Indirect Na+ dependency of urate and p-aminohippurate transport in pig basolateral membrane vesicles

1991 ◽  
Vol 261 (2) ◽  
pp. F265-F272 ◽  
Author(s):  
D. Werner ◽  
F. Roch-Ramel
Keyword(s):  
Proximal Tubule ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Organic Anions ◽  
Transport Processes ◽  
Basolateral Membrane Vesicles ◽  
Pig Kidney ◽  
Different Characteristics ◽  
Stimulation Of

Membrane vesicles were used to study the basolateral transport of urate and p-aminohippurate (PAH) in the proximal tubule of the pig kidney. Consistent with a cooperation between a Na(+)-2-oxoglutarate cotransporter and a 2-oxoglutarate-urate or a 2-oxoglutarate-PAH exchanger, urate and PAH uptakes were stimulated in presence of extravesicular 2-oxoglutarate when an inwardly directed Na+ gradient was applied. Both transports exhibited, however, different characteristics. The optimal 2-oxoglutarate concentration for stimulating uptakes was 10 microM for PAH and 150 microM for urate. Extravesicular chloride was required to observe a stimulation of PAH uptake but not of urate uptake. Transports of both PAH and urate exhibited different affinity sequences for various organic anions. Stimulated PAH uptake was inhibited by probenecid greater than cold PAH greater than urate = pyrazinoate greater than lactate, whereas stimulated urate uptake was inhibited by probenecid greater than cold urate greater than PAH and not by pyrazinoate or lactate. These results are consistent with independent transport processes for urate and PAH in pig basolateral membrane vesicles, both being indirectly driven by an inwardly directed Na+ gradient.

Urate transport in the proximal tubule: in vivo and vesicle studies

1985 ◽  
Vol 249 (6) ◽  
pp. F789-F798 ◽  
Author(s):  
A. M. Kahn ◽  
E. J. Weinman
Keyword(s):  
Proximal Tubule ◽  
Brush Border ◽  
Anion Exchanger ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Transport Processes ◽  
Basolateral Membrane Vesicles ◽  
Urate Transport ◽  
Rat Proximal Tubule

The transport of urate in the mammalian nephron is largely confined to the proximal tubule. Depending on the species, net reabsorption or net secretion is observed. The rat, like the human and the mongrel dog, demonstrates net reabsorption of urate and has been the most extensively studied species. The unidirectional reabsorption and secretion of urate in the rat proximal tubule occur via a passive and presumably paracellular route and by a mediated transcellular route. The reabsorption of urate, and possibly its secretion, can occur against an electrochemical gradient. A variety of drugs and other compounds affect the reabsorption and secretion of urate. The effects of these agents depend on their site of application (luminal or blood), concentration, and occasionally their participation in transport processes that do not have affinity for urate. Recent studies with renal brush border and basolateral membrane vesicles from the rat and brush border vesicles from the dog have determined the mechanisms for urate transport across the luminal and antiluminal membranes of the proximal tubule cell. Brush border membrane vesicles contain an anion exchanger with affinity for urate, hydroxyl ion, bicarbonate, chloride, lactate, p-aminohippurate (PAH), and a variety of other organic anions. Basolateral membrane vesicles contain an anion exchanger with affinity for urate and chloride but not for PAH. Both membrane vesicle preparations also permit urate translocation by simple diffusion. A model for the transcellular reabsorption and secretion of urate in the rat proximal tubule is proposed. This model is based on the vesicle studies, and it can potentially explain the majority of urate transport data obtained with in vivo techniques.

ATP-dependent transport of organic anions into isolated basolateral membrane vesicles from rat intestine

2004 ◽  
Vol 287 (4) ◽  
pp. G749-G756 ◽  
Author(s):  
Takahiro Shoji ◽  
Hiroshi Suzuki ◽  
Hiroyuki Kusuhara ◽  
Yuka Watanabe ◽  
Shingo Sakamoto ◽  
...  
Keyword(s):  
Rank Order ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Organic Anions ◽  
Dependent Manner ◽  
Basolateral Membrane Vesicles ◽  
High K ◽  
17Β Estradiol ◽  
Dependent Transport ◽  
Estradiol 17Β

