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  • 1
    Electronic Resource
    Electronic Resource
    Decreased Cellular Toxicity of Neomycin in a Clonal Cell Line Isolated from LLC-PK1 (1993)
    Springer
    Pharmaceutical research 10 (1993), S. 573-576 
    Details
    ISSN: 1573-904X
    Keywords: aminoglycoside nephrotoxicity ; apical membrane enzymes ; cell cloning ; neomycin-resistance ; kidney epithelial cell line
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract We have previously shown in LLC-PK1 cells, that apical membrane enzyme activity was inhibited by aminoglycoside antibiotics (Am. J. Physiol. 254, C251-C257, 1988). In the present study, the relationship between the lethal cytotoxic effect of aminoglycoside and its effect on apical membrane enzyme was examined by establishing aminoglycoside resistant cells. A clonal cell line, LLC-PK1/NRa3, was isolated from parent LLC-PK1 cells in the presence of neomycin. Neomycin inhibited colony formation and increased the number of floating dead cells in parent LLC-PK1 cultures. In contrast, these cytotoxic effects of neomycin were negligible or less pronounced in NRa3 cells, indicating that NRa3 cells were more resistant to neomycin compared with the parent cells. The inhibitory effect of neomycin on apical enzyme activity was significantly weaker in NRa3 cells than in the parent cells. These results suggest that a common mechanism is involved in the aminoglycoside-induced reductions in the apical enzyme activity and in cell viability of LLC-PK1 cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018954204094
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  • 2
    Electronic Resource
    Electronic Resource
    Modulation of Organic Cation Transport and Lipid Fluidity by Benzyl Alcohol in Rat Renal Brush-border Membranes (1996)
    Springer
    Pharmaceutical research 13 (1996), S. 1069-1072 
    Details
    ISSN: 1573-904X
    Keywords: renal transport ; organic cation ; membrane fluidity ; brush-border membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Organic cations are actively transported in renal brush-border membranes (BBM) by the H+/organic cation antiport system. In the present study, we investigated the relationship between membrane fluidity and organic cation transport in the BBM. Methods. The effects of benzyl alcohol, a membrane fluidizing agent, on the organic cation tetraethylammonium (TEA) uptake were studied using renal BBM vesicles isolated from rat kidney. BBM fluidity was assessed by fluorescence polarization technique. Results. H+ gradient-dependent uptake of TEA in BBM vesicles was inhibited by benzyl alcohol in a dose-dependent manner, with an apparent half inhibitory concentration of 18mM. The decrease in fluorescence anisotropy of l,6-diphenyl-l,3,5-hexatriene in BBM, which represents the increase in membrane fluidity, was correlated with the decrease in TEA transport activity. The dissipation rate of H+ gradient, a driving force for organic cation transport in BBM, was increased by benzyl alcohol. In addition, H+ gradient-independent TEA-TEA exchange was also inhibited by benzyl alcohol. These findings indicate that benzyl alcohol inhibits the uptake of TEA by affecting the intrinsic activity of the organic cation transporter and the H+ gradient dissipation rate. Conclusions. The membrane fluidity should be an important determinant for organic cation transport in renal BBM.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016066926269
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  • 3
    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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  • 4
    Electronic Resource
    Electronic Resource
    Effect of Cyclosporin Analogues and FK506 on Transcellular Transport of Daunorubicin and Vinblastine via P-glycoprotein (1996)
    Springer
    Pharmaceutical research 13 (1996), S. 1073-1077 
    Details
    ISSN: 1573-904X
    Keywords: P-glycoprotein ; cyclosporins ; FK506 ; daunorubicin ; vinblastine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. P-glycoprotein-mediated transcellular transport of anticancer agents and the inhibitory effect of cyclosporin analogs and FK506 were investigated. Methods. The transcellular transport of daunorubicin and vinblastine by monolayers of LLC-GA5-COL150 cells which overexpressed P-glycoprotein was measured in the presence and absence of cyclosporins or FK506. Results. Cyclosporins and FK506 inhibited P-glycoprotein-mediated transport of daunorubicin and vinblastine in the order of cyclosporin D, dihydrocyclosporin D 〉 cyclosporin A 〉 FK506 〉 cyclosporin C, dihydrocyclosporin C. The intracellular accumulation of the anticancer agents was highly associated with the transporting function of P-glycoprotein. The inhibitory effect of cyclosporin D was concentration-dependent. The inhibitory effect of the modulators on P-glycoprotein was not correlated with the immunosuppressive activity, but was correlated with their lipophilicity. Conclusions. In the transcellular transport system, lipophilicity may be one of the determinants for the inhibitory effect of various multidrug resistance modulators on the P-glycoprotein-mediated transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016019010339
