出版社：American Society for Biochemistry and Molecular Biology
摘要：We quantified the rates of incorporation of -linolenic acid(-LNA; 18:3n-3) into "stable" lipids (triacylglycerol, phospholipid,cholesteryl ester) and the rate of conversion of -LNA to docosahexaenoicacid (DHA; 22: 6n-3) in the liver of awake male rats on a high-DHA-containingdiet after a 5-min intravenous infusion of [1-14C]-LNA. At 5min, 72.7% of liver radioactivity (excluding unesterified fattyacid radioactivity) was in stable lipids, with the remainderin the aqueous compartment. Using our measured specific activityof liver -LNA-CoA, in the form of the dilution coefficient -LNA-CoA,we calculated incorporation rates of unesterified -LNA intoliver triacylglycerol,phospholipid, and cholesteryl ester as2,401, 749, and 9.6 nmol/s/g x 10–4, respectively, correspondingto turnover rates of 3.2, 8.7, and 2.9%/min and half-lives of8–24 min. A lower limit for the DHA synthesis rate from-LNA equaled 15.8 nmol/s/g x 10–4 (0.5% of the net incorporation rate). Thus, in rats on a high-DHA-containing diet,rates of ß-oxidation and esterification of -LNA intostable liver lipids are high, whereas its conversion to DHAis comparatively low and insufficient to supply significantDHA to the brain. High incorporation and turnover rates likelyreflect a high secretion rate by liver of stable lipids withinvery low density lipoproteins.Supplementary key words incorporation • turnover • synthesis • pulse labeling • infusion • diet
Abbreviations: DHA, docosahexaenoic acid (22:6n-3); di-17:0 PC, di-heptadecanoate phosphatidylcholine; EPA, eicosapentaenoic acid (20:5n-3); FAME, fatty acid methyl ester; LA, linoleic acid (18:2n-6); -LNA, -linolenic acid (18:3n-3)
-linolenic acid (
