Extensive incorporation of dietary δ-5,11,14 eicosatrienoate into the phosphatidylinositol pool

The acyl composition of phosphatidylinositol (PI) is remarkably resistant to dietary fatty acid modification. To investigate the basis of this selectivity, we have probed fatty acids lacking the usual methylene interrupted double bonds. When mice were fed Δ-5,11,14 20:3 as 3% of total lipid, this fatty acid, lacking the Δ-8 double bond essential for eicosanoid synthesis, replaced a significant quantity of 20:4(n - 6) in PI, but not PC and PE. By altering the acyl composition of PI, novel second messengers may be formed. This fatty acid structure thus provides a unique nutritional tool for investigating the basis of PI acyl specificity, and for determining the metabolic consequences of acyl alteration, in vivo.