Cochlear aqueduct flow resistance is not constant during evoked inner ear pressure change in the guinea pig

Wit, H. P.; Feijen, Robert A.; Albers, F. W. J.

doi:10.1016/s0378-5955(02)00738-4

Cited by 20 publications

(23 citation statements)

References 21 publications

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“…Previous studies have reported that endolymphatic pressure is not directly influenced by CSF pressure, as permeability of the cochlear aqueduct is not constant (13,37) and that a CSF pressure increase of more than 10 mmHg is needed to increase endolymphatic pressure (26,30). The present study detected no endolymphatic pressure change synchronized with heartbeat and no significant change in CSF pressure by isoproterenol, indicating that the increase in endolymphatic pressure by isoproterenol is unaffected by CSF changes.…”

Section: Discussioncontrasting

confidence: 46%

Endolymphatic sac is involved in the regulation of hydrostatic pressure of cochlear endolymph

Inamoto

Miyashita

Akiyama

et al. 2009

American Journal of Physiology-Regulatory, Integrative and Comp

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To clarify the role of the endolymphatic sac (ES) in the regulation of endolymphatic pressure, the effects of isoproterenol, a ␤-adrenergic receptor agonist, and acetazolamide, a potent carbonic anhydrase inhibitor, both of which decrease ES direct current potential on cochlear hydrostatic pressure, were examined in guinea pigs. When isoproterenol was applied intravenously, hydrostatic pressures of cochlear endolymph and perilymph were significantly increased with no change in endocochlear potential or the hydrostatic pressure of cerebrospinal fluid. Acetazolamide produced no marked change in the hydrostatic pressure of cochlear endolymph. In ears with an obstructed ES, the action of isoproterenol on the hydrostatic pressure of cochlear endolymph and perilymph was suppressed. These results suggest that the ES may regulate the hydrostatic pressure of the endolymphatic system via the action of the agents such as catecholamines on the ES. direct current potential; isoproterenol; acetazolamide THE ENDOLYMPHATIC SAC (ES), which is a part of the inner ear, is believed to absorb endolymph, since surgical blockage of the ES and the endolymphatic duct causes accumulation of endolymph in the cochlea and vestibule, as so-called endolymphatic hydrops (11), a characteristic pathological finding in Meniere's disease. Endolymphatic hydrops in the cochlea causes deafness, while endolymphatic hydrops in the vestibule causes vertigo (22, 31). Endolymph regulation is thus important for hearing and the sense of equilibrium (7,29). Although the ES is generally accepted to contain active ion transport systems and may absorb endolymph (11), no mechanisms of endolymph regulation by the ES have actually been established.ES direct current potential (ESP) and endocochlear direct current potential (EP) are known to be present in the ES and the cochlea, respectively (3, 12, 15). ESP and EP are generated by active ion transports in the ES and cochlea, respectively (3, 15, 21). ESP and EP can thus be used as indices of function for the ES and cochlea, respectively (15, 21). Catecholamines reportedly depress ESP through ␤-adrenergic receptors (19). The finding that isoproterenol, a ␤-adrenergic receptor agonist, at a dose of 12.5 g/kg decreases ESP without changing EP (16), suggests that isoproterenol would suppress active ion transport in the ES without inhibiting active ion transport in the cochlea. Acetazolamide, a potent carbonic anhydrase inhibitor, reportedly depresses ESP more sensitively than EP (32, 33). The result that cotreatment with isoproterenol and acetazolamide at doses producing near-maximum reduction of ESP depresses almost all parts of the ESP, suggesting that isoproterenol and acetazolamide may depress ESP via different mechanisms and that ESP may be composed of isoproterenol-and acetazolamide-sensitive parts (17).The ES has been hypothesized to regulate endolymphatic hydrostatic pressure (4, 9). However, no reports have described hydrostatic pressure regulation by the ES, as direct measurement of endolymphatic hydrostatic ...

