of inner and outer hair cells with only modest reduction in the spiral ganglion cell population. In the second case, without attributable hearing loss, there was only modest reduction in hair cell and spiral ganglion cell counts. Pathological changes were not observed in the ampullae of the semicircular canals or epithelium of the saccular or utricular maculae in either case. CONCLUSIONS The temporal bone pathologic correlate for furosemide-induced ototoxicity is edema and cystic degeneration of the stria vascularis. The degree of degenerative change appears dose-dependent. We infer that pathological changes may occur in the absence of a measurable immediate clinical effect. LEVEL OF EVIDENCE NA.
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Affiliation(s)
- Felipe Santos
- Department of Otolaryngology, Massachusetts Eye and Ear Infirmary Boston Massachusetts U.S.A.,Department of Otolaryngology Harvard Medical School Boston Massachusetts U.S.A
| | - Joseph B Nadol
- Department of Otolaryngology, Massachusetts Eye and Ear Infirmary Boston Massachusetts U.S.A.,Department of Otolaryngology Harvard Medical School Boston Massachusetts U.S.A
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Lee C, Holt JC, Jones TA. Effect of M-current modulation on mammalian vestibular responses to transient head motion. J Neurophysiol 2017; 118:2991-3006. [PMID: 28855291 DOI: 10.1152/jn.00384.2017] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 08/25/2017] [Accepted: 08/25/2017] [Indexed: 12/26/2022] Open
Abstract
The precise role and mechanisms underlying efferent modulation of peripheral vestibular afferent function are not well understood in mammals. Clarifying the details of efferent action may lead to new strategies for clinical management of debilitating disturbances in vestibular and balance function. Recent evidence in turtle indicates that efferent modulation of M-currents is likely one mechanism for modifying afferent discharge. M-currents depend in part on KCNQ potassium conductances (Kv7), which can be adjusted through efferent activation of M1, M3, and/or M5 muscarinic acetylcholine receptors (mAChRs). How KCNQ channels and altered M-currents affect vestibular afferent function in vivo is unclear, and whether such a mechanism operates in mammals is unknown. In this study we used the KCNQ antagonist XE991 and the KCNQ activator retigabine in anesthetized mice to evaluate the effects of M-current modulation on peripheral vestibular responses to transient head motion. At low doses of XE991, responses were modestly enhanced, becoming larger in amplitude and shorter in latency. Higher doses of XE991 produced transient response enhancement, followed by steady-state suppression where latencies and thresholds increased and amplitudes decreased. Retigabine produced opposite effects. Auditory function was also impacted, based on results of companion auditory brain stem response testing. We propose that closure of KCNQ channels transforms vestibular afferent behavior by suppressing responses to transient high-frequency stimuli while simultaneously enhancing responses to sustained low-frequency stimulation. Our results clearly demonstrate that KCNQ channels are critical for normal mammalian vestibular function and suggest that efferent action may utilize these mechanisms to modulate the dynamic characteristics and gain of vestibular afferent responses.NEW & NOTEWORTHY The role of calyceal KCNQ channels and associated M-current in normal mammalian vestibular function is unknown. Our results show that calyceal KCNQ channels are critical for normal vestibular function in the intact mammal. The findings provide evidence that efferent modulation of M-currents may act normally to differentially adjust the sensitivity of vestibular neurons to transient and tonic stimulation and that such mechanisms may be targeted to achieve effective clinical management of vestibular disorders.