The mechanism for the cellular extrusion of organic anions across the intestinal basolateral membrane was examined using isolated membrane vesicles from rat jejunum, ileum, and colon. It was found that 17β-estradiol 17β-d-glucuronide (E217βG) is taken up in an ATP-dependent manner into the basolateral membrane vesicles (BLMVs) but not into the brush-border or microsomal counterparts. The ATP-dependent uptake of E217βG into BLMVs from jejunum and ileum was described by a single component with a Km value of 23.5 and 8.31 μM, respectively, whereas that into the BLMVs from colon was described by assuming the presence of high ( Km = 0.82 μM)- and low-affinity ( Km = 35.4 μM) components. Taurocholate, 6-hydroxy-5,7-dimethyl-2-methylamino-4-(3-pyridylmethyl) benzothiazole glucuronide and taurolithocholate sulfate, but not leukotriene C4, were significantly taken up by the BLMVs. In addition to such substrate specificity, the inhibitor sensitivity of the ATP-dependent transport in BLMVs was similar to that of rat multidrug resistance-associated protein 3 (Mrp3), which is located on the basolateral membrane of enterocytes. Together with the fact that the rank order of the extent of the expression of Mrp3 (jejunum < ileum << colon) is in parallel with that of the extent of the transport of ligands, these results suggest that the ATP-dependent uptake of organic anions into isolated intestinal BLMVs is at least partly mediated by Mrp3.

Calbindin-D9k stimulates the calcium pump in rat enterocyte basolateral membranes

1989 ◽  
Vol 256 (1) ◽  
pp. G124-G128 ◽  
Author(s):  
J. R. Walters
Keyword(s):  
Vitamin D ◽  
Specific Activity ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Calcium Pump ◽  
Basolateral Membrane Vesicles ◽  
Calbindin D9k ◽  
Uptake Rates ◽  
Micromolar Range ◽  
Stimulation Of

Calbindin-D9k, a vitamin D-dependent Ca2+-binding protein, is closely associated with the transcellular absorption of calcium by mammalian enterocytes. Studies were performed to determine whether physiological concentrations of calbindin-D9k altered Ca2+ transport by the ATP-dependent Ca2+ pump in rat duodenal basolateral membrane vesicles. In solutions where free Ca2+ was buffered by EGTA, only a small stimulation of Ca2+ uptake rates could be demonstrated, and it was likely that this was secondary to changes in free Ca2+ concentration. However, a threefold stimulation of uptake by 30 microM calbindin-D9k was found when EGTA-free solutions were used, and changes in free Ca2+ activity or 45Ca2+ specific activity were avoided. The affinity for Ca2+ was reduced in this system but appeared to be stimulated by either calbindin-D9k or EGTA. Other Ca2+-binding proteins that bind Ca2+ in the micromolar range were found to increase Ca2+ uptake in the absence of EGTA. These experiments suggest that one of the actions of calbindin-D9k is to stimulate the rate of extrusion of Ca2+ from the enterocyte by increasing Ca2+ transport by the Ca2+ pump.

Na+ gradient-dependent glycine uptake in basolateral membrane vesicles from the dog kidney

1985 ◽  
Vol 249 (3) ◽  
pp. F338-F345
Author(s):  
S. J. Schwab ◽  
M. R. Hammerman
Keyword(s):  
Amino Acids ◽  
Membrane Potential ◽  
Brush Border ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Transport Processes ◽  
Basolateral Membrane Vesicles ◽  
Glycine Uptake ◽  
Dog Kidney ◽  
Dependent Transport

The imposition of a Na+ gradient (extravesicular greater than intravesicular) stimulated the uptake of [3H]glycine measured over time in basolateral membrane vesicles from dog kidney over that measured in the presence of a choline+ gradient or measured under Na+-equilibrated conditions. Na+ gradient-dependent uptake of [3H]glycine was stimulated by an intravesicular-negative membrane potential. Efflux of [3H]glycine was enhanced by an intravesicular-positive membrane potential. Substrate velocity analysis of net Na+-dependent [3H]glycine uptake over the range of amino acid concentrations from 10 to 500 microM demonstrated a single saturable transport system with apparent Km = 84 microM and apparent Vmax = 143 pmol [3H]glycine X mg protein-1 X 15 s-1. Counterflow of [3H]glycine was demonstrated in the presence of Na+ when basolateral vesicles were preloaded with glycine but not with L-alanine or L-proline. These findings are consistent with carrier-mediated, electrogenic cotransport of Na+ and glycine in basolateral vesicles. Unlike the case for [3H]glycine, Na+ gradient-dependent uptake of neither L-[3H]alanine nor L-[3H]proline was observed in basolateral vesicles. Na+ gradient-dependent uptake of all three amino acids was demonstrated in brush border vesicles from the dog kidney. We conclude that variability exists between basolateral and brush border membranes in terms of the presence or absence of Na+-dependent transport systems for specific amino acids. This variability probably reflects differences between the functional significances of the Na+-dependent transport processes in the two membranes.

