scholarly journals Taurocholate–sodium co-transport by brush-border membrane vesicles isolated from rat ileum

1978 ◽  
Vol 174 (3) ◽  
pp. 951-958 ◽  
Author(s):  
Heinrich Lücke ◽  
Gertraud Stange ◽  
Rolf Kinne ◽  
Heini Murer
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Electrical Potential ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Precipitation Method ◽  
Electrical Potential Difference ◽  
Vesicle Membrane ◽  
Brush Border Membranes ◽  
Taurocholate Transport

Uptake of taurocholate into brush-border membrane vesicles isolated from rat small intestine by a Ca2+ -precipitation method was investigated by using a rapid-filtration technique. Uptake of taurocholate by ileal brush-border membranes consisted of three phenomena: binding to the outside of the vesicles, transfer across the vesicle membrane and binding to the intravesicular compartment. The transport of taurocholate across the brush-border membranes was stimulated in the presence of Na+ compared with the presence of K+; stimulation was about 11-fold in the presence of a NaCl gradient (Nao>Nai), where the subscripts refer to ‘outside’ and ‘inside’ respectively, and 4-fold under equilibrium conditions for Na+ (Nao=Nai). In the presence of a Na+ gradient a typical ‘overshoot’ phenomenon was observed. Membranes preloaded with unlabelled taurocholate showed an accelerated entry of labelled taurocholate (tracer exchange) in the presence of Na+ compared with the presence of K+. The stimulation by Na+ was observed only in membrane preparations from the ileum. Addition of monactin, an ionophore for univalent cations, decreased the Na+-gradient-driven taurocholate uptake. The Na+-dependent taurocholate transport showed saturation kinetics and the phenomenon of counterflow and was inhibited by glycocholate. Other cations such as Li+, Rb+ and Cs+ could not replace Na+ in its stimulatory action. When the electrical potential difference across the vesicle membrane was altered by establishing different diffusion potentials (anion replacement; K+ gradient±valinomycin) a more-negative potential inside stimulated Na+-dependent taurocholate transport. These data demonstrate the presence of a rheogenic (potential sensitive) Na+–taurocholate co-transport system in ileal brush-border membranes and support the hypothesis that the reabsorption of bile acids in the ileum is a secondary active uptake.

scholarly journals Sulphate-ion/sodium-ion co-transport by brush-border membrane vesicles isolated from rat kidney cortex

1979 ◽  
Vol 182 (1) ◽  
pp. 223-229 ◽  
Author(s):  
Heinrich Lücke ◽  
Gertraud Stange ◽  
Heini Murer
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Rat Kidney ◽  
Electrical Potential ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Kidney Cortex ◽  
Electrical Potential Difference ◽  
Univalent Cations ◽  
Rat Kidney Cortex

Uptake of SO42− into brush-border membrane vesicles isolated from rat kindey cortex by a Ca2+-precipitation method was investigated by using a rapid-filtration technique. Uptake of SO42− by the vesicles was osmotically sensitive and represented transport into an intra-vesicular space. Transport of SO42− by brush-border membranes was stimulated in the presence of Na+, compared with the presence of K+ or other univalent cations. A typical ‘overshoot’ phenomenon was observed in the presence of an NaCl gradient (100mm-Na+ outside/zero mm-Na+ inside). Radioactive-SO42− exchange was faster in the presence of Na+ than in the presence of K+. Addition of gramicidin-D, an ionophore for univalent cations, decreased the Na+-gradient-driven SO42− uptake. SO42− uptake was only saturable in the presence of Na+. Counter-transport of Na+-dependent SO42− transport was shown with MoO42− and S2O32−, but not with PO42−. Changing the electrical potential difference across the vesicle membrane by establishing different diffusion potentials (anion replacement; K+ gradient±valinomycin) was not able to alter Na+-dependent SO42− uptake. The experiments indicate the presence of an electroneutral Na+/SO42−-co-transport system in brush-border membrane vesicles isolated from rat kidney cortex.