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  • 5
    Electronic Resource
    Electronic Resource
    Distribution Characteristics of Levofloxacin and Grepafloxacin in Rat Kidney (1999)
    Springer
    Pharmaceutical research 16 (1999), S. 534-539 
    Details
    ISSN: 1573-904X
    Keywords: levofloxacin ; grepafloxacin ; quinolone antibacterial drugs ; renal transport ; tissue distribution ; cortical slices
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To elucidate the renal distribution of quinolones, we examined the uptake of levofloxacin and grepafloxacin in vivo and in rat renal cortical slices. Methods. The plasma and various tissue concentrations of levofloxacin and grepafloxacin were measured after a bolus injection in rats, and tissue uptake clearance was calculated. Transport characteristics of quinolones in rat renal cortical slices were evaluated. Results. The tissue distribution of levofloxacin and grepafloxacin in the kidney was greater than in any other tissue, and the tissue uptake clearances of levofloxacin and grepafloxacin in the kidney cortex were 1.2 and 4.6 ml/min/g tissue, respectively. The uptake of levofloxacin and grepafloxacin in rat renal cortical slices was concentrative, as indicated by slice/medium ratios of 2.3 and 9.6 at 60 min, respectively. The uptake of levofloxacin and grepafloxacin in rat renal cortical slices showed saturation, and was significantly inhibited in the presence of quinidine (p 〈 .05), but not of tetraethylammonium or /p-aminohippurate. Conclusions. Renal distribution of levofloxacin and grepafloxacin may be mediated by a specific transport system for quinolones, distinct from the organic cation and organic anion transport systems in the kidney.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018871029244
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of Arbekacin and Vancomycin on Release of Lactate Dehydrogenase and Fragmentation of DNA in LLC-PK1 Kidney Epithelial Cells (1999)
    Springer
    Pharmaceutical research 16 (1999), S. 1132-1135 
    Details
    ISSN: 1573-904X
    Keywords: arbekacin ; vancomycin ; cisplatin ; apoptosis ; toxicity ; LLC-PK1 cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011919306412
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of Fosfomycin and Imipenem/ Cilastatin on Nephrotoxicity and Renal Excretion of Vancomycin in Rats (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 734-738 
    Details
    ISSN: 1573-904X
    Keywords: vancomycin ; fosfomycin ; imipenem/cilastatin ; nephrotoxicity ; protective effect ; renal handling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The effects of fosfomycin and imipenem/cilastatin on the nephrotoxicity of vancomycin were studied in rats, and those on the renal handling of vancomycin were also investigated in perfused kidneys. Methods. The protective effects of fosfomycin and imipenem/cilastatin on vancomycin nephrotoxicity were evaluated by increases in plasma concentration of creatinine and urea nitrogen in rats. The urinary excretion of vancomycin was measured and analyzed kinetically in the perfused rat kidney. Results. The nephrotoxicity induced by vancomycin (500 mg/kg, i.v.) was inhibited almost completely by co-administration of fosfomycin or imipenem/cilastatin. In the perfused rat kidney, the excretion ratio of vancomycin was less than those of p-aminohippurate and cimetidine, and greater than that of arbekacin, suggesting the secretion and reabsorption of vancomycin in renal tubules. The tissue/perfusate ratios of unbound vancomycin were not significantly changed by co-treatment with fosfomycin or imipenem/cilastatin. Imipenem/cilastatin significantly decreased the excretion ratio of vancomycin. Fosfomycin also decreased vancomycin excretion ratio, although this effect was not significant. Conclusions. The renal handling of vancomycin was different from those of organic anions and cations and an aminoglycoside antibiotic. The protective effects of fosfomycin and imipenem/cilastatin against the nephrotoxicity of vancomycin might be partly due to the change in renal handling of vancomycin, probably in its tubular secretion/ reabsorption, in rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011971019868
