Hepatic lipase-mediated hydrolysis versus liver uptake of HDL phospholipids and triacylglycerols by the perfused rat liver

Détails

ID Serval
serval:BIB_C533CE23AC82
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Hepatic lipase-mediated hydrolysis versus liver uptake of HDL phospholipids and triacylglycerols by the perfused rat liver
Périodique
Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism
Auteur(s)
Marques-Vidal Pedro, Azéma Christine, Collet Xavier, Chap Hugues, Perret Bertrand P.
ISSN
0005-2760
ISSN-L
1879-145X
Statut éditorial
Publié
Date de publication
03/1991
Peer-reviewed
Oui
Volume
1082
Numéro
2
Pages
185-194
Langue
anglais
Notes
Publication types: Journal Article
Publication Status: ppublish
Résumé
Hepatic triacylglycerol-lipase-mediated hydrolysis and liver uptake of high-density lipoprotein (HDL) lipid components were studied in a recirculating rat liver perfusion, a situation where the enzyme is physiologically expressed and active at the vascular bed. Human native HDL were labelled with tri-[3H]oleoylglycerol, [N-methyl-3H]dipalmitoylphosphatidylcholine (DPPC), 1-palmitoyl,2-[14C]linoleoylphosphatidylcholine (PLPC), 1-palmitoyl,2-[14C]linoleoylphosphatidyl-ethanolamine (PLPE) and 1-palmitoyl,2-[14C]palmitoylphosphatidylethanolamine (DPPE). (1) Relative degradation rates of phosphatidylethanolamine molecular species were 2- to 10-fold higher than those of phosphatidylcholine. Considering [14C] PLPC and [14C] PLPE as representative of HDL phosphatidylcholine and phosphatidylethanolamine, respectively, the amounts of lysophosphatidylcholine and lysophosphatidylethanolamine generated after a 60 min perfusion were comparable. The enzyme showed a clear preference for the molecular species bearing an unsaturated fatty acid at the 2 position of glycerol; this was the most pronounced in the case of phosphatidylethanolamine molecular species. (2) Relative liver uptake of HDL-phosphatidylethanolamine was 4- to 5-fold higher than that of HDL-phosphatidylcholine, irrespective of the constitutive fatty acids. Nevertheless, mass estimation indicated that 3 times more molecules of phosphatidylcholine than of phosphatidylethanolamine were transferred. No correlation could be found between the relative degradation rates of phospholipids and their relative liver uptake, indicating a dissociation between the two processes. (3) Perfusate decay and relative liver uptake of labelled HDL-triacylglycerol were higher than that of any phospholipid class. No circulating radiolabelled free fatty acids accumulated in the perfusate, but they were found acylated into liver cell phospholipids and triacylglycerols. (4) A prior 10-12-min washout of the liver vascular bed with heparin removed over 80% of the hepatic lipase activity, as assessed by specific immunoinhibition. Hepatic lipase-depleted liver displayed impaired phospholipid hydrolysis and triacyglycerol uptake, whereas the transfer of HDL phospholipids to liver tissue was unaffected.
Mots-clé
Cholesterol, HDL/metabolism, Lipase/blood, Liver/enzymology, Liver/metabolism, Phosphatidylcholines/metabolism, Phosphatidylethanolamines/metabolism, Phospholipids/metabolism, Triglycerides/metabolism, Biophysics, Biochemistry, Endocrinology
Pubmed
Web of science
Création de la notice
01/12/2016 16:02
Dernière modification de la notice
03/03/2018 21:15
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