Comparison of the metabolism of α‐linolenic acid and its Δ6 desaturation product, stearidonic acid, in cultured NIH‐3T3 cells

The incorporation and metabolism of α‐linolenic acid (18∶3n−3) and its Δ6 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 μg/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.