Ionophore-induced metabolism of phospholipids and eicosanoid production in porcine aortic endothelial cells: selective release of arachidonic acid from diacyl and ether phospholipids

Brown, Michael L.; Jakubowski, Joseph A.; Leventis, Lynn L.; Deykin, Daniel

doi:10.1016/0005-2760(87)90014-2

Cited by 39 publications

(9 citation statements)

References 22 publications

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“…Over 63% of plasmenylethanolamine molecular species in rabbit aorta contain arachidonic acid esterified to the sn-2 position as ascertained by capillary gas chromatography, fast atom bombardment mass spectrometry, and reverse-phase HPLC. Although plasmenylethanolamines are an important storage depot for arachidonic acid in other tissues such as platelets, Madin-Darby kidney cells, and endothelial cells (19)(20)(21), the fact that plasmenylethanolamines represent the major phospholipid storage depot for arachidonic acid in vascular smooth muscle cells has previously gone unrecognized. Furthermore, the loss of arachidonic acid from plasmenylethanolamine during angiotensin II stimulation suggests an important biologic role for plasmenylethanolamine molecular species as substrates for the phospholipases that are activated during signal transduction in smooth muscle cells.…”

Section: Discussionmentioning

confidence: 99%

Plasmenylethanolamine is the major storage depot for arachidonic acid in rabbit vascular smooth muscle and is rapidly hydrolyzed after angiotensin II stimulation.

Ford

Gross²

1989

Proc. Natl. Acad. Sci. U.S.A.

108

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The present study demonstrates that rabbit aortic intimal smooth muscle cells contain the majority of their endogenous arachidonic acid mass in plasmenylethanolamine molecular species. To demonstrate the potential significance of these plasmenylethanolamines as substrates for the smooth muscle cell phospholipases that are activated during agonist stimulation, aortic rings were prelabeled with [3H]arachidonic acid and stimulated with angiotensin II. Although the specific activities of the choline and inositol glycerophospholipid pools were similar after the labeling interval, ethanolamine glycerophospholipids had a specific activity of only 20% of the specific activity of choline and inositol glycerophospholipids. Despite the marked disparity in the specific activities of these three phospholipid classes, angiotensin II stimulation resulted in similar fractional losses (35-41%) of [3lljarachidonic acid from vascular smooth muscle choline, ethanolamine, and inositol glycerophospholipid classes. Reverse-phase HPLC demonstrated that >60% of the [3H]arachidonic acid released from ethanolamine glycerophospholipids after angiotensin II stimulation originated from plasmenylethanolamine molecular species. Taken together, the results demonstrate that the major phospholipid storage depot for arachidonic acid in vascular smooth muscle cells are plasmenylethanolamine molecular species which are important substrates for the phospholipase(s) that are activated during agonist stimulation.Icosanoids are important regulators of vascular smooth muscle cell contractile state, hypertrophy, and proliferation (1-6). Accordingly, significant attention has focused on the biochemical events responsible for the liberation of arachidonic acid from endogenous smooth muscle cell lipids during signal transduction. Arachidonic acid release from cellular phospholipids may occur directly in a single catalytic step by the action of phospholipase A2 or by a multistep sequential pathway initiated by phospholipase C and culminated by the sequential actions of diglyceride and monoglyceride lipases (7)(8)(9). Although recent studies demonstrated that radiolabeled arachidonic acid was released from choline, ethanolamine, and inositol glycerophospholipid in cultured smooth muscle cell pools after agonist stimulation, quantification of the amount of released radiolabeled arachidonic acid from each pool suggested that different phospholipid classes were primarily responsible for radiolabeled arachidonic acid release (10-13). Since the biochemical and physiologic properties of cultured smooth muscle cells differ substantially from properties of vascular smooth muscle cells in intact tissue, the present study was performed to assess the distribution of arachidonic acid mass in phospholipids and the fractional turnover of individual phospholipid molecular species in intact vascular smooth muscle. The results demonstrate that the majority of arachidonic acid mass in vascular smooth muscle is present in plasmenylethanolamine molecular species and that ...

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Section: Discussionmentioning

confidence: 99%

Plasmenylethanolamine is the major storage depot for arachidonic acid in rabbit vascular smooth muscle and is rapidly hydrolyzed after angiotensin II stimulation.