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Affiliation(s)
- Choongheon Lee
- Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, Lincoln, Nebraska; and
| | - J Chris Holt
- Department of Otolaryngology, Department of Neuroscience, and Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York
| | - Timothy A Jones
- Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, Lincoln, Nebraska; and
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Ding D, Liu H, Qi W, Jiang H, Li Y, Wu X, Sun H, Gross K, Salvi R. Ototoxic effects and mechanisms of loop diuretics. J Otol 2016; 11:145-56. [PMID: 29937824 DOI: 10.1016/j.joto.2016.10.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 10/17/2016] [Accepted: 10/18/2016] [Indexed: 12/22/2022] Open
Abstract
Over the past two decades considerable progress has been made in understanding the ototoxic effects and mechanisms underlying loop diuretics. As typical representative of loop diuretics ethacrynic acid or furosemide only induces temporary hearing loss, but rarely permanent deafness unless applied in severe acute or chronic renal failure or with other ototoxic drugs. Loop diuretic induce unique pathological changes in the cochlea such as formation of edematous spaces in the epithelium of the stria vascularis, which leads to rapid decrease of the endolymphatic potential and eventual loss of the cochlear microphonic potential, summating potential, and compound action potential. Loop diuretics interfere with strial adenylate cyclase and Na+/K+-ATPase and inhibit the Na-K-2Cl cotransporter in the stria vascularis, however recent reports indicate that one of the earliest effects in vivo is to abolish blood flow in the vessels supplying the lateral wall. Since ethacrynic acid does not damage the stria vascularis in vitro, the changes in Na+/K+-ATPase and Na-K-2Cl seen in vivo may be secondary effects results from strial ischemia and anoxia. Recent observations showing that renin is present in pericytes surrounding stria arterioles suggest that diuretics may induce local vasoconstriction by renin secretion and angiotensin formation. The tight junctions in the blood-cochlea barrier prevent toxic molecules and pathogens from entering cochlea, but when diuretics induce a transient ischemia, the barrier is temporarily disrupted allowing the entry of toxic chemicals or pathogens.
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Abstract
The modern era of evidence-based ototoxicity emerged in the 1940s following the discovery of aminoglycosides and their ototoxic side effects. New classes of ototoxins have been identified in subsequent decades, notably loop diuretics, antineoplastic drugs, and metal chelators. Ototoxic drugs are frequently nephrotoxic, as both organs regulate fluid and ion composition. The mechanisms of ototoxicity are as diverse as the pharmacological properties of each ototoxin, though the generation of toxic levels of reactive oxygen species appears to be a common denominator. As mechanisms of cytotoxicity for each ototoxin continue to be elucidated, a new frontier in ototoxicity is emerging: How do ototoxins cross the blood-labyrinth barrier that tightly regulates the composition of the inner ear fluids? Increased knowledge of the mechanisms by which systemic ototoxins are trafficked across the blood-labyrinth barrier into the inner ear is critical to developing new pharmacotherapeutic agents that target the blood-labyrinth barrier to prevent trafficking of ototoxic drugs and their cytotoxic sequelae.
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Affiliation(s)
- Peter S Steyger
- Oregon Hearing Research Center, Oregon Health and Science University, Portland, Oregon
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9
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Abstract
Acoustic exposure to high intensity and/or prolonged noise causes temporary or permanent threshold shifts in auditory perception, reflected by reversible or irreversible damage in the cochlea. Aminoglycoside antibiotics, used for treating or preventing life-threatening bacterial infections, also induce cytotoxicity in the cochlea. Combined noise and aminoglycoside exposure, particularly in neonatal intensive care units, can lead to auditory threshold shifts greater than simple summation of the two insults. The synergistic toxicity of acoustic exposure and aminoglycoside antibiotics is not limited to simultaneous exposures. Prior acoustic insult which does not result in permanent threshold shifts potentiates aminoglycoside ototoxicity. In addition, exposure to subdamaging doses of aminoglycosides aggravates noise-induced cochlear damage. The mechanisms by which aminoglycosides cause auditory dysfunction are still being unraveled, but likely include the following: 1) penetration into the endolymphatic fluid of the scala media, 2) permeation of nonselective cation channels on the apical surface of hair cells, and 3) generation of toxic reactive oxygen species and interference with other cellular pathways. Here we discuss the effect of combined noise and aminoglycoside exposure to identify pivotal synergistic events that can potentiate ototoxicity, in addition to a current understanding of aminoglycoside trafficking within the cochlea. Preventing the ototoxic synergy of noise and aminoglycosides is best achieved by using non-ototoxic bactericidal drugs, and by attenuating perceived noise intensity when life-saving aminoglycoside therapy is required.
