| Metabolic flux analysis of hepatocyte function in hormone- and amino acid-supplemented plasma. | |
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MedLine Citation:
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PMID: 12749840 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Understanding the metabolic and regulatory pathways of hepatocytes is important for biotechnological applications involving liver cells. Previous attempts to culture hepatocytes in plasma yielded poor functional results. Recently we reported that hormone (insulin and hydrocortisone) and amino acid supplementation reduces intracellular lipid accumulation and restores liver-specific function in hepatocytes exposed to heparinized human plasma. In the current study, we performed metabolic flux analysis (MFA) using a simplified metabolic network model of cultured hepatocytes to quantitively estimate the changes in lipid metabolism and relevant intracellular pathways in response to hormone and amino acid supplementation. The model accounts for the majority of central carbon and nitrogen metabolism, and assumes pseudo-steady-state with no metabolic futile cycles. We found that beta-oxidation and tricarboxylic acid (TCA) cycle fluxes were upregulated by both hormone and amino acid supplementation, thus enhancing the rate of lipid oxidation. Concomitantly, hormone and amino acid supplementation increased gluconeogenic fluxes. This, together with an increased rate of glucose clearance, caused an increase in predicted glycogen synthesis. Urea synthesis was primarily derived from ammonia and aspartate generated through transamination reactions, while exogenous ammonia removal accounted for only 3-6% of the urea nitrogen. Amino acid supplementation increased the endogenous synthesis of oxaloacetate, and in turn that of aspartate, a necessary substrate for the urea cycle. These findings from MFA provide cues as to which genes/pathways relevant to fatty acid oxidation, urea production, and gluconeogenesis may be upregulated by plasma supplementation, and are consistent with current knowledge of hepatic amino acid metabolism, which provides further credence to this approach for evaluating the metabolic state of hepatocytes under various environmental conditions. |
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Authors:
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Christina Chan; François Berthiaume; Kyongbum Lee; Martin L Yarmush |
Publication Detail:
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Type: Comparative Study; Evaluation Studies; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.; Validation Studies |
Journal Detail:
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Title: Metabolic engineering Volume: 5 ISSN: 1096-7176 ISO Abbreviation: Metab. Eng. Publication Date: 2003 Jan |
Date Detail:
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Created Date: 2003-05-16 Completed Date: 2004-01-22 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 9815657 Medline TA: Metab Eng Country: United States |
Other Details:
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Languages: eng Pagination: 1-15 Citation Subset: IM |
Affiliation:
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Center For Engineering in Medicine/Surgical Services, Massachusetts General Hospital, Harvard Medical School, and The Shriners Hospitals for Children, 55 Fruit Street, Bigelow 1401, Boston, MA 02114, USA. ireis@sbi.org |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Albumins
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biosynthesis Amino Acids / pharmacology* Ammonia / metabolism Animals Cell Culture Techniques / methods* Cells, Cultured Computer Simulation Energy Metabolism / physiology Female Hepatocytes / cytology, drug effects, metabolism* Hormones / metabolism, pharmacology* Humans Hydrocortisone / metabolism, pharmacology Insulin / metabolism, pharmacology Lipid Metabolism* Models, Biological* Plasma / metabolism* Rats Rats, Inbred Lew Triglycerides / metabolism Urea / metabolism |
| Grant Support | |
ID/Acronym/Agency:
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R01 DK 41709/DK/NIDDK NIH HHS; R01GM 07035/GM/NIGMS NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Albumins; 0/Amino Acids; 0/Hormones; 0/Triglycerides; 11061-68-0/Insulin; 50-23-7/Hydrocortisone; 57-13-6/Urea; 7664-41-7/Ammonia |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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