EFFECT OF ZINC-DEFICIENCY ON THE LIPID-COMPOSITION OF ERYTHROCYTE-MEMBRANES IN GROWING RATS

In a study with 3 x 8 male growing rats the effect of dietary Zn deficiency on the distribution of blood Zn and the phospholipid and fatty acid pattern of erythrocyte membranes was examined. Wistar rats with an initial live weight of 100 g were fed an egg albumin-based diet containing < 1 mg Zn/kg diet ad libitum (-ZnAl) for 28 days. Control rats were fed the basal diet supplemented with 50 mg Zn/kg either ad libitum (+ZnAl) or pair-fed (+ZnPF). Zn depletion resulted in decreased plasma and erythrocyte membrane Zn levels while erythrocyte cytosol Zn concentration remained constant. There was no detectable difference in erythrocyte phospholipid distribution between the three treatment groups. The -ZnAl group had elevated levels of C 22:6 in phosphatidylcholine and phosphatidylethanolamine as well as elevated C 24: 0 levels in sphingomyelin. At the same time C 16: 0 was reduced in phosphatidylcholine. Parameters describing erythrocyte membrane fluidity were calculated from-phospholipid, cholesterol and fatty acid distribution. They neither responded to dietary Zn deficiency nor to pair feeding. From the results obtained it can be concluded that the membrane protective effect of Zn seems to consist of a direct mode of action at the membrane surface.