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Takeda T, Takeda S, Kakigi A. A possible mechanism of the formation of endolymphatic hydrops and its associated inner ear disorders. Auris Nasus Larynx 2019; 47:25-41. [PMID: 31623941 DOI: 10.1016/j.anl.2019.09.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 08/29/2019] [Accepted: 09/12/2019] [Indexed: 12/19/2022]
Abstract
The pathology of Meniere's disease (MD) is well established to be endolymphatic hydrops. However, the mechanism underlying deafness and vertigo of MD or idiopathic endolymphatic hydrops is still unknown. In order to evaluate the pathogenesis of deafness and vertigo in MD, it seems to be rational to investigate the interrelationship between hydrops and inner ear disorders using animals with experimentally-induced endolymphatic hydrops. In spite of intense efforts by many researchers, the mechanism of vertiginous attack has been unexplained, because animals with experimental hydrops usually did not show vertiginous attack. Recently, there are two reports to succeed to evoke vertiginous attack in animals with experimental hydrops. In the present paper were first surveyed past proposals about underlying mechanism of the development of hydrops and inner ear disorders associated with hydrops, and were discussed the pathogenetic mechanism of vertiginous attack in hydrops. In conclusion, abrupt development of hydrops was thought to play a pivotal role in the onset of vertiginous seizure.
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Affiliation(s)
- Taizo Takeda
- Department of Otolaryngology, Kochi Medical School, Nankoku, Kochi, Japan
| | | | - Akinobu Kakigi
- Department of Otolaryngology-Head & Neck Surgery, Kobe University, Graduate School of Medicine, Hyogo, Japan.
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Salt AN, Plontke SK. Endolymphatic hydrops: pathophysiology and experimental models. Otolaryngol Clin North Am 2010; 43:971-83. [PMID: 20713237 DOI: 10.1016/j.otc.2010.05.007] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
It is well established that endolymphatic hydrops plays a role in Ménière disease, even though the precise role is not fully understood and the presence of hydrops in the ear does not always result in symptoms of the disease. It nevertheless follows that a scientific understanding of how hydrops arises, how it affects the function of the ear, and how it can be manipulated or reversed could contribute to the development of effective treatments for the disease. Measurements in animal models in which endolymphatic hydrops has been induced have given numerous insights into the relationships between hydrops and other pathologic and electrophysiological changes, and how these changes influence the function of the ear. The prominent role of the endolymphatic sac in endolymph volume regulation, and the cascade of histopathological and electrophysiological changes that are associated with chronic endolymphatic hydrops, have now been established. An increasing number of models are now available that allow specific aspects of the interrelationships to be studied. The yclical nature of Ménière symptoms gives hope that treatments can be developed to maintain the ear in permanent state of remission, possibly by controlling endolymphatic hydrops, thereby avoiding the rogressive damage and secondary pathologic changes that may also contribute to the patient's symptoms.
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Affiliation(s)
- Alec N Salt
- Department of Otolaryngology, Washington University School of Medicine, Box 8115, 660 South Euclid Avenue, St Louis, MO 63110, USA.
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Ichimiya I, Yoshida K, Hirano T, Suzuki M, Mogi G. Aspects of cochlear lateral wall inflammation. ACTA ACUST UNITED AC 2009. [DOI: 10.1080/1651386410018187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Salt AN, Brown DJ, Hartsock JJ, Plontke SK. Displacements of the organ of Corti by gel injections into the cochlear apex. Hear Res 2009; 250:63-75. [PMID: 19217935 DOI: 10.1016/j.heares.2009.02.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Revised: 01/16/2009] [Accepted: 02/05/2009] [Indexed: 11/20/2022]
Abstract
In order to transduce sounds efficiently, the stereocilia of hair cells in the organ of Corti must be positioned optimally. Mechanical displacements, such as pressure differentials across the organ caused by endolymphatic hydrops, may impair sensitivity. Studying this phenomenon has been limited by the technical difficulty of inducing sustained displacements of stereocilia in vivo. We have found that small injections (0.5-2 microL) of Healon gel into the cochlear apex of guinea pigs produced sustained changes of endocochlear potential (EP), summating potential (SP) and transducer operating point (OP) in a manner consistent with a mechanically-induced position change of the organ of Corti in the basal turn. Induced changes immediately recovered when injection ceased. In addition, effects of low-frequency bias tones on EP, SP and OP were enhanced during the injection of gel and remained hypersensitive after injection ceased. This is thought to result from the viscous gel mechanically limiting pressure shunting through the helicotrema. Cochlear microphonics measured as frequency was varied showed enhancement below 100 Hz but most notably in the sub-auditory range. Sensitivity to low-frequency biasing was also enhanced in animals with surgically-induced endolymphatic hydrops, suggesting that obstruction of the perilymphatic space by hydrops could contribute to the pathophysiology of this condition.
