Cynomolgus Monkey as a Clinically Relevant Model to Study Transport Involving Renal Organic Cation Transporters: In Vitro and In Vivo Evaluation

2015 ◽  
Vol 44 (2) ◽  
pp. 238-249 ◽  
Author(s):  
H. Shen ◽  
T. Liu ◽  
H. Jiang ◽  
C. Titsch ◽  
K. Taylor ◽  
...  
Keyword(s):  
Cynomolgus Monkey ◽  
Organic Cation ◽  
Organic Cation Transporters ◽  
Relevant Model ◽  
In Vivo Evaluation ◽  
Cation Transporters

Nitric oxide-induced regulation of renal organic cation transport after renal ischemia-reperfusion injury

2011 ◽  
Vol 301 (5) ◽  
pp. F997-F1004 ◽  
Author(s):  
R. Schneider ◽  
M. Meusel ◽  
B. Betz ◽  
M. Kersten ◽  
K. Möller-Ehrlich ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Organic Cation ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Fractional Excretion ◽  
Renal Ischemia ◽  
Organic Cation Transporters ◽  
Cation Transporters

Renal organic cation transporters are downregulated by nitric oxide (NO) in rat endotoxemia. NO generated by inducible NO synthase (iNOS) is substantially increased in the renal cortex after renal ischemia-reperfusion (I/R) injury. Therefore, we investigated the effects of iNOS-specific NO inhibition on the expression of the organic cation transporters rOct1 and rOct2 (Slc22a1 and Slc22a2, respectively) after I/R injury both in vivo and in vitro. In vivo, N6-(1-iminoethyl)-l-lysine (l-NIL) completely inhibited NO generation after I/R injury. Moreover, l-NIL abolished the ischemia-induced downregulation of rOct1 and rOct2 as determined by qPCR and Western blotting. Functional evidence was obtained by measuring the fractional excretion (FE) of the endogenous organic cation serotonin. Concordant with the expression of the rate-limiting organic cation transporter, the FE of serotonin decreased after I/R injury and was totally abolished by l-NIL. In vitro, ischemia downregulated both rOct1 and rOct2, which were also abolished by l-NIL; the same was true for the uptake of the organic cation MPP. We showed that renal I/R injury downregulates rOct1 and rOct2, which is most probably mediated via NO. In principle, this may be an autocrine effect of proximal tubular epithelial cells. We conclude that rOct1, or rOct1 and rOct2 limit the rate of the renal excretion of serotonin.

Abstract 14035: Renal Tubular Secretion and Cardiac Distribution of Dofetilide is Dependent on MATE1 Function

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Muhammad Erfan Uddin ◽  
Yan Jin ◽  
Alice A Gibson ◽  
Ingrid M Bonilla ◽  
Cynthia A Carnes ◽  
...  
Keyword(s):  
Organic Cation ◽  
Tubular Secretion ◽  
Hek293 Cells ◽  
Delayed Rectifier ◽  
Organic Cation Transporters ◽  
Wild Type ◽  
Renal Tubular Secretion ◽  
Cation Transporters ◽  
Renal Tubular

Introduction: Dofetilide is a delayed rectifier potassium channel inhibitor used to treat patients with atrial fibrillation and flutter, and its use is associated with a risk of QT prolongation and Torsades de Pointes . The mechanisms involved in dofetilide’s renal tubular secretion and its uptake into cardiomyocytes remain unknown. Previously reported drug-drug interaction (DDI) studies suggest the involvement of organic cation transporters. Here, we investigated the contribution of organic cation transporters (OCT2 and MATE1) to the pharmacokinetics of dofetilide to gain insight into its DDI potential. Hypothesis: Based on known DDIs with dofetilide, we hypothesize that OCT2 and/or MATE1 play a key role in the inter-individual variability in pharmacokinetics and pharmacodynamics of dofetilide. Methods: In vitro and ex vivo transport kinetics of dofetilide were determined in HEK293 cells stably transfected with OCT2 or MATE1, and in isolated cardiomyocytes, respectively. In vivo studies were performed in wild-type, OCT2-, and MATE1-deficient mice (n=5) receiving dofetilide (5 mg/kg, p.o., 2.5 mg/kg, i.v.), with or without several contraindicated drugs. Dofetilide concentrations in plasma and urine were determined by UPLC-MS/MS. Results: In vitro studies demonstrated that dofetilide is a good substrate of MATE1 but not OCT2. Deficiency of MATE1 was associated with increased plasma concentrations of dofetilide and with a significantly reduced urinary excretion (3-fold in females and 5-fold in males, respectively). Dofetilide accumulation in cardiomyocytes was increased by 2-fold in MATE1-deficient females, and pre-incubation with the MATE1 inhibitor cimetidine significantly reduced dofetilide uptake in wild-type cardiomyocytes. Several contraindicated drugs listed in the dofetilide prescribing information, including cimetidine, ketoconazole, increased dofetilide plasma exposure in wild-type mice by >2.8-fold. Conclusion: Renal secretion of dofetilide is mediated by MATE1 and is highly sensitive to inhibition by many widely used prescription drugs that can cause clinically relevant DDIs. Deficiency of MATE1 also increases accumulation in the heart which may contribute to individual variation in response to dofetilide.

