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  • 1
    Electronic Resource
    Electronic Resource
    Transport Characteristics of Ceftibuten, a New Cephalosporin Antibiotic, via the Apical H+/Dipeptide Cotransport System in Human Intestinal Cell Line Caco-2: Regulation by Cell Growth (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 1483-1487 
    Details
    ISSN: 1573-904X
    Keywords: cephalosporin antibiotics ; H +/dipeptide cotransporter ; Caco-2 cells ; cell growth ; intestinal absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The intestinal epithelial cell line Caco-2 possesses the H+/ dipeptide cotransport system responsible for uptake of oral cephalosporins. In this study, the transport characteristics of ceftibuten were examined from the viewpoint of cell growth in the Caco-2 cells. Methods. The uptake of cephalosporins by Caco-2 cell monolayers grown on plastic dishes was measured and analyzed kinetically. Results. The uptake of ceftibuten was increased by lowering pH of the incubation medium and was inhibited by excess dipeptide. The transport activity of ceftibuten was dependent on the duration of culture, being maximal on the 14th day after inoculation. Kinetic analysis revealed that the development of ceftibuten uptake was due to not only a decrease in Km but also to an increase in Vmax value. Conclusions. The uptake of ceftibuten is mediated by the apical H+/ dipeptide cotransport system which is regulated by cell growth and/or differentiation in the Caco-2 cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016235404598
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  • 2
    Electronic Resource
    Electronic Resource
    Transepithelial Transport of Diphenhydramine Across Monolayers of the Human Intestinal Epithelial Cell Line Caco-2 (2000)
    Springer
    Pharmaceutical research 17 (2000), S. 539-545 
    Details
    ISSN: 1573-904X
    Keywords: Caco-2 cells ; diphenhydramine ; transepithelial transport ; intestinal absorption ; intestinal secretion ; organic cation transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The transepithelial transport characteristics of theantihistamine, diphenhydramine, were studied in human intestinal Caco-2 cellmonolayers to elucidate the mechanisms of its intestinal absorption. Methods. The transepithelial transport and the cellular accumulationof diphenhydramine were measured using Caco-2 cell monolayersgrown in Transwell chambers. Results. The transepithelial transport of diphenhydramine from theapical to basolateral side was saturable, and the flux and cellularaccumulation of diphenhydramine were dependent on the apicalextracellular pH (pH 7.4 〉 6.5 〉 5.5). Transport and accumulation ofdiphenhydramine from the apical side were inhibited by anotherantihistamine, chlorpheniramine, while typical substrates for the renal organiccation transport system such as tetraethylammonium, cimetidine andguanidine had no effect. The transepithelial transport and cellularaccumulation of diphenhydramine from the basolateral side were alsopH-dependent and inhibited by chlorpheniramine. In addition, intracellulardiphenhydramine preloaded was preferentially effluxed to the apicalside, suggesting the involvement of the secretory pathway indiphenhydramine transport. Furthermore, diphenhydramine uptake from boththe apical and basolateral sides was stimulated by preloadingmonolayers with chlorpheniramine (trans-stimulation effect). Conclusions. Transepithelial transport of diphenhydramine acrossCaco-2 cells is mediated by pH-dependent, specific transport systemsthat exist in both the apical and basolateral membranes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007560731098
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  • 3
    Electronic Resource
    Electronic Resource
    N-terminal Halves of Rat H+/Peptide Transporters Are Responsible for Their Substrate Recognition (2000)
    Springer
    Pharmaceutical research 17 (2000), S. 15-20 
    Details
    ISSN: 1573-904X
    Keywords: peptide transporters ; chimeras ; intestinal absorption ; renal reabsorption ; β-lactam antibiotics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Peptide transporters PEPT1 and PEPT2 differ substantiallyin their substrate affinity and recognition. The aim of this study is todefine the structural domains which influence the functionalcharacteristics of both transporters Methods. Two kinds of chimeric peptide transporters (PEPT-N1C2and PEPT-N2C1) were constructed, and their functional characteristicswere compared with those of wild-type transporters in stabletransfectants. Results. PEPT-N1C2, the N-terminal half of rat PEPT1 and theC-terminal half of rat PEPT2, and the reciprocal chimera PEPT-N2C1were functionally expressed in LLC-PK1 cells. The pH-profiles of [14C]glycylsarcosine uptake by PEPT-N1C2 and PEPT-N2C1 were close tothose of PEPT1 and PEPT2, respectively. Substrate recognition forPEPT-N1C2 and PEPT-N2C1 was also similar to that of PEPT1 andPEPT2, respectively. However, substrate affinities for PEPT-N1C2were higher than those for PEPT1, although those for PEPT-N2C1 andPEPT2 were comparable. Conclusions. These results indicate that functional regions which areassociated with the extracellular pH changes and are responsible forsubstrate recognition of PEPT1 and PEPT2 may be located in theN-terminal halves of the proteins. In addition, it is suggested that thedomain to affect the substrate affinity exists in the C-terminal as wellas in the N-terminal half of rat PEPT2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007554105597
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