scholarly journals Taurocholate transport by rat intestinal basolateral membrane vesicles. Evidence for the presence of an anion exchange transport system.

1986 ◽  
Vol 78 (1) ◽  
pp. 44-50 ◽  
Author(s):  
S L Weinberg ◽  
G Burckhardt ◽  
F A Wilson
Keyword(s):  
Anion Exchange ◽  
Transport System ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Basolateral Membrane Vesicles ◽  
Taurocholate Transport

scholarly journals Mechanism of n-butyrate uptake in the human proximal colonic basolateral membranes

2002 ◽  
Vol 282 (4) ◽  
pp. G676-G682 ◽  
Author(s):  
S. Tyagi ◽  
J. Venugopalakrishnan ◽  
K. Ramaswamy ◽  
P. K. Dudeja
Keyword(s):  
Fatty Acid ◽  
Anion Exchange ◽  
Short Chain Fatty Acid ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Organ Donor ◽  
Chain Fatty Acid ◽  
Ph Gradient ◽  
Basolateral Membrane Vesicles ◽  
Exchange Inhibitor

Current studies were undertaken to characterize the mechanism of short-chain fatty acid (SCFA) transport in isolated human proximal colonic basolateral membrane vesicles (BLMV) utilizing a rapid-filtration n-[14C]butyrate uptake technique. Human colonic tissues were obtained from mucosal scrapings from organ donor proximal colons. Our results, consistent with the existence of a HCO[Formula: see text]/SCFA exchanger in these membranes, are summarized as follows: 1) n-[14C]butyrate influx was significantly stimulated into the vesicles in the presence of an outwardly directed HCO[Formula: see text] and an inwardly directed pH gradient; 2) n-[14C]butyrate uptake was markedly inhibited (∼40%) by anion exchange inhibitor niflumic acid (1 mM), but SITS and DIDS (5 mM) had no effect; 3) structural analogs e.g., acetate and propionate, significantly inhibited uptake of HCO[Formula: see text] and pH-gradient-driven n-[14C]butyrate; 4) n-[14C]butyrate uptake was saturable with a Kmfor butyrate of 17.5 ± 4.5 mM and a Vmaxof 20.9 ± 1.2 nmol · mg protein−1· 5 s−1; 5) n-[14C]butyrate influx into the vesicles demonstrated a transstimulation phenomenon; and 6) intravesicular or extravesicular Cl−did not alter the anion-stimulated n-[14C]butyrate uptake. Our results indicate the presence of a carrier-mediated HCO[Formula: see text]/SCFA exchanger on the human colonic basolateral membrane, which appears to be distinct from the previously described anion exchangers in the membranes of colonic epithelia.

Indirect coupling to Na+ of p-aminohippuric acid uptake into rat renal basolateral membrane vesicles

1987 ◽  
Vol 253 (5) ◽  
pp. F795-F801 ◽  
Author(s):  
H. Shimada ◽  
B. Moewes ◽  
G. Burckhardt
Keyword(s):  
Transport System ◽  
Equilibrium Distribution ◽  
Rat Kidney ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Kidney Cortex ◽  
Acid Uptake ◽  
Basolateral Membrane Vesicles ◽  
Rat Kidney Cortex ◽  
Indirect Coupling

Experiments with basolateral membrane vesicles prepared from rat kidney cortex were performed to study the mechanism by which p-aminohippuric acid (PAH) is taken up across the contraluminal membrane and is concentrated in proximal tubule cells. An inward Na+ gradient failed to stimulate [3H]PAH uptake compared with K+ or Li+ and did not cause intravesicular PAH accumulation above equilibrium distribution. In the absence of Na+, the dicarboxylates glutarate and suberate cis-inhibited and trans-stimulated [3H]PAH uptake, indicating a common transport system. In the presence of Na+, 10 microM glutarate in the incubation medium did not cis-inhibit, but rather stimulated [3H]PAH uptake and caused PAH accumulation above equilibrium distribution ("overshoot"). Li+ diminished this stimulation, but was without effect on [3H]PAH/PAH- and [3H]PAH/glutarate exchange. The data indicate the coexistence of a Na+ -coupled, Li+-sensitive transport system for dicarboxylates and a Li+ -insensitive PAH/dicarboxylate exchanger in the basolateral membrane. We propose that dicarboxylates are cotransported with Na+ into the cell and subsequently exchange for extracellular PAH at the basolateral membrane. PAH uptake is thereby indirectly coupled to Na+ via the Na+/dicarboxylate cotransporter.

