Document Detail

Volume flow rate of perilymph in the guinea-pig cochlea.
MedLine Citation:
PMID:  3198505     Owner:  NLM     Status:  MEDLINE    
The rate of longitudinal flow of perilymph has been measured using an ionic tracer technique. Spread of the tracer trimethylphenylammonium (TMPA) along the perilymphatic scalae was monitored with ion-selective microelectrodes following injection of a minute bolus (approximately 50 nl) of 150 mM TMPAC1 one turn away. This amount of TMPA had virtually no toxic effect on cochlear function. The spread of tracer by longitudinal volume flow and passive diffusion were separated by comparing tracer movements in both apical and basal directions along the scalae in two groups of animals. Experimental findings were compared with a mathematical model which combined diffusion and volume flow. Our results demonstrated that when electrodes were completely sealed into the cochlea, the rate of longitudinal volume flow in scala tympani was extremely slow, approximately 1.6 nl/min in the apical direction. Longitudinal flow was not detectable in scala vestibuli. When the otic capsule was perforated, flow rates of over 1 microliter/min were recorded in scala tympani, probably as a result of cerebrospinal fluid entry through the cochlear aqueduct. When the cochlea was sealed (with recording electrodes in place) and cerebrospinal fluid pressure was released, there was no significant basally-directed flow of perilymph in scala tympani. These findings support the concept that perilymph composition is maintained by local, cochlear mechanisms which do not involve longitudinal volume flow. They provide strong evidence that perilymph is not secreted in one region and resorbed at a spatially distant site.
K Ohyama; A N Salt; R Thalmann
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Hearing research     Volume:  35     ISSN:  0378-5955     ISO Abbreviation:  Hear. Res.     Publication Date:  1988 Sep 
Date Detail:
Created Date:  1989-01-18     Completed Date:  1989-01-18     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  7900445     Medline TA:  Hear Res     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  119-29     Citation Subset:  IM    
Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO 63110.
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MeSH Terms
Action Potentials
Cerebrospinal Fluid / physiology
Cochlea / physiology*
Cochlear Microphonic Potentials
Guinea Pigs
Labyrinthine Fluids / physiology*
Models, Biological
Models, Statistical
Perilymph / physiology*
Quaternary Ammonium Compounds / diagnostic use
Scala Tympani / physiology
Grant Support
Reg. No./Substance:
0/Quaternary Ammonium Compounds; 3426-74-2/phenyltrimethylammonium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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