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Affiliation(s)
- Alec N Salt
- Department of Otolaryngology, Box 8115, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
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Morizono T, Kondo T, Yamano T, Miyagi M, Shiraishi K. Chronological changes in the eighth cranial nerve compound action potential (CAP) in experimental endolymphatic hydrops: the effects of altering the polarity of click sounds. Acta Otolaryngol 2009:32-7. [PMID: 19221904 DOI: 10.1080/00016480902729835] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
CONCLUSION Using a guinea pig model of experimental endolymphatic hydrops, click sounds of altered polarity showed different latencies and amplitudes in hydropic compared with normal cochleae. Latency changes appeared as early as 1 week after endolymphatic obstruction. This method can help diagnose endolymphatic hydrops. OBJECTIVE The goal of the study was to develop an objective electrophysiological diagnosis of endolymphatic hydrops. MATERIALS AND METHODS Endolymphatic hydrops were created surgically in guinea pigs. The latency and the amplitude of the eighth cranial nerve compound action potential (CAP) for click sounds of altered polarity were measured up to 8 weeks after the surgery. RESULTS At early stages after surgery, the latency for condensation clicks became longer, and at later stages the latencies for both condensation and rarefaction became longer. The discrepancy in the latencies for rarefaction and condensation click sounds (rarefaction minus condensation) became larger by the first week after surgery, but no further discrepancy occurred thereafter. Compared with latency changes, amplitude changes in the CAP were rapid and progressive following surgery, suggesting ongoing damage to hair cells.
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Salt AN. Acute endolymphatic hydrops generated by exposure of the ear to nontraumatic low-frequency tones. J Assoc Res Otolaryngol 2004; 5:203-14. [PMID: 15357421 PMCID: PMC2538404 DOI: 10.1007/s10162-003-4032-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Low-frequency sounds presented at high nontraumatizing levels induce temporary hyperacusis in humans and animals. One explanation of this finding is that the basilar membrane operating point may be disturbed by an endolymph volume change. This possibility was investigated using volume and flow markers iontophoresed into the endolymphatic space of guinea pigs. Marker concentrations were measured with ion-selective microelectrodes placed apically and basally to the iontophoresis site during exposure of the ear to low-frequency tones. Concentration changes were interpreted quantitatively using a finite-element model of the endolymphatic space that allowed changes of endolymph cross-sectional area and flow to be derived. Stimulation with a 200 Hz tone at 115 dB SPL for 3 min produced marker concentration changes consistent with the induction of transient endolymphatic hydrops and a basally directed displacement of endolymph. Endocochlear potentials were greater than normal after the exposure when hydrops was present. During identical tone exposures of animals without marker, we found that action potential (AP) threshold changes and endolymph potassium changes associated with the hydropic state were small. Marker concentration changes were compared with changes in endocochlear potential and AP thresholds for a range of exposure frequencies and levels. AP hypersensitivity occurred with 200 Hz exposure levels below those inducing endolymph volume disturbances. Endolymph volume changes are thought to be the result of, rather than the cause of, changes in operating point of the cochlear transducer. The observations that auditory threshold and endolymph potassium changes are minimal under conditions where substantial endolymphatic hydrops is present is relevant to our understanding of the hearing loss in patients with Meniere's disease.
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Affiliation(s)
- Alec N Salt
- Department of Otolaryngology, Washington University School of Medicine, St Louis, MO 63110, USA.
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Hsu CJ, Tan CT, Shau WY, Chen YS, Yeh TH, Lin-Shiau SY. Na+,K+-ATPase and Ca2+-ATPase activities in the cochlear lateral wall following surgical induction of hydrops. Hear Res 2001; 156:95-103. [PMID: 11377885 DOI: 10.1016/s0378-5955(01)00270-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Na+,K+-ATPase and Ca2+-ATPase activities have not been studied quantitatively in the cochlea affected by endolymphatic hydrops. The present study was designed to measure quantitatively the Na+,K+-ATPase and Ca2+-ATPase activities in the cochlear lateral wall and the threshold of auditory brainstem response (ABR) for guinea pigs in the early stages (=2 months) of experimentally induced endolymphatic hydrops. A significant negative association was demonstrated between Ca2+-ATPase activity and the change in ABR threshold for hydropic cochleae (P=0.014), but not for control cochleae (P=0.123), although no such significant association was revealed between Na+,K+-ATPase activity and any change in ABR threshold for both hydropic cochleae (P=0.751) and control cochleae (P=0.352). A significant increase in Ca2+-ATPase activity in the cochlear lateral wall was observed for the hydropic ear, in which normal ABR thresholds were maintained, as compared to the control ear. On the contrary, a mild decrease in Ca2+-ATPase activity in the cochlear lateral wall was observed for the hydropic ear, in which ABR thresholds increased significantly. The present findings suggest that alterations of Ca2+-ATPase activity in the cochlear lateral wall may implicate disturbed calcium-homeostasis in the inner ear, resulting in hearing dysfunction in the early stages of experimentally induced endolymphatic hydrops.
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Affiliation(s)
- C J Hsu
- Department of Otorlaryngology, National Taiwan University Hospital, Taipei.
