Sex Differences in the mRNA, Protein, and Functional Expression of Organic Anion Transporter (Oat) 1, Oat3, and Organic Cation Transporter (Oct) 2 in Rabbit Renal Proximal Tubules

2005 ◽  
Vol 316 (2) ◽  
pp. 743-752 ◽  
Author(s):  
Carlotta E. Groves ◽  
Wendy B. Suhre ◽  
Nathan J. Cherrington ◽  
Stephen H. Wright
Keyword(s):  
Sex Differences ◽  
Organic Cation ◽  
Organic Anion ◽  
Organic Cation Transporter ◽  
Functional Expression ◽  
Proximal Tubules ◽  
Organic Anion Transporter ◽  
Renal Proximal Tubules ◽  
Anion Transporter

scholarly journals Renal secretion of hydrochlorothiazide involves organic anion transporter 1/3, organic cation transporter 2, and multidrug and toxin extrusion protein 2-K

2019 ◽  
Vol 317 (4) ◽  
pp. F805-F814
Author(s):  
Jia Yin ◽  
David J. Wagner ◽  
Bhagwat Prasad ◽  
Nina Isoherranen ◽  
Kenneth E. Thummel ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Organic Cation ◽  
Organic Anion ◽  
Organic Cation Transporter ◽  
Tubular Secretion ◽  
Organic Anion Transporter ◽  
Anion Transporters ◽  
Anion Transporter ◽  
Organic Cation Transporter 2 ◽  
Toxin Extrusion

Hydrochlorothiazide (HCTZ) is the most widely used thiazide diuretic for the treatment of hypertension either alone or in combination with other antihypertensives. HCTZ is mainly cleared by the kidney via tubular secretion, but the underlying molecular mechanisms are unclear. Using cells stably expressing major renal organic anion and cation transporters [human organic anion transporter 1 (hOAT1), human organic anion transporter 3 (hOAT3), human organic cation transporter 2 (hOCT2), human multidrug and toxin extrusion 1 (hMATE1), and human multidrug and toxin extrusion 2-K (hMATE2-K)], we found that HCTZ interacted with both organic cation and anion transporters. Uptake experiments further showed that HCTZ is transported by hOAT1, hOAT3, hOCT2, and hMATE2-K but not by hMATE1. Detailed kinetic analysis coupled with quantification of membrane transporter proteins by targeted proteomics revealed that HCTZ is an excellent substrate for hOAT1 and hOAT3. The apparent affinities ( Km) for hOAT1 and hOAT3 were 112 ± 8 and 134 ± 13 μM, respectively, and the calculated turnover numbers ( kcat) were 2.48 and 0.79 s−1, respectively. On the other hand, hOCT2 and hMATE2-K showed much lower affinity for HCTZ. The calculated transport efficiency ( kcat/ Km) at the single transporter level followed the rank order of hOAT1> hOAT3 > hOCT2 and hMATE2-K, suggesting a major role of organic anion transporters in tubular secretion of HCTZ. In vitro inhibition experiments further suggested that HCTZ is not a clinically relevant inhibitor for hOAT1 or hOAT3. However, strong in vivo inhibitors of hOAT1/3 may alter renal secretion of HCTZ. Together, our study elucidated the molecular mechanisms underlying renal handling of HCTZ and revealed potential pathways involved in the disposition and drug-drug interactions for this important antihypertensive drug in the kidney.

Acute regulation of OAT3-mediated estrone sulfate transport in isolated rabbit renal proximal tubules

2004 ◽  
Vol 287 (5) ◽  
pp. F1021-F1029 ◽  
Author(s):  
S. Soodvilai ◽  
V. Chatsudthipong ◽  
K. K. Evans ◽  
S. H. Wright ◽  
W. H. Dantzler
Keyword(s):  
Organic Anion ◽  
Basolateral Membrane ◽  
Anion Transport ◽  
Proximal Tubules ◽  
Organic Anion Transporter ◽  
Dependent Manner ◽  
Organic Anion Transport ◽  
Renal Proximal Tubules ◽  
Estrone Sulfate ◽  
Anion Transporter

