The intrinsic Cl - conductance of mouse kidney cortex brush-border membrane vesicles is not related to CFTR

1997 ◽  
Vol 434 (5) ◽  
pp. 575-580 ◽  
Author(s):  
N. King ◽  
W. H. Colledge ◽  
R. Ratcliff ◽  
M. J. Evans ◽  
N. L. Simmons
1978 ◽  
Vol 172 (1) ◽  
pp. 57-62 ◽  
Author(s):  
W Haase ◽  
A Schäfer ◽  
H Murer ◽  
R Kinne

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.


1980 ◽  
Vol 190 (2) ◽  
pp. 473-476 ◽  
Author(s):  
H S Tenenhouse ◽  
C R Scriver ◽  
E J Vizel

We studied (1) the effect of primary modulators of phosphate transport, namely the hypophosphataemic mouse mutant (Hyp) and low-phosphorus diet, on alkaline phosphatase activity in mouse renal-cortex brush-border membrane vesicles and (2) the effect of several primary inhibitors of alkaline phosphatase on phosphate transport. Brush-border membrane vesicles from Hyp-mouse kidney had 50% loss of Na+-dependent phosphate transport, but only 18% decrease in alkaline phosphatase activity. The low-phosphorus diet effectively stimulated Na+/phosphate co-transport in brush-border membrane vesicles (+ 118%), but increased alkaline phosphatase activity only slightly (+13%). Levamisole (0.1 mM) and EDTA (1.0 mM) inhibited brush-border membrane-vesicle alkaline phosphatase activity of 82% and 93% respectively, but had no significant effect on Na+/phosphate co-transport. We conclude that alkaline phosphatase does not play a direct role in phosphate transport across the brush-border membrane of mouse kidney.


1979 ◽  
Vol 182 (1) ◽  
pp. 223-229 ◽  
Author(s):  
Heinrich Lücke ◽  
Gertraud Stange ◽  
Heini Murer

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.


1994 ◽  
Vol 303 (3) ◽  
pp. 901-905 ◽  
Author(s):  
D A Griffith ◽  
S M Jarvis

The characteristics of hypoxanthine transport were examined in purified brush-border membrane vesicles isolated from guinea-pig kidney. Hypoxanthine uptake in the vesicles was specifically stimulated by both Na+ and an inside-negative potential, resulting in a transient accumulation of intravesicular hypoxanthine. Na(+)-dependent hypoxanthine influx was saturable (apparent Km 4.4 +/- 2.1 microM, Vmax. 128 +/- 29 pmol/min per mg of protein at 100 mM NaCl and 22 degrees C). Guanine, thymine, 5-fluorouracil and uracil inhibited hypoxanthine uptake (Ki values 1-30 microM), but adenine and the nucleosides inosine and thymidine were without effect. Guanine competitively inhibited Na(+)-dependent hypoxanthine influx, suggesting that it was a substrate for the active nucleobase transporter in guinea-pig renal membrane vesicles. A sigmoidal dependence between hypoxanthine influx and Na+ concentration was obtained (KNa 13 +/- 2 mM; Hill coefficient, h, 2.13 +/- 0.14), suggesting that at least two Na+ ions are transported per hypoxanthine molecule. This system differs from the Na(+)-nucleobase carrier in cultured LLC-PK1 renal cells, which has a stoichiometric coupling ratio of 1:1. These results represent the first demonstration of an active electrogenic nucleobase carrier in renal apical membrane vesicles.


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