The Experts below are selected from a list of 120 Experts worldwide ranked by ideXlab platform
Tetsuya Endo - One of the best experts on this subject based on the ideXlab platform.
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Uptake of perfluorooctanoic Acid by Caco-2 cells: Involvement of organic anion transporting polypeptides.
Toxicology Letters, 2017Co-Authors: Osamu Kimura, Koichi Haraguchi, Chiho Ohta, Nobuyuki Koga, Yoshihisa Kato, Yukiko Fujii, Tetsuya EndoAbstract:Abstract The mechanism underlying the intestinal absorption of perfluorooctanoic Acid (PFOA) was investigated using Caco-2 cells. The uptake of PFOA from the apical membrane of Caco-2 cells was fast, and pH, temperature, and concentration dependent, but Na + independent. Coincubation with sulfobromophthalein (BSP), glibenclamide, estron-3-sulfate, cyclosporine A or rifamycin SV, which are typical substrates or inhibitors of organic anion transporting polypeptides (OATPs), significantly decreased the uptake of PFOA. However, coincubation with probenecid or p -aminohippuric Acid, typical substrates of organic anion Transporters, did not decrease the uptake of PFOA. Furthermore, coincubation with l -lactic Acid or benzoic Acid, substrates of Monocarboxylic Acid Transporters, did not decrease PFOA uptake. The relationship between the initial uptake of PFOA and its concentration was saturable, suggesting the involvement of a carrier-mediated process. The calculated K m and uptake clearance ( V max / K m ) values for PFOA were 8.3 μM and 55.0 μL/mg protein/min, respectively. This clearance value was about 3-fold greater than that of the non-saturable uptake clearance ( K d : 18.1 μL/mg protein/min). Lineweaver–Burk plots revealed that BSP competitively inhibits the uptake of PFOA, with a K i value of 23.1 μM. These results suggest that the uptake of PFOA from the apical membranes of Caco-2 cells could be, at least in part, mediated by OATPs along with BSP.
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uptake of aristolochic Acid i into caco 2 cells by Monocarboxylic Acid Transporters
Biological & Pharmaceutical Bulletin, 2014Co-Authors: Osamu Kimura, Koichi Haraguchi, Chiho Ohta, Nobuyuki Koga, Yoshihisa Kato, Tetsuya EndoAbstract:The uptake mechanism of aristolochic Acid I (AAI) was investigated using Caco-2 cells cultured on dishes and permeable membranes. The uptake of AAI from the apical membrane of Caco-2 cells cultured on a dish was rapid, and a decrease in the pH of the incubation medium significantly increased uptake. Incubation at low temperature (4 degrees C) and treatment with sodium azide (a metabolic inhibitor) or carbonylcyanide p-trifluoromethoxyphenylhydrazone (a protonophore) significantly inhibited the AAI uptake. Coincubation with L-lactic Acid or benzoic Acid, typical substrates for the proton-linked Monocarboxylic Acid Transporters (MCTs), significantly decreased the AAI uptake, as did coincubation with alpha-cyano-4-hydroxycinnamate (an inhibitor of MCTs). Dixon plotting revealed the competitive inhibition of benzoic Acid on the AAI uptake. To confirm the AAI uptake via MCTs, the apical-to-basolateral transport of AAI was investigated using the Caco-2 cells cultured on the permeable membranes. The transport of AAI at pH 6.0 was markedly higher than that at pH 7.4, and was significantly decreased by coincubation with benzoic Acid. These results suggest that the uptake of AAI from the apical membrane of Caco-2 cells is mediated mainly by MCTs along with benzoic Acid.