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Affiliation(s)
- Hongzhe Li
- Oregon Hearing Research Center, Oregon Health and Science University, Portland, Oregon, USA
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10
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FORGE ANDREW. The endolymphatic surface of the stria vascularis in the guinea-pig and the effects of ethacrynic acid as shown by scanning electron microscopy. Clin Otolaryngol 2009. [DOI: 10.1111/j.1365-2273.1980.tb02119.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Freeman S, Priner R, Mager M, Sichel JY, Perez R, Elidan J, Sohmer H. Use of evoked potentials to objectively differentiate between selective vulnerability of cochlear and vestibular end organ function. J Basic Clin Physiol Pharmacol 2001; 11:193-200. [PMID: 11041383 DOI: 10.1515/jbcpp.2000.11.3.193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Auditory nerve brainstem evoked responses (ABR) have been used for several decades to investigate cochlear function. Recently techniques have been developed to elicit similar recordings from the vestibular end organs - short latency vestibular evoked potentials (VsEPs). Both ABR and VsEP reflect appropriate end organ function and may therefore be used to investigate the vulnerability of these end organs to various experimental insults, such as noise exposure and ototoxic drugs.
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Affiliation(s)
- S Freeman
- Department of Physiology, Hebrew University-Hadassah Medical School, Jerusalem, Israel
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13
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Abstract
Recent advances in molecular biology have been applied to inner ear research. Loop diuretic ototoxicity has been suggested, but not proven, to share a common mechanism with diuretic effects on renal tubules. The discovery of the molecular nature of the Na-K-2Cl cotransporter in the cochlea provided a better understanding of loop diuretic ototoxicity. In this review, we describe clinical reports of loop diuretic ototoxicity and other information obtained by physiological, biochemical and morphological investigations related to the mechanism sensitive to loop diuretics. Based on recent evidence for the molecular nature of the Na-K-2Cl cotransporter expressed in the mammalian cochlea, the underlying mechanisms of ototoxicity induced by loop diuretics are described.
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Affiliation(s)
- K Ikeda
- Department of Otorhinolaryngology, Tohoku University School of Medicine, Sendai, Japan
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Whitehead ML, Lonsbury-martin BL, Martin GK, Mccoy MJ. Otoacoustic Emissions: Animal Models and Clinical Observations. In: Van De Water TR, Popper AN, Fay RR, editors. Clinical Aspects of Hearing. New York: Springer; 1996. pp. 199-257. [DOI: 10.1007/978-1-4612-4068-6_7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Affiliation(s)
- J M Aran
- Laboratoire d'Audiologie Expérimentale, Hôpital Pellegrin, INSERM, Bordeaux, France
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Affiliation(s)
- P M Scott
- Department of ENT, Bristol Royal Infirmary, UK
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Abstract
A microelectrode was used to measure endocochlear potentials (EP) in adult chinchillas and to study the effects of a series of loop diuretics. EP was measured before, during and for several hours after the intravenous injection of the following loop diuretics: furosemide, piretanide, bumetanide, ethacrynic acid, indacrinone stereoisomers and ozolinone. The first four loop diuretics caused a substantial dose-related reduction of EP. The (-) isomer of indacrinone was found to cause a dose-related reduction of EP to a moderate degree. The (+) isomer of indacrinone and ozolinone caused very little change of EP, even in very high doses. Findings are consistent with data on the mechanism of action of these agents in the kidney.
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Affiliation(s)
- L P Rybak
- Department of Surgery, Southern Illinois University School of Medicine, Springfield 62794-9230
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Abstract
The interrelationship of stria vascularis and organ of Corti integrity was investigated. Strial morphology was altered by repeated injections of ethacrynic acid in the chinchilla. Although prolonged temporary strial damage was created, neither strial atrophy nor organ of Corti damage resulted.
