Document Detail

Osmotic properties of auditory hair cells in the leopard frog: evidence for water-permeable channels.
MedLine Citation:
PMID:  21044674     Owner:  NLM     Status:  MEDLINE    
When amphibian papillar hair cells (APHCs) of the leopard frog, Rana pipiens pipiens, are osmotically challenged, they exhibit a characteristically asymmetric (rectifying) response: small decreases (5%, or less) in the extracellular solution's osmolarity do not significantly affect the cells' volume; larger decreases produce a relatively slow volume increase in APHCs, while exposure to a hyperosmotic medium leads to rapid shrinking of these cells. Furthermore, the rate of volume change appears to be a function of the rate of extracellular osmotic change. These characteristics make the application of methods devised for the estimation of the osmotic permeability coefficient (P(f)) for semipermeable membranes - i.e., those with significant permeability only to water - to APHC membrane rather futile. We have, therefore, devised a method that takes both the permeability to solutes as well as the kinetics of the osmolarity change into consideration, in order to obtain estimates of P(f) that are to a large degree independent of these factors. We have compared the new and earlier methods. Using the new method, we have estimated the P(f) of APHCs' plasma membrane to be in the 10(-2)-cm/s range, and thus significantly larger than those reported for lipid bilayers. APHC's membrane P(f) appears to be cell-size independent and insensitive to extracellular mercury. These results suggest that APHCs express water-permeable channels in their plasma membrane. Furthermore, we suggest that asymmetric and rate dependent shape changes produced by osmolarity changes in APHCs imply the presence of significant permeability to solutes. The significance of transmembrane solute transport and water channel expression in amphibian auditory hair cells is discussed.
Nasser A Farahbakhsh; Jaime E Zelaya; Peter M Narins
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Video-Audio Media     Date:  2010-10-31
Journal Detail:
Title:  Hearing research     Volume:  272     ISSN:  1878-5891     ISO Abbreviation:  Hear. Res.     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-02-14     Completed Date:  2011-06-07     Revised Date:  2014-09-13    
Medline Journal Info:
Nlm Unique ID:  7900445     Medline TA:  Hear Res     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  69-84     Citation Subset:  IM    
Copyright Information:
Copyright © 2010 Elsevier B.V. All rights reserved.
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MeSH Terms
Analysis of Variance
Aquaporins / metabolism*
Cell Membrane / metabolism*
Cell Membrane Permeability*
Cell Size*
Hair Cells, Auditory / metabolism*
Models, Biological
Rana pipiens*
Water / metabolism*
Grant Support
Reg. No./Substance:
0/Aquaporins; 059QF0KO0R/Water

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

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