scholarly journals Distribution of organic anion transporters NaDC3 and OAT1-3 along the human nephron

2016 ◽  
Vol 311 (1) ◽  
pp. F227-F238 ◽  
Author(s):  
Davorka Breljak ◽  
Marija Ljubojević ◽  
Yohannes Hagos ◽  
Vedran Micek ◽  
Daniela Balen Eror ◽  
...  
Keyword(s):  
Organic Anion ◽  
Basolateral Membrane ◽  
Human Kidney ◽  
Initial Step ◽  
Proximal Tubules ◽  
Anion Transporters ◽  
Luminal Membrane ◽  
293 Cells ◽  
Outer Stripe ◽  
S3 Segment

The initial step in renal secretion of organic anions (OAs) is mediated by transporters in the basolateral membrane (BLM). Contributors to this process are primary active Na+-K+-ATPase (EC 3.6.3.9), secondary active Na+-dicarboxylate cotransporter 3 (NaDC3/SLC13A3), and tertiary active OA transporters (OATs) OAT1/SLC22A6, OAT2/SLC22A7, and OAT3/SLC22A8. In human kidneys, we analyzed the localization of these transporters by immunochemical methods in tissue cryosections and isolated membranes. The specificity of antibodies was validated with human embryonic kidney-293 cells stably transfected with functional OATs. Na+-K+-ATPase was immunolocalized to the BLM along the entire human nephron. NaDC3-related immunostaining was detected in the BLM of proximal tubules and in the BLM and/or luminal membrane of principal cells in connecting segments and collecting ducts. The thin and thick ascending limbs, macula densa, and distal tubules exhibited no reactivity with the anti-NaDC3 antibody. OAT1–OAT3-related immunostaining in human kidneys was detected only in the BLM of cortical proximal tubules; all three OATs were stained more intensely in S1/S2 segments compared with S3 segment in medullary rays, whereas the S3 segment in the outer stripe remained unstained. Expression of NaDC3, OAT1, OAT2, and OAT3 proteins exhibited considerable interindividual variability in both male and female kidneys, and sex differences in their expression could not be detected. Our experiments provide a side-by-side comparison of basolateral transporters cooperating in renal OA secretion in the human kidney.

Interaction of alpha-KG with basolateral organic anion transporter in isolated rabbit renal S3 proximal tubules

1995 ◽  
Vol 268 (6) ◽  
pp. F1109-F1116 ◽  
Author(s):  
S. Shpun ◽  
K. K. Evans ◽  
W. H. Dantzler
Keyword(s):  
Organic Anion ◽  
Basolateral Membrane ◽  
Proximal Tubules ◽  
Organic Anion Transporter ◽  
Anion Transporter ◽  
Significant Stimulation ◽  
S Uptake ◽  
S3 Segment ◽  
Uptake Data ◽  
Ethanesulfonic Acid

To understand the basolateral p-aminohippurate (PAH) transporter in the S3 segment of rabbit proximal tubules and its relationship to the transporter in the S2 segment, we measured the 30-s uptake and efflux of PAH across the basolateral membrane of single isolated S3 segments at 37 degrees C in bicarbonate-buffered media. Kinetic analysis of uptake data revealed a concentration of PAH at one-half Jmax of approximately 107 microM (same as in the S2 segment) but a Jmax of 600 fmol.min-1.nl-1 (one-tenth that of S2 segment). The coefficient for efflux across the basolateral membrane was also only one-sixth to one-tenth of that in the S2 segment. These data suggest that the basolateral PAH transporter is the same in both segments but that there are fewer transporters in the S3 than in the S2 segment. However, the apparent inhibitor constant values for cis-inhibition by probenecid (approximately 29 microM in S3, approximately 15 microM in S2) and by alpha-ketoglutarate (alpha-KG) in the presence of LiCl (approximately 40 microM in S3, approximately 160 microM in S2) suggest that the transporters may not be identical in the two segments. In bicarbonate-buffered medium, preloading the tubules with 100 microM alpha-KG did not trans-stimulate PAH uptake across the basolateral membrane, whereas preloading with 1.0 microM alpha-KG caused a significant stimulation of 43%. However, in N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid-buffered medium, preloading the tubules with 100 microM alpha-KG caused a twofold increase in PAH uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Immunolocalization of Multispecific Organic Anion Transporters, OAT1, OAT2, and OAT3, in Rat Kidney