scholarly journals A carrier-mediated transport for folate in basolateral membrane vesicles of rat small intestine

1987 ◽  
Vol 247 (1) ◽  
pp. 141-146 ◽  
Author(s):  
H M Said ◽  
R Redha
Keyword(s):  
Folic Acid ◽  
Anion Exchange ◽  
Membrane Surface ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Basolateral Membrane Vesicles ◽  
Exchange Inhibitor ◽  
Carrier Mediated Transport ◽  
Structural Analogues ◽  
Disulphonic Acid

The mechanism of exit of folate from the enterocyte, i.e. transport across the basolateral membrane, is not known. In this study we examined, using basolateral membrane vesicles, the transport of folic acid across the basolateral membrane of rat intestine. Uptake of folic acid by these vesicles represents transport of the substrate into the intravesicular compartment and not binding to the membrane surface. The rate of folic acid transport was linear for the first 1 min of incubation but decreased thereafter, reaching equilibrium after 5 min of incubation. The transport of folic acid was: (1) saturable as a function of concentration with an apparent Km of 0.6 +/- 0.17 microM and Vmax. of 1.01 +/- 0.11 pmol/30 s per mg of protein; (2) inhibited in a competitive manner by the structural analogues 5-methyltetrahydrofolate and methotrexate (Ki = 2 and 1.4 microM, respectively); (4) electroneutral; (5) Na+-independent; (6) sensitive to the effect of the anion exchange inhibitor 4,4′-di-isothiocyanatostilbene-2,2′-disulphonic acid (DIDS). These data indicate the existence of a carrier-mediated transport system for folic acid in rat intestinal basolateral membrane and demonstrate that the transport process is electroneutral, Na+-independent and sensitive to the effect of anion exchange inhibition.

Citrate uptake by basolateral and luminal membrane vesicles from rabbit kidney cortex

1983 ◽  
Vol 244 (6) ◽  
pp. F686-F695 ◽  
Author(s):  
K. E. Jorgensen ◽  
U. Kragh-Hansen ◽  
H. Roigaard-Petersen ◽  
M. I. Sheikh
Keyword(s):  
Transport System ◽  
Membrane Vesicle ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Rabbit Kidney ◽  
Kidney Cortex ◽  
Basolateral Membrane Vesicles ◽  
Experimental Conditions ◽  
Luminal Membrane ◽  
Dependent Transport

The mechanisms of tubular transport of citrate in renal basolateral and luminal membrane vesicles were studied under various experimental conditions. Both membrane preparations take up citrate by a Na+-dependent transport system, although with different characteristics. The uptake of citrate by basolateral membrane vesicles was insensitive to changes in membrane potential, which is indicative of electroneutral transport of the anion. The Na+-dependent uptake of citrate by luminal membrane vesicles was influenced by the presence of Na+salt anions of different permeabilities in the order: chloride greater than sulfate greater than gluconate. Furthermore, addition of citrate to membrane vesicle-potential-sensitive dye suspensions resulted in optical changes of the dye, indicative of electrogenic transfer of this compound. The apparent affinity of the citrate transport system located in luminal membrane vesicles, in contrast to basolateral membrane vesicles, was sensitive to changes in medium pH and was higher than that of basolateral membrane vesicles in the pH range studied. On the basis of these results a model for the transport of citrate by rabbit kidney proximal tubule is proposed.

Sensitivity of rat renal luminal and contraluminal sulfate transport systems to DIDS

1986 ◽  
Vol 250 (2) ◽  
pp. F226-F234 ◽  
Author(s):  
C. Bastlein ◽  
G. Burckhardt
Keyword(s):  
Transport System ◽  
Brush Border ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Transport Systems ◽  
Basolateral Membrane Vesicles ◽  
Sulfate Transport ◽  
Sulfate Uptake ◽  
Basolateral Membranes ◽  
Irreversible Inhibition

