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OCT2 (SLC22A2)

Molecular structure and Tissue distribution
The polyspecific cation transporter OCT2 has a more restricted expression pattern than OCT1 or OCT3. Similar to OCT1, OCT2 is expressed in epithelial cells and neurons. OCT2 is most strongly expressed in kidney but it is also expressed in lung, skin, brain and choroid plexus. In human proximal tubules OCT2 has been localized to all three segments whereas in rat kidney OCT2 is confined to the S2 and S3 segments. In the proximal tubule, OCT2 is located in the basolateral membrane whereas in trachea and bronchi OCT2 has been localized to the luminal membrane of the epithelial cells.

Interaction of OCT2 with endogenous compounds and drugs.
Human OCT2 translocates several cations that are also transported by hOCT1. For example hOCT2 translocates MPP, TEA, quinine, and metformin with similar Km values  as hOCT1 whereas it translocates acetylcholine with an about 4-fold lower Km value. Uptake by hOCT2 has also been demonstrated for choline, the neurotransmitters dopamine, norepinephrine, epinephrine, serotonin, histamine, agmatine, for the glutamate receptor antagonists amantadine and memantine, for the histamine H2 receptor antagonists cimetidine, famotidine and ranitidine, for the cytostatic cisplatin, and for the antihypertensive drug debrisoquine. Transport by hOCT2 has been described for more cations compared to hOCT1 and hOCT3 because OCT2 exhibits high expression in oocytes of Xenopus laevis and transport activity of nonreadioactively labelled compounds could be determined by electrical measurements.

Example for biomedical impact: The nephrotoxicity and ototoxicity of cisplatin is decreased after inhibition of OCT2.

Figure 1 Concentration dependent OCT2 mediated MPP uptake Figure 2 Inhibition of OCT2 mediated MPP uptake by decynium22

 

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3rd German Pharm-Tox Summit
Göttingen, Germany
26 February - 1 March 2018


Pharmaforum
Saarbrücken, Germany
8 March 2018

 

AAPS Workshop
Virginia, USA
16 - 18 April 2018

 

20th Barrier- and
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Bad Herrenalb, Germany
7 - 9 May 2018

Greifswalder Transporttage 2018
Greifswald, Germany
7 - 9 September 2018

 


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