2002 ◽  
Vol 13 (4) ◽  
pp. 848-857 ◽  
Author(s):  
Ryoji Kojima ◽  
Takashi Sekine ◽  
Masanao Kawachi ◽  
Seok Ho Cha ◽  
Yoshio Suzuki ◽  
...  
Keyword(s):  
Rat Kidney ◽  
Organic Anion ◽  
Basolateral Membrane ◽  
Organic Anions ◽  
Proximal Tubules ◽  
Transepithelial Transport ◽  
Thick Ascending Limb ◽  
Apical Surface ◽  
Organic Anion Transporters ◽  
Anion Transporters

ABSTRACT. Recently, a family of multispecific organic anion transporters has been identified, and several isoforms have been reported. However, the physiologic and pharmacologic roles of each isoform, except OAT1, in the transepithelial transport of organic anions in the kidney remain to be elucidated. To address this issue, it is essential to determine the intrarenal distribution and membrane localization of each OAT isoform along the nephron. In this study, the intrarenal distributions of rOAT1, rOAT2, and rOAT3 were investigated by an immunofluorescence method that used frozen rat serial kidney sections. Confocal microscopic analysis showed that immunoreactivity for rOAT1 was detected exclusively in the proximal tubules (S1, S2, S3) in the cortex with basolateral membrane staining. rOAT2 was detected in the apical surface of the tubules in the medullary thick ascending limb of Henle’s loop (MTAL) and cortical and medullary collecting ducts (CD). rOAT3 was localized in the basolateral digitation of the cell membrane in all the segments (S1, S2, and S3) of the proximal tubules, MTAL, cortical TAL, connecting tubules, and cortical and medullary CD. These results on the distribution of each OAT isoform will facilitate the understanding of the role of OATs in the renal processing of organic anions.

scholarly journals Gene Expression Levels and Immunolocalization of Organic Ion Transporters in the Human Kidney

2002 ◽  
Vol 13 (4) ◽  
pp. 866-874
Author(s):  
Hideyuki Motohashi ◽  
Yuji Sakurai ◽  
Hideyuki Saito ◽  
Satohiro Masuda ◽  
Yumiko Urakami ◽  
...  
Keyword(s):  
Basolateral Membrane ◽  
Mrna Level ◽  
Human Kidney ◽  
Proximal Tubules ◽  
Mrna Levels ◽  
Ion Transporters ◽  
Ion Transporter ◽  
Transporter Family ◽  
Immunohistochemical Analyses ◽  
Gene Expression Levels

ABSTRACT. Renal excretion of organic anions and cations is mediated by the organic ion transporter family (SLC22A). In this study, the mRNA levels of the organic ion transporters were quantified by real-time PCR in normal parts of renal tissues from seven nephrectomized patients with renal cell carcinoma, and the distributions and localization of human (h)OAT1, hOAT3, and hOCT2 proteins were investigated by immunohistochemical analyses in the human kidney. The expression level of hOAT3 mRNA was the highest among the organic ion transporter family, followed by that of hOAT1 mRNA. The hOCT2 mRNA level was the highest in the human OCT family, and the level of hOCTN2 mRNA was higher than that of hOCTN1. hOCT1 mRNA showed the lowest level of expression in organic ion transporter family. hOAT1, hOAT3, and hOCT2 proteins were detected in crude membranes from the kidney of all patients by Western blot analyses, whereas hOCT1 protein could not be detected. Immunohistochemical analyses showed that both hOAT1 and hOAT3 were localized to the basolateral membrane of the proximal tubules in the cortex, and hOCT2 was localized to the basolateral membrane of the proximal tubules in both the cortex and medullary ray. Immunohistochemical analyses of serial sections indicated that hOAT1, hOAT3, and hOCT2 were coexpressed in a portion of the proximal tubules. These results suggest that hOAT1, hOAT3, and hOCT2 play predominant roles in the transport of organic ions across the basolateral membrane of human proximal tubules.

scholarly journals Human organic anion transporter 2 is distinct from organic anion transporters 1 and 3 with respect to transport function

2015 ◽  
Vol 309 (10) ◽  
pp. F843-F851 ◽  
Author(s):  
Maja Henjakovic ◽  
Yohannes Hagos ◽  
Wolfgang Krick ◽  
Gerhard Burckhardt ◽  
Birgitta C. Burckhardt
Keyword(s):  
Organic Anion ◽  
Organic Anion Transporter ◽  
Substrate Uptake ◽  
Organic Anion Transporters ◽  
Counter Anion ◽  
Anion Transporters ◽  
Anion Transporter ◽  
293 Cells ◽  
High K ◽  
Resistance Protein