Proton-lactate co transport in basolateral membrane vesicles from rat jejunum

1996 ◽  
Vol 16 (6) ◽  
pp. 521-527
Author(s):  
Maria Novella Orsenigo ◽  
Marisa Tosco ◽  
Umberto Laforenza ◽  
Alide Faelli
Keyword(s):  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Rat Jejunum ◽  
Basolateral Membrane Vesicles ◽  
Strong Inhibition ◽  
Lactate Transport ◽  
Basolateral Membranes ◽  
Lactate Uptake ◽  
Stimulation Of

Proton-coupled lactate transport across the basolateral membrane of rat jejunal enterocyte was studied using well purified membrane vesicles. L-lactate uptake is stimulated by an inwardly directed H+ gradient; the effect of the pH difference is drastically reduced by FCCP and by pCMBS; unlabelled L-lactate causes a strong inhibition, whilst furosemide is uneffective. The H+ gradient-dependent stimulation of L-lactate uptake is significantly inhibited also by SCN−: this finding could explain results recently reported in the literature in which H+-lactate symport was not evidenced in basolateral membranes from rat jejunum.

scholarly journals l-tryptophan uptake by segment-specific membrane vesicles from the proximal tubule of rabbit kidney

1992 ◽  
Vol 286 (1) ◽  
pp. 103-110 ◽  
Author(s):  
H Jessen ◽  
M I Sheikh
Keyword(s):  
Proximal Tubule ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Rabbit Kidney ◽  
Basolateral Membrane Vesicles ◽  
Luminal Membrane ◽  
Transport Component ◽  
Pars Recta ◽  
Dependent Transport ◽  
Pars Convoluta

1. The mechanism of the renal transport of L-tryptophan by basolateral and luminal membrane vesicles prepared from either the pars convoluta or the pars recta of the rabbit proximal tubule was studied. The uptake of L-tryptophan by basolateral membrane vesicles from the pars convoluta was found to be an Na(+)-dependent transport event. The Na(+)-conditional influx of the amino acid was stimulated in the presence of an inwardly directed H+ gradient. Lowering the pH without an H+ gradient had no effect, indicating that L-tryptophan is co-transported with H+. 3. On the other hand, no transient accumulation of L-tryptophan was observed in the presence or absence of Na+ in basolateral membrane vesicles from the pars recta. 4. In luminal membrane vesicles from the pars recta, the transient Na(+)-dependent accumulation of L-tryptophan occurred via a dual transport system. In addition, an inwardly directed H+ gradient could drive the uphill transport of L-tryptophan into these vesicles in both the presence and the absence of an Na+ gradient. 5. By contrast, the uptake of L-tryptophan by luminal membrane vesicles from the pars convoluta was a strictly Na(+)-dependent and electrogenic transport process, mediated by a single transport component. 6. Investigation of the coupling ratio in luminal membrane vesicles suggested that 1 Na+:1 L-tryptophan are co-transported in the pars convoluta. In the pars recta, examination of the stoichiometry indicated that approx. 1 H+ and 2 Na+ (high affinity) or 1 Na+ (low affinity) are involved in the uptake of L-tryptophan.

Urate/α-ketoglutarate exchange in avian basolateral membrane vesicles

2002 ◽  
Vol 283 (4) ◽  
pp. C1144-C1154 ◽  
Author(s):  
Steven M. Grassl
Keyword(s):  
Proximal Tubule ◽  
Brush Border Membrane ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Basolateral Membrane Vesicles ◽  
Transport Pathways ◽  
Proximal Tubule Cells ◽  
Flux Measurements ◽  
Avian Kidney ◽  
Sufficient Magnitude

Membrane transport pathways for transcellular secretion of urate across the proximal tubule were investigated in avian kidney. The presence of coupled urate/α-ketoglutarate exchange was investigated in basolateral membrane vesicles (BLMV) by [14C]urate and [α-3H]ketoglutarate flux measurements. An inward Na gradient induced accumulation of α-ketoglutarate of sufficient magnitude to suggest a Na-dicarboxylate cotransporter. An inward Na gradient also induced concentrative accumulation of urate in the presence of α-ketoglutarate but not in its absence, suggesting urate/α-ketoglutarate exchange. α-Ketoglutarate-dependent stimulation of urate uptake was not observed in brush-border membrane vesicles. An outward urate gradient induced concentrative accumulation of α-ketoglutarate. α-Ketoglutarate-coupled urate uptake was specific for α-ketoglutarate, Cl dependent, and insensitive to membrane potential. α-Ketoglutarate-coupled urate uptake was inhibited by increasing p-aminohippurate (PAH) concentrations, and α-ketoglutarate-coupled PAH uptake was observed. α-Ketoglutarate-coupled PAH uptake was inhibited by increasing urate concentrations, and an outward urate gradient induced concentrative accumulation of PAH. These results suggest a Cl-dependent, α-ketoglutarate-coupled anion exchange mechanism as a pathway for active urate uptake across the basolateral membrane of urate-secreting proximal tubule cells.

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