scholarly journals Transport Mechanisms of Enoxacin in Rat Brush-Border Membrane of Renal Cortex: Interaction with Organic Cation Transport System and Ionic Diffusion Potential Dependent Uptake.

1995 ◽  
Vol 18 (2) ◽  
pp. 342-346 ◽  
Author(s):  
Takeshi HIRANO ◽  
Ken ISEKI ◽  
Mitsuru SUGAWARA ◽  
Shozo MIYAZAKI ◽  
Masahiko TAKADA ◽  
...  
Keyword(s):  
Transport System ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Organic Cation ◽  
Renal Cortex ◽  
Cation Transport ◽  
Diffusion Potential ◽  
Organic Cation Transport ◽  
Ionic Diffusion ◽  
Transport Mechanisms

Trans-stimulation effect on H(+)-organic cation antiport system in rat renal brush-border membranes

1991 ◽  
Vol 261 (5) ◽  
pp. F774-F778 ◽  
Author(s):  
T. Katsura ◽  
H. Maegawa ◽  
Y. Tomita ◽  
M. Takano ◽  
K. Inui ◽  
...  
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Organic Cation ◽  
Membrane Vesicles ◽  
Cation Transport ◽  
Organic Cation Transport ◽  
Renal Brush Border Membrane ◽  
Carbonyl Cyanide ◽  
Renal Brush Border Membranes ◽  
Renal Brush Border

Trans-stimulation effect on tetraethylammonium (an organic cation) transport was examined in rat renal brush-border membrane vesicles. The uptake of [14C]tetraethylammonium at pH 6.0-8.5 was stimulated by preloading the membrane vesicles with unlabeled tetraethylammonium. When the uptake was measured in preloaded membrane vesicles in the presence of carbonyl cyanide p-trifluoromethoxyphenylhydrazone, stimulation was observed at high pH but not at low pH. These results suggest that the mechanisms of the trans-stimulation effect on organic cation transport are different depending on the pH. When pH is low, the trans-stimulation is due to generation of an outward H+ gradient, which in turn stimulates [14C]tetraethylammonium uptake by H(+)-[14C]tetraethylammonium exchange. In contrast, when pH is high, the stimulation is due to direct exchange of tetraethylammonium for [14C]tetraethylammonium.

Essential tyrosine residues in transport of organic cations in renal BBMV

1987 ◽  
Vol 252 (6) ◽  
pp. F1065-F1072
Author(s):  
P. H. Hsyu ◽  
K. M. Giacomini
Keyword(s):  
Brush Border Membrane ◽  
Organic Cation ◽  
Renal Cortex ◽  
Initial Rate ◽  
Membrane Vesicles ◽  
Cation Transport ◽  
Time Dependent ◽  
Organic Cations ◽  
Organic Cation Transport ◽  
Tyrosine Residues

The effects of tyrosine modifying agents on organic cation transport in brush-border membrane vesicles prepared from rabbit renal cortex were investigated. Treatment of membranes with 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) and N-acetylimidazole reduced the initial rate of transport of N'-methylnicotinamide (NMN) significantly. The inactivation of NMN transport by NBD-Cl was concentration and time dependent. The maximal transport rate (Tmax) of NMN transport (18.4 +/- 4.3 pmol X s-1 X mg protein-1) in vesicles treated with NBD-Cl (0.15 mM) was reduced to 56% of the Tmax in the control vesicles (32.6 +/- 8.4 pmol X s-1 X mg protein-1, P less than 0.05); whereas the Km was not changed. Treatment with 2-mercaptoethanol reversed the reaction of NBD-Cl with sulfhydryl groups but did not significantly change the transport of NMN in the control or the treated membranes, suggesting that tyrosine but not sulfhydryl residues are involved. The overshoot of NMN uptake in the presence of a proton gradient was 3.38 +/- 0.67 pmol/mg protein in the untreated membranes and was reduced to 2.05 +/- 0.71 pmol/mg protein in the NBD-Cl-treated membranes (P less than 0.05). Studies with the pH-sensitive dye, acridine orange, demonstrated that NBD-Cl-treated vesicles were not leakier with respect to protons, suggesting that NBD-Cl may have specifically affected the organic cation-proton transporter.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

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

Renal brush-border chloride transport mechanisms characterized using a fluorescent indicator

1988 ◽  
Vol 254 (1) ◽  
pp. F114-F120 ◽  
Author(s):  
P. Y. Chen ◽  
N. P. Illsley ◽  
A. S. Verkman
Keyword(s):  
Brush Border ◽  
Time Course ◽  
Brush Border Membrane ◽  
Channel Blocker ◽  
Renal Cortex ◽  
Chloride Transport ◽  
Membrane Vesicles ◽  
Transport Mechanisms ◽  
Fluorescent Indicator ◽  
Cl Transport

Cl transport mechanisms in brush-border membrane vesicles (BBMV) isolated from rabbit renal cortex were characterized using the Cl-sensitive fluorescent indicator 6-methoxy-N-[3-sulfopropyl]quinolinium (SPQ). In control experiments using 36Cl, SPQ did not itself alter rates for Cl transport. Cl fluxes (JCl) in nanomoles per second per milligram vesicle protein in response to gradients of Cl and other ions were calculated from the SPQ fluorescence time course, fluorescence vs. [Cl] calibration, and BBMV glucose space (microliter/mg protein). For a 50 mM inwardly directed Cl gradient in BBMV (voltage and pH clamped) JCl was 0.26 +/- 0.01 nmol.s-1.mg-1 (mean +/- SD, 4 vesicle preparations). JCl was not altered by a 50 mM inwardly directed Na gradient (0.25 +/- 0.01 nmol.s-1.mg-1) but increased to 0.52 +/- 0.04 nmol.s-1.mg-1 when driven by a 1.5 pH unit inwardly directed proton gradient. The pH driven increase in JCl was blocked by H2DIDS (100 microM, JCl = 0.38 +/- 0.02 nmol.s-1.mg-1). In the absence of a gradient, JCl increased by 64 +/- 4% in the presence of 1 mM formate on both sides of the membrane; the increase was blocked by H2DIDS. JCl increased to 0.38 +/- 0.02 nmol.s-1.mg-1 for a 60-mV K valinomycin diffusion potential (internal positive); the increase was inhibited by the Cl channel blocker diphenylamine-2-carboxylate (DPC, 100 microM, JCl = 0.26 +/- 0.03 nmol.s-1.mg-1). Br and I transport was also blocked by DPC.(ABSTRACT TRUNCATED AT 250 WORDS)

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