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steric hindrance of 2 6 disubstituted benzoic Acid derivatives on the uptake via Monocarboxylic Acid Transporters from the apical membranes of caco 2 cells
Pesticide Biochemistry and Physiology, 2014Co-Authors: Kensuke Tsukagoshi, Osamu Kimura, Tetsuya EndoAbstract:Benzoic Acid is a typical substrate for Monocarboxylic Acid Transporters (MCTs), and easily taken up from the apical membranes of Caco-2 cells by MCTs. However, some benzoic Acid derivatives were sparingly taken up by Caco-2 cells. To elucidate the mechanism of lower uptake of the derivatives, we investigated the effect of substitution of benzene ring on the uptake by MCTs using Caco-2 cells. Among the benzoic Acid derivatives tested, the uptake of 2,6-disubstituted benzoic Acids was markedly lower than that of other benzoic Acids. Co-incubation of the 2,6-disubstituted derivatives with benzoic Acid did not decrease the uptake of benzoic Acid, while co-incubation with other derivatives significantly decreased the uptake of benzoic Acid. Kinetic analyses elucidated that the uptake of 2,6-dichlorobenzoic Acid and 2,3,6-trichlorobenzoic Acid did not involve the carrier-mediated process. The 2,6-disubstitution of benzoic Acid may prevent the access of carboxylic Acid group to MCTs expressed on the apical membranes of Caco-2 cells.
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Transepithelial transport of 4-chloro-2-methylphenoxyacetic Acid (MCPA) across human intestinal Caco-2 cell monolayers.
Basic & Clinical Pharmacology & Toxicology, 2012Co-Authors: Osamu Kimura, Kensuke Tsukagoshi, Moriaki Hayasaka, Tetsuya EndoAbstract:Mechanisms of transcellular transport of 4-chloro-2-methylphenoxyacetic Acid (MCPA) across the small intestine were investigated using Caco-2 cells cultured on permeable membranes. The cell monolayers were incubated with MCPA, either from apical side at pH 6.0 or 7.4, or basolateral side at pH 7.4. The accumulation and apical-to-basolateral transport of MCPA were markedly stimulated by the Acidic pH on the apical side (inwardly directed H+ gradient), dependent on metabolic energy and inhibited by co-incubation with acetic Acid or benzoic Acid. Without the H+ gradient, on the other hand, the basolateral-to-apical transport of MCPA (secretory transport) was higher than the apical-to-basolateral transport (absorptive transport), although the secretory transport of MCPA was markedly lower than the absorptive transport under the H+ gradient. Co-incubation of MCPA with probenecid from the basolateral side significantly inhibited the accumulation and transport of MCPA, whereas co-incubation with p-aminohippuric Acid did not. These results suggest that the absorptive transport of MCPA is mediated by H+-linked Monocarboxylic Acid Transporters expressed on the apical membranes, while secretory transport is mediated by a probenecid-sensitive transporter expressed on the basolateral membranes of Caco-2 cell monolayers.
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Uptake of triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic Acid) and dicamba (3,6-dichloro-2-methoxybenzoic Acid) from the apical membranes of the human intestinal Caco-2 cells
Archives of Toxicology, 2012Co-Authors: Osamu Kimura, Kensuke Tsukagoshi, Moriaki Hayasaka, Tetsuya EndoAbstract:We investigated whether the uptake of triclopyr (3, 5, 6-trichloro-2-pyridinyloxyacetic Acid) and dicamba (3,6-dichloro-2-methoxybenzoic Acid) across the apical membrane of Caco-2 cells was mediated via proton-linked Monocarboxylic Acid Transporters (MCTs). The uptake of triclopyr from the apical membranes was fast, pH-, temperature-, and concentration dependent, required metabolic energy to proceed, and was competitively inhibited by Monocarboxylic Acids such as benzoic Acid and ferulic Acid (substrates of l -lactic Acid-insensitive MCTs), but not by l -lactic Acid. Thus, the uptake of triclopyr in Caco-2 cells appears to be mediated mainly via l -lactic Acid-insensitive MCTs. In contrast, the uptake of dicamba (a benzoic Acid derivative) was slow, and it was both pH- and temperature dependent. Coincubation with ferulic Acid did not decrease the uptake of dicamba, although coincubation with benzoic Acid moderately decreased it. The uptake of dicamba appears to be mediated mainly via passive diffusion, which is in contrast to the uptake of benzoic Acid via MCTs. We speculate that the substituted groups in dicamba may inhibit uptake via MCTs.
