The effect of two isomeric octadecenoic acids on alkyl diacyl glycerides and neutral glycosphingolipids of Novikoff hepatoma cells

The addition of 150 μg ofcis-6-octadecenoic acid (6–18∶1) per milliliter to the growth medium of Novikoff hepatoma cells reduced the rate of multiplication of these cells, whereas the same level ofcis-9-octadecenoic acid (9–18∶1) was without effect. The quantity of alkyl diacyl glycerols in cells grown in medium containing 100 μg/ml of either 6–18∶1 or 9–18∶1 was reduced to about 10% of that observed in cells grown in unsupplemented media. The presence of 6–18∶1 acid led to an increase in the concentration of the dihexosyl ceramide and a corresponding decrease in that of the monohexosyl ceramides of the cells; whereas the presence of 9–18∶1 resulted in an increase in the relative amount of tetraglycosyl ceramide and corresponding reductions in those of mono- and dihexosyl ceramide. Possible causes for these changes are discussed.