Characterization of D-fructose transport by rat kidney brush-border membrane vesicles: changes in hypertensive rats

2001 ◽  
Vol 58 (12) ◽  
pp. 1961-1967 ◽  
Author(s):  
A. Mate ◽  
M.A. de la Hermosa ◽  
A. Barfull ◽  
J.M. Planas ◽  
C.M. Vázquez
1995 ◽  
Vol 309 (2) ◽  
pp. 643-647 ◽  
Author(s):  
B Stieger ◽  
B O′Neill ◽  
S Krähenbühl

In the presence of a 100 mM Na+ gradient, transport of L-carnitine into rat renal brush-border-membrane vesicles was linear over 30 s and showed an overshoot at 5 min. The uptake of L-carnitine was clearly less active in the presence of other cations such as Li+, K+, Cs+ or choline. In the presence of a Na+ gradient, L-carnitine uptake after 20 s was much higher for chloride as an anion than for SCN-, NO3-, gluconate or SO4(2-). In comparison with conditions with inside positive or no membrane potential, transport was higher in vesicles with an inside negative membrane potential, suggesting an electrogenic mechanism. The kinetic characterization of the Na(+)-dependent portion of L-carnitine transport revealed two transport systems with Km values of 17.4 +/- 3.9 microM and 15.0 +/- 6.0 mM, respectively. The transport could be inhibited in a concentration-dependent fashion by structural analogues such as butyrobetaine, L-acetylcarnitine, trimethyl-lysine and D-carnitine, but not by L-arginine or glycinebetaine.


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.


1991 ◽  
Vol 19 (3) ◽  
pp. 323S-323S ◽  
Author(s):  
J. SAYOS ◽  
J. J. CENTELLES ◽  
J. MALLOL ◽  
E. I. CANELA ◽  
C. LLUIS ◽  
...  

1992 ◽  
Vol 287 (2) ◽  
pp. 423-430 ◽  
Author(s):  
B J Simon ◽  
P Kulanthaivel ◽  
G Burckhardt ◽  
S Ramamoorthy ◽  
F H Leibach ◽  
...  

The presence of an ATP-driven H+ pump as measured by H+ uptake upon addition of ATP was not demonstrable in human placental brush-border membrane vesicles when used in their native form, owing to their right-side-out orientation. However, the presence of the H+ pump in these membranes became evident when the membrane vesicles were transiently exposed to 1% cholate, with subsequent removal of the detergent to re-form the vesicles. Apparently, cholate pretreatment reoriented the H+ pump from an inward-facing configuration to outward-facing. Consequently, H+ uptake in response to externally added ATP was easily demonstrable in these cholate-pretreated vesicles by using the delta pH indicator Acridine Orange. In addition, bafilomycin A1-sensitive ATPase activity was measurable in cholate-pretreated vesicles, but not in native intact vesicles, indicating reorientation of the H+ pump. The reoriented H+ pump was electrogenic because H+ uptake was stimulated by an inside-negative anion-diffusion potential or when the vesicles were voltage-clamped. ATP supported H+ uptake with an apparent Km of 260 microM. ITP and GTP supported the pump activity partially, whereas CTP and UTP did not. Mg2+ and Mn2+ were the most preferred bivalent cations. Co2+ and Zn2+ showed partial activity, whereas Ca2+ and Ba2+ showed little or no activity. The pump was inhibited by nanomolar concentrations of bafilomycin A1 and micromolar concentrations of N-ethylmaleimide, p-chloromercuribenzenesulphonate, NN-dicyclohexylcarbodi-imide and 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, but was relatively insensitive to oligomycin, vanadate and NaN3. The inhibition by N-ethylmaleimide was protectable by ATP. It is concluded that human placental brush-border membranes possess an ATP-driven H+ pump and that, on the basis of its characteristics, it belongs to the class of vacuolar (V-type) H+ pumps.


1990 ◽  
Vol 585 (1 Vitamin B6) ◽  
pp. 106-109 ◽  
Author(s):  
BARBARA B. BOWMAN ◽  
DONALD B. McCORMICK ◽  
ELIZABETH R. SMITH

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