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Section: Discussioncontrasting

confidence: 46%

Endolymphatic sac is involved in the regulation of hydrostatic pressure of cochlear endolymph

Inamoto

Miyashita

Akiyama

et al. 2009

American Journal of Physiology-Regulatory, Integrative and Comp

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“…We can quantify the characteristic of R A , if we divide the obtained R A C by the window compliance C [21]. As we know C is defined by the ratio of window pressure and volume for the human (round + oval) window.…”

Section: Discussionmentioning

confidence: 99%

“…Based on the work of Gopen et al [6] and Wit et al [21] on the inner ear, a simplified mechanical model was created (Figure 2(a)). This model describes the connections and interconnections between the three different compartments of the human body: the respiratory (C 1 ), the head (C 2 ), and the auditory systems (C 3 ).…”

Section: Modelmentioning

confidence: 99%

“…The second response "τ 2 " was a direct reaction to the cessation of the pressure stimulus. Later, Wit et al repeated a similar experiment on the guinea pig and calculated a new time constant called (R A C) [19][20][21]. R A C was mainly determined by the flow resistance of the aqueduct, combined with the compliance of the cochlear windows.…”

Section: Introductionmentioning

confidence: 99%

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The Estimation of the Time Constant of the Human Inner Ear Pressure Change by Noninvasive Technique

Traboulsi

Poumarat

Chazal

et al. 2009

Modelling and Simulation in Engineering

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We propose a noninvasive method to estimate the time constant. The calculation of this factor permits us to understand the pressure variations of the inner ear and also predict the behavior of the flow resistance of the cochlear aqueduct. A set of mathematical relationships incorporating the intralabyrinthine pressure, the intracranial pressure, and the time constant was applied. The modeling process describes the hydrodynamic effects of the cerebrospinal fluid in the intralabyrinthine fluid space, where the input and output of the created model are, respectively, the sinusoidal variation of the respiration signal and the distortion product of otoacoustic emissions. The obtained results were compared with those obtained by different invasive techniques. A long time constant was detected each time when the intracranial pressure increased; this phenomenon is related to the role of the cochlear aqueduct described elsewhere. The interpretation of this model has revealed the ability of these predictions to provide a greater precision for hydrodynamic variation of the inner ear, consequently the variation of the dynamic process of the cerebrospinal fluid.

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“…The inner ear pressure is controlled by sophisticated regulatory mechanisms which are not fully understood. The cochlear aqueduct plays a major role in the inner ear pressure regulation in case of pressure transfer via middle ear and ossicular chain [2]. Transfer of intracranial pressure to the inner ear can be regulated by the cochlear aqueduct [3].…”

Section: Introductionmentioning

confidence: 99%

Hydrostatic fluid pressure in the vestibular organ of the guinea pig

Park

Boeven

Vogel

et al. 2011

Eur Arch Otorhinolaryngol

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Since inner ear hair cells are mechano-electric transducers the control of hydrostatic pressure in the inner ear is crucial. Most studies analyzing dynamics and regulation of inner ear hydrostatic pressure performed pressure measurements in the cochlea. The present study is the first one reporting about absolute hydrostatic pressure values in the labyrinth. Hydrostatic pressure of the endolymphatic system was recorded in all three semicircular canals. Mean pressure values were 4.06 cmH(2)O ± 0.61 in the posterior, 3.36 cmH(2)O ± 0.94 in the anterior and 3.85 cmH(2)O ± 1.38 in the lateral semicircular canal. Overall hydrostatic pressure in the vestibular organ was 3.76 cmH(2)O ± 0.36. Endolymphatic hydrostatic pressure in all three semicircular canals is the same (p = 0.310). With regard to known endolymphatic pressure values in the cochlea from past studies vestibular pressure values are comparable to cochlear values. Until now it is not known whether the reuniens duct and the Bast's valve which are the narrowest passages in the endolymphatic system are open or closed. Present data show that most likely the endolymphatic system is a functionally open entity.

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Cochlear aqueduct flow resistance is not constant during evoked inner ear pressure change in the guinea pig

Cited by 20 publications

References 21 publications

Endolymphatic sac is involved in the regulation of hydrostatic pressure of cochlear endolymph

Endolymphatic sac is involved in the regulation of hydrostatic pressure of cochlear endolymph

The Estimation of the Time Constant of the Human Inner Ear Pressure Change by Noninvasive Technique

Hydrostatic fluid pressure in the vestibular organ of the guinea pig

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