Acute endolymphatic hydrops generated by exposure of the ear to nontraumatic low-frequency tones.

Acute endolymphatic hydrops generated by exposure of the ear to nontraumatic low-frequency tones. Research Abstract Details 

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Acute endolymphatic hydrops generated by exposure of the ear to nontraumatic low-frequency tones. Abstract Text:

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.

Acute endolymphatic hydrops generated by exposure of the ear to nontraumatic low-frequency tones. Publishing Authors By Initials

For similar inorganic chemicals: elements: metals, alkali: potassium research abstracts see: inorganic chemicals: elements: metals, alkali: potassium research

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Acute endolymphatic hydrops generated by exposure of the ear to nontraumatic low-frequency tones. Journal Published:

PUBLICATION TYPE: Research Support, U.S. Gov't,

Journal: Journal of the Association for Research in Otolary

VOLUME: 5

Page Numbers: 203-14

Journal Abbreviation: J. Assoc. Res. Otolaryngol.

ISSN: 1525-3961

DAY: 17

MONTH: Jun

YEAR: 2004

Acute endolymphatic hydrops generated by exposure of the ear to nontraumatic low-frequency tones. Information

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LANGUAGE: eng

NlmUniqueID: 100892857

Acute endolymphatic hydrops generated by exposure of the ear to nontraumatic low-frequency tones. Keywords Mesh Terms:

KEYWORDS: Potassium

MESH TERMS: metabolism

Chemical & Substance for Abstract: Acute endolymphatic hydrops generated by exposure of the ear to nontraumatic low-frequency tones. Information

Substance Name: Potassium

Registry Number: 7440-09-7

Grant and Affiliation Information for Acute endolymphatic hydrops generated by exposure of the ear to nontraumatic low-frequency tones.

AFFILIATION: Department of Otolaryngology, Washington University School of Medicine, St Louis, MO 63110, USA. salta@wustl.edu

Country: United States

AGENCY: United States NIDCD

GRANT: R01 DC01368

ACRONYM: DC

MEDLINETA: J Assoc Res Otolaryngol

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