| Abstract: | Intact human erythrocytes were treated, under non-haemolytic conditions at 37 degrees C, with synthetic phosphatidylcholine which has homologous, saturated acyl chains of 8-18 even-numbered carbon atoms (C8-C18-PC) or with lysophosphatidylcholine which has a saturated acyl chain of 8-18 carbon atoms (C8-C18-lysoPC). The C8-C14-PC and C12-C18-lysoPC species were rapidly incorporated into the erythrocytes and induced a shape change of the crenation (echinocyte formation) type. The site of the incorporation was found to be most probably on the outer leaflet of the membrane lipid bilayer. The extent of the shape change was dependent on the amount of each lipid incorporated. When the same amount of a PC or lysoPC species was incorporated into the membrane, about the same extent of crenation was induced, independent of acyl chain length. However, C16-PC, C18-PC, C8-lysoPC and C10-lysoPC, which were not incorporated into the erythrocytes, did not induce any shape change. It is therefore suggested that the hydrophobic moiety of these amphiphilic lipids may greatly contribute to their transfer from the outer medium into the erythrocyte membrane, but do not influence so much the perturbation of the membrane lipid bilayer which may be responsible for induction of the shape change. |
