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: Sulfate transport in human neutrophils.
    Author: Simchowitz L, Davis AO.
    Journal: J Gen Physiol; 1989 Jul; 94(1):95-124. PubMed ID: 2478661.
    Abstract:
    The mechanism by which SO4(2-) is transported across the plasma membrane of isolated human neutrophils was investigated. Unlike the situation in erythrocytes, SO4(2-) and other divalent anions are not substrates for the principal Cl-/HCO3- exchange system in these cells. At an extracellular concentration of 2 mM, total one-way 35SO4(2-) influx and efflux in steady-state cells amounted to approximately 17 mumol/liter of cell water per min. The intracellular SO4(2-) content was approximately 1 mM, approximately 25-fold higher than the passive distribution level. Internal Cl- trans stimulated 35SO4(2-) influx. Conversely, 35SO4(2-) efflux was trans stimulated by external Cl- (Km approximately 25 mM) and by external SO4(2-) (Km approximately 14 mM), implying the presence of a SO4(2-)/Cl- countertransport mechanism. The exchange is noncompetitively inhibited by 4-acetamido-4'-isothiocyanostilbene-2,2' -disulfonate (SITS) (Ki approximately 50 microM) and competitively blocked by alpha-cyano-4-hydroxycinnamate (Ki approximately 230 microM) and by ethacrynate (Ki approximately 7 microM); furosemide and probenecid also suppressed activity. The carrier exhibits broad specificity for a variety of monovalent (NO3- approximately Cl- greater than Br- greater than formate- greater than I- approximately p-aminohippurate-) and divalent WO4(2-) greater than oxalate2- greater than SO4(2-) greater than MoO4(2-) greater than SeO4(2-) greater than AsO4(2-) anions. There was little, if any, affinity for HCO3-, phosphate, or glucuronate. The influx of SO4(2-) is accompanied by an equivalent cotransport of H+, the ion pair H+ + SO4(2-) being transported together in exchange for Cl-, thereby preserving electroneutrality. These findings indicate the existence of a separate SO4(2-)/Cl- exchange carrier that is distinct from the neutrophil's Cl-/HCO3- exchanger. The SO4(2-) carrier shares several properties in common with the classical inorganic anion exchange mechanism of erythrocytes and with other SO4(2-) transport systems in renal and intestinal epithelia, Ehrlich ascites tumor cells, and astroglia.
    [Abstract] [Full Text] [Related] [New Search]