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Uptake of the mycotoxin ochratoxin A in liver cells occurs via the cloned organic anion transporting polypeptide

Kontaxi, M. and Echkardt, U. and Hagenbuch, B. and Stieger, B. and Meier, P. J. and Petzinger, E.. (1996) Uptake of the mycotoxin ochratoxin A in liver cells occurs via the cloned organic anion transporting polypeptide. The Journal of Pharmacology and Experimental Therapeutics, Vol. 279, H. 3. S. 1507-1513.

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Official URL: http://edoc.unibas.ch/dok/A5261724

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Abstract

Ochratoxin A (OTA) is a mycotoxin produced by mold. It mainly causes nephropathies in humans and domestic animals as a major pathogenic contaminant of cereals and animal feed. Upon p.o. uptake and intestinal absorption, a large part of OTA is taken up by hepatocytes and eliminated into bile. In the present study, hepatocellular uptake of radiolabeled [3H]OTA in isolated rat hepatocytes was characterized; a saturable (K(m) = 18.9 microM, Vmax = 473 pmol/mg/min), temperature (Aapp = 30.4 and 76.6 kilo Joule/mol) and energy-dependent mycotoxin transport was found. This OTA uptake was inhibited by various bile acids, sulfobromophthalein and the thrombin inhibitor CRC 220. Because all inhibitors are substrates of the organic anion-transporting polypeptide (oatp), a recently cloned hepatic carrier, uptake experiments were performed in oatp-cRNA-injected Xenopus laevis oocytes. These studies revealed an oatp-specific OTA uptake (K(m) = 16.6 microM). In contrast, OTA was not transported by the hepatic Na+/taurocholate-cotransporting polypeptide. Known oatp substrates cis-inhibited OTA uptake in oatp-cRNA-injected oocytes in close correlation with the results derived from isolated hepatocytes. These results identify OTA as a new substrate for oatp. They further support the multispecific nature of oatp-mediated transport and stress the importance of this carrier for hepatic clearance of xenobiotics.
Faculties and Departments:11 Rektorat und Verwaltung > Vizerektorat Forschung
UniBasel Contributors:Meier-Abt, Peter J.
Item Type:Article, refereed
Bibsysno:Link to catalogue
Publisher:Williams and Wilkins
ISSN:0022-3565
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:22 Mar 2012 14:24
Deposited On:22 Mar 2012 13:37

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