Sanjay K. Jain - One of the best experts on this subject based on the ideXlab platform.
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Dual Drug Delivery Using Lactic Acid Conjugated SLN for Effective Management of Neurocysticercosis
Pharmaceutical Research, 2015Co-Authors: Rekha Devi, Ankit Jain, Pooja Hurkat, Sanjay K. JainAbstract:Purpose The debut study was aimed to develop Lactic Acid (LA)-conjugated solid lipid nanoparticles (SLN-LA) bearing albendazole (ALB) and prednisolone (PRD) for effective management of neurocysticercosis (NCC). Methods LA was coupled to SLN by post-insertion technique. SLNs were characterized for particle size and size distribution, shape, and percent drug entrapment efficiency. In vitro drug release kinetics, fluorescence study and in vitro transendothelial transport, hematological studies and pharmacokinetic studies were carried out to predict the fullest drug delivery potential. Results Spherical SLNs (~100 nm) with good drug entrapments (~64 and ~78% for ALB and PRD, respectively) showed in vitro initial fast release (i.e., 20–40% drugs release in 4 h) followed by sustained release for more than 48 h. Fluorescence study and in vitro transendothelial transport depicted selective brain uptake of SLN-LA compared to SLN attributed to carrier mediated transport via Monocarboxylic Acid Transporters (MCT – 1/2/3). Pharmacokinetic parameters such as AUC_0-t and AUMC_0-t and Cl_last showed good drugs withholding capacity of SLNs. Organ distribution studies reflected high accumulation of drugs (ALB, 7.6 ± 0.31%; PRD, 5.21 ± 0.24%) in the brain after 24 h in case of SLN-LA as compared to plain drugs solution. SLN-LA in hematological studies revealed insignificant toxicity to blood cells. Conclusions The overall study paved the potential advances in brain targeting with synergistic acting drugs for effective management of NCC.
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Brain-specific delivery of rifampin from lactyl stearate-coupled liposomes via Monocarboxylic Acid Transporters
American Journal of Drug Delivery, 2006Co-Authors: Aviral Jain, Manish K. Chourasia, Vandana Soni, Nitin K. Jain, Piush Khare, Yashwant Gupta, Sanjay K. JainAbstract:Background The blood-brain barrier (BBB) is an obstacle for pharmacologists wishing to find treatments for patients with brain disorders. The BBB restricts the uptake of many valuable hydrophilic drugs and limits their efficacy because of the presence of tight junctions, a high metabolic capacity, low pinocytic vesicular traffic, and efficient efflux mechanisms. Aim The present study aimed to characterize lactyl stearate-coupled liposomes and their potential for the brain targeting of rifampin (rifampicin). Method A liposomal delivery system was prepared for achieving the brain-targeted delivery of rifampin in 21 albino rats utilizing the Monocarboxylic Acid transport system. Liposomes were prepared by the cast-film method using phosphatidylcholine and cholesterol. Similarly, lactyl stearate-coupled liposomal systems were prepared by casting lactyl stearate film with lipids. These liposomal formulations were characterized for entrapment efficiency, vesicle size, in vitro drug release (using dialysis membrane), and in vivo drug accumulation in various tissues. Results Coupling of lactyl stearate to liposomes had a profound influence on entrapment efficiency. Entrapment efficiency was reduced from 41.28 ± 2.02% in uncoupled liposomes to 34.23 ± 1.60% in coupled liposomes. The vesicle size was increased after coupling with lactyl stearate. The in vitro drug release for the uncoupled formulation LIPO-3 was 62.9 ± 3.01% after 24 hours, whereas that of the coupled formulation LIPO-3-Ls-III was 44.5 ± 2.09%. The percentage of rifampin dose recovered from the brain following administration of lactyl stearate-coupled liposomes to albino rats at different time intervals was about 6–8 times higher than with uncoupled liposomes and about 10–12 times higher than with the plain drug solution. Conclusion Lactyl stearate-coupled liposomes were better localized within the brain compared to uncoupled liposomes. Lactyl stearate-coupled liposomes could be an excellent carrier system for brain targeting of the hydrophilic drug rifampin.
