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Esterification of 8,11,14‐eicosatrienoate and arachidonate into alkylacyl‐ and diacylglycerophosphocholine by vascular endothelial cells
Author(s) -
Rosenthal Miriam D.,
Brown Morris E.,
Jones Janet E.
Publication year - 1988
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/bf02535658
Subject(s) - arachidonic acid , chemistry , phospholipase a2 , biochemistry , phospholipase , platelet activating factor , hydrolysis , phospholipid , polyunsaturated fatty acid , glycerophospholipids , fatty acid , chromatography , biology , enzyme , membrane , endocrinology
Agonist‐stimulated phospholipases release arachidonate, but not 8,11,14‐eicosatrienoate, from human endothelial cells. One source of the arachidonic acid is deacylation of 1‐alkyl‐2‐arachidonoyl‐glycerophosphocholine, with subsequent conversion of some of the resultant lysophospholipid to platelet‐activating factor. This study has compared the distribution of incorporated 8,11,14‐[ 14 C]‐eicosatrienoate in alkylacyl‐GPC and diacyl‐GPC with that of [ 14 C]arachidonate synthesized endogenously by desaturation of the 8,11,14‐[ 14 C]eicosatrienoate. Cells were incubated for 24 or 48 hr with 8,11,14‐[ 14 C]eicosatrienoate, and the resultant mixture of 14 C‐fatty acids in the cellular lipids was characterized by gas chromatography. The choline phospholipids were then separated, hydrolyzed with phospholipase C and derivatized to diradylbenzoates. Gas chromatographic analysis indicated extensive incorporation of [ 14 C]eicosatrienoate, as well as [ 14 C]arachidonate, into alkylacyl‐GPC. Although the ratio of esterified [ 14 C]arachidonate to [ 14 C]eicosatrienoate was greater in alkylacyl‐GPC than in diacyl‐GPC, the enrichment with [ 14 C]arachidonate was far less than the ratio of arachidonate/eicosatrienoate released from these cells. These results thus support the hypothesis that the acyl specificity of polyunsaturated fatty acid release is provided by the agonist‐stimulated phospholipase A 2 rather than the composition of the alkylacyl‐GPC.