Characterization of Mg(2+) efflux from rat erythrocytes non-loaded with Mg(2+)

Non-Mg(2+)-loaded rat erythrocytes with a physiological level of Mg(2+)(i) exhibited Mg(2+) efflux when incubated in nominally Mg(2+)-free media. Two types of Mg(2+) efflux were shown: (1) An Na(+)-dependent Mg(2+) efflux in NaCl and Na gluconate medium, which was inhibited by amiloride and quinidine, as was Na(2+)/Mg(2+) antiport in Mg(2+)-loaded rat erythrocytes; and (2) an Na(+)-independent Mg(2+) efflux in sucrose medium and choline Cl medium, which may be differentiated into SITS-sensitive Mg(2+) efflux at low Cl(-)(o) (in sucrose) and into SITS-insensitive Mg(2+) efflux at high Cl(-)(o) (in 150 mmol/l choline Cl).