ISSN:
1432-1424
Keywords:
renal electrolyte transport
;
sodium transport
;
hydrogen ion transport
;
renal proximal tubule
;
Na+/H+ exchange
;
rabbit kidney
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary In order to permit future characterization and possible isolation of the Na+−H+ exchanger from the apical membrane of proximal tubular cells, studies were performed to solubilize and reconstitute this transporter. Rabbit brush border membranes were prepared by a magnesium aggregation method, solubilized with the detergent octyl glucoside, and reconstituted into artificial phospholipid vesicles. In the presence of a pH gradient (pHin 6.0, pHout 8.0), the uptake of 1mm 22Na+ into the proteoliposomes was five- to sevenfold higher than into liposomes. Amiloride (2mm) inhibited proton gradient-stimulated uptake of sodium by 50%. As compared to proton gradient conditions, the uptake of sodium was lower in the absence of a pH gradient but was significantly higher when the outside and inside pH was 6.0 than 8.0. TheK a for sodium in reconstituted proteoliposomes studied under pH gradient conditions was 4mm. The uptake of sodium in proteoliposomes prepared from heat-denatured membrane proteins was significantly decreased. These studies demonstrate that proteoliposomes prepared from octyl glucoside-solubilized brush border membrane proteins and asolectin exhibit proton gradient-stimulated, amiloride-inhibitable, electroneutral uptake of sodium. The ability to solubilize and reconstitute the Na+−H+ exchanger from the apical membrane of the proximal tubule will be of value in isolating and characterizing this transporter.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01872814
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