METABOLISM OF [H-3] ARACHIDONIC-ACID BY N-3 POLYUNSATURATED FATTY ACID-ENRICHED PIGLET ALVEOLAR MACROPHAGES

The metabolism of [H-3]arachidonic acid (H-3-AA) by control and omega- 3 polyunsaturated fatty acid (n-3 PUFA)-enriched piglet alveolar macro phages (AM) was studied after a 4 and 24 h labeling period. H-3-AA met abolites were separated by gradient HPLC. Incorporation of exogenous H -3-AA for either 4 or 24 h was similar for n-3 PUFA-enriched AM compar ed with control AM. Calcium ionophore (A23187, 10 mu M) stimulated a g reater release of H-3-AA from n-3 PUFA-enriched AM compared with contr ol AM. Furthermore, AM labeled for 24 h had a lower spontaneous releas e and higher stimulated release than those labeled for only 4 h. The m ajor H-3-AA metabolites detected in AM supernatants were PGF(2 alpha), LTB(4), and 5-HETE. Significant amounts of H-3-PGE(2) were observed i n the supernatants of those cells labeled for 24 h, but not 4 h. The a bsence of H-3-TXB(2) was notable, since enzyme immunoassay detected si gnificant quantities of this AA metabolite in all of the stimulated ce ll supernatants. From these data we conclude that n-3 PUFA enrichment of piglet AM alters the metabolism of recently incorporated H-3-AA and that the metabolism of labeled AA may not parallel endogenous AA.