English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT

Released

Journal Article

Proton pathways in rat renal brush-border and basolateral membranes

MPS-Authors
/persons/resource/persons256395

Sabolić,  Ivan
Department of Physiology, Max Planck Institute of Biophysics, Max Planck Society;

/persons/resource/persons251310

Burckhardt,  Gerhard
Department of Physiology, Max Planck Institute of Biophysics, Max Planck Society;

External Resource
No external resources are shared
Fulltext (public)
There are no public fulltexts stored in PuRe
Supplementary Material (public)
There is no public supplementary material available
Citation

Sabolić, I., & Burckhardt, G. (1983). Proton pathways in rat renal brush-border and basolateral membranes. Biochimica et Biophysica Acta, Bioenergetics, 734(2), 210-220. doi:10.1016/0005-2736(83)90119-0.


Cite as: http://hdl.handle.net/21.11116/0000-0007-F67F-6
Abstract
The quenching of acridine orange fluorescence was used to monitor the formation and dissipation of pH gradients in brush-border and basolateral membrane vesicles isolated from rat kidney cortex. The fluorescence changes of acridine orange were shown to be sensitive exclusively to transmembrane delta pH and not to membrane potential difference. In brush-border membrane vesicles, an Na+ (Li+)-H+ exchange was confirmed. At physiological Na+ concentrations, 40-70% of Na+-H+ exchange was mediated by the electroneutral Na+-H+ antiporter; the remainder consisted of Na+ and H+ movements through parallel conductive pathways. Both modes of Na+-H+ exchange were saturable, with half-maximal rates at about 13 and 24 mM Na+, respectively. Besides a Na+ gradient, a K+ gradient was also able to produce an intravesicular acidification, demonstrating conductance pathways for H+ and K+ in brush-border membranes. Experiments with Cl- or SO2-4 gradients failed to demonstrate measurable Cl--OH- or SO2-4-OH- exchange by an electroneutral antiporter in brush-border membrane vesicles; only Cl- conductance was found. In basolateral membrane vesicles, neither Na+(Li+)-H+ exchange nor Na+ or K+ conductances were found. However, in the presence of valinomycin-induced K+ diffusion potential, H+ conductance of basolateral membranes was demonstrated, which was unaffected by ethoxzolamide and 4,4'-diisothiocyanostilbene-2,2-disulfonic acid. A Cl- conductance of the membranes was also found, but antiporter-mediated electroneutral Cl--OH- or SO2-4-OH- exchange could not be detected by the dye method. The restriction of the electroneutral Na+-H+ exchanger to the luminal membrane can explain net secretion of protons in the mammalian proximal tubule which leads to the reabsorption of bicarbonate.