Transport of monoamine transmitters by the organic cation transporter type 2, OCT2.
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Grundemann D, Koster S, Kiefer N, Breidert T, Engelhardt M, Spitzenberger F, Obermuller N, Schomig E
Transport of monoamine transmitters by the organic cation transporter type 2, OCT2.
J Biol Chem. 1998 Nov 20;273(47):30915-20.
- PubMed ID
- 9812985 [ View in PubMed]
- Abstract
The recently cloned apical renal transport system for organic cations (OCT2) exists in dopamine-rich tissues such as kidney and some brain areas (Grundemann, D., Babin-Ebell, J., Martel, F., Ording, N., Schmidt, A., and Schomig, E. (1997) J. Biol. Chem. 272, 10408-10413). The study at hand was performed to answer the question of whether OCT2 accepts dopamine and other monoamine transmitters as substrate. 293 cells were stably transfected with the OCT2r cDNA resulting in the 293OCT2r cell line. Expression of OCT2r in 293 cells induces specific transport of tritiated dopamine, noradrenaline, adrenaline, and 5-hydroxytryptamine (5-HT). Initial rates of specific 3H-dopamine, 3H-noradrenaline, 3H-adrenaline, and 3H-5-HT transport were saturable, the Km values being 2.1, 4.4, 1.9, and 3.6 mmol/liter. The corresponding Vmax values were 3.9, 1.0, 0. 59, and 2.5 nmol min-1.mg of protein-1, respectively. 1, 1'-diisopropyl-2,4'-cyanine (disprocynium24), a known inhibitor of OCT2 with a potent eukaliuric diuretic activity, inhibited 3H-dopamine uptake into 293OCT2r cells with an Ki of 5.1 (2.6, 9.9) nmol/liter. In situ hybridization reveals that, within the kidney, the OCT2r mRNA is restricted to the outer medulla and deep portions of the medullary rays indicating selective expression in the S3 segment of the proximal tubule. These findings open the possibility that OCT2r plays a role in renal dopamine handling.
DrugBank Data that Cites this Article
- Drug Transporters
Drug Transporter Kind Organism Pharmacological Action Actions Cocaine Sodium-dependent dopamine transporter Protein Humans NoInhibitorDetails Cocaine Solute carrier family 22 member 2 Protein Humans UnknownInhibitorDetails Dopamine Solute carrier family 22 member 2 Protein Humans UnknownSubstrateInhibitorDetails Epinephrine Solute carrier family 22 member 2 Protein Humans UnknownSubstrateDetails Norepinephrine Solute carrier family 22 member 2 Protein Humans UnknownSubstrateInhibitorDetails Reserpine Solute carrier family 22 member 2 Protein Humans UnknownSubstrateDetails Serotonin Solute carrier family 22 member 2 Protein Humans UnknownNot Available Details