CALCIUM PERMEABILITY AND ATPASE ACTIVITIES OF RED-BLOOD-CELLS OF MAGNESIUM DEFICIENT RATS

Decreased intracellular magnesium and potassium and increased solidum levels were shown in the erythrocytes of weanling rats fed a low magne sium diet for 8 days. Magnesium-dependent ATPase activity was signific antly increased in membranes obtained from Mg-deficient cells and the (Ca2+)- and (Na+ + K+)-stimulated activities were similar to control v alues. Calcium flux measurements clearly show that passive permeabilit y was significantly increased in red blood cells from Mg-deficient rat s. Moreover initial rates of calcium influx and to a lesser degree cal cium efflux were increased in ghosts prepared from Mg-deficient erythr ocytes. In agreement with our previous findings on the physico-chemica l parameters of these membranes, the present results strongly suggest that permeability properties rather than the pump activities are prima rily affected by dietary magnesium deficiency.