Ionophore-induced metabolism of phospholipids and eicosanoid production in porcine aortic endothelial cells: selective release of arachidonic acid from diacyl and ether phospholipids |
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Authors: | M L Brown J A Jakubowski L L Leventis D Deykin |
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Institution: | Department of Medicine and Biochemistry, Boston University School of Medicine, MA. |
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Abstract: | Confluent cultures of porcine aortic endothelial cells were prelabeled with 1 microM 14C]arachidonic acid complexed to 1 microM bovine serum albumin. After washing, the cells were stimulated with 1 microM A23187 for time intervals between 30 s and 30 min. Cellular lipids were extracted and separated into major lipid classes and phospholipid subclasses. The external medium was analyzed for released radioactive eicosanoids. The time-course of total release of 14C radioactivity demonstrated a biphasic nature of A23187-induced changes in endothelial cell lipids. Early, from 30 s to 5 min, substantial losses of 14C]arachidonic acid from diacylphosphatidylethanolamine and phosphatidylinositol, as well as an abrupt increase in diacylphosphatidylcholine-associated radioactivity were observed. These initial changes coincided with the release of 14C-labeled cyclooxygenase products. Later changes (5-30 min) included a sustained progressive loss of 14C radioactivity from alkenyl (alk-1-enyl) acylphosphatidylethanolamine and diacylphosphatidylcholine. These later changes coincided with the elaboration of 14C-labeled lipoxygenase products. Although unequivocal assignments cannot be made, the data suggest that specific pools of arachidonic acid provide precursors for individual classes of eicosanoids. |
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