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OCT1 (SLC22A1)

Molecular structure and Tissue distribution
OCT1 exhibits a broad tissue distribution. It is expressed in epithelial cells, some neurons, basophilic granulocytes and lymphocytes. In humans, it is most strongly expressed in the liver whereas in rodents, OCT1 is strongly expressed in liver, kidney and small intestine. In human and rat liver OCT1 has been localized to the sinusoidal membrane of hepatocytes and in mouse small intestine to the basolateral membrane of enterocytes. In rat kidney, OCT1 has been detected in the basolateral membrane of convoluted proximal tubles whereas in human kidney OCT1 has been localized to the luminal membrane of proximal and distal tubules. In the trachea and bronchi of human and rodents, OCT1 has is located in the luminal membrane of the epithelial cells.

Interaction of OCT1 with endogenous compounds and drugs.
Compounds that are transported by human hOCT1 include the model cations 1-methyl-4-phenyl-pyridinium (MPP) and tetraethylammonium (TEA), the endo­genous compounds choline, acetylcholine and agmatine. Drugs transported by human OCT1 are quinidine, quinine, acyclovir, ganciclovir, metformin and lamuvidine. For several drugs which inhibit OCTs but are not transported or have not been tested for transport, a higher affinity to hOCT1 was observed compared to hOCT2 or hOCT3. These include the glutamate receptor antagonist phencyclidine, the antagonists of histamine receptors diphenylhydramine and ranitidine, the antagonist of the muscarinic acetylcholine receptor atropine, and the antidepressant desipramine.

Example for biomedical impact: Diabetic patients with defect-mutations in OCT1 do not respond to treatment with metformin because metformin does not enter the hepatocytes and is excreted more rapidly in the kidney.

Figure 1 Concentration dependent OCT1 mediated MPP uptake Figure 2 Inhibition of OCT1 mediated MPP uptake by decynium22




New validated products:

  • mNtcp
  • mOct1


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

Saarbrücken, Germany
8 March 2018


AAPS Workshop
Virginia, USA
16 - 18 April 2018


20th Barrier- and

Bad Herrenalb, Germany
7 - 9 May 2018

Greifswalder Transporttage 2018
Greifswald, Germany
7 - 9 September 2018


Guidance for Industry (FDA and EMA)