Abstract
Purpose. This study was performed to determine the detailed mRNA distribution of organic cation transporters, rOCT1 and rOCT2, along the rat nephron and to distinguish the substrate affinities of these transporters.
Methods. The distributions of rOCT1 and rOCT2 mRNA were determined by reverse transcriptase polymerase chain reaction analysis of microdissected nephron segments. Using MDCK cells transfected with rOCT1 or rOCT2 cDNA, the inhibitory effects of various compounds on the uptake of [14C]tetraethylammonium were assessed.
Results. rOCT1 mRNA was detected primarily in the superficial and juxtamedullary proximal convoluted tubules, whereas rOCT2 mRNA was detected widely in the superficial and juxtamedullary proximal straight and convoluted tubules, medullary thick ascending limbs, distal convoluted tubule, and cortical collecting duct. The IC50 values for cationic drugs and endogenous cations on [14C]tetraethylammonium uptake across the basolateral membranes in the transfectants indicated that rOCT1 and rOCT2 had similar inhibitor specificity for many compounds but showed moderate differences in the specificity for several compounds, such as 1-methyl-4-phenylpyridinium, dopamine, disopyramide, and chlorpheniramine.
Conclusions. rOCT1 and rOCT2 possess similar but not identical multispecificities for various compounds with distinct distributions along the nephron, indicating that the two transporters share physiologic and pharmacologic roles in the renal handling of cationic compounds.
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REFERENCES
J. B. Pritchard and D. S. Miller. Mechanisms mediating renal secretion of organic anions and cations. Physiol. Rev. 73:765-796 (1993).
K. J. Ullrich. Specificity of transporters for ‘organic anion and organic cation’ in the kidney. Biochim. Biophys. Acta 1197:45-62 (1994).
H. Koepsell. Organic cation transporters in intestine, kidney, liver, and brain. Annu. Rev. Physiol. 60:243-266 (1998).
K. Inui, S. Masuda, and H. Saito. Cellular and molecular aspects of drug transport in the kidney. Kidney Int. 58:944-958 (2000).
D. Gründemann, V. Gorboulev, S. Gambaryan, M. Veyhl, and H. Koepsell. Drug excretion mediated by a new prototype of polyspecific transporter. Nature 372:549-552 (1994).
M. Okuda, H. Saito, Y. Urakami, M. Takano, and K. Inui. cDNA cloning and functional expression of a novel rat kidney organic cation transporter, OCT2. Biochem. Biophys. Res Commun. 224: 500-507 (1996).
R. Kekuda, P. D. Prasad, X. Wu, H. Wang, Y.-J. Fei, F. H. Leibach, and V. Ganapathy. Cloning and functional characterization of a potential-sensitive, polyspecific organic cation transporter (OCT3) most abundantly expressed in placenta. J. Biol. Chem. 273:15971-15979 (1998).
A. E. Busch, U. Karbach, D. Miska, V. Gorboulev, A. Akhoundova, C. Volk, P. Arndt, J. C. Ulzheimer, M. S. Sonders, C. Baumann, S. Waldegger, F. Lang, and H. Koepsell. Human neurons express the polyspecific cation transporter hOCT2, which translocates monoamine neurotrasmitters, amantadine, and memantine. Mol. Pharmacol. 54:342-352 (1998).
M. Okuda, Y. Urakami, H. Saito, and K. Inui. Molecular mechanisms of organic cation transport in OCT2-expressing Xenopus oocytes. Biochim. Biophys. Acta. 1417:224-231 (1999).
A. E. Busch, S. Quester, J. C. Ulzheimer, S. Waldegger, V. Gorboulev, P. Arndt, F. Lang, and H. Koepsell. Electrogenic properties and substrate specificity of the polyspecific rat cation transporter rOCT1. J. Biol. Chem. 271:32599-32604 (1996).
G. Nagel, C. Volk, T. Friedrich, J. C. Ulzheimer, E. Bamberg, and H. Koepsell. A reevaluation of substrate specificity of the rat cation transporter rOCT1. J. Biol. Chem. 272:31953-31956 (1997).
F. Martel, T. Vetter, H. Russ, D. Gründemann, I. Azevedo, H. Koepsell, and E. Shömig. Transport of small organic cations in the rat liver: the role of the organic cation transporter OCT1. Naunyn-Schmiedeberg's Arch. Pharmacol. 354:320-326 (1996).
U. Karbach, J. Kricke, F. Meyer-Wentrup, V. Gorboulev, C. Volk, D. Loffing-Cueni, B. Kaissling, S. Bachmann, and H. Koepsell. Localization of organic cation transporters OCT1 and OCT2 in rat kidney. Am. J. Physiol. 279:F679-F687 (2000).
