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

Details

Serval ID
serval:BIB_C533CE23AC82
Type
Article: article from journal or magazin.
Collection
Publications
Title
Hepatic lipase-mediated hydrolysis versus liver uptake of HDL phospholipids and triacylglycerols by the perfused rat liver
Journal
Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism
Author(s)
Marques-Vidal Pedro, Azéma Christine, Collet Xavier, Chap Hugues, Perret Bertrand P.
ISSN
0005-2760
ISSN-L
1879-145X
Publication state
Published
Issued date
03/1991
Peer-reviewed
Oui
Volume
1082
Number
2
Pages
185-194
Language
english
Notes
Publication types: Journal Article
Publication Status: ppublish
Abstract
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.
Keywords
Cholesterol, HDL/metabolism, Lipase/blood, Liver/enzymology, Liver/metabolism, Phosphatidylcholines/metabolism, Phosphatidylethanolamines/metabolism, Phospholipids/metabolism, Triglycerides/metabolism, Biophysics, Biochemistry, Endocrinology
Pubmed
Web of science
Create date
01/12/2016 15:02
Last modification date
20/08/2019 15:40
Usage data