| Phosphatidylethanol stimulates calcium-dependent cytosolic phospholipase A(2) activity of a macrophage cell line (RAW 264.7). | |
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MedLine Citation:
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PMID: 10895054 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The synthesis of inflammation mediators produced from arachidonic acid is regulated primarily by the cellular concentration of free arachidonic acid. Since intracellular arachidonic acid is almost totally present as phospholipid esters, the concentration of intracellular arachidonic acid is primarily dependent on the balance between the release of arachidonic acid from membrane phospholipids and the uptake of arachidonic acid into membrane phospholipids. Cytosolic phospholipase A(2) is a calciumdependent enzyme that catalyzes the stimulus-coupled hydrolysis of arachidonic acid from membrane phospholipids. Following exposure of macrophages to various foreign or endogenous stimulants, cytosolic phospholipase A(2) is activated. Treatment with these compounds may also stimulate phospholipase D activity, and, in the presence of ethanol, phospholipase D catalyzes the synthesis of phosphatidylethanol. A cell-free system was used to evaluate the effect of phosphatidylethanol on cytosolic phospholipase A(2) activity. Phosphatidylethanol (0.5 microM) added to 1-stearoyl-2-[(3)H]-arachidonoyl-sn-glycero-3-phosphocholine vesicles stimulated cytosolic phospholipase A(2) activity. However, high concentrations (20-100 microM) of phosphatidylethanol inhibited cytosolic phospholipase A(2) activity. Phosphatidic acid, the normal phospholipase D product, also stimulated cytosolic phospholipase A(2) activity at 0.5 microM, but had an inhibitory effect on cytosolic phospholipase A(2) activity at concentrations of 50 and 100 microM. Ethanol (20-200 mM), the precursor of phosphatidylethanol, added directly to the assay did not alter cytosolic phospholipase A(2) activity. These results suggest that phosphatidylethanol alters the physical properties of the substrate, and at lower concentrations of anionic phospholipids the substrate is more susceptible to hydrolysis. However, at high concentrations, phosphatidylethanol either reverses the alterations in physical properties of the substrate or phosphatidylethanol may be competing as the substrate. Both interactions may result in lower cytosolic phospholipase A(2) activity. |
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Authors:
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C Y Chang; K R Farrell; R C Baker |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Journal of biomedical science Volume: 7 ISSN: 1021-7770 ISO Abbreviation: J. Biomed. Sci. Publication Date: 2000 Jul-Aug |
Date Detail:
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Created Date: 2000-08-21 Completed Date: 2000-08-21 Revised Date: 2003-11-14 |
Medline Journal Info:
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Nlm Unique ID: 9421567 Medline TA: J Biomed Sci Country: SWITZERLAND |
Other Details:
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Languages: eng Pagination: 311-6 Citation Subset: IM |
Copyright Information:
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Copyright 2000 National Science Council, ROC and S. Karger AG, Basel |
Affiliation:
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Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS 39216, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Arachidonic Acid / metabolism Calcium / metabolism* Cell Extracts Chelating Agents / pharmacology Cytosol / drug effects, enzymology* Enzyme Activation / drug effects Ethanol / pharmacology Glycerophospholipids / pharmacology* Hydrolysis / drug effects Kinetics Liposomes / chemistry, drug effects, metabolism Macrophages / cytology, enzymology* Mice Phosphatidic Acids / pharmacology Phosphatidylcholines / metabolism Phospholipases A / metabolism* Tumor Cells, Cultured |
| Chemical | |
Reg. No./Substance:
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0/Cell Extracts; 0/Chelating Agents; 0/Glycerophospholipids; 0/Liposomes; 0/Phosphatidic Acids; 0/Phosphatidylcholines; 0/phosphatidylethanol; 506-32-1/Arachidonic Acid; 64-17-5/Ethanol; 7440-70-2/Calcium; EC 3.1.1.-/Phospholipases A |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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