An atypical anion transporter functioning at acid pH in neuroblastoma cells

At pH 7.4, 36Cl- uptake by neuroblastoma cells was Na(+)-independent, saturable and blocked by submicromolar concentrations of DIDS. This suggests that at this pH, Cl- transport is mediated by an exchanger analogous to erythroid band 3. At pH 6.2, 36Cl- uptake was markedly activated by external carboxylate anions such as acetate. Acetate-stimulated 36Cl- uptake was blocked by DIDS (IC50 = 0.15 microM). Saturation by external 36Cl- was observed with K0.5 = 8 mM. K0.5 was not modified by acetate. As 36Cl efflux is also activated by acetate, we suggest the presence, in neuroblastoma cells, of an anion exchanger activated by carboxylic anions. This exchanger is active when the extracellular pH is 6.0-6.5.