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Lohuis PJ, Klis SF, Klop WM, van Emst MG, Smoorenburg GF. Signs of endolymphatic hydrops after perilymphatic perfusion of the guinea pig cochlea with cholera toxin; a pharmacological model of acute endolymphatic hydrops. Hear Res 1999; 137:103-13. [PMID: 10545638 DOI: 10.1016/s0378-5955(99)00130-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
There are indications that endolymph homeostasis is controlled by intracellular cAMP levels in cells surrounding the scala media. Cholera toxin is a potent stimulator of adenylate cyclase, i.e. it increases cAMP levels. We hypothesized that perilymphatic perfusion of cholera toxin might increase endolymph volume by stimulating adenylate cyclase activity, providing us with a pharmacological model of acute endolymphatic hydrops (EH). Guinea pig cochleas were perfused with artificial perilymph (15 min), with or without cholera toxin (10 microg/ml). The endocochlear potential (EP) was measured during and after perfusion. The summating potential (SP), evoked by 2, 4 and 8 kHz tone bursts, was measured via an apically placed electrode 0, 1, 2, 3 and 4 h after perfusion. Thereafter, the cochleas were fixed to enable measurement of the length of Reissner's membrane, reflecting EH. After perfusion the EP increased significantly over time in the cholera toxin group as compared to the controls. Also, the SP increased gradually at all frequencies in the cholera toxin group. Comparison within animals showed that the increase in SP became significant after 2 h at 4 kHz, after 3 h at 2 kHz and after 4 h at 8 kHz. In the control group the SP did not change significantly. The compound action potential (CAP) amplitude decreased monotonically over time at all frequencies in both the cholera toxin group and the control group, but it decreased faster in the cholera toxin group. Also, the cochlear microphonics amplitude decreased over time at all frequencies in both groups, but the decrease was significant only in the cholera toxin group after 3 h at 2 and 4 kHz. Quantification of the length of Reissner's membrane showed a small but insignificant enlargement in the cholera toxin treated animals compared to controls. These results are in accord with our view that EH is accompanied by an increase in SP and a decrease in CAP. Our results partially confirm previous results of Feldman and Brusilow (Proc. Natl. Acad. Sci. USA (1973) 73, 1761-1764). New aspects in relation to that study are the significantly increased EP and SP. In the classical EH model, based on obstruction of the absorptive function of the endolymphatic sac, increased SPs are accompanied by decreased EPs. In this cholera toxin model of EH, it is unlikely that the endolymphatic sac is involved. Apparently, EH can be based on mechanisms located in the cochlea itself as opposed to mechanisms located in the endolymphatic sac.
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Affiliation(s)
- P J Lohuis
- Hearing Research Laboratories, Department of Otorhinolaryngology, Utrecht University, Room G.02.531, Heidelberglaan 100, NL-3584 CX, Utrecht, The Netherlands.
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Rappaport JM, Bhatt SM, Kimura RS, Lauretano AM, Levine RA. Electron microscopic temporal bone histopathology in experimental pneumococcal meningitis. Ann Otol Rhinol Laryngol 1999; 108:537-47. [PMID: 10378520 DOI: 10.1177/000348949910800603] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Bacterial meningitis is one of the most common causes of acquired profound sensorineural deafness in children. Measurement of hearing and examination of the cochlea is limited in patients suffering from acute meningitis. A rabbit model of pneumococcal meningitis was developed to identify the temporal bone histopathologic changes that occur in meningogenic labyrinthitis caused by Streptococcus pneumoniae. Light microscopy was previously performed on temporal bones from acutely meningitic rabbits with profound hearing loss as determined electrophysiologically. Extensive inflammation of the cochlea with endolymphatic hydrops was observed. The organ of Corti, however, showed preserved architecture in the majority of these animals. In order to further investigate these findings, a protocol was used to create meningitic rabbits with hearing loss ranging from early high-frequency loss to profound deafness. The temporal bones from 7 rabbits were examined by transmission electron microscopy. In cases of mild hearing loss, partial degeneration of the inner row of outer hair cells, as well as edema of efferent cochlear nerve endings and marginal cells of the stria vascularis, was seen. With increasing degrees of hearing loss, the remainder of the organ of Corti and intermediate cells of the stria showed ultrastructural abnormalities. Spiral ganglion cells and basal cells of the stria vascularis remained intact in all subjects. This study provides unique information regarding the histology and pathophysiology of meningogenic deafness. The clinical implications of these findings are discussed, with an emphasis on potentially reversible changes and therapeutic intervention.
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Affiliation(s)
- J M Rappaport
- Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, USA
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Abstract
We investigated the effect of acute endolymphatic hydrops on the positive endocochlear potential (+EP) and negative endocochlear potential (-EP). The +EP was measured in guinea pigs during injection (without outlet) and perfusion (with outlet) of artificial endolymph into the cochlear duct. The -EP was measured during anoxia after the injection or the perfusion had finished. Injection of artificial endolymph produced a slight transient increase in the +EP, and a significant decrease in the magnitude of the -EP. Chronic endolymphatic hydrops produces both +EP and -EP decrease. The +EP decrease in chronic endolymphatic hydrops may cause the chronic change of the inner ear. The +EP increase in acute endolymphatic hydrops may be caused by a shift of the basilar membrane. However, the mechanism of the 'transient' +EP increase is not clear. The -EP decrease was not observed in animals whose cochlear duct was perfused with artificial endolymph. Therefore, the artificial endolymph itself did not cause the decrease in magnitude of the -EP. Dysfunction of the hair cells is a possible explanation for the -EP decrease but the mechanism of such a decrease is not clear in the present study. However, the results of this study support the notion that small increases in endolymphatic pressure below the resolution of recent measurements (DeMott and Salt, 1997) can lead directly to a reduction of the -EP during hydrops. The animal model described here can eliminate the chronic effect of hydrops, therefore, this model is useful for investigations into the effect of hydrops itself on the inner ear and the mechanism of hearing loss in Ménière's disease.
