Involvement of human organic cation transporter 1 in the hepatic uptake of 1-(2-methoxyethyl)-2-methyl-4,9-dioxo-3-(pyrazin-2-ylmethyl)-4,9-dihydro-1H-naphtho[2,3-d]imidazolium bromide (YM155 monobromide), a novel, small molecule survivin suppressant.

1-(2-Methoxyethyl)-2-methyl-4,9-dioxo-3-(pyrazin-2-ylmethyl)-4,9-dihydro-1H-naphtho[2,3-d]imidazolium bromide (YM155 monobromide), which is a hydrophilic and cationic compound, exhibits antitumor activity in experimental human hormone refractory prostate carcinoma models. Urinary excretion was 18.3 to 28.

Characterization of the renal tubular transport of zonampanel, a novel alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor antagonist, by human organic anion transporters.

Zonampanel monohydrate (YM872; [2,3-dioxo-7-(1H-imidazol-1-yl)-6-nitro-1,2,3,4-tetrahydro-1-quinoxalinyl]acetic acid monohydrate) is a novel alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor antagonist. The major elimination route for zonampanel has been reported to be by urine via the kidneys. The purpose of this study is to elucidate the molecular mechanism of the renal excretion of zonampanel using cells stably expressing human organic anion transporters (hOAT) 1, hOAT2, hOAT3, and hOAT4, as well as human organic cation transporters (hOCT) 1 and hOCT2.

Human organic cation transporter 3 mediates the transport of antiarrhythmic drugs.

Antiarrhythmic drugs have been considered to be transported by the organic cation transport system. The purpose of this study was to elucidate the molecular mechanism underlying the transport of antiarrhythmic drugs using cells from the second segment of the proximal tubule (S2) cells of mice expressing human-organic cation transporter 3 (S2 human-OCT3). The antiarrhythmic drugs tested were cibenzoline, disopyramide, lidocaine, mexiletine, phenytoin, pilsicanide, procainamide and quinidine.

Interactions of human- and rat-organic anion transporters with pravastatin and cimetidine.

We have elucidated the interactions of human and rat organic anion transporters (hOATs and rOATs) with pravastatin and cimetidine. Pravastatin inhibited hOAT1/rOAT1, hOAT2/rOAT2, hOAT3/rOAT3, and hOAT4. The mode of inhibition was noncompetitive for hOAT1 and hOAT2, whereas it was competitive for hOAT3 and hOAT4.

Expression of human organic anion transporters in the choroid plexus and their interactions with neurotransmitter metabolites.

The purpose of the present study was to elucidate the expression of human organic anion transporter 1 (hOAT1) and hOAT3 in the choroid plexus of the human brain and their interactions with neurotransmitter metabolites using stable cell lines. Immunohistochemical analysis revealed that hOAT1 and hOAT3 are expressed in the cytoplasmic membrane and cytoplasm of human choroid plexus. Neurotransmitter metabolites, namely, 5-methoxyindole-3-acetic acid (5-MI-3-AA), homovanillic acid (HVA), vanilmandelic acid (VMA), 3,4-dihydroxyphenylacetic acid (DOPAC), 5-hydroxyindole-3-acetic acid (5-HI-3-AA), N-acetyl-5-hydroxytryptamine (NA-5-HTT), melatonin, 5-methoxytryptamine (5-MTT), 3,4-dihidroxymandelic acid (DHMA), 5-hydroxytryptophol, and 5-methoxytryptophol (5-MTP), but not methanephrine (MN), normethanephrine (NMN), and 3-methyltyramine (3-MT), at 2 mM, inhibited para-aminohippuric acid uptake mediated by hOAT1.

Evidence for a role of human organic anion transporters in the muscular side effects of HMG-CoA reductase inhibitors.

The purpose of this study was to elucidate the role of human organic anion transporters (human OATs) in the induction of drug-induced skeletal muscle abnormalities. 3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors have been clinically used for lowering plasma cholesterol levels, and are known to induce various forms of skeletal muscle abnormalities including myopathy and rhabdomyolysis. Immunohistochemical analysis revealed that human OAT1 and human OAT3 are localized in the cytoplasmic membrane of the human skeletal muscles.

Interactions of human organic anion transporters with diuretics.

The tubular secretion of diuretics in the proximal tubule has been shown to be critical for the action of drugs. To elucidate the molecular mechanisms for the tubular excretion of diuretics, we have elucidated the interactions of human organic anion transporters (hOATs) with diuretics using cells stably expressing hOATs. Diuretics tested were thiazides, including chlorothiazide, cyclothiazide, hydrochlorothiazide, and trichlormethiazide; loop diuretics, including bumetanide, ethacrynic acid, and furosemide; and carbonic anhydrase inhibitors, including acetazolamide and methazolamide.

Interaction of human and rat organic anion transporter 2 with various cephalosporin antibiotics.

Cephalosporin antibiotics are thought to be excreted into the urine via organic anion transporters (OATs) and OAT can mediate nephrotoxicity by cephalosporins, particularly by cephaloridine. The purpose of this study was to elucidate the interaction of human-OAT2 and rat-OAT2 with cephalosporin antibiotics using proximal tubule cells stably expressing human-OAT2 and rat-OAT2. Human-OAT2 is localized to the basolateral side of the proximal tubule, whereas rat-OAT2 is localized to the apical side of the proximal tubule.

