THE INFLUENCE OF A FISH OIL-ENRICHED DIET ON THE PHOSPHOLIPID FATTY-ACID TURNOVER IN THE RABBIT RED-CELL MEMBRANE IN-VIVO

The influence of the polyunsaturated fatty acid (PUFA) composition of the diet on the rate of fatty acid turnover of individual phospholipid s in the erythrocyte membrane in vivo was studied. Following modificat ion of the fatty acid composition of the membrane phospholipids by the use of a fish oil or a linoleic acid enriched diet, phospholipids-lab el led in the unsaturated fatty acid at the 2-position of the glycerol moiety-were introduced into the membrane of freshly isolated rabbit e rythrocytes. Thereafter, the labelled erythrocytes were reinjected int o the bloodstream of the animal. It appears that, with the exception o f 1-palmitoyl,2-linoleoyl phosphatidylcholine, all other phosphatidylc holines disappear faster from the erythrocytes of fish oil-fed rabbits than from the red cells of linoleic acid-fed rabbits. Another paramet er, which possibly influences the turnover rates of PUFA containing ph ospholipids, can be peroxidation. An attempt was made to measure perox idative damage of lipids in vivo by the introduction of 1-palmitoyl,2- cis-parinaroyl phosphatidylcholine (PnPC)-a probe to measure oxidative stress-into the membrane of freshly isolated erythrocytes, in the sam e way as is described for the radioactive phospholipids. The data demo nstrate that the fluorescent signal from the PnPC decreases at a fast rate which is independent of the dietary conditions.