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Affiliation(s)
- A Kakigi
- Department of Otolaryngology, Kochi Medical School, Nankoku, Japan
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Abstract
Previous work has shown that the endocochlear potential (EP) decreases with age in the gerbil. Concomitant with the EP decrease is an age-related loss of activity of Na,K-ATPase in the lateral wall and stria vascularis. We hypothesized that the EP decrease is associated with a similar decrease in the endolymphatic potassium concentration [Ke+]. This hypothesis was tested using double-barrelled, K(+)-selective electrodes introduced into scala media through the round window in young and quiet-aged gerbils. Results show that the means (+/- S.D.) of the [Ke+] in young and aged gerbils were not significantly different (178.2 +/- 14.2 mM and 171.2 +/- 34.4 mM, respectively), although the intersubject variability was much greater in the aged animals than in the young. These values of [Ke+] are slightly higher than those found for other mammals and may reflect the higher plasma osmolarity found in the gerbil. The concentration of perilymphatic potassium [Kp+] in scala tympani at the round window was also similar for the young and aged groups (3.57 +/- 1.17 mM and 4.18 +/- 2.03 mM, respectively). On the other hand, mean EP values in the young and aged gerbils were 92.0 +/- 5.7 mV and 64.8 +/- 15.8 mV, respectively and were statistically different (P < 0.001). Overall, EP and [Ke+] showed little correlation (R2 = 0.23), except that when [Ke+] fell below 150 mM, the EP was always less than 60 mV. An analysis of the chemical potential for Ke+ with respect to Kp+ shows that it was similar for young and aged gerbils (overall mean of 103.1 +/- 13.7 mV) and remained constant with respect to the EP, in spite of an overall electrochemical potential of Ke+ that varied from 120 to 210 mV. Thus, the system maintains Ke+ homeostasis at the expense of the EP, even when the EP is on the verge of collapse.
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Affiliation(s)
- R A Schmiedt
- Department of Otolaryngology and Communicative Sciences, Medical University of South Carolina, Charleston 29425-2242, USA.
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Nadol JB, Adams JC, Kim JR. Degenerative changes in the organ of Corti and lateral cochlear wall in experimental endolymphatic hydrops and human Menière's disease. ACTA OTO-LARYNGOLOGICA. SUPPLEMENTUM 1995; 519:47-59. [PMID: 7610892 DOI: 10.3109/00016489509121870] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The pathogenesis of sensorineural hearing loss in Menière's disease and experimental endolymphatic hydrops is not fully understood. At the light microscopic level, there is poor correlation between the histopathology and loss of sensitivity and speech discrimination. The results of electron microscopic investigation of histopathology and alterations in immunoreactivity in the organ of Corti and lateral cochlear wall in the hydropic guinea pig are presented. Loss of outer and inner hair cells and spiral ganglion cells, particularly in the apical turn was evident by light microscopy. By electron microscopy, further evidence of degeneration was detected in the cuticular plate of outer hair cells, neural endings of both inner and outer hair cells, myelinated dendritic fibers, spiral ganglion cells, and types I and II fibrocytes of the lateral cochlear wall. There was a marked decrease in immunoreactivity for a variety of enzymes, calcium binding proteins, structural proteins, and integral membrane proteins of gap junctions, particularly among type I and type II fibrocytes of the lateral cochlear wall. The evidence suggests that dysfunction and degeneration of hair cells, afferent neurons and fibrocytes of the lateral cochlear wall are involved in the pathogenesis of hearing loss in endolymphatic hydrops.
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Affiliation(s)
- J B Nadol
- Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA
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van Benthem PP, Klis SF, Albers FW, de Wildt DJ, Veldman JE, Huizing EH, Smoorenburg GF. The effect of nimodipine on cochlear potentials and Na+/K(+)-ATPase activity in normal and hydropic cochleas of the albino guinea pig. Hear Res 1994; 77:9-18. [PMID: 7928742 DOI: 10.1016/0378-5955(94)90249-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
In experimental endolymphatic hydrops (EEH) a decrease in the endocochlear potential (EP) has been reported and is thought to be due to decreased activity of the enzyme Na+/K(+)-ATPase in the stria vascularis. By stimulating Na+/K(+)-ATPase, the EP, and thereby cochlear function as a whole, might be restored. On the other hand, stimulation of stria vascularis Na+/K(+)-ATPase might result in excessive production of endolymph and thus produce or augment hydrops. In this study we have investigated the effect of intraperitoneally applied nimodipine on cochlear potentials and on Na+/K(+)-ATPase activity in the stria vascularis, both in normal cochleas (control) and in cochleas with EEH. Nimodipine is an L-type Ca(2+)-channel blocking agent with Na+/K(+)-ATPase stimulating properties at concentrations as low as 1.5 nM. The compound action potential (CAP), evoked by 2,4 and 8 kHz tone bursts was found to be depressed in the EEH ears with and without nimodipine treatment, and in the nimodipine treated control ears. Statistical analysis (ANOVA) showed that the effects of EEH and nimodipine on the CAP were additive. The negative summating potential (SP), measured extracochlearly at the apex, in response to 4 and 8 kHz tone bursts was significantly enhanced in the EEH ears. Nimodipine treatment did not affect the SP, neither in the control, nor in the EEH ears. Cytochemically, Na+/K(+)-ATPase activity appeared to be decreased in the oedematous stria vascularis of hydropic cochleas. No effect of nimodipine on Na+/K(+)-ATPase activity could be established ultracytochemically, neither in the controls nor in the EEH ears. In the lower turns of some of the nimodipine treated control cochleas a mild hydrops was seen during light-microscopic evaluation. Although it was not possible to prove a stimulatory effect of nimodipine on the enzyme Na+/K(+)-ATPase cytochemically, the finding of mild endolymphatic hydrops in nimodipine treated control ears suggests (a history of) increased endolymph production. This hydrops might be responsible for the depression of the CAP in the nimodipine treated ears.
