| Calcium-independent phospholipase A2 in isolated rabbit ventricular myocytes. | |
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MedLine Citation:
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PMID: 9930406 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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We characterized phospholipase A2 (PLA2) activity in isolated rabbit ventricular myocytes with respect to subcellular distribution, substrate specificity, and Ca2+ dependency. Membrane-associated PLA2 was found to be an order of magnitude greater than cytosolic PLA2. Ventricular myocyte PLA2 activity was enhanced following protease-activated receptor stimulation with thrombin and was found to be largely Ca2+-independent and selective for phospholipid substrates containing arachidonic acid at the sn-2 position. Immunoblot analysis using an antibody to cytosolic Ca2+-independent PLA2 from Chinese hamster ovary cells recognized a membrane-associated protein with a molecular mass of approximately 80 kDa; however, differences in pH optima, response to inhibitors, and substrate selectivity of membrane-associated and cytosolic PLA2 activity suggest the presence of multiple Ca2+-independent PLA2. Pretreatment with bromoenol lactone, a specific inhibitor of Ca2+-independent PLA2, significantly attenuated membrane-associated and cytosolic PLA2 in unstimulated and thrombin-stimulated myocytes. Pretreatment with methyl arachidonyl fluorophosphonate, mepacrine, or dibucaine had no significant effect on PLA2 activity under all conditions tested. Ventricular myocyte PLA2 activity was significantly inhibited by ATP, GTP, and their nonhydrolyzable analogs and was regulated by protein kinase C activity. These studies demonstrate the presence of one or more unique membrane-associated Ca2+-independent PLA2 in isolated ventricular myocytes that exhibit a preference for phospholipids with arachidonate at the sn-2 position and that are activated by thrombin stimulation. |
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Authors:
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J McHowat; M H Creer |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Lipids Volume: 33 ISSN: 0024-4201 ISO Abbreviation: Lipids Publication Date: 1998 Dec |
Date Detail:
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Created Date: 1999-03-30 Completed Date: 1999-03-30 Revised Date: 2007-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0060450 Medline TA: Lipids Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 1203-12 Citation Subset: IM |
Affiliation:
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Department of Pathology, St. Louis University School of Medicine, Missouri 63104, USA. mchowatj@slucare1.sluh.edu |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals CHO Cells Calcium / metabolism* Cricetinae Enzyme Activation Enzyme Stability Female Heart Ventricles / drug effects, enzymology* Phospholipases A / metabolism* Phospholipases A2 Protease Inhibitors / pharmacology Rabbits Recombinant Proteins / metabolism Subcellular Fractions / enzymology Substrate Specificity |
| Grant Support | |
ID/Acronym/Agency:
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HL54907-01/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Protease Inhibitors; 0/Recombinant Proteins; 7440-70-2/Calcium; EC 3.1.1.-/Phospholipases A; EC 3.1.1.4/Phospholipases A2 |
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