Enhanced susceptibility to erythrocyte "apoptosis" following phosphate depletion.

Among the sequelae of phosphate depletion is anaemia, due in part to a decreased life span of mature erythrocytes. Recent studies have disclosed that cellular stress leads to an increase of cytosolic Ca(2+) activity in erythrocytes thereby triggering cell shrinkage and breakdown of phosphatidylserine asymmetry of the cell membrane, both typical features of apoptosis. In the present experiments, phosphatidylserine exposure and cell size were measured by fluorescence-activated cell sorting (FACS) analysis of annexin binding and forward scatter, respectively.