Luminal transport system for choline+ in relation to the other organic cation transport systems in the rat proximal tubule

1996 ◽  
Vol 432 (3) ◽  
pp. 471-485 ◽  
Author(s):  
Karl J. Ullrich ◽  
Gerhard Rumrich
Keyword(s):  
Proximal Tubule ◽  
Transport System ◽  
Organic Cation ◽  
Cation Transport ◽  
The Other ◽  
Transport Systems ◽  
Organic Cation Transport ◽  
Rat Proximal Tubule

Amiloride as a probe substrate for investigation of organic cation transport system

2019 ◽  
Vol 34 (1) ◽  
pp. S73
Author(s):  
Chisa Kaneko ◽  
Tatsuya Kawasaki ◽  
Ryosuke Nakanishi ◽  
Yuichi Uwai ◽  
Tomohiro Nabekura
Keyword(s):  
Transport System ◽  
Organic Cation ◽  
Cation Transport ◽  
Organic Cation Transport

Molecular cloning of rabbit organic cation transporter rbOCT2 and functional comparisons with rbOCT1

2002 ◽  
Vol 283 (1) ◽  
pp. F124-F133 ◽  
Author(s):  
Xiaohong Zhang ◽  
Kristen K. Evans ◽  
Stephen H. Wright
Keyword(s):  
Proximal Tubule ◽  
Organic Cation ◽  
Organic Cation Transporter ◽  
Cation Transport ◽  
Rabbit Kidney ◽  
Organic Cation Transport ◽  
Major Contributor ◽  
Organic Cation Transporters ◽  
Functional Roles ◽  
Cation Uptake

Multiple organic cation transporters (OCTs) are present in rabbit kidney and may play different functional roles. We cloned rabbit OCT2 (rbOCT2) and compared its function with that of rabbit OCT1 (rbOCT1). In transiently transfected COS-7 cells, rbOCT1 and rbOCT2 mediated uptake of [3H]tetraethylammonium (TEA) with Ktvalues of 188 and 125 μM, respectively. n-Tetraalkylammonium compounds showed similar affinities for the two homologs, with IC50values for inhibition of OCT1- and OCT2-mediated [3H]TEA transport, respectively, of 4,538 and 1,395 μM for tetramethylammonium, 88.5 and 3.9 μM for tetrapropylammonium, 13.9 and 5.3 μM for tetrabutylammonium, and 8.8 and 7.6 μM for tetrapentylammonium. However, the transporters had very different affinities for cimetidine (CIM): IC50of 916 and 5.7 μM for rbOCT1 and rbOCT2, respectively. CIM inhibition of TEA uptake into single S2 segments of rabbit proximal tubule was used to estimate the contributions of OCT1 and OCT2 to basolateral organic cation uptake. The median IC50for CIM inhibition of TEA uptake was 12.3 μM, suggesting that OCT2 is the major contributor to basolateral organic cation transport in the S2 segment of proximal tubule in rabbit kidney.

scholarly journals Expression of renal organic cation transporter in Xenopus laevis oocytes

1992 ◽  
Vol 283 (2) ◽  
pp. 409-411 ◽  
Author(s):  
R Hori ◽  
M Hirai ◽  
T Katsura ◽  
M Takano ◽  
M Yasuhara ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Transport System ◽  
Organic Cation ◽  
Expression System ◽  
Fold Increase ◽  
Organic Cation Transporter ◽  
Sucrose Density Gradient ◽  
Cation Transport ◽  
Organic Cation Transport ◽  
Xenopus Laevis Oocytes

The expression of the organic cation transport system of rat renal proximal tubules has been studied in Xenopus laevis oocytes injected with poly(A)+ RNA from the rat renal cortex. The effectiveness of the technique was confirmed by examining expression of the Na+/D-glucose co-transporter. Compared with water-injected and non-injected oocytes, the injection of total poly(A)+ RNA resulted in about a 3-fold increase in tetraethylammonium (TEA) uptake activity. TEA uptake by poly(A)(+)-RNA-injected oocytes was time-dependent and was inhibited by cimetidine and HgCl2, but not by p-aminohippurate. After size-fractionation on a sucrose density gradient, a 1.4-2.4 kb poly(A)+ RNA fragment was identified that expressed the organic cation transport system in oocytes. These results demonstrate that the renal organic cation transporter was expressed in oocytes and that this expression system can provide an effective assay procedure for cloning of the organic cation transporter.

Organic cation transport in human renal brush-border membrane vesicles

1991 ◽  
Vol 261 (3) ◽  
pp. F443-F451 ◽  
Author(s):  
R. J. Ott ◽  
A. C. Hui ◽  
G. Yuan ◽  
K. M. Giacomini
Keyword(s):  
Proximal Tubule ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Organic Cation ◽  
Membrane Vesicles ◽  
Cation Transport ◽  
Brush Border Membrane Vesicles ◽  
Organic Cations ◽  
Organic Cation Transport ◽  
Renal Brush Border Membrane

The renal proximal tubule is responsible for the active elimination of organic cations. Studies in brush-border membrane vesicles (BBMV) suggest that active organic cation transport is mediated by an organic cation-proton antiporter. The goals of this study were to determine whether this transporter is expressed in human kidney and to elucidate its characteristics. Transport of the organic cations N1-[3H]methylnicotinamide (NMN) and [14C]tetraethylammonium (TEA) was determined by rapid filtration in BBMV of donor human kidneys. The uptake of NMN and TEA was driven against a concentration gradient by an outwardly directed proton gradient. NMN uptake was inhibited by the organic cations TEA, NMN, quinine, and cimetidine, but was not affected by p-aminohippuric acid, cephalexin, and polyamines. The electroneutral transport of NMN was characterized by a Km of 0.44 +/- 0.07 mM and a Vmax of 24.4 +/- 15.2 pmol.mg protein-1.s-1. The rate of proton efflux from BBMV increased in the presence of an inwardly directed TEA gradient. Preloading BBMV with NMN or TEA trans-stimulated the initial rate of uptake of TEA. Therefore the human proximal tubule expresses an organic cation-proton antiporter in the brush-border membrane. The antiporter is similar to that described in other mammalian species but shows some differences in its transport characteristics.

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