We investigated the regulation of organic anion transport driven by the organic anion transporter 3 (OAT3), a multispecific OAT localized at the basolateral membrane of the renal proximal tubule. PMA, a PKC activator, inhibited uptake of estrone sulfate (ES), a prototypic substrate for OAT3, in a dose- and time-dependent manner. This inhibition was reduced by 100 nM bisindoylmaleimide I (BIM), a specific PKC inhibitor. The α1-adrenergic receptor agonist phenylephrine also inhibited ES uptake, and this effect was reduced by BIM. These results suggest that PKC activation downregulates OAT3-mediated organic anion transport. In contrast, epidermal growth factor (EGF) increased ES uptake following activation of MAPK. Exposure to PGE2 or dibutyryl (db)-cAMP also enhanced ES uptake. Stimulation produced by PGE2 and db-cAMP was prevented by the PKA inhibitor H-89, indicating that this stimulation required PKA activation. In addition, inhibition of cyclooxygenase 1 (COX1) (but not COX2) inhibited ES uptake. Furthermore, the stimulatory effect of EGF was eliminated by inhibition of either COX1 or PKA. These data suggest that EGF stimulates ES uptake by a process in which MAPK activation results in increased PGE2 production that, in turn, activates PKA and subsequently stimulates ES uptake. Interestingly, EGF did not induce upregulation immediately following phenylephrine-induced downregulation; and phenylephrine did not induce downregulation immediately after EGF-induced upregulation. These data are the first to show the regulatory response of organic anion transport driven by OAT3 in intact renal proximal tubules.

Molecular Physiology of Renal p-Aminohippurate Secretion

Physiology ◽  
2001 ◽  
Vol 16 (3) ◽  
pp. 114-118 ◽  
Author(s):  
Gerhard Burckhardt ◽  
Andrew Bahn ◽  
Natascha A. Wolff
Keyword(s):  
Organic Anion ◽  
Organic Anions ◽  
Proximal Tubules ◽  
Organic Anion Transporter ◽  
Molecular Physiology ◽  
Renal Proximal Tubules ◽  
Anion Transporter ◽  
Tubule Lumen ◽  
Tubule Cells ◽  
Species Specific

Renal proximal tubules secrete various organic anions, including drugs and p-aminohippurate (PAH). Uptake of PAH from blood into tubule cells occurs by exchange with intracellular α-ketoglutarate and is mediated by the organic anion transporter 1. PAH exit into tubule lumen is species specific and may involve ATP-independent and -dependent transporters.

scholarly journals Organic anion transporter 3 (OAT3) and renal transport of the metal chelator 2,3-dimercapto-1-propanesulfonic acid (DMPS)

2010 ◽  
Vol 88 (2) ◽  
pp. 141-146 ◽  
Author(s):  
Matthias Rödiger ◽  
Xiaohong Zhang ◽  
Bernhard Ugele ◽  
Nikolaus Gersdorff ◽  
Stephen H. Wright ◽  
...  
Keyword(s):  
Organic Anion ◽  
Proximal Tubules ◽  
Organic Anion Transporter ◽  
Hek293 Cells ◽  
Renal Transport ◽  
Renal Proximal Tubules ◽  
Metal Chelator ◽  
Anion Transporter ◽  
Intact Rabbit ◽  
Organic Anion Transporter 3

Recent investigations involving intact rabbit renal proximal tubules indicated that organic anion transporter 3 (OAT3) may be involved in the transport of 2,3-dimercapto-1-propanesulfonic acid (DMPS). Therefore, we evaluated the interaction of OAT3 with DMPS to determine the effect of OAT3 on basolateral DMPS uptake. We used stably transfected HEK293 cells expressing human and rabbit orthologs of the exchanger OAT1 and OAT3. Using 6-carboxyfluorescein (6-CF) as a substrate, the IC50 determinations for reduced DMPS (DMPSH) revealed a stronger interaction with OAT1 than with OAT3 (rbOAT1, 123.3 ± 13.7; hOAT1, 85.1 ± 8.8; rbOAT3, 171.7 ± 22.3; and hOAT3, 172.2 ± 36.4 µmol/L). However, inhibition of 6-CF uptake by the oxidized form of DMPS (DMPSS), the main form of DMPS in the blood, showed a greater affinity for OAT3 (rbOAT1, 237.4 ± 23; hOAT1, 104.6 ± 13.1; rbOAT3, 52.4 ± 7.6; and hOAT3, 31.6 ± 6.6 µmol/L). To determine whether DMPSH and DMPSS are substrates for OAT3, we performed efflux studies with [14C]glutarate and inwardly directed gradients of glutarate. The inhibitors trans-stimulated the efflux of [14C]glutarate, suggesting that OAT3 may be able to transport both forms of DMPS. On the basis of the substantial interaction of OAT3 with DMPSS, we conclude that OAT3 represents the dominant basolateral player in renal detoxification processes resulting from use of DMPS.

