These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Mechanism of coupling between Cl- and OH- transport in renal brush-border membranes.
    Author: Ives HE, Chen PY, Verkman AS.
    Journal: Biochim Biophys Acta; 1986 Dec 01; 863(1):91-100. PubMed ID: 3778914.
    Abstract:
    The coupling mechanism for Cl- and H+/OH- transport in renal brush-border vesicles was examined from intravesicular pH changes following imposed H+ and Cl- gradients. Vesicles were loaded with 6-carboxyfluorescein and exposed to H+ gradients and Cl-, gluconate, or sulfate gradients, each with and without a K+/valinomycin voltage clamp. Parallel experiments were performed with vesicles equilibrated with 10 mM HCO3- or 5 mM formate. Rate of H+/OH- transport was determined from the initial rate of change in 6-carboxyfluorescein fluorescence, vesicle buffer capacity and the relationship between fluorescence and vesicle pH. In contrast to gluconate or sulfate, Cl- caused enhanced H+/OH- transport under all conditions. This difference was eliminated with voltage clamping in the presence of gluconate, SO4(2-), or HCO3-, but not in the presence of formate. These findings were not affected by the method of preparation of the vesicles. Electrically coupled Cl-/OH- transport was not inhibited by 100 microM DIDS (4,4'-diisothiocyanostilbene-2,2'-disulfonate) or 100 microM DBDS (4,4'-dibenzamidostilbene-2,2'-disulfonate). SITS (4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonate) was found to be a protonophore at concentrations greater than 500 microM. As a control for the method, we demonstrated amiloride inhibitable, electroneutral Na+-H+ exchange (H+ flux = 107 +/- 9 nmol/s per mg, 100 mM Na+) and electroneutral, DBDS inhibitable Cl(-)-HCO3- exchange in sealed human red blood cell ghosts. Therefore, electroneutral Cl(-)-OH- or HCO3- exchange does not measurably contribute to Cl- transport in the proximal tubule brush border. Cl(-)-formate exchange with formic acid recycling appears to be the only electroneutral coupling mechanism between Cl- and OH- transport demonstrable in renal brush-border membrane vesicles.
    [Abstract] [Full Text] [Related] [New Search]