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

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.

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.

Potential differences influence amino acid/Na+ symport rates in larval Manduca sexta midgut brush-border membrane vesicles.

1994 ◽  
Vol 189 (1) ◽  
pp. 55-67
Author(s):  
R Parthasarathy ◽  
W R Harvey
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Manduca Sexta ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Rate Determining Step ◽  
Half Saturation Constant

The time-dependent fluorescence intensity of an intravesicular potential-sensitive dye was used to probe the real-time kinetics of potential difference (PD)-dependent amino acid/Na+ symport at pH9 into brush-border membrane vesicles obtained from larval Manduca sexta midgut. Neutral amino acids (alanine, proline) are symported at higher rates as the vesicles are hyperpolarized. The symport rates of acidic (glutamate) and basic (arginine) amino acids are almost PD-independent. The half-saturation constant of alanine is PD-independent between -108 and -78 mV, although the maximal symport velocity increases by half as the voltage is increased. Amino acid throughput is evidently enhanced as the relatively high transmembrane PDs (> 150 mV, lumen positive) measured in vivo are approached. The half-saturation concentrations of Na+ were in the range 15-40 mmol l-1 for most of the amino acids examined and increased with voltage for alanine. The Vmax observed as a function of cation or amino acid concentration increased as the vesicle was hyperpolarized in the case of leucine and alanine. The data support the hypothesis that carrier and substrates are at equilibrium inasmuch as substrate translocation seems to be the rate-determining step of symport.

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.

Indirect coupling of urate and p-aminohippurate transport to sodium in human brush-border membrane vesicles

1996 ◽  
Vol 270 (1) ◽  
pp. F61-F68 ◽  
Author(s):  
F. Roch-Ramel ◽  
B. Guisan ◽  
L. Schild
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Indirect Coupling ◽  
Sodium Gradient ◽  
Beta Hydroxybutyrate ◽  
Sodium Cotransport ◽  
Stimulation Of

[14C]urate and p-[14C]aminohippurate (PAH) uptake by human brush-border membrane vesicles (BBMV) were measured in the presence of an inwardly oriented sodium gradient. No direct sodium cotransport was observed. Indirect [14C]urate coupling to sodium transport was demonstrated by cis-stimulation of [14C]urate with nicotinate or pyrazinoate (PZA) in the extravesicular medium but not by adding lactate, alpha-ketoglutarate, or beta-hydroxybutyrate. Indirect sodium coupling of [14C]PAH uptake was observed only when alpha-ketoglutarate was added to the extravesicular medium, a mechanism similar to that of basolateral membranes. The ability for PZA (and nicotinate) to cis-stimulate urate uptake was correlated with a high apparent affinity for the urate/anion exchanger. In urate-loaded vesicles, for identical medium concentrations, [14C]PZA uptake via the urateanion exchanger was 10 times higher than [14C]lactate uptake. Such high PZA affinity for the urate exchanger, working in parallel with PZA sodium cotransport can account for the stimulation of urate reabsorption by PZA in vivo.

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.

Cholera toxin facilitates calcium transport in jejunal brush border vesicles

1986 ◽  
Vol 64 (5) ◽  
pp. 568-574 ◽  
Author(s):  
David D. Maenz ◽  
G. W. Forsyth
Keyword(s):  
Cholera Toxin ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Equilibrium Dialysis ◽  
Membrane Vesicles ◽  
Second Messenger ◽  
Brush Border Membrane Vesicles ◽  
Ionophore A23187

Cholera toxin is very well characterized in terms of the activation of adenylate cyclase. In some systems, however, this cyclase activation does not seem to account for all of the physiological responses to the toxin. On the premise that cholera toxin may also exert effects through other second messenger compounds we have studied the effect of cholera toxin on the rate of Ca2+ movement across the membrane of intestinal brush border vesicles. Increasing concentrations of cholera toxin progressively accelerated the passive uptake of Ca2+ into, and the efflux of Ca2+ from, an osmotically active space in brush border membrane vesicles. This effect of cholera toxin was saturable by excess Ca2+ and was relatively specific, as the toxin did not affect vesicle permeability to an uncharged polar solute. The toxin had two high affinity Ca2+ binding sites on the A subunit as measured by equilibrium dialysis. Ca2+ transport facilitated by cholera toxin was temperature dependent, required the holotoxin, and could be inhibited by preincubation of the toxin with excess free ganglioside GM1.This increased rate of Ca2+ influx caused by the in vitro addition of cholera toxin to brush border membrane vesicles may have physiological significance as it was comparable to rates observed with the Ca ionophore A23187. Similar effects occurring in vivo could permit cholera toxin to increase cytoplasmic Ca2+ concentrations and to produce accompanying second messenger effects.

scholarly journals Toxicity, Binding, and Permeability Analyses of FourBacillus thuringiensis Cry1 δ-Endotoxins Using Brush Border Membrane Vesicles of Spodoptera exigua and Spodoptera frugiperda

1999 ◽  
Vol 65 (2) ◽  
pp. 457-464 ◽  
Author(s):  
Ke Luo ◽  
David Banks ◽  
Michael J. Adang
Keyword(s):  
Binding Site ◽  
Spodoptera Frugiperda ◽  
Brush Border ◽  
Spodoptera Exigua ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Binding Assays ◽  
Competition Binding

ABSTRACT The binding and pore formation properties of four Bacillus thuringiensis Cry1 toxins were analyzed by using brush border membrane vesicles from Spodoptera exigua andSpodoptera frugiperda, and the results were compared to the results of toxicity bioassays. Cry1Fa was highly toxic and Cry1Ac was nontoxic to S. exigua and S. frugiperda larvae, while Cry1Ca was highly toxic to S. exigua and weakly toxic to S. frugiperda. In contrast, Cry1Bb was active against S. frugiperda but only marginally active against S. exigua. Bioassays performed with iodinated Cry1Bb, Cry1Fa, and Cry1Ca showed that the effects of iodination on toxin activity were different. The toxicities of I-labeled Cry1Bb and Cry1Fa against Spodoptera species were significantly less than the toxicities of the unlabeled toxins, while Cry1Ca retained its insecticidal activity when it was labeled with 125I. Binding assays showed that iodination prevented Cry1Fa from binding to Spodoptera brush border membrane vesicles. 125I-labeled Cry1Ac, Cry1Bb, and Cry1Ca bound with high-affinities to brush border membrane vesicles fromS. exigua and S. frugiperda. Competition binding experiments performed with heterologous toxins revealed two major binding sites. Cry1Ac and Cry1Fa have a common binding site, and Cry1Bb, Cry1C, and Cry1Fa have a second common binding site. No obvious relationship between dissociation of bound toxins from brush border membrane vesicles and toxicity was detected. Cry1 toxins were also tested for the ability to alter the permeability of membrane vesicles, as measured by a light scattering assay. Cry1 proteins toxic to Spodoptera larvae permeabilized brush border membrane vesicles, but the extent of permeabilization did not necessarily correlate with in vivo toxicity.

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.

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