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brain specific delivery of rifampin from lactyl stearate coupled liposomes via Monocarboxylic Acid Transporters
American Journal of Drug Delivery, 2006Co-Authors: Aviral Jain, Manish K. Chourasia, Vandana Soni, Nitin K. Jain, Piush Khare, Yashwant Gupta, Sanjay K. JainAbstract:Background The blood-brain barrier (BBB) is an obstacle for pharmacologists wishing to find treatments for patients with brain disorders. The BBB restricts the uptake of many valuable hydrophilic drugs and limits their efficacy because of the presence of tight junctions, a high metabolic capacity, low pinocytic vesicular traffic, and efficient efflux mechanisms.
Osamu Kimura - One of the best experts on this subject based on the ideXlab platform.
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Uptake of perfluorooctanoic Acid by Caco-2 cells: Involvement of organic anion transporting polypeptides.
Toxicology Letters, 2017Co-Authors: Osamu Kimura, Koichi Haraguchi, Chiho Ohta, Nobuyuki Koga, Yoshihisa Kato, Yukiko Fujii, Tetsuya EndoAbstract:Abstract The mechanism underlying the intestinal absorption of perfluorooctanoic Acid (PFOA) was investigated using Caco-2 cells. The uptake of PFOA from the apical membrane of Caco-2 cells was fast, and pH, temperature, and concentration dependent, but Na + independent. Coincubation with sulfobromophthalein (BSP), glibenclamide, estron-3-sulfate, cyclosporine A or rifamycin SV, which are typical substrates or inhibitors of organic anion transporting polypeptides (OATPs), significantly decreased the uptake of PFOA. However, coincubation with probenecid or p -aminohippuric Acid, typical substrates of organic anion Transporters, did not decrease the uptake of PFOA. Furthermore, coincubation with l -lactic Acid or benzoic Acid, substrates of Monocarboxylic Acid Transporters, did not decrease PFOA uptake. The relationship between the initial uptake of PFOA and its concentration was saturable, suggesting the involvement of a carrier-mediated process. The calculated K m and uptake clearance ( V max / K m ) values for PFOA were 8.3 μM and 55.0 μL/mg protein/min, respectively. This clearance value was about 3-fold greater than that of the non-saturable uptake clearance ( K d : 18.1 μL/mg protein/min). Lineweaver–Burk plots revealed that BSP competitively inhibits the uptake of PFOA, with a K i value of 23.1 μM. These results suggest that the uptake of PFOA from the apical membranes of Caco-2 cells could be, at least in part, mediated by OATPs along with BSP.
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uptake of aristolochic Acid i into caco 2 cells by Monocarboxylic Acid Transporters
Biological & Pharmaceutical Bulletin, 2014Co-Authors: Osamu Kimura, Koichi Haraguchi, Chiho Ohta, Nobuyuki Koga, Yoshihisa Kato, Tetsuya EndoAbstract:The uptake mechanism of aristolochic Acid I (AAI) was investigated using Caco-2 cells cultured on dishes and permeable membranes. The uptake of AAI from the apical membrane of Caco-2 cells cultured on a dish was rapid, and a decrease in the pH of the incubation medium significantly increased uptake. Incubation at low temperature (4 degrees C) and treatment with sodium azide (a metabolic inhibitor) or carbonylcyanide p-trifluoromethoxyphenylhydrazone (a protonophore) significantly inhibited the AAI uptake. Coincubation with L-lactic Acid or benzoic Acid, typical substrates for the proton-linked Monocarboxylic Acid Transporters (MCTs), significantly decreased the AAI uptake, as did coincubation with alpha-cyano-4-hydroxycinnamate (an inhibitor of MCTs). Dixon plotting revealed the competitive inhibition of benzoic Acid on the AAI uptake. To confirm the AAI uptake via MCTs, the apical-to-basolateral transport of AAI was investigated using the Caco-2 cells cultured on the permeable membranes. The transport of AAI at pH 6.0 was markedly higher than that at pH 7.4, and was significantly decreased by coincubation with benzoic Acid. These results suggest that the uptake of AAI from the apical membrane of Caco-2 cells is mediated mainly by MCTs along with benzoic Acid.
