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Mediated (nonactive) transport of glucose in Mammalian cells and its regulation.
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MedLine Citation:
PMID:  19873627     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Mediated (nonactive) transport of glucose in mammalian cells is characterized by saturation kinetics, stereospecificity, sensitivity to inhibition by phlorizin and certain sulfhydryl-blocking agents, a temperature coefficient of about 2, an inability to utilize metabolic energy, and countertransport. Countertransport can be explained by the development of carrier gradients in the cell membrane and provides the best evidence for carrier mobility. Efforts to identify and isolate chemical components of the transport system, have not been successful. Transport among different types of mammalian cells shows a wide range of activities (V(max) values differ by three or more orders of magnitude) and different sensitivities to hormones. Glucose enters the liver cell by mediated transport, as shown by a difference in the penetration rates of D- and L-glucose and sensitivity to phlorizin. The activity of the system is one of the highest known. Transport in muscle is the most important rate-controlling step for glucose utilization and is strongly accelerated by hypoxia, work, and insulin. The effect of work or insulin is strongly inhibited by metabolism, of fatty acids. Insulin also stimulates glucose transport in adipose tissue. Using isolated fat cells, it could be shown that insulin is rapidly bound to sites on the cell surface. The effect is lost within a few minutes after the exogenous hormone is removed. The bound insulin is not released as such, but is metabolized to unknown products. Binding is prevented by preexposure of cells to maleimide, which presumably blocks certain sulfhydryl groups at or near the insulin-binding site. Pretreatment with insulin protects against maleimide. Digestion of the cell with trypsin eliminates the acceleration of glucose transport and the inhibition of lipolysis by insulin. The glucose transport and adenyl cyclase systems are not grossly affected by trypsin, indicating that the insulin effector system is a separate entity.
C R Park; O B Crofford; T Kono
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of general physiology     Volume:  52     ISSN:  0022-1295     ISO Abbreviation:  J. Gen. Physiol.     Publication Date:  1968 Jul 
Date Detail:
Created Date:  2010-06-29     Completed Date:  2010-06-29     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2985110R     Medline TA:  J Gen Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  296-318     Citation Subset:  -    
Department of Physiology, Vanderbilt University School of Medicine, Nashville, Tennessee 37203.
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Journal Information
Journal ID (nlm-ta): J Gen Physiol
ISSN: 0022-1295
ISSN: 1540-7748
Publisher: The Rockefeller University Press
Article Information
Copyright © 1968 by The Rockefeller University Press
Print publication date: Day: 1 Month: 7 Year: 1968
Volume: 52 Issue: 1
First Page: 296 Last Page: 318
ID: 2225787
PubMed Id: 19873627

Mediated (Nonactive) Transport of Glucose in Mammalian Cells and its Regulation
C. R. Park
O. B. Crofford
T. Kono
From the Department of Physiology, Vanderbilt University School of Medicine, Nashville, Tennessee 37203

Article Categories:
  • Transport across Cell Membranes
    • Article

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