M. Sugawara-Yokoo, Y. Urakami, H. Koyama, K. Fujikura, S. Masuda, H. Saito, T. Naruse, K. Inui, and K. Takata. Differential localization of organic cation transporters rOCT1 and rOCT2 in the basolateral membrane of rat kidney proximal tubules. Histochem. Cell Biol. 114:175-180 (2000).
V. Gorboulev, J. C. Ulzheimer, A. Akhoundova, I. Ulzheimer-Teuber, U. Karbach, S. Quester, C. Baumann, F. Lang, A. E. Busch, and H. Koepsell. Cloning and characterization of two human polyspecific organic cation transporters. DNA Cell Biol. 16: 871-881 (1997).
L. Zhang, M. J. Dresser, A. T. Gray, S. C. Yost, S. Terashita, and K. M. Giacomini. Cloning and functional expression of a human liver organic cation transporter. Mol. Pharmacol. 51:913-921 (1997).
D. Gründemann, S. Köster, N. Kiefer, T. Breidert, M. Engelhardt, F. Spitzenberger, N. Obermüller, and E. Schömig. Transport of monoamine transmitters by the organic cation transporter type 2, OCT2. J. Biol. Chem. 273:30915-30920 (1998).
L. Zhang, M. E. Schaner, and K. M. Giacomini. Functional characterization of an organic cation transporter (hOCT1) in a transiently transfected human cell line (HeLa). J. Pharmacol. Exp. Ther. 286:354-361 (1998).
Y. Urakami, M. Okuda, S. Masuda, H. Saito, and K. Inui. Functional characteristics and membrane localization of rat multispecific organic cation transporters, OCT1 and OCT2, mediating tubular secretion of cationic drugs. J. Pharmacol. Exp. Ther. 287: 800-805 (1998).
Y. Urakami, M. Okuda, S. Saito, and K. Inui. Hormonal regulation of organic cation transporter OCT2 expression in rat kidney. FEBS Lett. 473:173-176 (2000).
S. Masuda, H. Saito, H, Nonoguchi, K. Tomita, and K. Inui. mRNA distribution and membrane localization of the OAT-K1 organic anion transporter in rat renal tubules. FEBS Lett. 407: 127-131 (1997).
M. M. Bradford. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal. Biochem. 72:248-254 (1976).
D. P. O'Connell, S. J. Botkin, S. I. Ramos, D. R. Sibley, M. A. Ariano, R. A. Felder, and R. M. Carey. Localization of dopamine D1A receptor protein in rat kidneys. Am. J. Physiol. 268:F1185-F1197 (1995).
F. Ibarra, A. Aperia, L. Svensson, A. Eklöf, and P. Greengard. Bidirectional regulation of Na−, K+-ATPase activity by dopamine and an α-adrenergic agonist. Proc. Natl. Acad. Sci. USA 90:21-24 (1993).
H. Koepsell, V. Gorboulev, and P. Arndt. Molecular pharmacology of organic cation transporters in kidney. J. Membr. Biol. 167:103-117 (1999).
W. H. Dantzler, S. H. Wright, V. Chatsudthipong, and O. H. Brokl. Basolateral tetraethylammonium transport in intact tubules: specificity and trans-stimulation. Am. J. Physiol. 261:F386-F392 (1991).
L. Zhang, W. Gorset, M. J. Dresser, and K. M. Giacomini. The interaction of n-tetraalkylammonium compounds with a human organic cation transporter, hOCT1. J. Pharmacol. Exp. Ther. 288: 1192-1198 (1999).
A. E. Busch, S. Quester, J. C. Ulzheimer, V. Gorboulev, A. Akhoundova, S. Waldegger, F. Lang, and H. Koepsell. Monoamine neurotransmitter transport mediated by the polyspecific cation transporter rOCT1. FEBS Lett. 395:153-156 (1996).
D. Gründemann, G. Liebich, N. Kiefer, S. Köster, and E, Schömig. Selective substrates for non-neuronal monoamine transporters. Mol. Pharmacol. 56:1-10 (1999).
T. Budimann, E. Bamberg, H. Kopsell, and Nagel, G. Mechanism of electrogenic cation transport by the cloned organic cation transporter 2 from rat. J. Biol. Chem 257:29413-29420 (2000).
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Urakami, Y., Okuda, M., Masuda, S. et al. Distinct Characteristics of Organic Cation Transporters, OCT1 and OCT2, in the Basolateral Membrane of Renal Tubules. Pharm Res 18, 1528–1534 (2001). https://doi.org/10.1023/A:1013070128668
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DOI: https://doi.org/10.1023/A:1013070128668