Document Detail


A novel sorbitol transport mechanism in cultured renal papillary epithelial cells.
MedLine Citation:
PMID:  2513728     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The renal papillary epithelial cell line, GRB-PAP1, accumulates sorbitol when grown in a hypertonic (500 mosmol/kgH2O) bathing medium. When the cells are returned to a 300 mosmol/kgH2O medium, they lose their sorbitol rapidly to the bath. Sorbitol movement across the membranes of these cells was investigated by studying the uptake of radioactive sorbitol and related compounds. Sorbitol uptake increased 71-fold when cells grown in 500 mosmol/kgH2O medium were exposed to a 300 mosmol/kgH2O test solution. The magnitude of the permeability increase was proportional to the size of the change in the osmolality of the bathing medium and not the absolute osmolality. Sorbitol uptake was a linear function of medium sorbitol concentration with no sign of saturation at sorbitol concentrations up to 315 mM. Although the permeability of other polyols was increased when the osmolality was reduced, competition between sorbitol and related sugars and polyols could not be demonstrated. Both the increased sorbitol uptake after a decrease in medium osmolality and the decrease to control permeability after return to the original osmolality were complete within 30 s. A wide variety of transport inhibitors and ion substitutions failed to alter the magnitude of the sorbitol permeability increase. The most effective inhibitor was quinidine, 1 mM reducing sorbitol uptake by 73%. The sorbitol permeability increase could also be blocked by reducing the temperature to 0 degrees C. Nonspecific uptake of sorbitol, such as endocytosis, was shown to be of only minor significance. The large increase in sorbitol permeability and subsequent sorbitol efflux enables these cells to withstand large decreases in osmolality without excessive swelling and consequent damage. A similar compensatory mechanism may operate in vivo in the renal papilla during the onset of diuresis.
Authors:
A W Siebens; K R Spring
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The American journal of physiology     Volume:  257     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1989 Dec 
Date Detail:
Created Date:  1990-02-02     Completed Date:  1990-02-02     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  F937-46     Citation Subset:  IM    
Affiliation:
Laboratory of Kidney and Electrolyte Metabolism, National Heart, Lung, and Blood Institute, Bethesda, Maryland 20892.
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MeSH Terms
Descriptor/Qualifier:
Animals
Biological Transport / drug effects
Carbon Radioisotopes
Cell Line
Diuretics / pharmacology
Epithelium / drug effects,  metabolism
Galactitol / pharmacology
Inositol / pharmacology
Kidney Medulla / metabolism*
Kinetics
Mannitol / pharmacology
Osmolar Concentration
Radioisotope Dilution Technique
Sorbitol / metabolism*
Sucrose / metabolism,  pharmacology
Chemical
Reg. No./Substance:
0/Carbon Radioisotopes; 0/Diuretics; 50-70-4/Sorbitol; 57-50-1/Sucrose; 608-66-2/Galactitol; 69-65-8/Mannitol; 6917-35-7/Inositol

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


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