The effect of organic anion transporter 3 inhibitor probenecid on bumetanide levels in the brain: an integrated in vivo
 microdialysis study in the rat

Accumulation of detrimental glutathione-conjugated metabolites in the brain potentially causes neurological disorders, and must therefore be exported from the brain. However, in vivo mechanisms of glutathione-conjugates efflux from the brain remain unknown. We investigated the involvement of transporters in glutathione-conjugates efflux using 6-bromo-7-[11C]methylpurine ([11C]1), which enters the brain and is converted into its glutathione conjugate, S-(7-[11C]methylpurin-6-yl)glutathione ([11C]2). In mice of control and knockout of P-glycoprotein/breast cancer resistance protein and multidrug resistance-associated protein 2 ([ Mrp2] −/−), [11C]2 formed in the brain was rapidly cleared, with no significant difference in efflux rate. In contrast, [11C]2 formed in the brain of Mrp1 −/− mice was slowly cleared, whereas [11C]2 microinjected into the brain of control and Mrp1 −/− mice was 75% cleared within 60 min, with no significant difference in efflux rate. These suggest that Mrp1 contributes to [11C]2 efflux across cell membranes, but not BBB. Efflux rate of [11C]2 formed in the brain was significantly lower in Mrp4 −/− and organic anion transporter 3 ( Oat3) −/− mice compared with control mice. In conclusion, Mrp1, Oat3, and Mrp4 mediate [11C]2 efflux from the brain. Mrp1 may contribute to [11C]2 efflux from brain parenchymal cells, while extracellular [11C]2 is likely cleared across the BBB, partly by Oat3 and Mrp4.

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Rat Organic Anion Transporter 3 (rOAT3) is Responsible for Brain-to-Blood Efflux of Homovanillic Acid at the Abluminal Membrane of Brain Capillary Endothelial Cells

Journal of Cerebral Blood Flow & Metabolism ◽

10.1097/01.wcb.0000050062.57184.75 ◽

2003 ◽

Vol 23 (4) ◽

pp. 432-440 ◽

Cited By ~ 60

Author(s):

Shinobu Mori ◽

Hitomi Takanaga ◽

Sumio Ohtsuki ◽

Tsuneo Deguchi ◽

Young-Sook Kang ◽

...

Keyword(s):

Endothelial Cells ◽

Homovanillic Acid ◽

Organic Anion ◽

Organic Anion Transporter ◽

Indoxyl Sulfate ◽

Brain Capillary ◽

Anion Transporter ◽

Capillary Endothelial Cells ◽

Organic Anion Transporter 3 ◽

The Brain

The mechanism that removes homovanillic acid (HVA), an end metabolite of dopamine, from the brain is still poorly understood. The purpose of this study is to identify and characterize the brain-to-blood HVA efflux transporter at the rat blood–brain barrier (BBB). Using the Brain Efflux Index method, the apparent in vivo efflux rate constant of [3H]HVA from the brain, keff, was determined to be 1.69 × 10–2 minute–1. This elimination was significantly inhibited by para-aminohippuric acid (PAH), benzylpenicillin, indoxyl sulfate, and cimetidine, suggesting the involvement of rat organic anion transporter 3 (rOAT3). rOAT3-expressing oocytes exhibited [3H]HVA uptake (Km = 274 μmol/L), which was inhibited by several organic anions, such as PAH, indoxyl sulfate, octanoic acid, and metabolites of monoamine neurotransmitters. Neurotransmitters themselves did not affect the uptake. Furthermore, immunohistochemical analysis suggested that rOAT3 is localized at the abluminal membrane of brain capillary endothelial cells. These results provide the first evidence that rOAT3 is expressed at the abluminal membrane of the rat BBB and is involved in the brain-to-blood transport of HVA. This HVA efflux transport system is likely to play an important role in controlling the level of HVA in the CNS.

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Role of blood-brain barrier organic anion transporter 3 (OAT3) in the efflux of indoxyl sulfate, a uremic toxin: its involvement in neurotransmitter metabolite clearance from the brain

Journal of Neurochemistry ◽

10.1046/j.1471-4159.2002.01108.x ◽

2002 ◽

Vol 83 (1) ◽

pp. 57-66 ◽

Cited By ~ 139

Author(s):

Sumio Ohtsuki ◽

Hiroshi Asaba ◽

Hitomi Takanaga ◽

Tsuneo Deguchi ◽

Ken-ichi Hosoya ◽

...

