Glycerol permeability of human fetal and adult erythrocytes and of a model membrane

When erythrocytes from different mammalian species are compared, the hemolysis rate in 0.3 M glycerol is seen to be directly related to the percentage of lecithin in the erythrocyte phospholipid. Since this percentage is higher in erythrocytes from human adults than in those from infants, the hemolysis times in 0.3 M glycerol were compared. As expected, hemolysis was more rapid in the adult cell, which is therefore more permeable to glycerol under these conditions.The permeability to glycerol of a film of erythrocyte lipids in vitro was next examined in a model system containing the two phases water and butanol. Lipid introduced into the bulk butanol appears as a film at the interface. When equal amounts of total lipid extracted from adult and fetal erythrocytes were introduced into the butanol phase of two such chambers, the initial flux of glycerol-14C across the lipid boundary was greater in the cell containing lipid from adult erythrocytes than in the cell containing fetal erythrocyte lipid. This difference corresponds qualitatively to the difference in hemolysis time measured in the intact erythrocytes.