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steric hindrance of 2 6 disubstituted benzoic Acid derivatives on the uptake via Monocarboxylic Acid Transporters from the apical membranes of caco 2 cells
Pesticide Biochemistry and Physiology, 2014Co-Authors: Kensuke Tsukagoshi, Osamu Kimura, Tetsuya EndoAbstract:Benzoic Acid is a typical substrate for Monocarboxylic Acid Transporters (MCTs), and easily taken up from the apical membranes of Caco-2 cells by MCTs. However, some benzoic Acid derivatives were sparingly taken up by Caco-2 cells. To elucidate the mechanism of lower uptake of the derivatives, we investigated the effect of substitution of benzene ring on the uptake by MCTs using Caco-2 cells. Among the benzoic Acid derivatives tested, the uptake of 2,6-disubstituted benzoic Acids was markedly lower than that of other benzoic Acids. Co-incubation of the 2,6-disubstituted derivatives with benzoic Acid did not decrease the uptake of benzoic Acid, while co-incubation with other derivatives significantly decreased the uptake of benzoic Acid. Kinetic analyses elucidated that the uptake of 2,6-dichlorobenzoic Acid and 2,3,6-trichlorobenzoic Acid did not involve the carrier-mediated process. The 2,6-disubstitution of benzoic Acid may prevent the access of carboxylic Acid group to MCTs expressed on the apical membranes of Caco-2 cells.
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Transepithelial transport of 4-chloro-2-methylphenoxyacetic Acid (MCPA) across human intestinal Caco-2 cell monolayers.
Basic & Clinical Pharmacology & Toxicology, 2012Co-Authors: Osamu Kimura, Kensuke Tsukagoshi, Moriaki Hayasaka, Tetsuya EndoAbstract:Mechanisms of transcellular transport of 4-chloro-2-methylphenoxyacetic Acid (MCPA) across the small intestine were investigated using Caco-2 cells cultured on permeable membranes. The cell monolayers were incubated with MCPA, either from apical side at pH 6.0 or 7.4, or basolateral side at pH 7.4. The accumulation and apical-to-basolateral transport of MCPA were markedly stimulated by the Acidic pH on the apical side (inwardly directed H+ gradient), dependent on metabolic energy and inhibited by co-incubation with acetic Acid or benzoic Acid. Without the H+ gradient, on the other hand, the basolateral-to-apical transport of MCPA (secretory transport) was higher than the apical-to-basolateral transport (absorptive transport), although the secretory transport of MCPA was markedly lower than the absorptive transport under the H+ gradient. Co-incubation of MCPA with probenecid from the basolateral side significantly inhibited the accumulation and transport of MCPA, whereas co-incubation with p-aminohippuric Acid did not. These results suggest that the absorptive transport of MCPA is mediated by H+-linked Monocarboxylic Acid Transporters expressed on the apical membranes, while secretory transport is mediated by a probenecid-sensitive transporter expressed on the basolateral membranes of Caco-2 cell monolayers.