scholarly journals Interaction of Ethambutol with Human Organic Cation Transporters of the SLC22 Family Indicates Potential for Drug-Drug Interactions during Antituberculosis Therapy

2013 ◽  
Vol 57 (10) ◽  
pp. 5053-5059 ◽  
Author(s):  
Xiaolei Pan ◽  
Li Wang ◽  
Dirk Gründemann ◽  
Douglas H. Sweet
Keyword(s):  
Drug Interactions ◽  
Organic Cation ◽  
Organic Anion ◽  
Organic Cation Transporter ◽  
Significant Inhibition ◽  
Organic Anion Transporter ◽  
Pharmacokinetic Studies ◽  
Antituberculosis Therapy ◽  
Anion Transporter

ABSTRACTAccording to the 2012 WHO global tuberculosis (TB) report (http://apps.who.int/iris/bitstream/10665/75938/1/9789241564502_eng.pdf), the death rate for tuberculosis was over 1.4 million patients in 2011, with ∼9 million new cases diagnosed. Moreover, the frequency of comorbidity with human immunodeficiency virus (HIV) and with diabetes is on the rise, increasing the risk of these patients for experiencing drug-drug interactions (DDIs) due to polypharmacy. Ethambutol is considered a first-line antituberculosis drug. Ethambutol is an organic cation at physiological pH, and its major metabolite, 2,2′-(ethylenediimino)dibutyric acid (EDA), is zwitterionic. Therefore, we assessed the effects of ethambutol and EDA on the function of human organic cation transporter 1 (hOCT1), hOCT2, and hOCT3 and that of EDA on organic anion transporter 1 (hOAT1) and hOAT3. Potent inhibition of hOCT1- and hOCT2-mediated transport by ethambutol (50% inhibitory concentration [IC50] = 92.6 ± 10.9 and 253.8 ± 90.8 μM, respectively) was observed. Ethambutol exhibited much weaker inhibition of hOCT3 (IC50= 4.1 ± 1.6 mM); however, significant inhibition (>80%) was observed at physiologically relevant concentrations in the gastrointestinal (GI) tract after oral dosing. EDA failed to exhibit any inhibitory effects that warranted further investigation. DDI analysis indicated a strong potential for ethambutol interaction on hOCT1 expressed in enterocytes and hepatocytes and on hOCT3 in enterocytes, which would alter absorption, distribution, and excretion of coadministered cationic drugs, suggesting thatin vivopharmacokinetic studies are necessary to confirm drug safety and efficacy. In particular, TB patients with coexisting HIV or diabetes might experience significant DDIs in situations of coadministration of ethambutol and clinical therapeutics known to be hOCT1/hOCT3 substrates (e.g., lamivudine or metformin).

Role of MAPK and PKA in regulation of rbOCT2-mediated renal organic cation transport

2007 ◽  
Vol 293 (1) ◽  
pp. F21-F27 ◽  
Author(s):  
Sunhapas Soodvilai ◽  
Atip Chatsudthipong ◽  
Varanuj Chatsudthipong
Keyword(s):  
Organic Cation ◽  
Chinese Hamster ◽  
Organic Cation Transporter ◽  
Inhibitory Effect ◽  
Cell System ◽  
Proximal Tubules ◽  
Common Pathway ◽  
Renal Proximal Tubules ◽  
Organic Cation Transporter 2 ◽  
Heterologous Cell

The effects of protein kinases MAPK and PKA on the regulation of organic cation transporter 2 (OCT2) were investigated both in a heterologous cell system [Chinese hamster ovary (CHO-K1) cells stably transfected with rabbit (rb)OCT2] and in native intact rabbit renal proximal S2 segments. Inhibition of MEK (by U-0126) or PKA (by H-89) reduced transport activity of rbOCT2 in CHO-K1 cells. The inhibitory effect of U-0126 combined with H-89 produced no additive effect, indicating that the action of PKA and MAPK in the regulation of rbOCT2 is in a common pathway. Activation of PKA by forskolin stimulated rbOCT2 activity, and this stimulatory effect was eliminated by H-89, indicating that the stimulation required PKA activation. In S2 segments of rabbit renal proximal tubules, activation of MAPK (by EGF) and PKA (by forskolin) stimulated activity of rbOCT2, and this activation was abolished by U-0126 and H-89, respectively. This is the first study to show that MAPK and PKA are involved, apparently in a common pathway, in the regulation of OCT2 activity in both a heterologous cell system and intact renal proximal tubules.

