Metabolic fate of an oral tracer dose of 3c-docosahexaenoic acid
triglycerides in the rat.
Brossard, Nicole, Martine Croset, Jean Lecerf, Christiane Pachiaudi,
Sylvie Normand, V[acute]eronique Chirouze, Olga Macovschi, Jean Paul
Riou, Jean Louis Tayot, and Michel Lagarde.
INSERM U 352, Chimie Biologique INSA-Lyon, Villeurbanne, France;
INSERM U 197, Facult[acute]e de M[acute]edecine A. Carrel, Lyon,
France; 3IMEDEX, Z.I. Les Troques, Chaponost, France
APStracts 2:0290R, 1995.
The appearance of 13C-docosahexaenoic acid (13C-22:6n-3) in rat
lipoprotein, blood cell and brain lipids was followed as a function
of time after the ingestion of triglycerides (TG) containing 13C
-22:6n-3. The time course of 13C abundance in 22:6n-3 of various lipid
pools, measured by gas-chromatography combustion-isotope mass
spectrometry, established precursor-product relationships within
lipids. The 13C-22:6n-3 was rapidly incorporated into
VLDL/Chylomicron-TG and unesterified fatty acids bound to albumin,
with a concomitant maximal appearance at 3 h and further decline.
Lyso-phosphatidylcholines (lyso-PC) bound to albumin were also
enriched in 13C-22:6n-3 and their labeling appeared to be mainly due
to hepatic secretion at the earliest time points. From 12 h post
-ingestion, the synthesis of 13C-22:6n-3-lyso-PC was twice higher than
that of unesterified 13C-22:6n-3, making lyso-PC a potential source
of 22:6n-3 supply for tissues. The labeling of platelet, red cell and
brain phospholipids presented different kinetics, presumably
involving the two lipid forms of 13C-22:6n-3 bound to albumin, to
different extents. We conclude that 13C-22:6n-3 esterified in TG is
rapidly redistributed within blood lipoproteins and the albumin
fraction and that its incorporation in lipid species bound to albumin
influences its uptake by target tissues.
Received 24 April 1995; accepted in final form 18 October 1995.
APS Manuscript Number R244-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 14 November 95