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Uptake of triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic Acid) and dicamba (3,6-dichloro-2-methoxybenzoic Acid) from the apical membranes of the human intestinal Caco-2 cells
Archives of Toxicology, 2012Co-Authors: Osamu Kimura, Kensuke Tsukagoshi, Moriaki Hayasaka, Tetsuya EndoAbstract:We investigated whether the uptake of triclopyr (3, 5, 6-trichloro-2-pyridinyloxyacetic Acid) and dicamba (3,6-dichloro-2-methoxybenzoic Acid) across the apical membrane of Caco-2 cells was mediated via proton-linked Monocarboxylic Acid Transporters (MCTs). The uptake of triclopyr from the apical membranes was fast, pH-, temperature-, and concentration dependent, required metabolic energy to proceed, and was competitively inhibited by Monocarboxylic Acids such as benzoic Acid and ferulic Acid (substrates of l -lactic Acid-insensitive MCTs), but not by l -lactic Acid. Thus, the uptake of triclopyr in Caco-2 cells appears to be mediated mainly via l -lactic Acid-insensitive MCTs. In contrast, the uptake of dicamba (a benzoic Acid derivative) was slow, and it was both pH- and temperature dependent. Coincubation with ferulic Acid did not decrease the uptake of dicamba, although coincubation with benzoic Acid moderately decreased it. The uptake of dicamba appears to be mediated mainly via passive diffusion, which is in contrast to the uptake of benzoic Acid via MCTs. We speculate that the substituted groups in dicamba may inhibit uptake via MCTs.
Aviral Jain - One of the best experts on this subject based on the ideXlab platform.
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Brain-specific delivery of rifampin from lactyl stearate-coupled liposomes via Monocarboxylic Acid Transporters
American Journal of Drug Delivery, 2006Co-Authors: Aviral Jain, Manish K. Chourasia, Vandana Soni, Nitin K. Jain, Piush Khare, Yashwant Gupta, Sanjay K. JainAbstract:Background The blood-brain barrier (BBB) is an obstacle for pharmacologists wishing to find treatments for patients with brain disorders. The BBB restricts the uptake of many valuable hydrophilic drugs and limits their efficacy because of the presence of tight junctions, a high metabolic capacity, low pinocytic vesicular traffic, and efficient efflux mechanisms. Aim The present study aimed to characterize lactyl stearate-coupled liposomes and their potential for the brain targeting of rifampin (rifampicin). Method A liposomal delivery system was prepared for achieving the brain-targeted delivery of rifampin in 21 albino rats utilizing the Monocarboxylic Acid transport system. Liposomes were prepared by the cast-film method using phosphatidylcholine and cholesterol. Similarly, lactyl stearate-coupled liposomal systems were prepared by casting lactyl stearate film with lipids. These liposomal formulations were characterized for entrapment efficiency, vesicle size, in vitro drug release (using dialysis membrane), and in vivo drug accumulation in various tissues. Results Coupling of lactyl stearate to liposomes had a profound influence on entrapment efficiency. Entrapment efficiency was reduced from 41.28 ± 2.02% in uncoupled liposomes to 34.23 ± 1.60% in coupled liposomes. The vesicle size was increased after coupling with lactyl stearate. The in vitro drug release for the uncoupled formulation LIPO-3 was 62.9 ± 3.01% after 24 hours, whereas that of the coupled formulation LIPO-3-Ls-III was 44.5 ± 2.09%. The percentage of rifampin dose recovered from the brain following administration of lactyl stearate-coupled liposomes to albino rats at different time intervals was about 6–8 times higher than with uncoupled liposomes and about 10–12 times higher than with the plain drug solution. Conclusion Lactyl stearate-coupled liposomes were better localized within the brain compared to uncoupled liposomes. Lactyl stearate-coupled liposomes could be an excellent carrier system for brain targeting of the hydrophilic drug rifampin.
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brain specific delivery of rifampin from lactyl stearate coupled liposomes via Monocarboxylic Acid Transporters
American Journal of Drug Delivery, 2006Co-Authors: Aviral Jain, Manish K. Chourasia, Vandana Soni, Nitin K. Jain, Piush Khare, Yashwant Gupta, Sanjay K. JainAbstract:Background The blood-brain barrier (BBB) is an obstacle for pharmacologists wishing to find treatments for patients with brain disorders. The BBB restricts the uptake of many valuable hydrophilic drugs and limits their efficacy because of the presence of tight junctions, a high metabolic capacity, low pinocytic vesicular traffic, and efficient efflux mechanisms.