Keyword(s):

Blood Brain Barrier ◽

Organic Anion ◽

Organic Anion Transporter ◽

Indoxyl Sulfate ◽

Uremic Toxin ◽

Anion Transporter ◽

Metabolite Clearance ◽

Organic Anion Transporter 3 ◽

The Brain

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Drug interaction between celecoxib and methotrexate in organic anion transporter 3–transfected renal cells and in rats in vivo

European Journal of Pharmacology ◽

10.1016/j.ejphar.2010.04.051 ◽

2010 ◽

Vol 640 (1-3) ◽

pp. 168-171 ◽

Cited By ~ 11

Author(s):

Akimitsu Maeda ◽

Shuichi Tsuruoka ◽

Kentarou Ushijima ◽

Yoshikatsu Kanai ◽

Hitoshi Endou ◽

...

Keyword(s):

Drug Interaction ◽

Organic Anion ◽

Organic Anion Transporter ◽

Renal Cells ◽

Anion Transporter ◽

Organic Anion Transporter 3

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Benzyl [11C]Hippurate as an Agent for Measuring the Activities of Organic Anion Transporter 3 in the Brain and Multidrug Resistance-Associated Protein 4 in the Heart of Mice

Journal of Medicinal Chemistry ◽

10.1021/acs.jmedchem.6b00454 ◽

2016 ◽

Vol 59 (12) ◽

pp. 5847-5856 ◽

Cited By ~ 3

Author(s):

Tatsuya Kikuchi ◽

Toshimitsu Okamura ◽

Maki Okada ◽

Masanao Ogawa ◽

Chie Suzuki ◽

...

Keyword(s):

Multidrug Resistance ◽

Organic Anion ◽

Organic Anion Transporter ◽

Anion Transporter ◽

Organic Anion Transporter 3 ◽

The Brain

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Organic anion transporter 3 (Oat3/Slc22a8) knockout mice exhibit altered clearance and distribution of penicillin G

AJP Renal Physiology ◽

10.1152/ajprenal.00319.2007 ◽

2007 ◽

Vol 293 (4) ◽

pp. F1332-F1341 ◽

Cited By ~ 68

Author(s):

Adam L. VanWert ◽

Rachel M. Bailey ◽

Douglas H. Sweet

Keyword(s):

Knockout Mice ◽

Drug Disposition ◽

Organic Anion ◽

Organic Anion Transporter ◽

Penicillin G ◽

Anion Transporter ◽

Organic Anion Transporter 3

The interaction of renal basolateral organic anion transporter 3 (Oat3) with commonly used pharmacotherapeutics (e.g., NSAIDs, β-lactams, and methotrexate) has been studied extensively in vitro. However, the in vivo role of Oat3 in drug disposition, in the context of other transporters, glomerular filtration, and metabolism, has not been established. Moreover, recent investigations have identified inactive human OAT3 polymorphisms. Therefore, this investigation was designed to elucidate the in vivo role of Oat3 in the disposition of penicillin G and prototypical substrates using an Oat3 knockout mouse model. Oat3 deletion resulted in a doubling of penicillin's half-life ( P < 0.05) and a reduced volume of distribution ( P < 0.01), together yielding a plasma clearance that was one-half ( P < 0.05, males) to one-third ( P < 0.001, females) of that in wild-type mice. Inhibition of Oat3 abolished the differences in penicillin G elimination between genotypes. Hepatic accumulation of penicillin was 2.3 times higher in male knockouts ( P < 0.05) and 3.7 times higher in female knockouts ( P < 0.001). Female knockouts also exhibited impaired estrone-3-sulfate clearance. Oat3 deletion did not impact p-aminohippurate elimination, providing correlative evidence to studies in Oat1 knockout mice that suggest Oat1 governs tubular uptake of p-aminohippurate. Collectively, these findings are the first to indicate that functional Oat3 is necessary for proper elimination of xenobiotic and endogenous compounds in vivo. Thus Oat3 plays a distinct role in determining the efficacy and toxicity of drugs. Dysfunctional human OAT3 polymorphisms or instances of polypharmacy involving OAT3 substrates may result in altered systemic accumulation of β-lactams and other clinically relevant compounds.

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