AN ATYPICAL ANION TRANSPORTER FUNCTIONING AT ACID PH IN NEUROBLASTOMA-CELLS

At pH 7.4, Cl-36(-) uptake by neuroblastoma cells was Nas-independent, saturable and blocked by submicromolar concentrations of DIDS. This s uggests that at this pH, Cl- transport is mediated by an exchanger ana logous to erythroid band 3. At pH 6.2, Cl-36(-) uptake was markedly ac tivated by external carboxylate anions such as acetate. Acetate-stimul ated Cl-36(-) uptake was blocked by DIDS (IC50 = 0.15 mu M). Saturatio n by external Cl-36(-) was observed with K-0.5 = 8 mM. K-0.5 was not m odified by acetate. As Cl-36 efflux is also activated by acetate, we s uggest the presence, in neuroblastoma cells, of an anion exchanger act ivated by carboxylic anions. This exchanger is active when the extrace llular pH is 6.0-6.5. (C) 1995 Academic Press, Inc.