Differential pharmacological in vitro properties of organic cation transporters and regional distribution in rat brain

2006 ◽  
Vol 50 (8) ◽  
pp. 941-952 ◽  
Author(s):  
Anne Amphoux ◽  
Vincent Vialou ◽  
Eva Drescher ◽  
Michael Brüss ◽  
Clotilde Mannoury La Cour ◽  
...  
Keyword(s):  
Rat Brain ◽  
Organic Cation ◽  
Regional Distribution ◽  
Organic Cation Transporters ◽  
Cation Transporters

Multiple binding sites in organic cation transporters require sophisticated procedures to identify interactions of novel drugs

2019 ◽  
Vol 400 (2) ◽  
pp. 195-207 ◽  
Author(s):  
Hermann Koepsell
Keyword(s):  
Binding Sites ◽  
Organic Cation ◽  
Cation Binding ◽  
Organic Cation Transporters ◽  
High Affinity ◽  
Multiple Binding Sites ◽  
Novel Drugs ◽  
Cation Transporters ◽  
Influence Of Substrate

AbstractIn vitroevaluation of drugs for interaction with transporters is essential during drug development. As polyspecific organic cation transporters (OCTs) are critical for pharmacokinetics of many cationic drugs,in vitrotesting of human OCT1 and human OCT2 is recommended. In the currently applied tests it is determined whether uptake of one model cation in stably transfected epithelial cells is inhibited using a substrate concentration in the micromolar range. In this review experimental evidence for the existence of low- and high-affinity cation binding sites in OCTs that may interact with drugs is compiled. Most data were obtained from studies performed with rat Oct1. Whereas overlapping low-affinity cation binding sites are directly involved in transport, the high-affinity cation binding sites may induce allosteric inhibition of transport. Remarkably, high-affinity inhibition is only observed when uptake is measured using nanomolar substrate concentrations far below the respectiveKmvalues. Affinities of inhibitors are dependent on molecular structure and concentration of the employed substrate. Because the currently appliedin vitrotests for identification of interaction of novel drugs with OCTs do not consider the influence of substrate structure and are not capable of identifying high-affinity inhibition, more sophisticated testing protocols are proposed.

Organic Cation Transporters are Involved in Fluoxetine Transport Across the Blood-Brain Barrier in Vivo and in Vitro

2021 ◽  
Vol 18 ◽  
Author(s):  
Min Wang ◽  
Yingying Sun ◽  
Bingying Hu ◽  
Zhisheng He ◽  
Shanshan Chen ◽  
...  
Keyword(s):  
Blood Brain Barrier ◽  
Cellular Uptake ◽  
Organic Cation ◽  
Brain Barrier ◽  
Organic Cation Transporters ◽  
Cellular Accumulation ◽  
Blood Brain ◽  
The Brain

Background : The research and development of drugs for the treatment of central nervous system diseases faces many challenges at present. One of the most important questions to be answered is, how does the drug cross the blood-brain barrier to get to the target site for pharmacological action. Fluoxetine is widely used in clinical antidepressant therapy. However, the mechanism by which fluoxetine passes through the BBB also remains unclear. Under physiological pH conditions, fluoxetine is an organic cation with a relatively small molecular weight (<500), which is in line with the substrate characteristics of organic cation transporters (OCTs). Therefore, this study aimed to investigate the interaction of fluoxetine with OCTs at the BBB and BBB-associated efflux transporters. This is of great significance for fluoxetine to better treat depression. Moreover, it can provide a theoretical basis for clinical drug combinations. Methods: In vitro BBB model was developed using human brain microvascular endothelial cells (hCMEC/D3), and the cellular accumulation was tested in the presence or absence of transporter inhibitors. In addition, an in vivo trial was performed in rats to investigate the effect of OCTs on the distribution of fluoxetine in the brain tissue. Fluoxetine concentration was determined by a validated UPLC-MS/MS method. Results: The results showed that amantadine (an OCT1/2 inhibitor) and prazosin (an OCT1/3 inhibitor) significantly decreased the cellular accumulation of fluoxetine (P <.001). Moreover, we found that N-methylnicotinamide (an OCT2 inhibitor) significantly inhibited the cellular uptake of 100 and 500 ng/mL fluoxetine (P <.01 and P <.05 respectively). In contrast, corticosterone (an OCT3 inhibitor) only significantly inhibited the cellular uptake of 1000 ng/mL fluoxetine (P <.05). The P-glycoprotein (P-gp) inhibitor, verapamil, and the multidrug resistance resistance-associated proteins (MRPs) inhibitor, MK571, significantly decreased the cellular uptake of fluoxetine. However, intracellular accumulation of fluoxetine was not significantly changed when fluoxetine was incubated with the breast cancer resistance protein (BCRP) inhibitor Ko143. Furthermore, in vivo experiments proved that corticosterone and prazosin significantly inhibited the brain-plasma ratio of fluoxetine at 5.5 h and 12 h, respectively. Conclusion: OCTs might play a significant role in the transport of fluoxetine across the BBB. In addition, P-gp, BCRP, and MRPs seemed not to mediate the efflux transport of fluoxetine.

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