Phylogentically, organic anion transporter (OAT)1 and OAT3 are closely related, whereas OAT2 is more distant. Experiments with human embryonic kidney-293 cells stably transfected with human OAT1, OAT2, or OAT3 were performed to compare selected transport properties. Common to OAT1, OAT2, and OAT3 is their ability to transport cGMP. OAT2 interacted with prostaglandins, and cGMP uptake was inhibited by PGE2 and PGF2α with IC50 values of 40.8 and 12.7 μM, respectively. OAT1 (IC50: 23.7 μM), OAT2 (IC50: 9.5 μM), and OAT3 (IC50: 1.6 μM) were potently inhibited by MK571, an established multidrug resistance protein inhibitor. OAT2-mediated cGMP uptake was not inhibited by short-chain monocarboxylates and, as opposed to OAT1 and OAT3, not by dicarboxylates. Consequently, OAT2 showed no cGMP/glutarate exchange. OAT1 and OAT3 exhibited a pH and a Cl− dependence with higher substrate uptake at acidic pH and lower substrate uptake in the absence of Cl−, respectively. Such pH and Cl− dependencies were not observed with OAT2. Depolarization of membrane potential by high K+ concentrations in the presence of the K+ ionophore valinomycin left cGMP uptake unaffected. In addition to cGMP, OAT2 transported urate and glutamate, but cGMP/glutamate exchange could not be demonstrated. These experiments suggest that OAT2-mediated cGMP uptake does not occur via exchange with monocarboxylates, dicarboxylates, and hydroxyl ions. The counter anion for electroneutral cGMP uptake remains to be identified.

scholarly journals A role for the organic anion transporter OAT3 in renal creatinine secretion in mice

2012 ◽  
Vol 302 (10) ◽  
pp. F1293-F1299 ◽  
Author(s):  
Volker Vallon ◽  
Satish A. Eraly ◽  
Satish Ramachandra Rao ◽  
Maria Gerasimova ◽  
Michael Rose ◽  
...  
Keyword(s):  
Organic Anion ◽  
Basolateral Membrane ◽  
Tubular Secretion ◽  
Organic Anion Transporter ◽  
Xenopus Laevis Oocytes ◽  
Mean Values ◽  
Anion Transporters ◽  
Anion Transporter ◽  
Neutral Compounds ◽  
Quantitative Contribution

Tubular secretion of the organic cation, creatinine, limits its value as a marker of glomerular filtration rate (GFR) but the molecular determinants of this pathway are unclear. The organic anion transporters, OAT1 and OAT3, are expressed on the basolateral membrane of the proximal tubule and transport organic anions but also neutral compounds and cations. Here, we demonstrate specific uptake of creatinine into mouse mOat1- and mOat3-microinjected Xenopus laevis oocytes at a concentration of 10 μM (i.e., similar to physiological plasma levels), which was inhibited by both probenecid and cimetidine, prototypical competitive inhibitors of organic anion and cation transporters, respectively. Renal creatinine clearance was consistently greater than inulin clearance (as a measure of GFR) in wild-type (WT) mice but not in mice lacking OAT1 ( Oat1−/−) and OAT3 ( Oat3−/−). WT mice presented renal creatinine net secretion (0.23 ± 0.03 μg/min) which represented 45 ± 6% of total renal creatinine excretion. Mean values for renal creatinine net secretion and renal creatinine secretion fraction were not different from zero in Oat1−/− (−0.03 ± 0.10 μg/min; −3 ± 18%) and Oat3−/− (0.01 ± 0.06 μg/min; −6 ± 19%), with greater variability in Oat1−/−. Expression of OAT3 protein in the renal membranes of Oat1−/− mice was reduced to ∼6% of WT levels, and that of OAT1 in Oat3−/− mice to ∼60%, possibly as a consequence of the genes for Oat1 and Oat3 having adjacent chromosomal locations. Plasma creatinine concentrations of Oat3−/− were elevated in clearance studies under anesthesia but not following brief isoflurane anesthesia, indicating that the former condition enhanced the quantitative contribution of OAT3 for renal creatinine secretion. The results are consistent with a contribution of OAT3 and possibly OAT1 to renal creatinine secretion in mice.

scholarly journals Participation of mercuric conjugates of cysteine, homocysteine, and N-acetylcysteine in mechanisms involved in the renal tubular uptake of inorganic mercury.

