FORMATION OF 22-CARBON AND 24-CARBON 6-DESATURATED FATTY-ACIDS FROM EXOGENOUS DEUTERATED ARACHIDONIC-ACID IS ACTIVATED IN THP-1 CELLS AL HIGH SUBSTRATE CONCENTRATIONS

Deuterated arachidonic acid (AA, [H-2(8)]20:4 n-6) 1-25 mu M, is conve rted to other fatty acids, as evaluated by gas chromatography-mass spe ctrometry, in THP-1 cells. The major products, in the 1 to 10 mu M ran ge, are 22:4 (elongated) and 20:3 (reduced in 5). At 25 mu M, 24:4, 24 :5 and 22:5 accumulate, with [H-2(8)]/[H-2(0)] ratios higher than in A A. At high AA concentration preferential conversion to elongated fatty acids with 5 unsaturations, through a 6 desaturase takes place and th e 4-desaturated 22:5 appears to be formed through B-oxidation of 24:5.