Differential effects of lipids on the osmotic fragility of hamster erythrocytes

1. 1. There was no difference in osmotic potential between erythrocytes of control and heat-exposed hamster, thus the increased red cell osmotic fragility of the heat-exposed animal is related to membrane properties of the erythrocytes. 2. 2. Linolenoyl sorbitol at 4 μg/ml (9 · 10^-6 M) increased the osmotic stability of the erythrocytes of both animal groups in a parallel fashion. This lipid did not modify the frequency distribution of hemolysis of the erythrocytes. 3. 3. At 65% hemolysis, added linolenoyl and stearoyl sorbitol similarly protected both groups of erythrocytes. At 95% hemolysis, specific interactions were apparent: linolenoyl sorbitol (at 6 μg/ml) induced almost full protection against osmotic hemolysis of both groups of erythrocytes. Stearoyl sorbitol (at 6 μg/ml) was only partially effective, and the protection afforded to the erythrocytes from heat-exposed animals was particularly limited. 4. 4. Linolenoyl sorbitol expanded the erythrocyte membrane at hypotonic media more effectively than stearoyl sorbitol. 5. 5. The data support the hypothesis that the unsaturated acyl groups of the membrane lipids contribute to higher osmotic stability of the erythrocyte.