4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) was tested as an inhibitor of the sulfate transport systems in rat renal brush border and basolateral membrane vesicles. Na+-driven sulfate uptake into brush border membrane vesicles was half-maximally inhibited at 350 microM DIDS. Proton gradient-driven sulfate uptake into basolateral membrane vesicles was competitively inhibited by DIDS with a Ki of 2.4 microM. The Km for delta pH-driven sulfate uptake was 5.4 microM. The different affinities of the sulfate transport systems for DIDS correlated with different substrate specificities. The luminal transport system accepted a smaller range of anions than the contraluminal system and did not operate as a Na+-independent anion exchanger. After treatment of basolateral membrane vesicles with 50 microM DIDS at pH 8.4 for 30 min, an irreversible inhibition of sulfate uptake was observed. With brush border membranes, only a small irreversible inhibition was obtained. Lack of inhibition after treatment of basolateral membranes with DIDS at pH 6.4 indicated that DIDS reacted with deprotonated amino groups of the transport protein. Sulfate was protected from the irreversible inhibition by DIDS. Sodium-driven uptake of L-glutamate and methylsuccinate into basolateral membrane vesicles was not irreversibly inhibited by DIDS, indicating a specific action of DIDS on the contraluminal sulfate transport system. Irreversible and substrate-protectable inhibition of sulfate transport render DIDS suitable for future affinity labeling studies on the sulfate transport system in basolateral membranes.

Evidence for carrier-mediated Cl-SO4 exchange in rabbit ileal basolateral membrane vesicles

1987 ◽  
Vol 253 (3) ◽  
pp. G404-G410 ◽  
Author(s):  
C. M. Schron ◽  
R. G. Knickelbein ◽  
P. S. Aronson ◽  
J. W. Dobbins
Keyword(s):  
Anion Exchange ◽  
Brush Border ◽  
Initial Velocity ◽  
Brush Border Membrane ◽  
Basolateral Membrane ◽  
Electrical Potential ◽  
Membrane Vesicles ◽  
Disulfonic Acid ◽  
Basolateral Membrane Vesicles ◽  
Beta Hydroxybutyrate

In rabbit ileal basolateral membrane (BLM) vesicles, an outwardly directed Cl gradient ([Cl] in/out = 60/6 mM) stimulated the initial velocity of SO4 uptake compared with uptake in the absence of Cl. Under Cl gradient conditions, SO4 was transiently accumulated at a concentration twice that found at equilibrium ("overshoot"). Chloride gradient-stimulated SO4 uptake was markedly reduced by inhibitors of anion exchange (4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid, 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid) and was saturable (SO4 Km = 0.302 +/- 0.064 mM; Vmax = 1.59 +/- 0.22 nmol SO4 . mg protein-1 . min-1). SO4 uptake by BLM vesicles was not stimulated by imposition of an inside-positive electrical potential, suggesting that the stimulation by a Cl gradient was not due to an induced electrical potential. Oxalate, nitrate, iodide, and bromide inhibited the initial velocity of Cl gradient-stimulated SO4 uptake, whereas phosphate, beta-hydroxybutyrate, lactate, and p-aminohippurate had no effect. When SO4 uptake by BLM vesicles was compared with that of brush-border membrane vesicles, Cl gradient-stimulated SO4 uptake was found predominantly in the BLM preparation. In conclusion, these findings provide evidence for a carrier on the ileal basolateral membrane that mediates Cl-SO4 exchange.

Characterization of ATP-dependent Ca2+ transport in the basolateral membrane vesicles from proximal and distal tubules of the rabbit kidney

1991 ◽  
Vol 69 (2-3) ◽  
pp. 109-114 ◽  
Author(s):  
Chidambaram Ramachandran ◽  
Meanthan Chan ◽  
Michèle G. Brunette
Keyword(s):  
Transport System ◽  
Ph Dependence ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Distal Tubule ◽  
Optimal Concentration ◽  
Rabbit Kidney ◽  
Maximal Velocity ◽  
Basolateral Membrane Vesicles ◽  
Distal Tubules

Basolateral membrane vesicles were prepared from purified proximal and distal tubules of the rabbit kidney. The properties of the ATP-dependent Ca2+ transport were investigated. In both membranes, there was a high affinity, ATP-dependent Ca2+ transport system (Km = 0.1 μM). The optimal concentration of Mg2+ was 0.5 mM and the optimal concentration of ATP was 1 mM. The nucleotide specificity and pH dependence of the Ca2+ transport in both membranes were similar. In basolateral membrane vesicles, calmodulin had no effect on Ca2+ transport. However, in basolateral membrane vesicles depleted of calmodulin, exogeneous calmodulin increased the Ca2+ transport by increasing maximal velocity. There were no major differences in the properties of the ATP-dependent Ca2+ transport system in these two membranes. These findings are discussed in relation to why parathyroid hormone differentially modulates Ca2+ transport in these two segments of the nephron.Key words: Ca2+ transport, ATP-dependent, kidney, proximal tubule, distal tubule, basolateral membrane.

