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.

Expression of Human Polyspecific Renal Organic Cation Transport Activity in Xenopus laevis Oocytes

1997 ◽  
Vol 86 (6) ◽  
pp. 753-755 ◽  
Author(s):  
Joanne K. Chun ◽  
Micheline Piquette-Miller ◽  
Lei Zhang ◽  
Kathleen M. Giacomini
Keyword(s):  
Xenopus Laevis ◽  
Organic Cation ◽  
Cation Transport ◽  
Organic Cation Transport ◽  
Xenopus Laevis Oocytes ◽  
Transport Activity

scholarly journals Expression of Na+-independent amino acid transport in Xenopus laevis oocytes by injection of rabbit kidney cortex mRNA

1992 ◽  
Vol 281 (3) ◽  
pp. 717-723 ◽  
Author(s):  
J Bertran ◽  
A Werner ◽  
G Stange ◽  
D Markovich ◽  
J Biber ◽  
...  
Keyword(s):  
Amino Acids ◽  
Xenopus Laevis ◽  
Transport System ◽  
Sucrose Density Gradient ◽  
Rabbit Kidney ◽  
Kidney Cortex ◽  
Xenopus Laevis Oocytes ◽  
Transport Pathways ◽  
Arginine Uptake ◽  
Dose Dependent Increase

Poly(A)+ mRNA was isolated from rabbit kidney cortex and injected into Xenopus laevis oocytes. Injection of mRNA resulted in a time- and dose-dependent increase in Na(+)-independent uptake of L-[3H]alanine and L-[3H]arginine. L-Alanine uptake was stimulated about 3-fold and L-arginine uptake was stimulated about 8-fold after injection of mRNA (25-50 ng, after 3-6 days) as compared with water-injected oocytes. T.I.C. of oocyte extracts suggested that the increased uptake actually represented an increase in the oocyte content of labelled L-alanine and L-arginine. The expressed L-alanine uptake, obtained by subtracting the uptake in water-injected oocytes from that in mRNA-injected oocytes, showed saturability and was inhibited completely by 2-aminobicyclo[2,2,1]heptane-2-carboxylic acid (BCH) and L-arginine. The expressed L-arginine uptake in mRNA-injected oocytes also showed saturability, being completely inhibited by L-dibasic amino acids) and partially inhibited by BCH. Expression of both L-alanine and L-arginine uptake showed clear cis-inhibition by cationic (e.g. L-arginine) and neutral (e.g. L-leucine) amino acids. In all, this points to the expression of a Na(+)-independent transport system with broad specificity (i.e. b degree, (+)-like). In addition, part of the expressed uptake of L-arginine could be due to a system y(+)-like transporter. After size fractionation through a sucrose density gradient, the mRNA species encoding these increased transport activities (Na(+)-independent transport of L-alanine and of L-arginine) were found in fractions of an average mRNA chain-length of 1.8-2.4 kb. On the basis of these results, we conclude that Na(+)-independent transport system(s) for L-alanine and L-arginine from rabbit renal cortical tissues, most likely proximal tubules, are expressed in Xenopus laevis oocytes. These observations may represent the first steps towards expression and cloning of these transport pathways.

Peritubular organic cation transport in isolated rabbit proximal tubules

1994 ◽  
Vol 266 (3) ◽  
pp. F450-F458 ◽  
Author(s):  
C. E. Groves ◽  
K. K. Evans ◽  
W. H. Dantzler ◽  
S. H. Wright
Keyword(s):  
Organic Cation ◽  
High Capacity ◽  
Organic Cation Transporter ◽  
Cation Transport ◽  
Proximal Tubules ◽  
Organic Cation Transport ◽  
Inhibitory Potency ◽  
Renal Proximal Tubules ◽  
Michaelis Constants ◽  
Maximal Capacity

The physiological characteristics of peritubular organic cation transport were examined by measuring the transport of the organic cation tetraethylammonium (TEA) in rabbit renal proximal tubule suspensions and isolated nonperfused rabbit renal proximal tubules. Peritubular organic cation transport in both single S2 segments and suspensions of isolated renal proximal tubules was found to be a high-capacity, high-affinity, carrier-mediated process. For tubule suspensions, the maximal capacity of the carrier for TEA (Jmax) and the concentration of TEA at 1/2 Jmax (Kt) (1.49 +/- 0.21 nmol.min-1.mg dry wt-1 and 131 +/- 16 microM, respectively), did not differ significantly from those measured in single S2 segments (Jmax, 1.16 +/- 0.075 nmol.min-1.mg dry wt-1; Kt, 108 +/- 10 microM). In addition, the pattern of inhibition of peritubular TEA transport by long-chain n-tetraalkylammonium compounds (n = 1-5) was both qualitatively and quantitatively similar in single S2 segments and tubule suspensions, exhibiting an increase in inhibitory potency with increasing alkyl chain length. For example, in tubule suspensions, apparent Michaelis constants for inhibition of TEA uptake ranged from 1.3 mM for tetramethylammonium (TMA) to 0.8 microM for tetrapentylammonium (TPeA). To determine whether these compounds were substrates for the peritubular organic cation transporter, their effect on the efflux of [14C]TEA from tubule suspensions was examined. A concentration of 0.5 mM of the short-chain tetraalkyls TMA or TEA increased the efflux of [14C]TEA (i.e., trans-stimulated) from tubules in suspension. The longer-chain tetraalkyls tetrapropylammonium, tetrabutylammonium, and TPeA all decreased the efflux of [14C]TEA from tubules in suspension; TPeA completely blocked efflux.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Sign in / Sign up

Export Citation Format

Share Document