Document Detail


Characterization of phospholipase A2 activity in rat aorta smooth muscle cells.
MedLine Citation:
PMID:  6824708     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Phospholipase A activity was measured in homogenates and acid extracts of smooth muscle cells from rat aorta and mesenteric artery using [1-14 C]oleate-labeled autoclaved Escherichia coli and 1-[1-14C]stearyl-2-acyl-3-sn-glycerophosphorylethanolamine as substrates. The results demonstrate the presence of neutral-active phospholipase(s) A that exclusively catalyze the release of fatty acid from the 2-position of phospholipids. Optimal activity was at pH 7.5, and there was an absolute requirement for low concentrations of Ca2+. Mg2+ did not substitute for Ca2+, and EGTA inhibited the activity. Phospholipase A2 activity was predominantly membrane-associated and was solubilized by homogenization in 0.18 N H2SO4. Sulfuric acid extracts of rat aortic smooth muscle cells were four times more active than extracts of mesenteric artery (710 vs. 170 nmol/h per mg protein). By comparison, acid extracts of rat lung, heart, and liver were less active (60-75 nmol/h per mg). Indomethacin, sodium meclofenamate, mepacrine and chlorpromazine, but not dexamethasone or aspirin, inhibited acid-solubilized phospholipase(s) A2 between 10(-6) and 10(-3) M in a dose-dependent manner. Preincubation with p-bromophenacyl bromide or diethylpyrocarbonate inhibited phospholipase(s) A2, suggesting the presence of a histidine residue at the active site. An extract from the leaves of feverfew plant (Tanacetum parthenium) was also a potent inhibitor of aortic smooth muscle phospholipase(s) A2.
Authors:
J K Thakkar; N Sperelakis; D Pang; R C Franson
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  750     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  1983 Jan 
Date Detail:
Created Date:  1983-04-15     Completed Date:  1983-04-15     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  134-40     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Animals
Aorta / enzymology
Hydrogen-Ion Concentration
Kinetics
Liver / enzymology
Lung / enzymology
Mesenteric Arteries / enzymology
Muscle, Smooth, Vascular / enzymology*
Myocardium / enzymology
Organ Specificity
Phospholipases / metabolism*
Phospholipases A / metabolism*
Phospholipases A2
Plants, Medicinal
Rats
Sesquiterpenes
Tanacetum parthenium
Grant Support
ID/Acronym/Agency:
HL-07244/HL/NHLBI NIH HHS; HL-19242/HL/NHLBI NIH HHS; HL-24907/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
0/Sesquiterpenes; EC 3.1.-/Phospholipases; EC 3.1.1.-/Phospholipases A; EC 3.1.1.4/Phospholipases A2

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