LEUCINE UPTAKE IN BRUSH-BORDER MEMBRANE VESICLES FROM THE MIDGUT OF A LEPIDOPTERAN LARVA, PHILOSAMIA CYNTHIA

1990 ◽  
Vol 149 (1) ◽  
pp. 207-221
Author(s):  
V. FRANCA SACCHI ◽  
BARBARA GIORDANA ◽  
FLAVIA CAMPANINI ◽  
PATRIZIA BONFANTI ◽  
GIORGIO M. HANOZET
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Electrical Potential ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Electrical Potential Difference ◽  
Experimental Conditions ◽  
Leucine Uptake ◽  
Leucine Transport

A potassium- or sodium-activated cotransport of leucine occurs in brush-border membrane vesicles prepared from the midgut of larvae of Philosamia cynthia Drury). The potassium chemical gradient can drive a twofold accumulation of leucine, which is greatly increased under experimental conditions that presumably provide an electrical potential difference (δψ) Kinetic parameters show that leucine transport is improved by these conditions and by a pH gradient similar to that occurring in vivo. However, these gradients cannot drive an intravesicular accumulation of leucine in the absence of potassium. The potassium-dependence of leucine uptake shows that 20% of the transport is potassium-independent and that K50 and Vmax are 30.3± 3.2mmoll−1 and 2584±148pmol 7 s−1mg−1 protein, respectively. The potassium-independent component of leucine transport is also carrier-mediated and some evidence is reported suggesting that the same carrier can cross the membrane as binary carrier and leucine) or ternary (carrier, leucine and potassium) complexes, each having a different mobility

Regulation of Na+-Pi cotransport by 1,25-dihydroxyvitamin D3 in rabbit duodenal brush-border membrane

1982 ◽  
Vol 242 (5) ◽  
pp. G533-G539 ◽  
Author(s):  
B. Hildmann ◽  
C. Storelli ◽  
G. Danisi ◽  
H. Murer
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Precipitation Method ◽  
Dihydroxyvitamin D3 ◽  
1,25 Dihydroxyvitamin D3 ◽  
Pi Transport ◽  
Sodium Dependent ◽  
Cotransport System

Brush-border membrane vesicles were isolated from rabbit duodenum by a Mg2+ precipitation method, and phosphate transport was analyzed by a rapid filtration technique. Uptake of inorganic phosphate (Pi) was stimulated by an inwardly directed sodium gradient, indicating the operation of a Na-Pi cotransport system in brush-border membrane vesicles. Treatment of the animals with ethane-1-hydroxy-1,1-diphosphonate (EHDP), which is known to decrease the circulating levels of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], reduced within 3 days the sodium-dependent Pi transport in the brush-border vesicles. Injections of 1,25(OH)2D3 into rabbits increased within 9 h the sodium-dependent Pi transport in membranes from EHDP-treated animals as well as in untreated ones. The Na-D-glucose cotransport system appeared to be unaffected by these maneuvers. These results suggest that the Na-Pi cotransport system is an important site of regulation of intestinal transepithelial Pi transport by 1,25(OH)2)D3.

Electroneutral Na+/H+exchange in brush-border membrane vesicles fromPenaeus japonicus hepatopancreas

1998 ◽  
Vol 274 (2) ◽  
pp. R486-R493 ◽  
Author(s):  
Sebastiano Vilella ◽  
Vincenzo Zonno ◽  
Laura Ingrosso ◽  
Tiziano Verri ◽  
Carlo Storelli
Keyword(s):  
Kinetic Parameters ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Electrical Potential ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Hill Coefficient ◽  
Uptake Kinetic ◽  
Ph Dependent ◽  
Transmembrane Electrical Potential

An electroneutral Na+/H+exchange mechanism (dimethylamiloride inhibitable, Li+ sensitive, and Ca2+ insensitive) was identified in brush-border membrane vesicles (BBMV) from Kuruma prawn hepatopancreas by monitoring Na+-dependent H+ fluxes with the pH-sensitive dye acridine orange and measuring22Na+uptake. Kinetic parameters measured under short-circuited conditions were the Na+ concentration that yielded one-half of the maximal dissipation rate ( F max) of the preset transmembrane ΔpH ( K Na) = 15 ± 2 mM and F max = 3,626 ± 197 Δ F ⋅ min−1 ⋅ mg protein−1, with a Hill coefficient for Na+ of ∼1. In addition, the inhibitory constant for dimethylamiloride was found to be ∼1 μM. The electroneutral nature of the antiporter was assessed in that an inside-negative transmembrane electrical potential neither affected kinetic parameters nor stimulated pH-dependent (intracellular pH > extracellular pH)22Na+uptake. In contrast, electrogenic pH-dependent22Na+uptake was observed in lobster hepatopancreatic BBMV. Substitution of chloride with gluconate resulted in increasing K Na and decreasing Δ F max, which suggests a possible role of chloride in the operational mechanism of the antiporter. These results indicate that a Na+/H+exchanger, resembling the electroneutral Na+/H+antiporter model, is present in hepatopancreatic BBMV from the Kuruma prawn Penaeus japonicus.

