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  Taurocholate - sodium co-transport by brush-border membrane vesicles isolated from rat ileum

Lücke, H., Stange, G., Kinne, R., & Murer, H. (1978). Taurocholate - sodium co-transport by brush-border membrane vesicles isolated from rat ileum. Biochemical Journal, 174(3), 951-958. doi:10.1042/bj1740951.

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 Creators:
Lücke, Heinrich1, Author              
Stange, Gertraud1, Author              
Kinne, Rolf1, Author              
Murer, Heini1, Author              
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1Department of Physiology, Max Planck Institute of Biophysics, Max Planck Society, ou_2068297              

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 Abstract: Uptake of taurocholate into brush-border membrane vesicles isolated from rat small intestine by a Ca2+ -precipitation method was investigated by using a rapid-filtration technique. Uptake of taurocholate by ileal brush-border membranes consisted of three phenomena: binding to the outside of the vesicles, transfer across the vesicle membrane and binding to the intravesicular compartment. The transport of taurocholate across the brush-border membranes was stimulated in the presence of Na+ compared with the presence of K+; stimulation was about 11-fold in the presence of a NaCl gradient (Nao>Nai), where the subscripts refer to `outside' and `inside' respectively, and 4-fold under equilibrium conditions for Na+ (Nao=Nai). In the presence of a Na+ gradient a typical `overshoot' phenomenon was observed. Membranes preloaded with unlabelled taurocholate showed an accelerated entry of labelled taurocholate (tracer exchange) in the presence of Na+ compared with the presence of K+. The stimulation by Na+ was observed only in membrane preparations from the ileum. Addition of monactin, an ionophore for univalent cations, decreased the Na+-gradient-driven taurocholate uptake. The Na+-dependent taurocholate transport showed saturation kinetics and the phenomenon of counterflow and was inhibited by glycocholate. Other cations such as Li+, Rb+ and Cs+ could not replace Na+ in its stimulatory action. When the electrical potential difference across the vesicle membrane was altered by establishing different diffusion potentials (anion replacement; K+ gradient±valinomycin) a more-negative potential inside stimulated Na+-dependent taurocholate transport. These data demonstrate the presence of a rheogenic (potential sensitive) Na+–taurocholate co-transport system in ileal brush-border membranes and support the hypothesis that the reabsorption of bile acids in the ileum is a secondary active uptake.

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Language(s): eng - English
 Dates: 1978-03-281978-09-15
 Publication Status: Published in print
 Pages: 8
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1042/bj1740951
PMID: 581553
PMC: PMC1186000
 Degree: -

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Title: Biochemical Journal
Source Genre: Journal
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Publ. Info: London : Published by Portland Press on behalf of the Biochemical Society.
Pages: - Volume / Issue: 174 (3) Sequence Number: - Start / End Page: 951 - 958 Identifier: ISSN: 0264-6021
CoNE: https://pure.mpg.de/cone/journals/resource/110992357308158