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Affiliation(s)
- P P van Benthem
- Department of Otorhinolaryngology, University Hospital Utrecht, The Netherlands
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Ichimiya I, Adams JC, Kimura RS. Changes in immunostaining of cochleas with experimentally induced endolymphatic hydrops. Ann Otol Rhinol Laryngol 1994; 103:457-68. [PMID: 8203812 DOI: 10.1177/000348949410300607] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Cochleas with experimentally induced endolymphatic hydrops were immunostained for Na+,K(+)-ATPase, intracellular Ca(++)-ATPase, carbonic anhydrase, aldehyde dehydrogenase, calcium-binding proteins, vimentin, and the gap junction protein, connexin 26. No changes in immunostaining of hydropic ears were observed 1 week after blockage of the endolymphatic duct. Two weeks to 1 month after the operation, immunostaining of type I fibrocytes in the spiral ligament, which are positive for all but Na+,K(+)-ATPase, was slightly decreased on the operated side. These changes became more pronounced 3 months after the operation. However, staining for Na+,K(+)-ATPase of the stria vascularis and of type II fibrocytes of the spiral ligament was not reduced until 6 months postoperative. The reduction of enzymes and other cell constituents that may be involved in ion balance of cochlear fluids indicates that cells in the spiral ligament play an important role in cochlear homeostasis and that they merit further study in animal and human otopathology.
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Affiliation(s)
- I Ichimiya
- Department of Otolaryngology, Oita Medical University, Japan
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Salt AN, DeMott J. Time course of endolymph volume increase in experimental hydrops measured in vivo with an ionic volume marker. Hear Res 1994; 74:165-72. [PMID: 7518819 DOI: 10.1016/0378-5955(94)90184-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A new method has been developed to measure the cross-sectional area (CSA) of scala media in the living cochlea. The method has some advantages over histological methods, in which tissues may shrink or move during processing. In the present study, scala media CSA was measured in the second turn of guinea-pig cochleas in which endolymphatic hydrops was induced surgically. The area measurement method used an iontophoretic injection of a volume marker into scala media, during which the concentration of marker in endolymph was monitored with an ion-selective microelectrode. The measured marker concentration was inversely proportional to the CSA of endolymph. The marker we used was the anion arsenic hexafluoride (AsF6-), which was almost ideal for the purpose as it was retained well in endolymph. Area was measured in normal animals and in hydropic animals at times from 4 days to 16 weeks after endolymphatic duct obstruction. The results showed that hydrops develops within days of ablation of the endolymphatic duct. The degree of hydrops was compared with electrophysiological measures of function, including the endocochlear potential, action potential thresholds and the amplitudes of the cochlear microphonic, summating potential and action potentials. In the initial stages of hydrops development, electrophysiological changes were small. In contrast, there were marked functional changes between 8 and 16 weeks, when endolymph volume was no longer increasing. If the same is true for dysfunction in the ears of patients with Ménière's Disease, then it may not be possible to restore normal function simply by alleviating the hydrops.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- A N Salt
- Department of Otolaryngology, Washington University Medical School, St. Louis, MO 63110
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Abstract
A guinea pig model with surgically induced endolymphatic hydrops of the inner ear has been developed and studied over the past thirty years. The aim of such studies is to obtain insight into physiological processes associated with endolymphatic hydrops in man and in particular in Menière's disease where endolymphatic hydrops is systematically encountered at post-mortem examination of the temporal bones. The present review attempts to draw together the data pertaining to functional modifications of inner ear function in the animal model. For simplicity the data are categorised under five main titles: electrochemical modifications, electrophysiological modifications, pressure and hydrops, sensitivity to other insults and vestibular dysfunction. One of the most striking observations that can be made is that the data originating from different authors are very variable. There is, however, some evidence suggesting that the evolution of the auditory dysfunction could be considered as consisting of a series of different phases. This kind of information could serve as a basic framework for future research on the animal model.
