Document Detail

On the mechanism of a high-frequency force generator in outer hair cells isolated from the guinea pig cochlea.
MedLine Citation:
PMID:  2895478     Owner:  NLM     Status:  MEDLINE    
Isolated mammalian outer hair cells elongate or shorten respectively by several micrometres when electrically hyperpolarized or depolarized. The experiments in this paper were designed to locate the force-generating mechanism that drives length changes in outer hair cells, and to determine some of its basic properties. The whole-cell mode of the patch-clamp technique was used to stimulate cells electrically and to perfuse them with specific drugs. The pattern of displacement of cellular organelles, and the relative displacements of the cell base and apex during electrical stimulation with the cell mechanically anchored at various points along its length, suggest that the force-generating mechanism is distributed throughout the length of the cell. Further experiments altering the shape, volume and intracellular pressure of outer hair cells suggest that the mechanism is closely associated with the plasma membrane. These experiments also demonstrate that the characteristic tubular shape of outer hair cells is maintained by membrane-associated structures with elastic properties that enable the cell to return to its original shape after deformation. The mechanism controlling length changes may, therefore, be composed of two elements in parallel, namely a force generating element and a passive elastic element. Inhibitors of ATP synthesis, or the presence of the non-hydrolysable ATP analogue AMP.PNP, perfused into outer hair cells, failed to inhibit length changes. Drugs against actin, including phalloidin, cytochalasin B and cytochalasin D, and against tubulin, including colchicine, nocodazole and colcemid, also failed to inhibit length changes. We conclude that the force-generating mechanism is, therefore, unlike most other forms of cell motility, and possible alternative hypotheses are briefly discussed.
M C Holley; J F Ashmore
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Proceedings of the Royal Society of London. Series B, Containing papers of a Biological character. Royal Society (Great Britain)     Volume:  232     ISSN:  0080-4649     ISO Abbreviation:  Proc. R. Soc. Lond., B, Biol. Sci.     Publication Date:  1988 Jan 
Date Detail:
Created Date:  1988-04-28     Completed Date:  1988-04-28     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  7505889     Medline TA:  Proc R Soc Lond B Biol Sci     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  413-29     Citation Subset:  IM    
Department of Physiology, The Medical School, Bristol, UK.
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MeSH Terms
Actins / metabolism
Adenosine Triphosphate / metabolism
Cell Movement / drug effects
Cytochalasins / pharmacology
Electric Conductivity
Guinea Pigs
Hair Cells, Auditory / cytology,  drug effects,  physiology*,  ultrastructure
Membrane Potentials
Microscopy, Fluorescence
Microscopy, Interference
Osmolar Concentration
Phalloidine / pharmacology
Tubulin / metabolism
Reg. No./Substance:
0/Actins; 0/Cytochalasins; 0/Tubulin; 17466-45-4/Phalloidine; 56-65-5/Adenosine Triphosphate

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

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