1998 ◽  
Vol 9 (4) ◽  
pp. 551-561
Author(s):  
R K Zalups ◽  
D W Barfuss
Keyword(s):  
Basolateral Membrane ◽  
Inorganic Mercury ◽  
Fecal Excretion ◽  
Outer Medulla ◽  
Renal Uptake ◽  
Luminal Membrane ◽  
Outer Stripe ◽  
Mercuric Ions ◽  
Renal Tubular ◽  
The One

Mechanisms involved in the renal uptake of inorganic mercury were studied in rats administered a nontoxic 0.5 mumol/kg intravenous dose of inorganic mercury with or without 2.0 mumol/kg cysteine, homocysteine, or N-acetylcysteine. The renal disposition of mercury was studied 1 h after treatment in normal rats and rats that had undergone bilateral ureteral ligation. In addition, the disposition of mercury (including the urinary and fecal excretion of mercury) was evaluated 24 h after treatment. In normal rats, coadministering inorganic mercury plus cysteine or homocysteine caused a significant increase in the renal uptake of mercury 1 h after treatment. The enhanced renal uptake of mercury was due to increased uptake of mercury in the renal outer stripe of the outer medulla and/or renal cortex. Ureteral ligation caused reductions in the renal uptake of mercury in all groups except for the one treated with inorganic mercury plus N-acetylcysteine. Thus, it appears that virtually all of the mercury taken up by the kidneys of the normal rats treated with inorganic mercury plus N-acetylcysteine occurred at the basolateral membrane. Urinary excretory data also support this notion, in that the rate of excretion of inorganic mercury was greatest in the rats treated with inorganic mercury plus N-acetylcysteine. Our data also indicate that uptake of inorganic mercury in the kidneys of rats treated with inorganic mercury plus cysteine occurred equally at both luminal and basolateral membranes. In addition, the renal uptake of mercury in rats treated with inorganic mercury plus homocysteine occurred predominantly at the basolateral membrane with some component of luminal uptake. The findings of the present study confirm that there are at least two distinct mechanisms involved in the renal uptake of inorganic mercury, with one mechanism located on the luminal membrane and the other located on the basolateral membrane. Our findings also show that cysteine and homologs of cysteine, when coadministered with inorganic mercury, greatly influence the magnitude and/or site of uptake of mercuric ions in the kidney.

Intracellular pH in snake renal proximal tubules

1995 ◽  
Vol 269 (4) ◽  
pp. R822-R829 ◽  
Author(s):  
Y. K. Kim ◽  
W. H. Dantzler
Keyword(s):  
Intracellular Ph ◽  
Basolateral Membrane ◽  
Distal Portion ◽  
Proximal Tubules ◽  
Disulfonic Acid ◽  
Renal Tubules ◽  
Garter Snakes ◽  
Luminal Membrane ◽  
Rate Of Recovery ◽  
Ethanesulfonic Acid

Intracellular pH (pHi) was studied in isolated proximal renal tubules of garter snakes (Thamnophis spp.) with oil-filled lumens under control conditions [N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES)-buffered medium with pH 7.4 at 25 degrees C] and in response to NH4Cl pulse. pHi was measured with the pH-sensitive fluorescent dye 2',7'-bis(2-carboxyethyl)-5,6-carboxyfluorescein (BCECF). Control resting pHi (7.1) and acidification in response to NH4Cl pulse (minimum pHi, 6.6) were essentially the same in snake tubules with oil-filled lumens or perfused lumens and in rabbit S2 proximal tubules with oil-filled lumens. Rate of recovery of pHi (dpHi/dt) from acid to resting level in snake tubules (2.5 x 10(-3) pH U/s was about one-third of that in rabbit tubules. Resting pHi and dpHi/dt from acid to resting level were Na+ dependent in the distal portion but not the proximal portion of snake proximal tubules. However, dpHi/dt was not influenced by amiloride or 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid in snake proximal tubules, suggesting that the effect of Na+ on dpHi/dt and resting pHi may involve membrane potential. This study also indicates that oil-filled lumens do not interfere with measurements of resting pHi and do permit evaluation of pHi regulation at the basolateral membrane without complications from transport at the luminal membrane.

Hepatocyte Basolateral Membrane Organic Anion Transporters

The Liver ◽  
2009 ◽  
pp. 305-321 ◽  
Author(s):  
Jo H. Choi ◽  
John W. Murray ◽  
Allan W. Wolkoff
Keyword(s):  
Organic Anion ◽  
Basolateral Membrane ◽  
Organic Anion Transporters ◽  
Anion Transporters

scholarly journals Effect of electroneutral luminal and basolateral lactate transport on intracellular pH in salamander proximal tubules.

