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Hepatic uptake of cholecystokinin octapeptide by organic anion-transporting polypeptides OATP4 and OATP8 of rat and human liver

Ismair, M. G. and Stieger, B. and Cattori, V. and Hagenbuch, B. and Fried, M. and Meier, P. J. and Kullak-Ublick, G. A.. (2001) Hepatic uptake of cholecystokinin octapeptide by organic anion-transporting polypeptides OATP4 and OATP8 of rat and human liver. Gastroenterology, Vol. 121, H. 5. pp. 1185-1190.

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Official URL: http://edoc.unibas.ch/dok/A5261651

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Abstract

BACKGROUND & AIMS: Cholecystokinin (CCK) is a major gastrointestinal peptide hormone that is released postprandially from the small intestine and exerts marked effects on gallbladder and gastrointestinal motility. The smaller isoforms CCK-8 and CCK-4 are rapidly taken up into hepatocytes, metabolized, and excreted into bile. Our aim was to identify and characterize the hepatocellular CCK-8 uptake system. METHODS: CCK-8 uptake was measured in Xenopus laevis oocytes expressing the organic anion-transporting polypeptides of rat liver (Oatp1, Oatp2, Oatp3, or Oatp4) and of human liver (OATP-A, OATP-B, OATP-C, or OATP8) and in primary cultured rat hepatocytes. RESULTS: Rat Oatp4 and human OATP8 efficiently mediated CCK-8 uptake in oocytes, with Michaelis constant (Km) values of 14.9 +/- 2.9 micromol/L and 11.1 +/- 2.9 micromol/L, respectively. CCK-8 uptake by hepatocytes was also saturable, with a Km of 6.7 +/- 2.1 micromol/L. The Km value in rat hepatocytes is consistent with Oatp4-mediated transport. CONCLUSIONS: CCK-8 is selectively transported by rat Oatp4 and human OATP8, both of which are exclusively expressed at the basolateral membrane of hepatocytes. These 2 transporters are the first and probably the predominant hepatic uptake systems for CCK-8 and may be critical for the rapid clearance of this hormone from the circulation.
Faculties and Departments:11 Rektorat und Verwaltung > Vizerektorat Forschung
UniBasel Contributors:Meier-Abt, Peter J.
Item Type:Article, refereed
Article Subtype:Research Article
Bibsysno:Link to catalogue
Publisher:Saunders
ISSN:0016-5085
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:22 Mar 2012 14:23
Deposited On:22 Mar 2012 13:35

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