Kensuke Tsukagoshi - One of the best experts on this subject based on the ideXlab platform.
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steric hindrance of 2 6 disubstituted benzoic Acid derivatives on the uptake via Monocarboxylic Acid Transporters from the apical membranes of caco 2 cells
Pesticide Biochemistry and Physiology, 2014Co-Authors: Kensuke Tsukagoshi, Osamu Kimura, Tetsuya EndoAbstract:Benzoic Acid is a typical substrate for Monocarboxylic Acid Transporters (MCTs), and easily taken up from the apical membranes of Caco-2 cells by MCTs. However, some benzoic Acid derivatives were sparingly taken up by Caco-2 cells. To elucidate the mechanism of lower uptake of the derivatives, we investigated the effect of substitution of benzene ring on the uptake by MCTs using Caco-2 cells. Among the benzoic Acid derivatives tested, the uptake of 2,6-disubstituted benzoic Acids was markedly lower than that of other benzoic Acids. Co-incubation of the 2,6-disubstituted derivatives with benzoic Acid did not decrease the uptake of benzoic Acid, while co-incubation with other derivatives significantly decreased the uptake of benzoic Acid. Kinetic analyses elucidated that the uptake of 2,6-dichlorobenzoic Acid and 2,3,6-trichlorobenzoic Acid did not involve the carrier-mediated process. The 2,6-disubstitution of benzoic Acid may prevent the access of carboxylic Acid group to MCTs expressed on the apical membranes of Caco-2 cells.
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Transepithelial transport of 4-chloro-2-methylphenoxyacetic Acid (MCPA) across human intestinal Caco-2 cell monolayers.
Basic & Clinical Pharmacology & Toxicology, 2012Co-Authors: Osamu Kimura, Kensuke Tsukagoshi, Moriaki Hayasaka, Tetsuya EndoAbstract:Mechanisms of transcellular transport of 4-chloro-2-methylphenoxyacetic Acid (MCPA) across the small intestine were investigated using Caco-2 cells cultured on permeable membranes. The cell monolayers were incubated with MCPA, either from apical side at pH 6.0 or 7.4, or basolateral side at pH 7.4. The accumulation and apical-to-basolateral transport of MCPA were markedly stimulated by the Acidic pH on the apical side (inwardly directed H+ gradient), dependent on metabolic energy and inhibited by co-incubation with acetic Acid or benzoic Acid. Without the H+ gradient, on the other hand, the basolateral-to-apical transport of MCPA (secretory transport) was higher than the apical-to-basolateral transport (absorptive transport), although the secretory transport of MCPA was markedly lower than the absorptive transport under the H+ gradient. Co-incubation of MCPA with probenecid from the basolateral side significantly inhibited the accumulation and transport of MCPA, whereas co-incubation with p-aminohippuric Acid did not. These results suggest that the absorptive transport of MCPA is mediated by H+-linked Monocarboxylic Acid Transporters expressed on the apical membranes, while secretory transport is mediated by a probenecid-sensitive transporter expressed on the basolateral membranes of Caco-2 cell monolayers.