K+-neutral amino acid symport of Bombyx mori larval midgut: a system operative in extreme conditions

1998 ◽  
Vol 274 (5) ◽  
pp. R1361-R1371 ◽  
Author(s):  
B. Giordana ◽  
M. G. Leonardi ◽  
M. Casartelli ◽  
P. Consonni ◽  
P. Parenti
Keyword(s):  
Amino Acid ◽  
Bombyx Mori ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Electrical Potential ◽  
Membrane Vesicles ◽  
Ph Gradient ◽  
Electrical Potential Difference ◽  
Posterior Midgut ◽  
Solution Bathing

The K+-dependent symporter for leucine and other neutral amino acids expressed along the midgut of the silkworm Bombyx mori operates with best efficiency in the presence of a steep pH gradient across the brush-border membrane, with external alkaline pH values up to 11, and an electrical potential difference (Δψ) of ∼200 mV. Careful determinations of leucine kinetics as a function of external amino acid concentrations between 50 and 1,000 μM, performed with brush-border membrane vesicles (BBMV) obtained from the middle and posterior midgut regions, revealed that the kinetic parameter affected by the presence of a ΔpH was the maximal rate of transport. The addition of Δψ caused a further marked increase of the translocation rate. At nonsaturating leucine concentrations in the solution bathing the external side of the brush-border membrane, leucine accumulation within BBMV and midgut cells was not only driven by the gradient of the driver cation K+ and Δψ but occurred also in the absence of K+. The ability of the symporter to translocate the substrate in its binary form allows the intracellular accumulation of leucine in the absence of K+, provided that a pH gradient, with alkaline outside, is present. The mechanisms involved in this accumulation are discussed.

An electroneutral anion exchange mechanism is present in brush-border membranes isolated from eel kidney

1997 ◽  
Vol 272 (4) ◽  
pp. R1143-R1148 ◽  
Author(s):  
S. Vilella ◽  
L. Ingrosso ◽  
V. Zonno ◽  
T. Schettino ◽  
C. Storelli
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Electrical Potential ◽  
Potential Gradient ◽  
Membrane Vesicles ◽  
Anguilla Anguilla ◽  
Brush Border Membrane Vesicles ◽  
Disulfonic Acid ◽  
Luminal Membrane ◽  
Transmembrane Electrical Potential

The mechanism of bicarbonate translocation across the luminal membrane of the eel (Anguilla anguilla) kidney tubular cells was studied by monitoring the uptake of H14CO3- into isolated brush-border membrane vesicles. Results indicate that the presence of a transmembrane outwardly directed Cl- gradient was able to transiently accumulate H14CO3- into the vesicular space, whereas neither an inwardly directed sodium gradient nor a transmembrane electrical potential gradient (inside positive) was able to stimulate the H14CO3- influx. This anion-dependent H14CO3- uptake was inhibited by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, suggesting that an anion exchanger was present in the brush-border membrane vesicles.

Effects of cations on pH gradient-stimulated sulfate transport in rabbit ileal brush-border membrane vesicles

1985 ◽  
Vol 249 (5) ◽  
pp. G614-G621 ◽  
Author(s):  
C. M. Schron ◽  
R. G. Knickelbein ◽  
P. S. Aronson ◽  
J. Della Puca ◽  
J. W. Dobbins
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Electrical Potential ◽  
Membrane Vesicles ◽  
Disodium Salt ◽  
Brush Border Membrane Vesicles ◽  
Ph Gradient ◽  
Disulfonic Acid ◽  
Rabbit Ileum ◽  
External K

