AbstractIncorporation of exogenous 14C arachidonate by human skin fibroblasts was found to be significantly greater than that of either 14C linoleate or α‐14C linolenate. Arachidonate was preferentially esterified in the PI + PS and PE classes of phospholipids. Over 40 of the incorporated 14C arachidonate was chain elongated in 24 hours. Cells were also grown in lipid‐free medium to enhance PUFA desaturation and elongation and the utilization of various ω 6 and ω 3 metabolites examined. Whereas 14C linoleate partitioned approximately 50:50 between PL and TAG, eicosatrienoate (20:3 ω 6) was selectively sequestered in TAG. Arachidonate and docosatetraenoate (22:4 ω 6) were preferentially incorporated into phospholipids; the PI + PS fraction was most highly enriched with arachidonate. Modification of α‐14C linolenate was more extensive than that of 14C linoleate. Docosapentaenoate (22:5 ω 3) was the major ω 3 14C PUFA of PI + PS and PE. Eicosapentaeonate was not selectively incorporated into phospholipids; within phospholipids the 20:5 ω 3 was primarily in PC. These results indicate that human skin fibroblasts exhibit acyl specificity in the esterification of polyunsaturated fatty acids, including preferential utilization of arachidonate rather than other prostaglandin precursors in the PI
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