Publications

• Characterization of uremic toxin transport by organic anion transporters in the kidney.

  Deguchi T., Kusuhara H., Takadate A., Endou H., Otagiri M., Sugiyama Y.

  <h4>Background</h4>Harmful uremic toxins, such as indoxyl sulfate (IS), 3-carboxy-4-methyl-5-propyl-2-furanpropionate (CMPF), indoleacetate (IA), and hippurate (HA), accumulate to a high degree in uremic plasma. IS has been shown to be a substrate of rat organic anion transporter 1 (rOat1) and rOa ... >> More

  <h4>Background</h4>Harmful uremic toxins, such as indoxyl sulfate (IS), 3-carboxy-4-methyl-5-propyl-2-furanpropionate (CMPF), indoleacetate (IA), and hippurate (HA), accumulate to a high degree in uremic plasma. IS has been shown to be a substrate of rat organic anion transporter 1 (rOat1) and rOat3. However, the contribution of rOat1 and rOat3 to the renal uptake transport process of IS and other uremic toxins in the kidney remains unknown.<h4>Methods</h4>The cellular uptake of uremic toxins was determined using stable transfectants of rOat1/hOAT1 and rOat3/hOAT3 cells. Also, the uptake of uremic toxins by rat kidney slices was characterized to evaluate the contribution of rOat1 and rOat3 to the total uptake by kidney slices using inhibitors of rOat1 (p-aminohippurate) and rOat3 (pravastatin and benzylpenicillin).<h4>Results</h4>Saturable uptake of IS, CMPF, IA, and HA by rOat1 was observed with Km values of 18, 154, 47, and 28 micromol/L, respectively, whereas significant uptake of IS and CMPF, but not of IA or HA, was observed in rOat3-expressing cells with Km values of 174 and 11 micromol/L, respectively. Similar parameters were obtained for human OAT1 and OAT3. Kinetic analysis of the IS uptake by kidney slices revealed involvement of two saturable components with Km1 (24 micromol/L) and Km2 (196 micromol/L) values that were comparable with those of rOat1 and rOat3. The Km value of CMPF uptake by kidney slices (22 micromol/L) was comparable with that of rOat3, while the corresponding values of IA and HA (42 and 33 micromol/L, respectively) were similar to those of rOat1. PAH preferentially inhibited the uptake of IA and HA by kidney slices, while pravastatin and benzylpenicillin preferentially inhibited the uptake of CMPF. The effect of these inhibitors on the uptake of IS by kidney slices was partial.<h4>Conclusions</h4>rOat1/hOAT1 and rOat3/hOAT3 play major roles in the renal uptake of uremic toxins on the basolateral membrane of the proximal tubules. Both OAT1 and OAT3 contribute almost equally to the renal uptake of IS. OAT3 mainly accounts for CMPF uptake by the kidney, while OAT1 mainly accounts for IA and HA uptake. << Less

  Kidney Int. 65:162-174(2004) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.

• Molecular cloning and functional analyses of OAT1 and OAT3 from cynomolgus monkey kidney.

  Tahara H., Shono M., Kusuhara H., Kinoshita H., Fuse E., Takadate A., Otagiri M., Sugiyama Y.

  <h4>Purpose</h4>The functional characterization of monkey OAT1 (SLC22A6) and OAT3 (SLC22A8) was carried out to elucidate species differences in the OAT1- and OAT3-mediated transport between monkey and human.<h4>Methods</h4>The cDNAs of monkey OAT1 and OAT3 were isolated from monkey kidney, and the ... >> More

  <h4>Purpose</h4>The functional characterization of monkey OAT1 (SLC22A6) and OAT3 (SLC22A8) was carried out to elucidate species differences in the OAT1- and OAT3-mediated transport between monkey and human.<h4>Methods</h4>The cDNAs of monkey OAT1 and OAT3 were isolated from monkey kidney, and their stable transfectants were established in HEK293 cells (mkOAT1- and mkOAT3-HEK). Transport studies were performed using cDNA transfectants, and kinetic parameters were compared among rat, monkey and human.<h4>Results</h4>The amino acid sequences of mkOAT1 and mkOAT3 exhibit 97% and 96% identity to their corresponding human orthologues. For OAT1, there was no obvious species difference in the K(m) values and the relative transport activities of 11 substrates with regard to p-aminohippurate transport. For OAT3, there was no species difference in the K(m) values and in the relative transport activities of nine substrates with regard to benzylpenicillin transport between monkey and human. However, the relative transport activities of indoxyl sulfate, 3-carboxy-4-methyl-5-propyl-2-furanpropionate, and estrone-3-sulfate showed a difference between primates and rat and gave a poor correlation.<h4>Conclusions</h4>These results suggest that monkey is a good predictor of the renal uptake of organic anions in the human. << Less

  Pharm. Res. 22:647-660(2005) [PubMed] [EuropePMC]

  This publication is cited by 4 other entries.