Further evidence for the existence of an intrinsic bicarbonate-stimulated Mg2+-ATPase in brush border membranes isolated from rat kidney cortex

1979 ◽  
Vol 49 (3) ◽  
pp. 235-251 ◽  
Author(s):  
E. Kinne-Saffran ◽  
R. Kinne
Keyword(s):  
Brush Border ◽  
Rat Kidney ◽  
Kidney Cortex ◽  
Rat Kidney Cortex ◽  
Brush Border Membranes

ATP-dependent H+ pump in membrane vesicles from rat kidney cortex

1985 ◽  
Vol 248 (6) ◽  
pp. F835-F844 ◽  
Author(s):  
I. Sabolic ◽  
W. Haase ◽  
G. Burckhardt
Keyword(s):  
Horseradish Peroxidase ◽  
Brush Border ◽  
Rat Kidney ◽  
Membrane Vesicles ◽  
Kidney Cortex ◽  
Rat Kidney Cortex ◽  
Basolateral Membranes ◽  
Brush Border Membranes ◽  
Endocytotic Vesicles

The presence of membrane vesicles containing an ATP-driven H+ pump was demonstrated in rat kidney cortex homogenate using the delta pH-sensitive dye acridine orange (AO). These vesicles were purified by differential and Percoll density gradient centrifugation. ATP-driven H+ uptake was about 20-fold enriched compared with the homogenate. Determination of marker enzyme activities indicated that these vesicles do not originate from brush border and basolateral membranes, lysosomes, endoplasmic reticulum, mitochondria, Golgi membranes, or red blood cells. The identity with brush border membranes was further excluded by the absence of Na+-H+ exchange. Renal cortical endocytotic vesicles that had taken up horseradish peroxidase or fluorescein isothiocyanate-labeled dextran (FITC-dextran) after injection of these substances into rats in vivo comigrated with the H+ pump activity on the Percoll gradient. Similar characteristics of the H+ pump demonstrated by the AO method and by fluorescence changes of in vivo trapped FITC-dextran proved the identity of H+ pump-containing vesicles with endocytotic vesicles. ATP-driven H+ uptake into endocytotic vesicles was stimulated by Cl- and weakly inhibited by oligomycin. N-ethylmaleimide, dicyclohexylcarbodiimide, and Dio-9 were stronger inhibitors. Histochemical studies revealed that horseradish peroxidase-filled endocytotic vesicles are localized in the apical region of proximal tubule cells. An H+ pump with similar characteristics, but much lower activity, was found in brush border membranes, basolateral membranes, and mitochondria isolated by standard techniques, suggesting a possible contamination of these preparations with endocytotic vesicles.

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.

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