Characterization of Na+‐independent Mg2+ efflux from erythrocytes

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Abstract
Na+‐independent Mg2+ efflux from Mg2+‐loaded human, rat and chicken erythrocytes was reduced by extracellular Cl−. Na+‐independent Mg2+ efflux at low extracellular Cl− concentration (sucrose medium) was inhibited by SITS and was nearly insensitive to SITS in 150 mM choline Cl medium. The inhibition of Mg2+ efflux by extracellular Cl− and DIDS could be overcome by the lipophilic permeant tetraphenylphosphonium cation. Na+‐independent Mg2+ efflux from human and rat erythrocytes in sucrose and choline Cl medium was inhibited by cAMP and by amiloride and amiloride analogues. The results indicate that Na+‐independent Mg2+ efflux in high Cl− medium is performed by a similar or the same Mg2+ efflux system, operating in sucrose medium in which the efflux of Mg2+ is accompanied by the efflux of Cl− for charge compensation.