Metabolic fate of an oral tracer dose of [13C]docosahexaenoic acid triglycerides in the rat.
The appearance of 13C in rat lipoprotein, blood cells, 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 very low density lipoprotein-chylomicron-TG and unesterified fatty acids bound to albumin, with a concomitant maximal appearance at 3 h and further decline. Lysophosphatidylcholines (lysoPC) 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 postingestion, the synthesis of [13C]22:6n-3-lysoPC was twice as high as that of unesterified [13C]22:6n-3, making lysoPC a potential source of 22:6n-3 supply for tissues. The labeling of platelets, red blood cells, 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.
Brossard
N
N
Institut National de la Santé et de la Recherche Médicale (INSERM) U 352, Chimie Biologique, Institut National des Sciences Appliquées-Lyon, Villeurbanne, France.
Croset
M
M
Lecerf
J
J
Pachiaudi
C
C
Normand
S
S
Chirouze
V
V
Macovschi
O
O
Riou
J P
JP
Tayot
J L
JL
Lagarde
M
M
D000284:Administration, Oral; D000818:Animals; D001773:Blood Cells / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D002247:Carbon Isotopes; D004281:Docosahexaenoic Acids / Q000378:metabolism*; D008055:Lipids / Q000096:biosynthesis; D008074:Lipoproteins / Q000096:biosynthesis; D008297:Male; D010743:Phospholipids / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012709:Serum Albumin / Q000096:biosynthesis; D013997:Time Factors; D014280:Triglycerides / Q000378:metabolism*
D002247:Carbon Isotopes; D008055:Lipids; D008074:Lipoproteins; D010743:Phospholipids; D012709:Serum Albumin; D014280:Triglycerides; D004281:Docosahexaenoic Acids