COMPARISON OF THE METABOLISM OF ALPHA-LINOLENIC ACID AND ITS DELTA-6 DESATURATION PRODUCT, STEARIDONIC ACID, IN CULTURED NIH-3T3 CELLS

The incorporation and metabolism of alpha-linolenic acid (18:3n-3) and its DELTA6 desaturase product, stearidonic acid (18:4n-3), were compared by NIH-3T3 cells. In the presence of fetal calf serum, cells accumulated exogenously added 18:3n-3 and 18:4n-3 apparently at the expense of oleic acid (18:1n-9). Both 18:3n-3 and 18:4n-3 were elongated and desaturated to eicosatetraenoic acid (20:4n-3), eicosapentaenoic acid (20:5n-3) and docosapentaenoic acid (22:5n-3), but not to docosahexaenoic acid (22:6n-3), and were incorporated into phospholipids and triacylglycerols. Over a 4-d period, the growth of NIH-3T3 cells was slightly stimulated in the presence of 18:3n-3 (20 mug/mL) but was strongly inhibited in the presence of 18:4n-3 at the same concentration. This inhibition may be caused by enhanced lipid peroxidation as a result of the high levels of 18:4n-3 present.