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Affiliation(s)
- A J Duvall
- Department of Otolaryngology, Medical School, University of Minnesota, Minneapolis 55455
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20
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Abstract
Previous studies have shown a reduction of the ototoxicity of furosemide in chinchillas pretreated with organic acid transport inhibitors. The current studies were designed to investigate whether such a protective effect could be observed in chinchillas receiving ethacrynic acid. Chinchillas weighing 400-600 g were injected with saline followed by ethacrynic acid 12.5 mg/kg i.v. (controls) or one of three organic acids (probenecid, penicillin G and or sodium salicylate) 50 mg/kg i.v., thirty minutes prior to ethacrynic acid injection (experimentals). Endocochlear potential (EP) and compound action potential of the eighth nerve (CAP) elicited by click stimuli were simultaneously monitored before and after injection in both groups. The mean change in EP and CAP findings are consistent with observations by other investigators of the actions of these loop diuretics in the isolated loop of Henle. In the latter tissues, the 'furosemide-like loop diuretics' appear to have a different mechanism of action than does ethacrynic acid. It appears from the findings of the present study that the actions of furosemide and ethacrynic acid on the cochlea are by different mechanisms as well.
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Affiliation(s)
- L P Rybak
- Department of Surgery, Southern Illinois University School of Medicine, Springfield 62794-9230
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Abstract
Ototoxicity is a disabling adverse effect of several widely used classes of drugs, such as diuretics, anti-inflammatory agents, antineoplastic agents and aminoglycoside antibiotics. High-dose therapy with either diuretics or anti-inflammatory agents is primarily associated with acute and transient impairment of hearing or tinnitus. In contrast, long term treatment with antineoplastic agents or aminoglycoside antibiotics is typically associated with delayed and irreversible loss of hearing; lesion in the organ of Corti include the destruction of auditory sensory cells. Vestibular function can also be compromised by ototoxic drugs. Occasional cases of ototoxicity have been reported for a variety of other therapeutic compounds and environmental toxins. In addition, the simultaneous administration of multiple agents which are potentially ototoxic can lead to synergistic loss of hearing. Exposure to loud noise may also potentiate the hearing loss due to cochleotoxic drugs. Ototoxic agents can impair the sensory processing of sound at many cellular or subcellular sites. However, the molecular mechanisms of ototoxicity have not been established for most of these drugs, and structure-toxicity relationships have not been determined. It has therefore been difficult to predict the ototoxic potential of new drugs, and rational approaches to the prevention of ototoxicity are still lacking. The clinical and experimental features of ototoxicity are reviewed for several classes of drugs, with an emphasis on current knowledge of the mechanism and the possibilities for the prevention of ototoxicity for each.
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Affiliation(s)
- M Y Huang
- Kresge Hearing Research Institute, University of Michigan, Ann Arbor
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Abstract
Endocochlear potential (EP) and eighth nerve action potential (AP) were measured in chinchillas. We investigated the interaction of quinine with the loop diuretics furosemide and ethacrynic acid to determine whether the cochlear effects of these agents are attenuated by pretreatment with quinine. Animals were injected with either furosemide, 25 mg/kg intravenously (IV), or ethacrynic acid, 15 mg/kg IV. Control animals injected without pretreatment were found to have a large decrease in EP, with a decrease of compound action potentials (CAP) amplitude and an elevation of CAP threshold. Animals pretreated with quinine, 25 mg/kg, were found to have a significantly smaller reduction of EP and CAP amplitude following injection of either diuretic. No significant differences in urine volumes were noted between experimental and control groups. Quinine is known to cause nonspecific changes in the membranes of epithelial cells, which may cause alterations of the transport of organic anions by such tissues. Such an effect on epithelial cells in the cochlea may cause reduced uptake of loop diuretics in this organ, resulting in reduced toxicity.
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Affiliation(s)
- L P Rybak
- Department of Surgery, SIU School of Medicine 62794-9230
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Abstract
This article considers the types of deafness in small animals and how electrodiagnostic testing can aid in evaluating auditory dysfunction.
