Deoxygenation-induced cation movements in sickle cells were inhibited 80% to 85% by the anion transport inhibitor, 4,4′-diisothiocyano- 2,2′disulfostilbene (DIDS). Morphologic sickling was not altered by DIDS treatment, demonstrating that morphologic sickling was not sufficient to produce cation leaks in sickle cells. DIDS inhibition of deoxygenation-induced cation flux was not affected when l- replaced Cl- , indicating that conductive anion movements did not limit cation flux in deoxygenated cells treated with DIDS. Inhibition was irreversible after preincubation with DIDS at 37 degrees C for 20 minutes, and was not affected by the oxygenation state of cells at the time of drug exposure. Sulfate self-exchange was inhibited at lower DIDS concentrations than was deoxygenation-induced flux. Incubation of cells with DIDS at 4 degrees C produced progressive blockade of sulfate exchange, but did not alter deoxygenation-induced cation fluxes. Other stilbene disulfonates, including compounds incapable of covalent reactions, also inhibited deoxygenation-induced cation movements, although several other inhibitors of anion exchange did not. Dissociation of the inhibition of anion exchange and deoxygenation- induced cation flux indicates that the DIDS effect on deoxygenation- induced cation movements does not involve the well-characterized stilbene binding site of the anion exchanger. These data provide evidence for a membrane constituent on the external surface of oxygenated sickle cells capable of interacting with DIDS to prevent the increase in cation permeability associated with sickling.

This content is only available as a PDF.
Sign in via your Institution