Molecular mechanisms of organic cation transport in OCT2-expressing Xenopus oocytes
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.
Read the paper
Related studies
- Ferulic acid regulates the AKT/GSK-3β/CRMP-2 signaling pathway in a middle cerebral artery occlusion animal model
- Novel Pharmacokinetic/Pharmacodynamic Parameters Quantify the Exposure–Effect Relationship of Levofloxacin against Fluoroquinolone-Resistant Escherichia coli
- Photochemical behavior of levofloxacin
- Correlation Between Dissolution Profiles of Salt-Form Drugs in Biorelevant Bicarbonate Buffer and Oral Drug Absorption: Importance of Dose/ Fluid Volume Ratio
- Evaluation of the synergistic potential and mechanisms of action for de novo designed cationic antimicrobial peptides
- Synthesis of [11C]levofloxacin
Go deeper in Evidence Hub
Evidence Hub adds a study data sheet (design, sample size, evidence level, key numbers), an AI summary and a chat grounded in the paper's text.