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Affiliation(s)
- K C Horner
- Inserm U229, Laboratoire d'Audiologie Expérimentale, Hôpital Pellegrin, Bordeaux, France
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Tsujikawa S, Yamashita T, Meyer zum Gottesberge AM, Tomoda K, Kumazawa T. Experimental interruption of the endolymphatic duct and its effect on the DC potential in the endolymphatic sac. Acta Otolaryngol 1992; 112:785-90. [PMID: 1456033 DOI: 10.3109/00016489209137475] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The endolymphatic sac (ES) of the guinea pig was isolated from the remainder of the inner ear by means of surgical interruption of the endolymphatic duct (ED). The DC potential in the ES lumen and the morphology of the ES were studied using glass micro-electrodes and a light microscope at various time intervals after the interruption of ED. The DC potential did not significantly change 1 h postoperatively, compared to findings in the non-operated ear, but a significant decrease of the DC potential was observed after 1, 3 and 7 days postoperatively. A histologically-stainable substance in the ES lumen was enhanced on the operated side. The isolated ES shows a disturbance of mechanism(s) maintaining the DC potential and there is a secretion of a stainable substance into its lumen.
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Affiliation(s)
- S Tsujikawa
- Department of Otolaryngology, Kansai Medical University, Osaka, Japan
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Tono T, Morizono T. Low-frequency modulation of compound action potential in experimental perilymphatic fistula and endolymphatic hydrops. Hear Res 1992; 60:27-33. [PMID: 1500374 DOI: 10.1016/0378-5955(92)90055-r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We have tested the hypothesis that the cause of cochlear dysfunction associated with perilymphatic fistula (PLF) is closely related to endolymphatic hydrops (ELH). Using guinea pigs, we studied the tone-burst elicited compound action potential (CAP) and its modulation as caused by a 50 Hz biasing tone in experimental PLF. We compared these results with those of experimental ELH. Following perilymph aspiration through the perforated round window membrane, mild but significant elevations of CAP thresholds at tested frequencies were found. A reduction in the amplitude of cochlear microphonics (CM) for a 50 Hz sine wave appeared to correlate with these CAP threshold changes. However, there were no significant changes in the modulation effect of the 50 Hz biasing tone on the CAP elicited by an 8 kHz tone burst. This finding differed from that in ears with experimental ELH, in which significant reductions of both 50 Hz CM and the degree of CAP modulation were consistently observed. We concluded that it is unlikely that the underlying mechanisms of a modification to the low frequency response of the base of the cochlea following perilymph aspiration is linked to that of experimental ELH.
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Affiliation(s)
- T Tono
- Department of Otolaryngology, University of Minnesota Medical School, Minneapolis
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Ikeda K, Morizono T. Ionic activities of the inner ear fluid and ionic permeabilities of the cochlear duct in endolymphatic hydrops of the guinea pig. Hear Res 1991; 51:185-92. [PMID: 2032956 DOI: 10.1016/0378-5955(91)90035-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Ionic activities (K+, Na+, and Cl-) of the perilymph and endolymph of the basal turn were measured using ion-selective microelectrodes in experimentally induced endolymphatic hydrops of the guinea pig. Three months following the obstruction of the endolymphatic duct and sac, the endocochlear potential (EP) of hydroptic ears was measured at 59.7 +/- 9.6 mV (N = 12) which was significantly lower than the EP of the contralateral control ears (84.4 +/- 2.8 mV, N = 12). A paired t-test (P greater than 0.05) showed no significant differences of ion concentrations of the inner ear fluid between the hydroptic and contralateral ears. Ion permeabilities of the cochlear duct following anoxia were calculated according to the Nernst-Planck equation. Comparing hydroptic and normal ears following anoxia, a statistically significant decrease was observed in the permeability coefficients for K+. Similarly, K+ conductance was significantly lower in the hydroptic ears than in the normal ears. Total conductance of the cochlear duct, defined as the sum of each ion conductance, was 0.560 siemens in the normal ears and 0.217 siemens in the hydroptic ears. On the basis of the Goldman-Hodgkin-Katz equation, preexisting negative EP in the normal state was calculated to be -24.5 mV in normal ears and -21.4 mV in hydroptic ears. Therefore, the positive component of the EP was 108.9 mV in normal ears and 81.1 mV in hydroptic ears. These findings suggest that the pathophysiology of hydrops involves changes in K+ permeability and the inhibition of the electrogenic transport processes.
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Affiliation(s)
- K Ikeda
- Department of Otolaryngology, Tohoku University School of Medicine, Japan
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Ito Z, Kusakari J, Takeyama M, Nishikawa N, Hara A, Nakata H. The effect of furosemide on the endocochlear potential in ears with experimentally induced endolymphatic hydrops. ACTA OTO-LARYNGOLOGICA. SUPPLEMENTUM 1991; 481:83-7. [PMID: 1927494 DOI: 10.3109/00016489109131352] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The endocochlear potential (EP) was measured in 38 guinea pigs with experimentally induced endolymphatic hydrops at the 3rd, 6th, 12th and 24th postoperative weeks, and the effects of furosemide (FUR, 50 or 80 mg/kg) on the EP were examined. A time-related reduction of the EP from the normal value and increased susceptibility to FUR were disclosed in the hydropic animals. Furthermore, 24-week animals given 80 mg/kg FUR showed a significantly slower recovery rate of the EP than the other groups, indicating impairment of the strial function progressive with post-operative time. The negative component of the EP was considered to be unimpaired until at least 12 weeks after the surgery.