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Affiliation(s)
- M H Sims
- Department of Animal Science, University of Tennessee College of Veterinary Medicine, Knoxville
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24
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Affiliation(s)
- L P Rybak
- Division of Otolaryngology, Southern Illinois University School of Medicine, Springfield 62708
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Anniko M, Wróblewski R. Simultaneous investigations of elemental changes in individual cells of the stria vascularis and in endolymph. Arch Otorhinolaryngol 1988; 244:346-9. [PMID: 3348750 DOI: 10.1007/bf00497462] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Using the microprobe for energy dispersive X-ray microanalysis, the elemental compositions of both the individual cells of the stria vascularis and of the endolymph were followed simultaneously under normal conditions and after the administration of 120 mg/kg ethacrynic acid (EA). Marginal cells and intermediate cells showed reversible increases in potassium and decreases in sodium concentrations. Shifts in the ionic composition of endolymph occurred later than after elemental changes in the strial cells. The present results indicate that the marginal and the intermediate cells are the primary target for EA-induced ototoxicity. However, generalized toxic effects of EA are also indicated, with a general leakage of different elements occurring during the 30-60 min period after EA administration.
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Affiliation(s)
- M Anniko
- Department of Otolaryngology-Head & Neck Surgery, Umeå University Hospital, Sweden
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Abstract
Ultrastructural changes in the guinea pig spiral prominence were studied at various times after a single intravenous injection of ethacrynic acid (40 mg/kg body-weight). Initial swelling of endolymph-facing epithelial cells was followed by dilatation of the intercellular spaces and marked shrinkage of the stroma cells surrounding the spiral prominence vessel. While the changes in the stria vascularis and the spiral prominence progressed at about the same pace, the regression to normal ultrastructure set in earlier in the spiral prominence.
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Abstract
The temporal bones of a patient who suffered sudden deafness and ataxia after administration of both furosemide and ethacrynic acid, were prepared for light and electron microscopy. There was no loss of hair or supporting cells. However, some hair cells, in both the vestibular neuroepithelium and the organ of Corti, particularly in the basal turn, were more densely staining and more granular than normal. Membrane whorls also were common within mitochondria of such cells. The endoplasmic reticulum of some spiral ganglion cells was dilated. The major cytologic changes were found in the stria vascularis of the cochlea and dark cell areas of the vestibular system. There was marked dilatation of the intercellular fluid spaces, consistent with the biochemical observation that loop diuretics interfere first with enzyme systems responsible for fluid transport within the inner ear.
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Abstract
The Davis theory of mechano-electrical transduction asserts that the endocochlear potential and the hair cell resting potential summate to provide a driving force for current flow through the hair cell. However, while a variety of agents which depress the endocochlear potential simultaneously depress auditory nerve sensitivity and reduce the cochlear microphonic, recent reports suggest that the hair cells may be depolarised without such effects ensuing. The relevant literature is reviewed.
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29
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Forge A. The endolymphatic surface of the stria vascularis in the guinea-pig and the effects of ethacrynic acid as shown by scanning electron microscopy. Clin Otolaryngol 1980; 5:87-95. [PMID: 7371215 DOI: 10.1111/j.1365-2273.1980.tb01633.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Examination of the endolymphatic surface of the stria vascularis showed, in agreement with previous studies, the marginal cells to be hexagonal in shape and that most possessed microvilli. However, the cells in the apical turns were more profusely covered with microvilli than those at the base and, particularly in the basal turns, there was some variation in the surface detail of the cells. These results may indicate differences in the physiological state of the cells. In the early period of ethacrynic acid intoxication (15-30 minutes post-injection), when rapid changes in endolymphatic potential and ion-fluxes occur, the surface of the marginal cells showed only slight distortion. The most dramatic changes were noted 1 hour post-injection, and involved swelling of the cells and loss of microvilli. This distortion persisted up to 2 hours post-injection. The possible explanation for these findings is discussed.
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Abstract
Aminoglycoside antibiotics are frequently employed in the treatment of serious infections caused by aerobic gram negative bacilli. The use of these potent antibacterial agents is limited by the risks of ototoxicity and nephrotoxicity. Aminoglycosides are excreted by glomerular filtration at a rate proportional to the serum concentration. Impaired renal excretion reduces the rate of clearance from the serum. Utilizing information about aminoglycoside pharmacokinetics, the susceptibility of infecting pathogens to aminoglycosides, and risk factors for ototoxicity, physicians can attempt to optimize the administratioin of an aminoglycoside to maximize the therapeutic efficacy and to minimize the risk of ototoxicity. Periodic assessments of renal function and of aminoglycoside levels in the serum are essential to guide therapy. The otolaryngologist and audiologist must be able to provide information about ototoxicity to medical colleagues using these drugs. They should also be prepared to evaluate and follow patients who develop sensorineural inner ear dysfunction during or after a course of therapy with an aminoglycoside antibiotic.