1987 ◽  
Vol 90 (6) ◽  
pp. 799-831 ◽  
Author(s):  
A W Siebens ◽  
W F Boron
Keyword(s):  
Intracellular Ph ◽  
Initial Rate ◽  
Basolateral Membrane ◽  
Proximal Tubules ◽  
Tiger Salamander ◽  
Organic Substrates ◽  
Luminal Membrane ◽  
Acid Extrusion ◽  
Intracellular Alkalinization ◽  
Basolateral Membrane Potential

We used microelectrodes to examine the effects of organic substrates, particularly lactate (Lac-), on the intracellular pH (pHi) and basolateral membrane potential (Vbl) in isolated, perfused proximal tubules of the tiger salamander. Exposure of the luminal and basolateral membranes to 3.6 mM Lac- caused pHi to increase by approximately 0.2, opposite to the decrease expected from nonionic diffusion of lactic acid (HLac) into the cell. Addition of Lac- to only the lumen also caused alkalinization, but only if Na+ was present. This alkalinization was not accompanied by immediate Vbl changes, which suggests that it involves luminal, electroneutral Na/Lac cotransport. Addition of Lac- to only the basolateral solution caused pHi to decrease by approximately 0.08. The initial rate of this acidification was a saturable function of [Lac-], was not affected by removal of Na+, and was reversibly reduced by alpha-cyano-4-hydroxycinnamate (CHC). Thus, the pHi decrease induced by basolateral Lac- appears to be due to the basolateral entry of H+ and Lac-, mediated by an H/Lac cotransporter (or a Lac-base exchanger). Our data suggest that this transporter is electroneutral and is not present at the luminal membrane. A key question is how the addition of Lac- to the lumen increases pHi. We found that inhibition of basolateral H/Lac cotransport by basolateral CHC reduced the initial rate of pHi increase caused by luminal Lac-. On the other hand, luminal CHC had no effect on the luminal Lac(-)-induced alkalinization. These data suggest that when Lac- is present in the lumen, it enters the cell from the lumen via electroneutral Na/Lac cotransport and then exists with H+ across the basolateral membrane via electroneutral H/Lac cotransport. The net effect is transepithelial Lac- reabsorption, basolateral acid extrusion, and intracellular alkalinization.

Transporters involved in renal excretion of N-carbamoylglutamate, an orphan drug to treat inborn n-acetylglutamate synthase deficiency

2014 ◽  
Vol 307 (12) ◽  
pp. F1373-F1379 ◽  
Author(s):  
Elisabeth Schwob ◽  
Yohannes Hagos ◽  
Gerhard Burckhardt ◽  
Birgitta C. Burckhardt
Keyword(s):  
Orphan Drug ◽  
Organic Anion ◽  
Xenopus Laevis Oocytes ◽  
Human Embryonic Kidney ◽  
Estrone Sulfate ◽  
Anion Transporters ◽  
293 Cells ◽  
Acetylglutamate Synthase ◽  
Inborn Defects ◽  
The Impact

Inborn defects in N-acetylglutamate (NAG) synthase (NAGS) cause a reduction of NAG, an essential cofactor for the initiation of the urea cycle. As a consequence, blood ammonium concentrations are elevated, leading to severe neurological disorders. The orphan drug N-carbamoylglutamate (NCG; Carbaglu), efficiently overcomes NAGS deficiency. However, not much is known about the transporters involved in the uptake, distribution, and elimination of the divalent organic anion NCG. Organic anion-transporting polypeptides (OATPs) as well as organic anion transporters (OATs) working in cooperation with sodium dicarboxylate cotransporter 3 (NaDC3) accept a wide variety of structurally unrelated drugs. To test for possible interactions with OATPs and OATs, the impact of NCG on these transporters in stably transfected human embryonic kidney-293 cells was measured. The two-electrode voltage-clamp technique was used to monitor NCG-mediated currents in Xenopus laevis oocytes that expressed NaDC3. Neither OATPs nor OAT2 and OAT3 interacted with NCG, but OAT1 transported NCG. In addition, NCG was identified as a high-affinity substrate of NaDC3. Preincubation of OAT4-transfected human embryonic kidney-293 cells with NCG showed an increased uptake of estrone sulfate, the reference substrate of OAT4, indicating efflux of NCG by OAT4. In summary, NaDC3 and, to a lesser extent, OAT1 are likely to be responsible for the uptake of NCG from the blood. Efflux of NCG across the luminal membrane into the tubular lumen probably occurs by OAT4 completing renal secretion of this drug.

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