THE EFFECT OF N-3 FATTY-ACIDS ON OSMOTIC FRAGILITY OF RAT ERYTHROCYTES

In order to study the effect of n - 3 fatty acids on the physical state of the erythrocyte membrane, measured as osmotic fragility, rats were fed a diet supplemented in n - 3 fatty acids (1.5 ml/day, 35% 20:5, 30% 22:6) for 21 days. With salt concentrations ranging from 0.37% to 0.44%, osmotic resistance was increased by 25% to 45% in cells from n - 3-fed animals compared to controls. No change was observed in either phospholipid or cholesterol content in the membrane. A small, but still significant difference (P < 0.05) in phospholipid sub-class distribution was observed in that the phosphatidylethanolamine fraction was decreased and the phosphatidylserine fraction increased after n - 3 supplementation. The major change was, however, that the level of eicosapentaenoic acid (20:5(n - 3)) in phospholipids was increased from 1.5% of total fatty acids to 4.5%. This increase was mainly at the expense of linoleic acid (18:2(n - 6)). No change was observed in the level of docosahexaenoic acid (22:6(n - 3)). It is thus concluded that both the fatty acid composition and the nature of the phospholipid polar head group may influence the osmotic fragility of erythrocytes.