Incorporation of sphingomyelin increases thermostability of human erythrocyte membrane and resistance of erythrocytes against thermal hemolysis

Erythrocytes of various mammal species differ markedly in their resistance against thermally induced hemolysis that was assumed related to the different sphingomyelin content of their membranes (J. Therm. Biol. 18 (1993) 177). In this work, two choline-containing lipids, sphingomyelin and phosphatidylcholine, were incorporated into the membrane of human erythrocytes and the resulting effect on thermal resistance and membrane thermostability of these cells was studied measuring thermohemolysis upon exposure to constant temperature and electrolyte leakage during transient heating, respectively. While sphingomyelin increased thermal resistance by 56% and increased the inducing temperature T_m of electrolyte leakage by 1±0.2°C, phosphatidylcholine produced practically no effect. The results show that sphingomyelin alone stabilized the structure of plasma membrane providing thermal stability to membrane proteins and in turn to whole cells as well.