Molecular mechanisms of organic cation transport in OCT2-expressing Xenopus oocytes.

Article Details

Citation

Okuda M, Urakami Y, Saito H, Inui K

Molecular mechanisms of organic cation transport in OCT2-expressing Xenopus oocytes.

Biochim Biophys Acta. 1999 Mar 4;1417(2):224-31.

PubMed ID
10082798 [ View in PubMed
]
Abstract

The molecular mechanisms of organic cation transport by rat OCT2 was examined in the Xenopus oocyte expression system. When extracellular Na+ ions were replaced with K+ ions, uptake of tetraethylammonium (TEA) by OCT2-expressing oocytes was decreased, suggesting that TEA uptake by OCT2 is dependent on membrane potential. Kinetic analysis revealed that the decreased TEA uptake by ion substitution was caused at least in part by decreased substrate affinity. Acidification of extracellular buffer resulted in decreased uptake of TEA, whereas TEA efflux from OCT1- and OCT2-expressing oocytes was not stimulated by inward proton gradient, in consistent with basolateral organic cation transport in the kidney. Inhibition of TEA uptake by various organic cations revealed that apparent substrate spectrum of OCT2 was similar with that of OCT1. However, the affinity of procainamide to OCT1 was higher than that to OCT2. Uptake of 1-methyl-4-phenylpyridinium was stimulated by OCT2 as well as OCT1, but uptake of levofloxacin, a zwitterion, was not stimulated by both OCTs. These results suggest that OCT2 is a multispecific organic cation transporter with the characteristics comparable to those of the basolateral organic cation transporter in the kidney.

DrugBank Data that Cites this Article

Drug Transporters
DrugTransporterKindOrganismPharmacological ActionActions
CholineSolute carrier family 22 member 2ProteinHumans
Unknown
Substrate
Inhibitor
Details
Choline salicylateSolute carrier family 22 member 1ProteinHumans
Unknown
Substrate
Inhibitor
Details
Choline salicylateSolute carrier family 22 member 2ProteinHumans
Unknown
Substrate
Inhibitor
Details
CimetidineSolute carrier family 22 member 2ProteinHumans
Unknown
Substrate
Inhibitor
Details
NicotineSolute carrier family 22 member 2ProteinHumans
Unknown
Inhibitor
Details