scholarly journals Radiation-inactivation studies on brush-border-membrane vesicles. General considerations, and application to the glucose and phosphate carriers

1988 ◽  
Vol 252 (3) ◽  
pp. 807-813 ◽  
Author(s):  
R Béliveau ◽  
M Demeule ◽  
H Ibnoul-Khatib ◽  
M Bergeron ◽  
G Beauregard ◽  
...  
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Dose Range ◽  
Polyacrylamide Gel Electrophoresis ◽  
Membrane Vesicles ◽  
Molecular Size ◽  
Brush Border Membrane Vesicles ◽  
Kidney Cortex ◽  
Rat Kidney Cortex ◽  
Radiation Inactivation

Radiation-inactivation studies were performed on brush-border-membrane vesicles purified from rat kidney cortex. No alteration of the structural integrity of the vesicles was apparent in electron micrographs of irradiated and unirradiated vesicles. The size distributions of the vesicles were also similar for both populations. The molecular sizes of two-brush-border-membrane enzymes, alkaline phosphatase and 5′-nucleotidase, estimated by the radiation-inactivation technique, were 104800 +/- 3500 and 89,400 +/- 1800 Da respectively. Polyacrylamide-gel-electrophoresis patterns of membrane proteins remained unaltered by the radiation treatment, except in the region of higher-molecular-mass proteins, where destruction of the proteins was visible. The molecular size of two of these proteins was estimated from their mobilities in polyacrylamide gels and was similar to the target size, estimated from densitometric scanning of the gel. Intravesicular volume, estimated by the uptake of D-glucose at equilibrium, was unaffected by irradiation. Uptake of Na+, D-glucose and phosphate were measured in initial-rate conditions to avoid artifacts arising from a decrease in the driving force caused by a modification of membrane permeability. Na+-independent D-glucose and phosphate uptakes were totally unaffected in the dose range used (0-9 Mrad). The Na+-dependent uptake of D-glucose was studied in irradiated vesicles, and the molecular size of the transporter was found to be 288,000 Da. The size of the Na+-dependent phosphate carrier was also estimated, and a value of 234,000 Da was obtained.

scholarly journals Studies on the orientation of brush-border membrane vesicles

1978 ◽  
Vol 172 (1) ◽  
pp. 57-62 ◽  
Author(s):  
W Haase ◽  
A Schäfer ◽  
H Murer ◽  
R Kinne
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Rat Kidney ◽  
Freeze Fracture ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Immunological Methods ◽  
Kidney Cortex ◽  
Asymmetric Distribution ◽  
Rat Kidney Cortex

Orientation of rat renal and intestinal brush-border membrane vesicles was studied with two independent methods: electron-microscopic freeze-fracture technique and immunological methods. With the freeze-fracture technique a distinct asymmetric distribution of particles on the two membrane fracture faces was demonstrated; this was used as a criterion for orientation of the isolated membrane vesicles. For the immunological approach the accessibility or inaccessibility of aminopeptidase M localized on the outer surface of the cell membrane to antibodies was used. With both methods we showed that the brush-border membrane vesicles isolated from rat kidney cortex and from rat small intestine for transport studies are predominantly orientated right-side out.

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.

Creatine Transport in Brush-Border Membrane Vesicles Isolated from Rat Kidney Cortex

2001 ◽  
Vol 12 (9) ◽  
pp. 1819-1825
Author(s):  
MARTA GARCÍA-DELGADO ◽  
MARÍA J. PERAL ◽  
MERCEDES CANO ◽  
MARÍA L. CALONGE ◽  
ANUNCIACIÓN A. ILUNDÁIN
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Kidney Cortex ◽  
Nipecotic Acid ◽  
Rat Kidney Cortex ◽  
High Affinity ◽  
Creatine Uptake ◽  
Creatine Transport

Abstract. The kidney efficiently salvages creatine from the urine; however, the mechanism(s) that mediates renal creatine reabsorption has not been investigated. This study characterizes the creatine transport mechanism in brush-border membrane vesicles isolated from the rat renal cortex. An osmolality plot revealed that creatine is transported into an osmotically active space and that it is also bound to the membranes. An inwardly directed NaCl gradient stimulated creatine uptake and the time course of uptake exhibited an overshoot phenomenon, which indicates the presence of an active process for creatine in these membranes. The uptake of creatine showed an absolute requirement for both Na+ and Cl-. The NaCl gradient—dependent creatine uptake was stimulated by a valinomycin-induced, inside-negative, K+-diffusion potential, which suggests that the uptake process is electrogenic. Stoichiometric analyses indicated a probable couple ratio of 2 Na+:1 Cl-:1 creatine molecule. The kinetic study showed that creatine is transported by a high-affinity system (Km of 15 μM). Creatine uptake was inhibited by a 100-fold excess of various compounds with the following potency order: cold creatine = guanidinopropionic acid > nipecotic acid > γ-aminobutyric acid (GABA) = β-alanine = betaine, whereas carnitine, glycine, taurine, and choline were without effect. This pattern of inhibition differs from that observed for GABA uptake (unlabeled GABA = GPA > β-alanine > nipecotic acid ≫ creatine). The conclusion drawn was that the apical membrane of the renal cortical tubules contains an active, high-affinity, electrogenic, 2 Na+/1 Cl-/creatine cotransporter.

Na(+)-dependent biotin transport into brush-border membrane vesicles from rat kidney

1990 ◽  
Vol 258 (4) ◽  
pp. F840-F847 ◽  
Author(s):  
B. Baur ◽  
H. Wick ◽  
E. R. Baumgartner
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Rat Kidney ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Kidney Cortex ◽  
Nonanoic Acid ◽  
Thioctic Acid ◽  
Michaelis Constant ◽  
Rat Kidney Cortex

The mechanisms of biotin reabsorption in rat kidney cortex were investigated using isolated brush-border membrane vesicles. An inwardly directed Na+ gradient specifically stimulated a transient biotin overshoot. Biotin transport was not affected by a valinomycin-induced K(+)-diffusion potential, and biotin(-)-Na+ stoichiometry was found to be 1:1. As a function of concentration, the uptake showed saturation in the presence of a Na+ gradient with an apparent Michaelis constant (Km) of 55 microM and Vmax of 217 pmol.mg protein-1.25 s-1. Desthiobiotin, 250 microM, norbiotin, bisnorbiotin, thioctic acid, valeric acid, probenecid, and nonanoic acid inhibited the transport of 30 microM biotin, whereas other biotin derivatives, as well as biocytin and organic acids found in the urine of biotinidase-deficient patients, did not. Preloading of the vesicles with biotin, desthiobiotin, norbiotin, and thioctic acid in the presence of Na+ increased initial uptake of biotin from the incubation medium (trans-stimulation). Our results indicate that biotin absorption in rat kidney fulfills the criteria for a specific carrier-mediated and electroneutral Na(+)-biotin- cotransport in a 1:1 ratio. The results are discussed in context with congenital biotinidase deficiency in humans.

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