Relative contribution of V-H+ATPase and NA+/ H+ exchanger to bicarbonate reabsorption in proximal convoluted tubules of old rats

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With aging, the kidney develops a progressive deterioration of several structures and functions. Proximal tubular acidification is impaired in old rats with a decrease in the activity of brush border Na+/ H+ exchange and a fall of H-ion flux measured with micropuncture experiments. In the present wo...

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Autores principales: Fiori, M., Radrizzani, M., Díaz-sylvester, P., Müller, A., Corti, T., Monserrat, A., Amorena, C.
Formato: Artículo publishedVersion
Publicado: 2006
Materias:
Aging
Kidney
Micropuncture experiments
Na+/H+ exchange
V-H+-ATPase
Western blot
amiloride derivative
bafilomycin
bicarbonate
isoprotein
protein antibody
proton transporting adenosine triphosphatase
sodium proton exchange protein
sodium proton exchange protein 3
aged
animal cell
animal experiment
animal model
animal tissue
article
cell isolation
controlled study
in vitro study
kidney acidifying capacity
kidney proximal tubule
membrane vesicle
nonhuman
priority journal
punch biopsy
rat
Western blotting
Amiloride
Animals
Bicarbonates
Blotting, Western
Hydrogen-Ion Concentration
Kidney Tubules, Proximal
Microvilli
Rats
Sodium Channel Blockers
Sodium-Hydrogen Antiporter
Vacuolar Proton-Translocating ATPases
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_14749718_v5_n5_p367_Fiori
https://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=artiaex&d=paper_14749718_v5_n5_p367_Fiori_oai
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Repositorio Digital de la Universidad de Buenos Aires (UBA) de Universidad de Buenos Aires
Descripción
Sumario:With aging, the kidney develops a progressive deterioration of several structures and functions. Proximal tubular acidification is impaired in old rats with a decrease in the activity of brush border Na+/ H+ exchange and a fall of H-ion flux measured with micropuncture experiments. In the present work we evaluate the contribution of 5-N-ethyl-n-isopropyl amiloride- (EIPA) and bafilomycin-sensitive bicarbonate flux (JHCO3-) in proximal convoluted tubules of young and aged rats. We performed micropuncture experiments inhibiting the Na+/H+ exchanger with EIPA (10-4 M) and the V-H+ ATPase with bafilomycin (10-6 M). We used antibodies against the NHE3 isoform of the Na+/H+ exchanger and the subunit E of the V-H+ ATPase for detecting by Western blot the abundance of these proteins in brush border membrane vesicles from proximal convoluted tubules of young and old rats. The abundance of NHE3 and the V-H+ ATPase was similar in 18-month-old and 3-month-old rats. The bicarbonate flux in old rats was 30% lower than in young rats. EIPA reduced JHCO3- by 60% and bafilomycin by 30% in young rats; in contrast, EIPA reduced JHCO3- by ∼40% and bafilomycin by ∼50% in old rats. The JHCO3- inhibited by bafilomycin was the same in young and old rats: 0.62.nmol · cm-2 · s-1 and 0.71.nmol · cm-2 · s-1, respectively. However, the EIPA-sensitive fraction was larger in young than in old rats: 1.26.nmol · cm-2 · s-1 vs. 0.85 nmol · cm-2 · s-1, respectively. These results suggest that the component more affected in bicarbonate reabsorption of proximal convoluted tubules from aged rats is the Na+-H+ exchanger, probably a NHE isoform different from NHE3. © 2006 The Authors Journal compilation © Blackwell Publishing Ltd/Anatomical Society of Great Britain and Ireland 2006.

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