ZINC DEPLETION AND THE LIPID-COMPOSITION OF THE ERYTHROCYTE-MEMBRANE OF RATS FORCE-FED A DIET CONTAINING LINSEED OIL

The present study investigated the effect of zinc depletion on lipid c omposition of the erythrocyte membrane and on in-vitro fragility of er ythrocytes in rats force-fed a diet containing linseed oil. Male Sprag ue-Dawley rats were force-fed a semisynthetic diet containing either 2 5 mg Zn/kg or 0.8 mg Zn/kg. Within 10 days, a severe zinc deficiency w as induced which has been proved by lowered plasma zinc concentration (by 71 %) and lowered activity of alkaline phosphatase in plasma (by 5 9 %). Zinc depletion in rats fed linseed oil diet did not change conce ntrations of phospholipids and cholesterol in the erythrocyte membrane . In contrast, zinc depletion caused changes of the fatty acid composi tion of erythrocyte membrane phospholipids which were different for th e individual phospholipd classes. Most pronounced changes were observe d in phosphatidylcholine. In phosphatidylcholine, zinc depletion cause d elevated percentages of palmitic acid (16:0), stearic acid (18:0) an d eicosapentaenoic acid (20:5) but lowered percentages of linoleic aci d (18:2) and docosapentaenoic acid (22:5 n-3). Total percentages of n- 3 fatty acids were elevated in phosphatidylcholine of zinc depleted ra ts, unchanged in plasmalogen phosphatidylethanolamine, and lowered in diacyl phosphatidylethanolamine, phosphatidylserine and sphingomyelin. Zinc depletion also elevated in-vitro fragility of erythrocytes incub ated with hypoosmotic sodium chloride solutions. The present study in connection with former studies shows that zinc depletion causes charac teristic changes of phosphatidylcholine fatty acid composition whereas changes of fatty acid composition of other phospholipd classes are de pending on the dietary fat. The present study in connection with forme r studies also indicates that the increased fragility of erythrocytes in zinc depleted rats is independent of the dietary fat.