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Affiliation(s)
- Z Ito
- Department of Otolaryngology, University Hospital, Tsukuba, Japan
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21
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Sakagami M, Fukazawa K, Kitamura K, Doi K, Mori N, Matsunaga T. Transport of HRP through Reissner's membrane in experimental endolymphatic hydrops. Acta Otolaryngol 1991; 111:872-8. [PMID: 1759573 DOI: 10.3109/00016489109138424] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Unilateral endolymphatic hydrops was produced in guinea pigs by cauterization of the endolymphatic sac. Measurements of compound action potential (CAP), cochlear microphonics (CM) and negative summating potential (-SP) confirmed endolymphatic hydrops three months after surgery. In both control and hydropic ears, reaction product of HRP was observed only on the perilymphatic surface of the epithelial cells of Reissner's membrane after 10 min perfusion, while it was observed on both the endolymphatic and perilymphatic surfaces after 30 min perfusion. Epithelial tight junctions were not stained and labelled pinocytotic vesicles were observed in the epithelial cells. These findings suggest that the transport of HRP through Reissner's membrane is unchanged in endolymphatic hydrops and that the epithelial junctions are tight regardless of the distension of Reissner's membrane.
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Affiliation(s)
- M Sakagami
- Department of Otolaryngology, Osaka University Medical School, Japan
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Yoon TH, Paparella MM, Schachern PA. Otosclerosis involving the vestibular aqueduct and Menière's disease. Otolaryngol Head Neck Surg 1990; 103:107-12. [PMID: 2117717 DOI: 10.1177/019459989010300116] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The coexistence of otosclerosis and endolymphatic hydrops in the temporal bone have been described; however, the mechanism for the development of endolymphatic hydrops in otosclerosis remains unknown. Among 128 temporal bones with otosclerosis, involvement of the vestibular aqueduct by otosclerosis was observed in four temporal bones from two patients. In all four, the vestibular aqueduct was filled with active otosclerotic foci; the lumen of the endolymphatic duct and sac was narrowed as a result of fibrosis, and endolymphatic hydrops, more severe in the pars inferior than the pars superior, was observed. Collapse of the ductus reuniens and dilated saccule was seen in three temporal bones. Our study indicates that otosclerotic obstruction of the vestibular aqueduct may create a disturbance of the outflow and/or absorption of endolymph, leading to the development of endolymphatic hydrops and Meniere's disease, thus supporting the theory of longitudinal flow of endolymph.
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Affiliation(s)
- T H Yoon
- Department of Otolaryngology, University of Minnesota School of Medicine, Minneapolis 55455
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Rascol O, Clanet M, Montastruc JL. Calcium antagonists and the vestibular system: a critical review of flunarizine as an antivertigo drug. Fundam Clin Pharmacol 1989; 3 Suppl:79s-87s. [PMID: 2693294 DOI: 10.1111/j.1472-8206.1989.tb00478.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Flunarizine, a diphenylalkylamine, is one of the most popular antivertiginous drugs used nowadays in France. However, until now, there are very few preliminary data about the physiological or pathophysiological functions of calcium in the vestibular system. Moreover, experimental and clinical arguments are still insufficient to clearly demonstrate that 1) flunarizine is an effective antivertiginous drug and 2) this putative antivertiginous property is really due to the anticalcic action of the drug and not to a more classical antagonistic effect on H1 receptors. Much more work is needed before accepting the indication of any anticalcic drug as an effective antivertigo treatment.
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Affiliation(s)
- O Rascol
- Laboratoire de Pharmacologie Médicale et Clinique INSERM U317, Faculté de Médecine, Toulouse, France
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Sziklai I, Horner KC, Ferrary E, Sterkers O, Amiel C. Electrochemical composition of the cochlear fluids in the early experimental hydrops. Preliminary results. Acta Otolaryngol 1989; 107:371-4. [PMID: 2756827 DOI: 10.3109/00016488909127524] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The composition of endolymph and perilymph was studied in the guinea pig cochlea after 2 and 6 weeks of blockage of the vestibular aqueduct in an experimental model of hydrops. Compound action potential was monitored several times in the observation period. The endocochlear potential was measured and the endolymph was sampled at the first and third turns of the scala media. The Na, K, and Cl concentrations were determined in nanolitre aliquots of endolymph and of perilymph, the latter sampled from the basal scala vestibuli. After 2 weeks, no change in endolymphatic electrochemical composition was observed. After 6 weeks, endocochlear potential was decreased by 25% at both cochlear turns; K concentration was decreased in endolymph of the basal turn and Cl concentration was decreased in both turns; the calculated osmolality (Na + K + Cl) was decreased in both turns. These results indicate that the blockage of the vestibular aqueduct induced early auditory dysfunction whereas alterations of the electrochemical composition of endolymph occurred later after a time lag of more than 2 and less than 6 weeks.
