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Lipids of myocardial membranes: Susceptibility of a fraction enriched in sarcolemma to hydrolysis by an exogenous mammalian phospholipase A 2
Author(s) -
Owens K.,
Pang D. C.,
Franson R. C.,
Weglicki W. B.
Publication year - 1980
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02534226
Subject(s) - sarcolemma , lipidology , clinical chemistry , membrane , chemistry , hydrolysis , fraction (chemistry) , phospholipase , biochemistry , chromatography , biophysics , enzyme , biology
A myocardial membrane fraction enriched in sarcolemma was used to determine the susceptibility of the lipids to hydrolysis by a phospholipase A 2 from granulocytes. After incubation (37 C, pH 7.0, 5 mM Ca 2+ ) with the phospholipase A 2 for 30 min, a more than 3‐fold increase in unesterified fatty acids was found (up to 47 nmol/mg protein; P<0.001) relative to a control incubated without phospholipase A 2 or Ca 2+ . This included a 10‐fold increase in the arachidonic acid content (up to 42 mol %) and at least a 7‐fold increase in lysophosphatidylethanolamine (up to 7.4 mol% total phospholipid‐P). However, the exogenous phospholipase did not augment the quantity of lysophosphatidylcholine produced by endogenous phospholipases in the presence of Ca 2+ (5 mM). These results demonstrate the in vitro susceptibility of phospholipids of myocardial membranes, particularly phosphatidylethanolamine, to the neutral‐active, Ca 2+ ‐dependent phospholipase A 2 from granulocytes. This work may be relevant to myocardial inflammation and tissue damage during ischemia, where heterolytic injury of the myocardium may occur subsequent to the accumulation of granulocytes.