Document Detail

Permeability of arachidonic acid metabolites through the round window membrane in chinchillas.
MedLine Citation:
PMID:  1636418     Owner:  NLM     Status:  MEDLINE    
Our previous studies showed that samples of middle ear effusion contain high concentrations of arachidonic acid metabolites (AAMs); both prostaglandins (PGs) and leukotrienes (LTs). Since abnormal levels of AAMs in the perilymph seem to be associated with salicylate ototoxicity and the round window membrane (RWM) is the most likely route of entry from the middle ear to the inner ear, it would be important to know the permeability of AAMs through the RWM. Permeability of AAMs was determined by applying labeled and standard representatives AAMs on the RWM and counting radioactivity or measuring concentrations of AAMs in perilymph at different time intervals. Using chinchillas as experimental animals, samples of perilymph were obtained through a fenestration made at the helicotrema of the cochlea after 0.5, 1, 2, and 4, hours from placing tritiated or standard PGE2, 6-keto-PGF1 alpha, LTB4, LTC4 and 15-hydroxyeicosatetraenoic acid (HETE) over RWMs. Radioactivity in the perilymph was determined by a scintillation counter and concentrations of AAMs were measured by reverse phase high performance liquid chromatography (RP-HPLC) and radioimmunoassay. AAMs, which are twenty carbon fatty acids, were found to cross the RWM readily. Radioactivity and concentrations of AAMs in perilymph were detected in 30 minutes and peaked by one hour from the application of AAMs on the RWM. The results of this study suggest that AAMs such as PGs and LTs present in the middle ear fluid can cross the RWM readily and enter into the perilymphatic space of the cochlea. Sensorineural hearing loss observed in chronic otitis media could be mediated by PGs and LTs in the middle ear effusion crossing over to the inner ear through the RWM.
S H Lee; H W Woo; T T Jung; C Lee; S K Miller; Y M Park; S K Hwang
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Acta oto-laryngologica. Supplementum     Volume:  493     ISSN:  0365-5237     ISO Abbreviation:  Acta Otolaryngol Suppl     Publication Date:  1992  
Date Detail:
Created Date:  1992-08-26     Completed Date:  1992-08-26     Revised Date:  2008-02-13    
Medline Journal Info:
Nlm Unique ID:  0370355     Medline TA:  Acta Otolaryngol Suppl     Country:  SWEDEN    
Other Details:
Languages:  eng     Pagination:  165-9     Citation Subset:  IM    
Department of Surgery, Loma Linda University School of Medicine, CA 92354.
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MeSH Terms
Adrenal Cortex Hormones / classification,  diagnostic use,  metabolism
Anti-Bacterial Agents / classification,  diagnostic use,  metabolism
Arachidonic Acid / metabolism*
Chinchilla / metabolism,  physiology*
Chromatography, Liquid
Ear, Middle / metabolism,  pathology,  physiopathology
Hearing Loss, Sensorineural / etiology
Leukotrienes / metabolism,  pharmacology
Otitis Media with Effusion / complications,  metabolism*
Perilymph / chemistry
Prostaglandins / metabolism,  pharmacology
Round Window, Ear / metabolism*
Reg. No./Substance:
0/Adrenal Cortex Hormones; 0/Anti-Bacterial Agents; 0/Leukotrienes; 0/Prostaglandins; 506-32-1/Arachidonic Acid

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