| Origin of hepatic very-low-density lipoprotein triacylglycerol: the contribution of cellular phospholipid. | |
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MedLine Citation:
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PMID: 8973583 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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When rat hepatocytes were cultured for 24 h in the absence of exogenous fatty acid, the amount of very-low-density lipoprotein (VLDL) triacylglycerol (TAG) secreted (114 +/- 14 micrograms/mg of cell protein) could not be accounted for by the mass of TAG lost from the cells (29 +/- 6.1 micrograms/mg of cell protein) during this period (n = 12). Of the balance (85 +/- 14 micrograms/mg; 94 +/- 15 nmol/mg), a maximum of only 37 nmol/mg of cell protein of TAG could be accounted for by fatty acids synthesized de novo. When labelled exogenous oleate (initial concentration, 0.75 nM) was present in the culture medium, the net gain in cellular plus VLDL TAG (253 +/- 38 micrograms/mg of cell protein per 24 h) was greater than that contributed by the exogenous fatty acid (155 +/- 18.2 micrograms/mg of cell protein, n = 5). Again, the balance (98.8 +/- 18.2 micrograms/mg of cell protein per 24 h) was too great to be accounted for by fatty acid synthesis de novo. In experiments in which cellular glycerolipids were prelabelled with [9, 10(n)-3H]oleic acid, following removal of the labelled fatty acid, there was a net increase in labelled cellular plus VLDL TAG over the next 24 h. That cellular phospholipids are the source of a substantial part of the excess TAG synthesized is supported by the following evidence. (1) The loss of prelabelled cellular phospholipid during culture was greater than could be accounted for by secretion into the medium. (2) During culture of cells prelabelled with 1,2-di-[l-14C]palmitoyl phosphatidylcholine, a substantial amount of label was secreted as VLDL TAG. (3) In pulse-chase experiments, the kinetics of labelled phospholipid turnover were consistent with conversion into a non-phospholipid pool. The enzymology involved in the transfer of phospholipid fatty acids into TAG is probably complex, but the present results suggest that this pathway may represent an important route by which extracellular fatty acids are channelled into VLDL TAG. |
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Authors:
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D Wiggins; G F Gibbons |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The Biochemical journal Volume: 320 ( Pt 2) ISSN: 0264-6021 ISO Abbreviation: Biochem. J. Publication Date: 1996 Dec |
Date Detail:
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Created Date: 1997-01-27 Completed Date: 1997-01-27 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 2984726R Medline TA: Biochem J Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 673-9 Citation Subset: IM |
Affiliation:
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Nuffield Department of Clinical Medicine, University of Oxford, Radclifle Infirmary. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Cells, Cultured Kinetics Lipoproteins, VLDL / biosynthesis* Liver / metabolism* Male Oleic Acid / metabolism Phospholipids / metabolism* Radioisotope Dilution Technique Rats Rats, Wistar Time Factors Triglycerides / biosynthesis* Tritium |
| Chemical | |
Reg. No./Substance:
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0/Lipoproteins, VLDL; 0/Phospholipids; 0/Triglycerides; 0/very low density lipoprotein triglyceride; 10028-17-8/Tritium; 112-80-1/Oleic Acid |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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