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  • 8
    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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  • 9
    Electronic Resource
    Electronic Resource
    Evaluation of Renal Tubular Secretion and Reabsorption of Levofloxacin in Rats (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 508-511 
    Details
    ISSN: 1573-904X
    Keywords: levofloxacin ; quinolone antibacterial drugs ; renal secretion ; organic cation transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Levofloxacin, a quinolone antibacterial drug, is a zwitterion at physiological pH. We examined the effect of cationic and anionic drugs on renal excretion of levofloxacin by means of in vivo clearance to characterize the mechanisms of renal excretion of this drug. Methods. In vivo clearance was studied in male Wistar albino rats. A bolus dose of 2.85 mg/kg of levofloxacin was administered, followed by a constant infusion of 7.08 μg/min. Cimetidine, tetraethylammonium, or p-aminohippurate was administered as a bolus and incorporated into the infusion solution. After reaching steady state, urine and blood concentrations were measured, and pharmacokinetic parameters were calculated. Results. Renal clearance was 2.56 ± 0.42 ml/min in control, which accounted for 34% of the total body clearance. Renal clearance was significantly decreased to 0.83 ± 0.25 ml/min by cimetidine (p〈.05), corresponding to 32% of the control value. The cationic drug, tetraethylammonium also reduced the renal clearance of levofloxacin, but the effect of the anionic drug, p-aminohippurate, was slight. The clearance ratio of levofloxacin, which was calculated by renal clearance divided by the plasma unbound fraction and the glomerular filtration rate, was 1.60 ± 0.38 in the control and it was decreased to 0.68 ± 0.17 and 1.11 ± 0.22 by cimetidine and tetraethylammonium, respectively. Conclusions. The present results suggest that the renal excretion of levofloxacin in rats involves tubular secretion and reabsorption, in addition to glomerular filtration, and that tubular secretion is inhibited by cimetidine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012111902798
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  • 10
    Electronic Resource
    Electronic Resource
    Kinetic Analysis of Tetraethylammonium Transport in the Kidney Epithelial Cell Line, LLC-PK1 (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 1236-1240 
    Details
    ISSN: 1573-904X
    Keywords: organic cation ; epithelial transport ; LLC-PK1 ; kinetic model ; levofloxacin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The aims of this study were to establish a kinetic means of analyzing the membrane transport of organic cations in renal epithelial cells, and to simultaneously evaluate drug interactions in apical and basolateral membranes. Methods. Tetraethylammonium (TEA) transport was measured using LLC-PK1, cell monolayers grown on microporous membrane filters. After incubating the cells with unlabeled TEA or other drugs, apical or basolateral medium was changed to that containing labeled TEA, and transcellular transport and cellular accumulation were measured. Clearance from apical medium to cells (CL12), cells to apical medium (CL21), cells to basolateral medium (CL23) and basolateral medium to cells (CL32) were calculated based on a three compartment model. Results. TEA was accumulated progressively in the monolayers from the basolateral side and was transported unidirectionally to the apical side. CL32 was greater than CL12 and CL23 was greater than CL21. Therefore, the rate limiting step of TEA transport from the basolateral to the apical medium was the cell-to-apical step. Co-incubation of TEA with procainamide decreased the transport parameters of TEA, CL12, CL21 and CL32, whereas that with levofloxacin decreased only CL12 and CL21, not affecting the parameters in basolateral membranes. Conclusions. Using a simple model, we analyzed the transport of organic cation in kidney epithelial cell line, LLC-PK1 This method can be useful for the analysis of cation transport and drug interactions in the apical and basolateral membranes of renal tubules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012119210434
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