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Uptake of triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic Acid) and dicamba (3,6-dichloro-2-methoxybenzoic Acid) from the apical membranes of the human intestinal Caco-2 cells
Archives of Toxicology, 2012Co-Authors: Osamu Kimura, Kensuke Tsukagoshi, Moriaki Hayasaka, Tetsuya EndoAbstract:We investigated whether the uptake of triclopyr (3, 5, 6-trichloro-2-pyridinyloxyacetic Acid) and dicamba (3,6-dichloro-2-methoxybenzoic Acid) across the apical membrane of Caco-2 cells was mediated via proton-linked Monocarboxylic Acid Transporters (MCTs). The uptake of triclopyr from the apical membranes was fast, pH-, temperature-, and concentration dependent, required metabolic energy to proceed, and was competitively inhibited by Monocarboxylic Acids such as benzoic Acid and ferulic Acid (substrates of l -lactic Acid-insensitive MCTs), but not by l -lactic Acid. Thus, the uptake of triclopyr in Caco-2 cells appears to be mediated mainly via l -lactic Acid-insensitive MCTs. In contrast, the uptake of dicamba (a benzoic Acid derivative) was slow, and it was both pH- and temperature dependent. Coincubation with ferulic Acid did not decrease the uptake of dicamba, although coincubation with benzoic Acid moderately decreased it. The uptake of dicamba appears to be mediated mainly via passive diffusion, which is in contrast to the uptake of benzoic Acid via MCTs. We speculate that the substituted groups in dicamba may inhibit uptake via MCTs.
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uptake of phenoxyacetic Acid derivatives into caco 2 cells by the Monocarboxylic Acid Transporters
Toxicology Letters, 2009Co-Authors: Osamu Kimura, Kensuke Tsukagoshi, Tetsuya EndoAbstract:Abstract The uptake mechanism of phenoxyacetic Acid (PA) and its chlorine derivatives, 4-chlorophenoxyacetic Acid (4-CPA), 2,4-dichlorophenoxyacetic Acid (2,4-D), and 2,4,5-trichlorophenoxyacetic Acid (2,4,5-T), was investigated using Caco-2 cells. The cells were incubated with PA, 4-CPA, 2,4-D or 2,4,5-T at pH 6.0 and 37 °C. The order of uptake and lipophilicity expressed by n-octanol partition coefficients were PA
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Uptake of 4-chloro-2-methylphenoxyacetic Acid (MCPA) from the apical membrane of Caco-2 cells by the Monocarboxylic Acid transporter.
Toxicology and Applied Pharmacology, 2007Co-Authors: Osamu Kimura, Kensuke Tsukagoshi, Tetsuya EndoAbstract:The cellular uptake mechanism of 4-chloro-2-methylphenoxyacetic Acid (MCPA), a phenoxyacetic Acid derivative, was investigated using Caco-2 epithelial cells. The cells were incubated with 50 {mu}M MCPA at pH 6.0 and 37 deg. C, and the uptake of MCPA from the apical membranes was measured. The uptake of MCPA was significantly decreased by incubation at low temperature (4 {sup o}C) and markedly increased by lowering the extracellular pH. Pretreatment with a protonophore, carbonylcyanide-p-(trifluoromethoxy)phenylhydrazone (25 {mu}M), or metabolic inhibitors, 2,4-dinitrophenol (1 mM) and sodium azide (10 mM), significantly decreased the uptake of MCPA by 53%, 45% and 48%, respectively. Coincubation of MCPA with 10 mM L-lactic Acid or {alpha}-cyano-4-hydroxycinnamate, which is a substrate or an inhibitor of the Monocarboxylic Acid Transporters (MCTs), significantly decreased the uptake of MCPA by 31% and 20%, respectively, and coincubation with benzoic Acid profoundly decreased the uptake by 68%. In contrast, coincubation with succinic Acid (a dicarboxylic Acid) did not affect the uptake. Kinetic analysis of initial MCPA uptake suggested that MCPA is taken up via a carrier-mediated process [K{sub m} = 1.37 {+-} 0.15 mM, V{sub max} = 115 {+-} 6 nmol (mg protein){sup -1} (3 min){sup -1}]. Lineweaver-Burk plots show that benzoic Acid competitively inhibitsmore » the uptake of MCPA with a K{sub i} value of 4.68 {+-} 1.76 mM. A trans-stimulation effect on MCPA uptake was found in cells preloaded with benzoic Acid. These results suggest that the uptake of MCPA from the apical membrane of Caco-2 cells is mainly mediated by common MCTs along with benzoic Acid but also in part by L-lactic Acid.« less