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Affiliation(s)
- I Sziklai
- INSERM U.251, Département de Physiologie, Faculté Xavier Bichat, Université, Paris, France
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van Deelen GW, Ruding PR, Smoorenburg GF, Veldman JE, Huizing EH. Electrocochleographic changes in relation to cochlear histopathology in experimental endolymphatic hydrops. Acta Otolaryngol 1988; 105:193-201. [PMID: 3389104 DOI: 10.3109/00016488809096998] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The relation between electrocochleographic and histological changes in experimental endolymphatic hydrops was studied 1, 2, 4, or 8 months after obliteration of the endolymphatic sac. An increase in the compound Action Potential (AP) threshold was found 2, 4, and 8 months after obliteration. This increase was strongly correlated with loss of outer hair cells, nerve fibres and spiral ganglion cells. An enhanced negative Summating Potential (SP) and an enhanced SP-AP ratio were found mainly in animals with an endolymphatic hydrops without further cochlear pathology. A normal or decreased SP and SP-AP ratio was regularly recorded in animals with both an endolymphatic hydrops and a variety of other histopathological changes in the inner ear. An increased second peak (N2) in the AP waveform was recorded from 63% (15/24) of the hydropic ears, equally divided over the four groups. There was no obvious correlation between the increased N2 and other electrophysiological or histological findings.
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Affiliation(s)
- G W van Deelen
- Department of Otorhinolaryngology, University Hospital, Utrecht, The Netherlands
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Meyer zum Gottesberge AM. Imbalanced calcium homeostasis and endolymphatic hydrops. ACTA OTO-LARYNGOLOGICA. SUPPLEMENTUM 1988; 460:18-27. [PMID: 3074617 DOI: 10.3109/00016488809125131] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In this paper the current state of knowledge of the development in experimental endolymphatic hydrops (EEH) is summarized, with particular emphasis on calcium. An imbalanced Ca2+ homeostasis in the inner ear is demonstrated using EEH as an animal model for Meniere's disease. The possibility of a receptor-mediated Ca2+ transport across the epithelial layer, especially the light cells, and of 'chemical signal' as an initiating modulating factor in the disturbance of Ca2+ homeostasis was suggested. It is pointed out that melanin is capable of binding calcium and may act as a buffering system. Finally, the possible malfunction of the Ca-overloaded melanocytes on the inner ear function is discussed.
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Abstract
The temporal bones of an individual with documented unilateral Meniere's disease were prepared for light and electron microscopy. A morphometric analysis was performed on hair cells, spiral ganglion cells, dendritic fibers in the osseous spiral lamina, afferent and efferent endings, and afferent synaptic contacts. In the ear with Meniere's disease, we found hair cell damage, including disruption of the cuticular bodies and basalward displacement of some outer hair cells. There was no significant difference in the number of hair cells or spiral ganglion cells on the two sides. There was a significant decrease, however, in the number of afferent nerve endings and afferent synapses at the base of both inner and outer hair cells in the ear with Meniere's disease as compared to the contralateral ear.
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Meyer zum Gottesberge-Orsulakova AM, Kaufmann R. Is an imbalanced calcium-homeostasis responsible for the experimentally induced endolymphatic hydrops? Acta Otolaryngol 1986; 102:93-8. [PMID: 3739695 DOI: 10.3109/00016488609108651] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The target of the investigations were the presumably ion-transporting cells of the vestibular organ, i.e. the area of 'dark cells' of the semicircular canal and utriculus. Those cells have been assayed for structural changes by LM and EM and for alterations of the ionic content (LAMMA) in coloured guinea pigs with unilaterally induced endolymphatic hydrops. Characteristically changed structures of the secretory epithelium and disordered pigmentation in the vestibular organ were noted. Those cellular alterations were accompanied by intracellular ionic changes, especially an increased level of Ca2+ in the light cells and melanocytes. Our investigations show that, at least for experimental hydrops, an imbalanced homeostasis of Ca exists that may be responsible for the enlargement of the endolymphatic space.
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Abstract
The scala media of the adult cochlea in mammals comprises a morphologically closed compartment sealed with tight junctions of the intermediate to tight types. The unique ionic composition of endolymph is maintained by the stria vascularis through active reabsorption of sodium and active secretion of potassium against ionic gradients. The subtectorial space is only a partially closed compartment which communicates with the endolymph via holes in the tectorial membrane at its outer insertion to the organ of Corti. Hardesty's membrane divides the subtectorial space into two compartments: one facing the surfaces of inner hair cells and one facing the surfaces of outer hair cells. In the study of comparative anatomy, hair cells, e.g. in the lizard, basilar papilla are of two types: those covered with a tectorial membrane and those being free-standing lacking the tectorial membrane. The ionic environment of the hair cell surface seems to be the same, independent of whether covered with a tectorial membrane or not. The tectorial membrane itself is semipermeable to ions in the endolymphatic space. Only the surface structures of the hair cell with the sensory hairs facing the subtectorial space are exposed to the high concentration of potassium, whereas the remaining parts of the hair cell are surrounded by a fluid having a more normal extracellular type of ionic composition (cortilymph/perilymph). During embryonic development the ionic composition of endolymph develops in parallel with the morphologic maturation of the stria vascularis. A completely mature composition of endolymph is reached before any electrophysiological potentials in the cochlea can be elicited. The sensory hair surface of hair cells has reached a mature morphology prior to the maturation of endolymph. In several species the tectorial membrane is morphologically only partially mature when the increase of the potassium concentration of endolymph starts. Drugs primarily affecting the stria vascularis causing a transient change of the ionic composition of endolymph result in a transient dysfunction of inner ear potentials. If the ionic changes persist for longer time, morphological changes can occur in both the stria vascularis and the hair cells of the organ of Corti. Whether such changes are primarily caused by the ototoxic drug itself or by changes in the ionic composition of endolymph has to be explored further.
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