Impairment of renal organic anion transport mediated by organic anion transporter 1 (Oat1) and 3 (Oat3) in acute myocardial ischemic and reperfusion injury in rats

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.

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Organic anion transport in choroid plexus from wild-type and organic anion transporter 3 (Slc22a8)-null mice

AJP Renal Physiology ◽

10.1152/ajprenal.00356.2003 ◽

2004 ◽

Vol 286 (5) ◽

pp. F972-F978 ◽

Cited By ~ 42

Author(s):

Destiny Sykes ◽

Douglas H. Sweet ◽

Simon Lowes ◽

Sanjay K. Nigam ◽

John B. Pritchard ◽

...

Keyword(s):

Choroid Plexus ◽

Organic Anion ◽

Anion Transport ◽

Organic Anion Transporter ◽

Null Mouse ◽

Organic Anion Transport ◽

Wild Type ◽

Estrone Sulfate ◽

Anion Transporter ◽

Organic Anion Transporter 3

The choroid plexus actively transports endogenous, xenobiotic, and therapeutic compounds from cerebrospinal fluid to blood, thereby limiting their exposure to the central nervous system (CNS). Establishing the mechanisms responsible for this transport is critical to our understanding of basic choroid plexus physiology and will likely impact drug targeting to the CNS. We recently generated an organic anion transporter 3- (Oat3)-null mouse, which exhibited loss of PAH, estrone sulfate, and taurocholate transport in kidney and of fluorescein (FL) transport in choroid plexus. Here, we measured the uptake of four Oat3 substrates by choroid plexus from wild-type and Oat3-null mice to establish 1) the contribution of Oat3 to the apical uptake of each substrate and 2) the Na dependence of transport by Oat3 in the intact tissue. Mediated transport of PAH and FL was essentially abolished in tissue from Oat3-null mice. In contrast, only a 33% reduction in estrone sulfate uptake was observed in tissue from Oat3-null mice and, surprisingly, no reduction in taurocholate uptake could be detected. For PAH, FL, and estrone sulfate, all Oat3-mediated transport was Na dependent. However, estrone sulfate and taurocholate also exhibited additional mediated and Na-dependent components of uptake that were not attributed to Oat3, demonstrating the complexity of organic anion transport in this tissue and the need for further examination of expressed transporters and their energetics.

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Regulation by protein kinase C of organic anion transport driven by rat organic anion transporter 3 (rOAT3)

Life Sciences ◽

10.1016/s0024-3205(00)00694-9 ◽

2000 ◽

Vol 67 (9) ◽

pp. 1087-1093 ◽

Cited By ~ 47

Author(s):

Michio Takeda ◽

Takashi Sekine ◽

Hitoshi Endou

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Organic Anion ◽

Anion Transport ◽

Organic Anion Transporter ◽

Organic Anion Transport ◽

Kinase C ◽

Anion Transporter ◽

Organic Anion Transporter 3

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Cyclic AMP stimulates sorting of the canalicular organic anion transporter (Mrp2/cMoat) to the apical domain in hepatocyte couplets

Journal of Cell Science ◽

10.1242/jcs.111.8.1137 ◽

1998 ◽

Vol 111 (8) ◽

pp. 1137-1145 ◽

Cited By ~ 1

Author(s):

H. Roelofsen ◽

C.J. Soroka ◽

D. Keppler ◽

J.L. Boyer

Keyword(s):

Apical Membrane ◽

Organic Anion ◽

Anion Transport ◽

Transport Protein ◽

Organic Anion Transporter ◽

Multidrug Resistance Protein ◽

Multidrug Resistance Protein 2 ◽

Apical Domain ◽

Anion Transporter ◽

Resistance Protein

The canalicular membrane of rat hepatocytes contains an ATP-dependent multispecific organic anion transporter, also named multidrug resistance protein 2, that is responsible for the biliary secretion of several amphiphilic organic anions. This transport function is markedly diminished in mutant rats that lack the transport protein. To assess the role of vesicle traffic in the regulation of canalicular organic anion transport, we have examined the redistribution of the transporter to the canalicular membrane and the effect of cAMP on this process in isolated hepatocyte couplets, which retain secretory polarity. The partial disruption of cell-cell contact, due to the isolation procedure, leaves the couplet with both remnant apical membranes, as a source of apical proteins, and an intact apical domain and lumen, to which these proteins are targeted. The changes in distribution of the transporter were correlated to the apical excretion of a fluorescent substrate, glutathione-methylfluorescein. The data obtained in this study show that the transport protein, endocytosed from apical membrane remnants, first is redistributed along the basolateral plasma membrane. Then it is transcytosed to the remaining apical pole in a microtubule-dependent fashion, followed by the fusion of transporter-containing vesicles with the apical membrane. The cAMP analog dibutyrylcAMP stimulates all three steps, resulting in increased apically located transport protein, glutathione-methylfluorescein transport activity and apical membrane circumference. These findings indicate that the organic anion transport capacity of the apical membrane in hepatocyte couplets is regulated by cAMP-stimulated sorting of the multidrug resistance protein 2 to the apical membrane. The relevance of this phenomenon for the intact liver is discussed.

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ATP-dependent multispecific organic anion transport system in rat erythrocyte membrane vesicles

AJP Cell Physiology ◽

10.1152/ajpcell.1992.262.1.c104 ◽

1992 ◽

Vol 262 (1) ◽

pp. C104-C110 ◽

Cited By ~ 43

Author(s):

M. Heijn ◽

R. P. Oude Elferink ◽

P. L. Jansen

Keyword(s):

Bile Acids ◽

Transport System ◽

Organic Anion ◽

Membrane Vesicles ◽

Organic Anions ◽

Anion Transport ◽

Maximal Velocity ◽

Organic Anion Transport ◽

Anion Transporter ◽

Anion Transport System

The uptake of oxidized glutathione (GSSG) into inside-out membrane vesicles of Wistar rat erythrocytes was studied. Uptake was ATP dependent, into an osmotically active space, and saturable. Analysis of saturable ATP-dependent GSSG uptake showed two affinities for GSSG [concentration for half-maximal velocity (K1/2 1), 26 microM; K 1/2 2, 4 mM; maximum transport rate (Vmax 1), 100 pmol.mg-1.min-1; Vmax 2, 360 pmol.mg-1.min-1]. Interactions of the high-affinity system with different organic compounds were studied. Leukotriene C4, bromosulfophthalein-S-glutathione, and 2,4-dinitrophenyl-S-glutathione were effective inhibitors. In addition, anionic nonglutathione conjugates, like indocyanine green, rose bengal, dibromosulfophthalein, and sulfated or glucuronidated (divalent) bile acids inhibited GSSG transport. Monovalent bile acids had no influence on GSSG transport. Inhibition by 2,4-dinitrophenyl-S-glutathione [inhibition constant (Ki) = 2.6 microM] and sulfated glycolithocholic acid (Ki = 2.9 microM) was purely competitive. The use of adenosinetriphosphatase (ATPase) inhibitors suggested a resemblance with E1E2-type ATPase. Vesicles of erythrocytes isolated from the TR- rat, a mutant rat strain with a defective biliary secretion of organic anions, have an impaired uptake of GSSG (Vmax was decreased 2-fold). In conclusion, erythrocytes have an ATP-dependent organic anion transport system that can be inhibited by a broad range of organic anions. This system is very similar if not identical to the hepatocanalicular ATP-dependent organic anion transporter.

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