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Carrier-mediated hepatic uptake of peptidic endothelin antagonists in rats

Akhteruzzaman, S. and Kato, Y. and Kouzuki, H. and Suzuki, H. and Hisaka, A. and Stieger, B. and Meier, P. J. and Sugiyama, Y.. (1999) Carrier-mediated hepatic uptake of peptidic endothelin antagonists in rats. The Journal of Pharmacology and Experimental Therapeutics, Vol. 290, H. 3. S. 1107-1115.

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Official URL: http://edoc.unibas.ch/dok/A5261690

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Abstract

The endothelin antagonist BQ-123, an anionic cyclopentapeptide, is taken up by rat hepatocytes through active transport systems. Here, we have examined the hepatocellular uptake mechanism for several BQ-123 derivatives with anionic charges using isolated rat hepatocytes. BQ-485, a linear peptide, BQ-518, a cyclic peptide, and compound A, a cyclic peptide with a cationic moiety, were taken up by hepatocytes in a concentration-dependent manner. The uptake of BQ-485 was most efficient, whereas compound A showed comparable uptake with BQ-123. The uptake of these peptides was Na(+)- and energy-dependent, suggesting that active transport mechanisms are involved in their uptake into hepatocytes. BQ-485, BQ-518, and compound A can almost completely inhibit both the Na(+)-dependent and -independent uptake of [(3)H]BQ-123, with inhibition constants (K(i)) that are comparable to the Michaelis-Menten constants (K(m)) for their Na(+)-dependent and -independent uptake, respectively. Inhibition by BQ-485 was competitive, and the uptake of BQ-485 can be inhibited by BQ-123, with K(i) values that are comparable with the K(m) values for BQ-123 uptake. The uptake of BQ-123 by COS-7 cells transfected with either Na(+)-dependent taurocholate-cotransporting polypeptide (Ntcp) or Na(+)-independent basolateral organic anion-transporting polypeptide (oatp1) was minimal. Thus, these three peptides share the transporters that also recognize BQ-123 but appear to differ from Ntcp and oatp1.
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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