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Abstract
The effects of intra-arterial 30-, 40-, and 50-mg/kg doses of ethacrynic acid upon cochlear function in guinea pigs were studied for periods of three to five hours. Cochlear potentials recorded in the first turn included the endocochlear potential, whole nerve response, cochlear microphonics, and summating potentials in scala media, scala tympani, and scala vestibuli. Evidence of organ of Corti damage at 50 mg/kg was found in addition to electrical impedance changes in the cochlear membranes at all dose levels.
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Brown RD, Manno JE, Daigneault EA, Manno BR. Comparative acute ototoxicity of intravenous bumetanide and furosemide in the pure-bred beagle. Toxicol Appl Pharmacol 1979; 48:157-69. [PMID: 452038 DOI: 10.1016/s0041-008x(79)80018-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Abstract
Guidelines are suggested for the surveillance and prevention of ototoxicity in adults, based on experience and a compilation of opinions from otolaryngologists and infectious disease specialists. The influence of dosage and renal function on serum levels and their relevance to ototoxicity are discussed. Indications for testing of inner ear function are considered.
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Abstract
Chinchillas were given either a single injection of the diuretic bumetanide (18 mg/kg body weight) or saline-sodium hydroxide and sacrificed at 10 min, 1 hr and 24 hr after the injection. Slight stria edema was present at 10 min, marked edema at 1 hr and no edema 24 h after bumetanide. The edema began in the first cochlear turn at 10 min and spread to the second turn by 1 hr. Along with edema, marginal cell bulging, potential capillary constriction and the formation of marginal cell membranous structures occurred after bumetanide treatment.
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Abstract
After i.v. injection of 50 mg/kg ethacrynic acid (EA), potassium concentration in the endolymph (Ke+) measured with K+-specific microelectrodes decreases by 10 mM at the most and endocochlear potential falls to negative values. Potassium concentration in the perilymph (Kp+) generally does not change, but sometimes a transient decrease in Kp+ level of about 0.5 mM was observed, presumably due to the electrogenic effect of the time-related decrease of the endocochlear potential. When anoxia is induced approximately 120 min after EA administration Ke+ slowly decreases. The decrease in Ke+ 50 min after the arrest of ventilation is smaller when compared with the Ke+ anoxic decrease without preceding EA administration. The endocochlear potential, which falls to negative values during anoxia after EA administration, does not return to the zero level as in the case when only anoxia is applied. Similarly, during anoxia, which follows EA administration, the perilymphatic Ke+ concentration increases more slowly than in the case when only anoxia is introduced. It is assumed from the results that EA abolishes activity of the positive electrogenic K+ pump and reduces the passive permeability of the walls of the cochlear duct to the potassium ions.
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Anniko M. Reversible and irreversible changes of the stria vascularis. An evaluation of the effects of ethacrynic acid separately and in combination with atoxyl. Acta Otolaryngol 1978; 85:349-59. [PMID: 665208 DOI: 10.3109/00016487809121463] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The morphological changes in the cochlea following administration of ethacrynic acid occur initially in the stria vascularis of the basal coils as an increased intracellular vesiculation of the marginal cells followed by inter- and intracellular oedema in the intermediate cell layer. The combined administration of ethacrynic acid and atoxyl (individual doses) can cause irreversible damage to the cochlear hair cells and the stria vascularis, while the administration of each of them separately in the same low dose did not cause hair cell degeneration or persistent morphological changes of the stria vascularis. An increased penetration of atoxyl into the cochlea is likely to occur due to the ethacrynic acid-induced changes in the permeability of the endolymphatic partition so that the earlier known penetration of atoxyl into the cochlea is increased.
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