Interactions of human organic anion transporters and human organic cation transporters with nonsteroidal anti-inflammatory drugs.

The purpose of this study was to elucidate the interactions of human organic anion transporters (hOATs) and human organic cation transporters (hOCTs) with nonsteroidal anti-inflammatory drugs (NSAIDs) using cells stably expressing hOATs and hOCTs. NSAIDs tested were acetaminophen, acetylsalicylate, salicylate, diclofenac, ibuprofen, indomethacin, ketoprofen, mefenamic acid, naproxen, piroxicam, phenacetin, and sulindac. These NSAIDs inhibited organic anion uptake mediated by hOAT1, hOAT2, hOAT3, and hOAT4.

Characterization of methotrexate transport and its drug interactions with human organic anion transporters.

Life-threatening drug interactions are known to occur between methotrexate and nonsteroidal anti-inflammatory drugs (NSAIDs), probenecid, and penicillin G. The purpose of this study was to characterize methotrexate transport, as well as to determine the site and the mechanism of drug interactions in the proximal tubule. Mouse proximal tubule cells stably expressing basolateral human organic anion transporters (hOAT1 and hOAT3) and apical hOAT (hOAT4) were established.

Role of human organic anion transporter 4 in the transport of ochratoxin A.

The purpose of this study was to investigate the characteristics of ochratoxin A (OTA) transport by multispecific human organic anion transporter 4 (hOAT4) using mouse proximal tubule cells stably transfected with hOAT4 (S(2) hOAT4). Immunohistochemical analysis revealed that hOAT4 protein was localized to the apical side of the proximal tubule. S(2) hOAT4 expressed hOAT4 protein in the apical side as well as basolateral side and the cells were cultured on the plastic dish for experiments.

Interaction of human organic anion transporters 2 and 4 with organic anion transport inhibitors.

The organic anion transport system is involved in the tubular excretion and reabsorption of various drugs and substances. The purpose of this study was to characterize the effects of various organic anion transport inhibitors on renal organic anion transport using proximal tubule cells stably expressing human organic anion transporter 2 (hOAT2) and hOAT4. Immunohistochemical analysis revealed that hOAT2 is localized to the basolateral side of the proximal tubule in the kidney.

Involvement of rat organic anion transporter 3 (rOAT3) in cephaloridine-induced nephrotoxicity: in comparison with rOAT1.

This study was performed to elucidate the possible involvement of organic anion transporter 3 (OAT3) in cephaloridine (CER)-induced nephrotoxicity and compare the substrate specificity between rOAT3 and rat OAT1 (rOAT1) for various cephalosporin antibiotics, using proximal tubule cells stably expressing rOAT3 (S2 rOAT3) and rOAT1 (S2 rOAT1). S2 rOAT3 exhibited a CER uptake and a higher susceptibility to CER cytotoxicity than did mock, which was recovered by probenecid. Various cephalosporin antibiotics significantly inhibited both estrone sulfate uptake in S2 rOAT3 and para-aminohippuric acid uptake in S2 rOAT1.

Interaction of human organic anion transporters with various cephalosporin antibiotics.

Cephalosporin antibiotics are thought to be excreted into the urine via organic anion transporters (OATs). The purpose of this study was to elucidate the interaction of human-OATs with various cephalosporin antibiotics, using proximal tubule cells stably expressing human-OAT1, human-OAT3 and human-OAT4. Human-OAT1 and human-OAT3 are localized to the basolateral side of the proximal tubule, whereas human-OAT4 is localized to the apical side.

Human organic anion transporters and human organic cation transporters mediate renal transport of prostaglandins.

Prostaglandin E(2) (PGE(2)) and prostaglandin F(2 alpha) (PGF(2 alpha)) have been used for the induction of labor and the termination of pregnancy. Renal excretion is shown to be an important pathway for the elimination of PGE(2) and PGF(2 alpha). The purpose of this study was to elucidate the molecular mechanism of renal PGE(2) and PGF(2 alpha) transport using cells stably expressing human organic anion transporter (hOAT) 1, hOAT2, hOAT3, and hOAT4, and human organic cation transporter (hOCT) 1 and hOCT2.

Human organic anion transporters and human organic cation transporters mediate renal antiviral transport.

Renal excretion is an important elimination pathway for antiviral agents, such as acyclovir (ACV), ganciclovir (GCV), and zidovudine (AZT). The purpose of this study was to elucidate the molecular mechanisms of renal ACV, GCV, and AZT transport using cells stably expressing human organic anion transporter 1 (hOAT1), hOAT2, hOAT3, and hOAT4, and human organic cation transporter 1 (hOCT1) and hOCT2. Time- and concentration-dependent uptake of ACV and GCV was observed in hOAT1- and hOCT1-expressing cells.

Human organic anion transporters mediate the transport of tetracycline.

The purpose of this study was to elucidate the molecular mechanism for renal tetracycline transport by human organic anion transporters (hOATs) using proximal tubular cells stably expressing hOATs. The cells stably expressing hOAT1, hOAT2, hOAT3 and hOAT4 exhibited a higher amount of [3H]tetracycline uptake compared with mock cells. The apparent Km values for hOAT2-, hOAT3- and hOAT4-mediated tetracycline uptakes were 439.