Sodium exchange time of perilymph

Juhn, Steven S; Pearce, John; Guzowski, John P.

doi:10.1007/bf00456700

Cited by 4 publications

(2 citation statements)

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“…To date, most studies of inner ear fluid (endolymph) homeostasis have focused on major cationic and anionic transport mechanisms (Naftalin and Harrison 1958;Juhn et al 1976;Yamasaki et al 2000;Steel and Kros 2001). However, with the identification of the aquaporin family of water channel-forming proteins, new lines of investigation have been opened with which to investigate the potential role of these water channels in maintaining endolymph homeostasis and normal inner ear function.…”

Section: Introductionmentioning

confidence: 99%

Expression of Aquaporin 1 and 5 in the Developing Mouse Inner Ear and Audiovestibular Assessment of an Aqp5 Null Mutant

Merves¹,

Krane

Dou³

et al. 2003

JARO - Journal of the Association for Research in Otolaryngolog

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To examine the potential roles of aquaporins 1 and 5 (AQP1 and AQP5, respectively) in inner ear development and function, we defined their spatial and temporal expression patterns in the developing mouse inner ear and examined the morphologic and physiologic effects of loss of Aqp5 function. Standard in situ hybridization (ISH) and immunohistochemical (IHC) assays were used for expression studies with routine morphologic, behavioral, and physiologic assessments of hearing and balance in Aqp5 null mutant mice. AQP1 was first detected at embryonic day 10.5 (E10.5) in the otocyst but eventually localized to specific nonsensory portions of the inner ear and connective tissue cells surrounding the membranous labyrinth. AQP5 displayed specific cochlear expression, first detectable at E15.5 in the nonsensory epithelium and later restricted to the lateral wall of the cochlear duct near the spiral prominence. AQP5 expression continued through postnatal periods with a change of expression domain to the stria vascularis between postnatal day 7 (P7) and P14. By in situ hybridization and immunohistochemical techniques, subtle differences between transcript and protein expression patterns were noted for both AQP1 and 5. Although AQP5 is dynamically expressed in the developing mouse inner ear, adult Aqp5 knockout mice show normal hearing when tested and normal inner ear structural development. These results suggest redundant or alternative mechanisms that likely regulate water homeostasis in the developing and mature inner ear.

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Section: Introductionmentioning

confidence: 99%

Expression of Aquaporin 1 and 5 in the Developing Mouse Inner Ear and Audiovestibular Assessment of an Aqp5 Null Mutant

Merves¹,

Krane

Dou³

et al. 2003

JARO - Journal of the Association for Research in Otolaryngolog

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“…Most studies on endolymph homeostasis 5,6 have focused on the regulation and transport of ions such as sodium and potassium into or out of the endolymphatic compartment. In contrast, the regulation of water molecules has only recently begun to generate interest with respect to this process.…”

Section: Introductionmentioning

confidence: 99%

Developmental Expression of Aquaporin 2 in the Mouse Inner Ear

et al. 2000

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Objectives:The maintenance of endolymph homeostasis is critical for the inner ear to perform its functions of hearing and maintaining balance. The identification and cloning of aquaporins (a family of water channel proteins) has allowed the study of a novel cellular mechanism potentially involved in endolymph homeostasis. The objective of the present study was to define the developmental temporal and spatial expression pattern of aquaporin 2 (Aqp2) in the developing mouse inner ear. Study Design: A systematic immunohistochemical study of Aqp2 protein expression was performed on embryonic mouse inner ears ranging from embryonic day 10 (otocyst stage) to embryonic day 18 (just before birth). Methods: Serial cryosections of embryonic mouse inner ears were used for immunohistochemical experiments. A rabbit polyclonal antisera raised against a synthetic Aqp2 peptide was used with a standard nickel intensified 3,3-diaminobenzidine reaction protocol for immunolocalization of Aqp2 in tissue sections. Results: Aquaporin 2 is expressed diffusely in the early otocyst, then becomes progressively restricted as the inner ear matures. During early cochlear duct formation (embryonic days 12 and 13), expression of Aqp2 is homogeneous; later, it becomes restricted to specific regions of the endolymphatic compartment (embryonic days 15 and 18). Similar restriction of expression patterns could be noted for the vestibular structures. Endolymphatic duct and sac and stria vascularis expression of Aqp2 was noted to occur fairly late during development but demonstrated a distinct pattern of immunolabeling. Conclusions: Aquaporin 2 shows an early and specific pattern of expression in the developing mouse inner ear, suggesting a significant role for this water channel protein in the development of endolymph homeostasis and meriting further functional studies of Aqp2 in the inner ear.

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Experimental Alteration of Physiological State of Inner Ear Fluids

Juhn

1977

Ann Otol Rhinol Laryngol

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Mechanisms of endolymphatic hydrops formation in the inner ear are not yet fully understood. The available knowledge of the composition and the function of inner ear fluids, of mechanisms for maintenance of microhomeostasis, and the possible factors responsible for hydrops formation were reviewed. The nature of the functional barrier systems of the inner ear was investigated by measuring the amount of intravenously or intracisternally injected test substances which entered the perilymph. Based on studies of the osmotic relationship between the blood and the perilymph, an hypothesis of hydrops formation is proposed. The hypothesis predicts an osmotic imbalance, resulting from an upset of the homeostasis between the fluid compartments and the tissues of the inner ear, as a factor responsible for endolymphatic hydrops formation. An osmotic imbalance can be induced by various experimental conditions including metabolic disorders. The results of animal experiments strongly suggest the necessity of further survey of metabolic imbalance in Ménière's patients.

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Sodium exchange time of perilymph

Cited by 4 publications

References 0 publications

Expression of Aquaporin 1 and 5 in the Developing Mouse Inner Ear and Audiovestibular Assessment of an Aqp5 Null Mutant

Expression of Aquaporin 1 and 5 in the Developing Mouse Inner Ear and Audiovestibular Assessment of an Aqp5 Null Mutant

Developmental Expression of Aquaporin 2 in the Mouse Inner Ear

Experimental Alteration of Physiological State of Inner Ear Fluids

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