Influence of dietary fat on metabolism of (14-14C)erucic acid in the perfused rat liver. Distribution of metabolites in lipid classes |
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Authors: | Gunhild Hølmer Ragnhild Rønneberg |
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Affiliation: | (1) Department of Biochemistry and Nutrition, Technical University of Denmark, Lyngby, Denmark;(2) Directorate of Fisheries, Institute of Nutrition, Bergen, Norway |
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Abstract: | Two groups of rats were fed diets containing 20% by weight of either partially hydrogenated marine oil supplemented with sunflower
seed oil (PHMO) or palm oil (PO) for 8 wk. Using a liver perfusion system, the effect of dietary long chain monoenoic fatty
acids on the uptake and metabolism of 14-14C]erucic acid was studied. The perfusion times were 15 and 60 min, respectively. The two groups showed equal ability for erucic
acid uptake in the liver but differed in the channeling of the fatty acids into various metabolic pathways. A higher metabolic
turnover of 22∶1 in the PHMO livers relative to the PO livers was demonstrated by an increased recovery of total 14C]labeling in the triglyceride (TG) and phospholipid (PL) fractions, already evident after 15 min of perfusion. The chainshortening
capacity was highest in the PHMO group, reflected by a higher 14C]18∶1 incorporation in both TG and PL, and increasing from 15 to 60 min of perfusion. The amount of 14C]18∶1 found in PL and TG after 60 min of perfusion of livers from rats fed PO corresponded to that shown for the PHMO group
after 15 min. The PL demonstrated a discrimination against 22∶1 compared to TG, and, when available, 18∶1 was highly preferred
for PL-synthesis.
The total fatty acid distribution in the TG, as determined by gas liquid chromatography (GLC), reflected the composition of
the dietary fats. In the total liver PL, 22∶1 and 20∶1 were present in negligible amounts, although the PHMO diet contained
12–13% of both 22∶1 and 20∶1. In the free fatty acid fraction (FFA), the major part of the radioactivity (≈80%) was 14-14C]erucic acid, and only small amounts of 14C]18∶1(<2%) were presents, even after 60 min of perfusion. The shortened-chain 18∶1 was readily removed from the FFA pool
and preferentially used for lipid esterification. |
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