Daunomycin secretion by killfish renal proximal tubules

1995 ◽  
Vol 269 (2) ◽  
pp. R370-R379 ◽  
Author(s):  
D. S. Miller
Keyword(s):  
Organic Cation ◽  
Basolateral Membrane ◽  
Organic Cation Transporter ◽  
Proximal Tubules ◽  
Epifluorescence Microscopy ◽  
Buffer Solution ◽  
Simple Diffusion ◽  
Renal Proximal Tubules ◽  
Cellular Accumulation ◽  
Tubular Lumen

Epifluorescence microscopy and video-image analysis were used to measure the uptake of the fluorescent anthracycline daunomycin by intact killifish renal proximal tubules. When tubules were incubated in medium containing 2-5 microM daunomycin, the drug accumulated in the cells and the tubular lumen. At steady state, luminal fluorescence was two to three times greater than cellular fluorescence. Luminal accumulation of daunomycin was reduced when tubules were exposed to the multidrug-resistance (MDR) transporter modifiers verapamil and cyclosporin A (CSA), but not tetraethylammonium (TEA), a model substrate for the renal organic cation transport system. NaCN and vanadate reduced luminal drug accumulation. In contrast, cellular daunomycin accumulation was not affected by verapamil, CSA, TEA, or vanadate and was only slightly reduced by NaCN. When the pH of the buffer solution was decreased from 8.25 to 7.25, luminal, but not cellular, accumulation of daunomycin was again reduced by CSA; however, TEA now reduced cellular and luminal accumulation. These findings are consistent with daunomycin being actively secreted in killifish proximal tubule by two mechanisms. At pH 8.25, daunomycin crossed the basolateral membrane by simple diffusion and was secreted into the tubular lumen by the MDR transporter. At pH 7.25, daunomycin was transported across the basolateral membrane by simple diffusion and carrier-mediated uptake on the organic cation transporter and was secreted into the lumen by the MDR transporter and the organic cation/H+ exchanger.

Peritubular organic cation transport in isolated rabbit proximal tubules

1994 ◽  
Vol 266 (3) ◽  
pp. F450-F458 ◽  
Author(s):  
C. E. Groves ◽  
K. K. Evans ◽  
W. H. Dantzler ◽  
S. H. Wright
Keyword(s):  
Organic Cation ◽  
High Capacity ◽  
Organic Cation Transporter ◽  
Cation Transport ◽  
Proximal Tubules ◽  
Organic Cation Transport ◽  
Inhibitory Potency ◽  
Renal Proximal Tubules ◽  
Michaelis Constants ◽  
Maximal Capacity

The physiological characteristics of peritubular organic cation transport were examined by measuring the transport of the organic cation tetraethylammonium (TEA) in rabbit renal proximal tubule suspensions and isolated nonperfused rabbit renal proximal tubules. Peritubular organic cation transport in both single S2 segments and suspensions of isolated renal proximal tubules was found to be a high-capacity, high-affinity, carrier-mediated process. For tubule suspensions, the maximal capacity of the carrier for TEA (Jmax) and the concentration of TEA at 1/2 Jmax (Kt) (1.49 +/- 0.21 nmol.min-1.mg dry wt-1 and 131 +/- 16 microM, respectively), did not differ significantly from those measured in single S2 segments (Jmax, 1.16 +/- 0.075 nmol.min-1.mg dry wt-1; Kt, 108 +/- 10 microM). In addition, the pattern of inhibition of peritubular TEA transport by long-chain n-tetraalkylammonium compounds (n = 1-5) was both qualitatively and quantitatively similar in single S2 segments and tubule suspensions, exhibiting an increase in inhibitory potency with increasing alkyl chain length. For example, in tubule suspensions, apparent Michaelis constants for inhibition of TEA uptake ranged from 1.3 mM for tetramethylammonium (TMA) to 0.8 microM for tetrapentylammonium (TPeA). To determine whether these compounds were substrates for the peritubular organic cation transporter, their effect on the efflux of [14C]TEA from tubule suspensions was examined. A concentration of 0.5 mM of the short-chain tetraalkyls TMA or TEA increased the efflux of [14C]TEA (i.e., trans-stimulated) from tubules in suspension. The longer-chain tetraalkyls tetrapropylammonium, tetrabutylammonium, and TPeA all decreased the efflux of [14C]TEA from tubules in suspension; TPeA completely blocked efflux.(ABSTRACT TRUNCATED AT 250 WORDS)

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