Depression of calcium pump activity in renal cortex of vitamin D-deficient rats with secondary hyperparathyroidism

1990 ◽  
Vol 123 (4) ◽  
pp. 438-444 ◽  
Author(s):  
Yusuke Tsukamoto ◽  
Teiichi Tamura ◽  
Michiyo Saitoh ◽  
Yumiko Takita ◽  
Toshiaki Nakano
Keyword(s):  
Vitamin D ◽  
Secondary Hyperparathyroidism ◽  
Hormonal Regulation ◽  
Serum Calcium Level ◽  
Renal Cortex ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Calcium Pump ◽  
Basolateral Membrane Vesicles ◽  
Pump Activity

Abstract. To examine the hormonal regulation of the ATP-dependent Ca2+ pump in the kidneys, the ATP-dependent Ca2+ uptake by the basolateral membrane vesicles in the renal cortex was measured using radioactive calcium (45Ca2+) in rats with vitamin D deficiency or rats undergoing thyroparathyroidectomy. The Vmax of the Ca2+ pump activity was increased not only by administering calcitriol, but also by normalizing the serum calcium level in vitamin D-deficient rats. PTH suppressed the Ca2+ pump activity in normocalcemic vitamin D-deficient rats. Thyroparathyroidectomy did not affect the Ca2+ pump activity in the kidneys of normal rats. It was concluded that the ATP-dependent Ca2+ pump activity was depressed by secondary hyperparathyroidism in vitamin D-deficient rats.

scholarly journals Characterization of sodium-dependent and sodium-independent nucleoside transport systems in rabbit brush-border and basolateral plasma-membrane vesicles from the renal outer cortex

1989 ◽  
Vol 264 (1) ◽  
pp. 223-231 ◽  
Author(s):  
T C Williams ◽  
A J Doherty ◽  
D A Griffith ◽  
S M Jarvis
Keyword(s):  
Brush Border ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Nucleoside Transport ◽  
Transport Systems ◽  
Facilitated Diffusion ◽  
Basolateral Membrane Vesicles ◽  
Plasma Membrane Vesicles ◽  
Outer Cortex ◽  
Overshoot Phenomenon

The transport of uridine into rabbit renal outer-cortical brush-border and basolateral membrane vesicles was compared at 22 degrees C. Uridine was taken up into an osmotically active space in the absence of metabolism for both types of membrane vesicles. Uridine influx by brush-border membrane vesicles was stimulated by Na+, and in the presence of inwardly directed gradients of Na+ a transient overshoot phenomenon was observed, indicating active transport. Kinetic analysis of the saturable Na+-dependent component of uridine flux indicated that it was consistent with Michaelis-Menten kinetics (Km 12 +/- 3 microM, Vmax. 3.9 +/- 0.9 pmol/s per mg of protein). The sodium:uridine coupling stoichiometry was found to be consistent with 1:1 and involved the net transfer of positive charge. In contrast, uridine influx by basolateral membrane vesicles was not dependent on the cation present and was inhibited by nitrobenzylthioinosine (NBMPR). NBMPR-sensitive uridine transport was saturable (Km 137 +/- 20 microM, Vmax. 5.2 +/- 0.6 pmol/s per mg of protein). Inhibition of uridine flux by NBMPR was associated with high-affinity binding of NBMPR to the basolateral membrane (Kd 0.74 +/- 0.46 nM). Binding of NBMPR to these sites was competitively blocked by adenosine and uridine. These results indicate that uridine crosses the brush-border surface of rabbit proximal renal tubule cells by Na+-dependent pathways, but permeates the basolateral surface by NBMPR-sensitive facilitated-diffusion carriers.

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