In brush-border membrane vesicles from rabbit ileum, we previously reported pH gradient-stimulated SO4 uptake and presented evidence that this represents carrier-mediated SO4-OH exchange. In the present study inhibitors of SO4-OH exchange (H-SO4 cotransport) were shown not to inhibit Na-SO4 cotransport, suggesting that these are two separate carrier-mediated transport mechanisms. While pH gradient-stimulated SO4 uptake was inhibited 87% by 0.1 mM 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, disodium salt (DIDS) and 79% by 1.0 mM furosemide, Na+-stimulated SO4 uptake was only inhibited 11 and 0%, respectively. K+ (20 mM), Cl (5 mM), and oxalate (0.25 mM) inhibited pH gradient-stimulated SO4 uptake (38-65%) but had no effect on Na+-stimulated SO4 uptake. Finally, at Na+ concentrations (10 mM) significantly less than that required for Na+-stimulated SO4 uptake (60-100 mM), external Na+ inhibited pH gradient-stimulated SO4 uptake, suggesting two independent effects of this cation. SO4 uptake was also inhibited by external K+ both in the presence and absence of a pH gradient. A Dixon plot of the DIDS-sensitive SO4 uptake under pH gradient conditions yielded a straight line, indicating a single site of interaction between external K+ and the SO4-OH carrier (apparent Ki = 7.2 mM). In contrast to the inhibition by external K+, internal K+ stimulated SO4 uptake. This effect was DIDS sensitive and not enhanced by valinomycin, suggesting an interaction of internal K+ with the SO4-OH exchanger independent of a K+-induced electrical potential. SO4 uptake and the effects of K+ were pH modulated with less SO4 uptake and less K+ effect at higher pH.(ABSTRACT TRUNCATED AT 250 WORDS)

Transport of N1-methylnicotinamide across brush border membrane vesicles from rabbit kidney

1985 ◽  
Vol 249 (6) ◽  
pp. F903-F911 ◽  
Author(s):  
S. H. Wright
Keyword(s):  
Brush Border ◽  
Organic Cation ◽  
Electrical Potential ◽  
Membrane Vesicles ◽  
Rabbit Kidney ◽  
Electrical Potential Difference ◽  
Vesicle Membrane ◽  
Parallel Processes ◽  
Luminal Membrane ◽  
Uptake Process

A preparation of isolated brush border membranes from the rabbit renal cortex was used to examine the characteristics of N1-methylnicotinamide (NMN) transport in the kidney. Transport was independent of the presence of Na+ under Na+ equilibrium conditions. However, outwardly directed Na+ gradients stimulated NMN uptake, whereas inwardly directed Na+ gradients inhibited NMN uptake. Transport appeared to involve two parallel processes: one saturable with a Jmax of 5 nmol X mg protein-1 X min-1 and an apparent Kt of 0.6 mM, and a second that behaved like passive diffusion. Countertransport of NMN was observed when vesicles were preloaded with either NMN or another organic cation, tetraethylammonium (TEA). TEA and several structural analogues, as well as a wide variety of other organic cations and bases, were effective inhibitors of NMN uptake, though nicotinamide and p-aminohippuric acid did not interact with the uptake process. Outwardly directed proton gradients (pH 6.0 in, 7.6 out) stimulated transport, suggesting that NMN uptake may involve a countertransport of H+. The electrical potential difference across the vesicle membrane was manipulated using gradients of the permeant organic ion thiocyanate (SCN-); an outwardly directed gradient of SCN- (i.e., a depolarizing condition) stimulated uptake and produced a transient accumulation of NMN above that noted at equilibrium, whereas an inwardly directed SCN- gradient inhibited uptake of NMN. The data can be explained by postulating the presence of an electrogenic NMN+-H+ antiporter in the rabbit luminal membrane that could play a role in organic cation secretion.

scholarly journals Aboral changes in d-glucose transport by human intestinal brush-border membrane vesicles

1986 ◽  
Vol 237 (1) ◽  
pp. 229-234 ◽  
Author(s):  
M K Bluett ◽  
N N Abumrad ◽  
N Arab ◽  
F K Ghishan
Keyword(s):  
Glucose Transport ◽  
Brush Border ◽  
Terminal Ileum ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Intestinal Brush Border Membrane ◽  
Proximal Intestine ◽  
Taurocholate Transport ◽  
Colonic Transport

D-Glucose transport was investigated in isolated brush-border membrane vesicles from human small intestine. Characteristics of D-glucose transport from the jejunum were compared with that in the mid and terminal ileum. Jejunal and mid-ileal D-glucose transport was Na+-dependent and electrogenic. The transient overshoot of jejunal D-glucose transport was significantly greater than corresponding values in mid-ileum. The terminal ileum did not exhibit Na+-dependent D-glucose transport, but did exhibit Na+-dependent taurocholate transport. Na+-glucose co-transport activity as measured by tracer-exchange experiments was greatest in the jejunum, and diminished aborally. We conclude that D-glucose transport in man is Na+-dependent and electrogenic in the proximal intestine and directly related to the activity of D-glucose-Na+ transporters present in the brush-border membranes. D-Glucose transport in the terminal ileum resembles colonic transport of D-glucose.

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