Characterization of Mg2+ efflux from rat erythrocytes non-loaded with Mg2+

Non-Mg2+-loaded rat erythrocytes with a physiological level of Mg-i(2+) exh ibited Mg2+ efflux when incubated in nominally Mg2+-free media. Two types o f Mg2+ efflux were shown: (1) An Na+-dependent Mg2+ efflux in NaCl and Na g luconate medium, which was inhibited by amiloride and quinidine, as was Na2 +/Mg2+ antiport in Mg2+-loaded rat erythrocytes; and (2) an Na+-independent Mg2+ efflux in sucrose medium and choline Cl medium, which may be differen tiated into SITS-sensitive Mg2+ efflux at low Cl-o(-) (in sucrose) and into SITS-insensitive Mg2+ efflux at high Cl-o(-) (in 150 mmol/l choline Cl). ( C) 1999 Elsevier Science B.V. All rights reserved.