Ford

Gross²

1989

Proc. Natl. Acad. Sci. U.S.A.

108

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“…We have hypothesized that arachidonic acid released from diacyl PE and from PI was used by cyclooxygenase and that arachidonic acid originating from diacyl PC and alkenyl PE gave rise to 15-HETE. 6 In contrast, Colard et al 24 observed that agonist-induced release of arachidonic acid in platelets did not proceed directly from diacyl PC but was preceded by a transfer of arachidonic acid from diacyl PC to primarily diacyl PE before release.…”

Section: Discussionmentioning

confidence: 99%

“…We have previously shown that in fourth-passage PAECs prelabeled with l-[ 14 C]arachidonic acid, stimulation with A23187 led to a rapid loss of radiolabel from PI and diacyl PE. 6 This time course coincided with the appearance of radiolabeled 6-keto-PGF la and several other cyclooxygenase-derived products. Later in the time course, significant losses of [ 14 C]arachidonic acid from alkenyl PE and diacyl PC corresponded to the appearance of 15-HETE and other minor lipoxygenase products.…”

Section: Discussionmentioning

confidence: 99%

“…6 Fatty acid methyl esters were prepared by heating the individual phospholipids (with an internal standard, 17:0, added for quantification of mass) at 90°C for 1 hour in 6% acetyl chloride in methanol. After addition of a second internal standard to monitor recovery (15:0 methyl ester), the preparation was dried under N 2 and redissolved in hexane, and an aliquot was injected into a PerkinElmer Model 3500 gas chromatograph (PerkinElmer Corp., Norwalk, Conn.).…”

Section: Fatty Acid Analysismentioning

confidence: 99%

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Passage state affects arachidonic acid content and eicosanoid release in porcine aortic endothelial cells.

Brown

Deykin

1991

Arterioscler Thromb

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Porcine aortic endothelial cells were cultured through four passages from primary cultures. The arachidonic acid content of individual phospholipid classes and the release of 6-keto-prostaglandin F la and 15-hydroxyeicosatetraenoic acid in response to 1 /tM ionophore A23187 were assayed at each passage. The content of arachidonic acid in phosphatidylinositol and diacyl phosphatidylethanolamine remained constant at passage 1 but declined at passage 2 by approximately 29% and at passage 4 by approximately 59%. The release of 6-keto-prostaglandin F la was also unchanged at passage 1 but decreased by 60% at passage 2 and by 82% from its original value at passage 4. In contrast, the arachidonic acid content of diacyl phosphatidylcholine and of alkenyl phosphatidylethanolamine decreased with each passage, by 34% at passage 1, 59% at passage 2, 71% at passage 3, and 76% of the original value at passage 4. Stimulation with arachidonic acid reversed the passage effect. The release of 15-hydroxyeicosatetraenoic acid decreased by 82% at passage 1 and diminished to a 97% decrement from the original value by passage 4. When stimulated with arachidonic acid, 15-hydroxyeicosatetraenoic acid steadily decreased by approximately 70% at passages 3 and 4. The data indicate that passage state strikingly and nonuniformly affects phospholipid class arachidonic acid content and eicosanoid release in response to agonist stimulation. (Arteriosclerosis and Thrombosis 1991;11:167-173) E ndothelial cells possess the ability to release metabolites of arachidonic acid, including prostacyclin (PGI 2 ) and 15-hydroxyeicosatetraenoic acid (15-HETE). PGI 2 , a product of the cyclooxygenase pathway, is a powerful vasodilator and a potent inhibitor of platelet aggregation. Its release provides at least one mechanism for maintaining a nonthrombogenic vascular surface. 15-HETE is the monohydroxylated metabolite of arachidonic acid produced by 15-lipoxygenase. The role of 15-HETE as a vascular autacoid has not been fully established, but it does modulate cellular lipid metabolism, influencing phospholipase A 2 activity, 1 leukotriene synthesis, 2 and PGI 2 synthesis.

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“…Arachidonic acid transfer between cell phospholipids is thought to involve a phospholipase A2-mediated production of lyso derivatives, followed by their reesterification at the 2-position by mechanisms operating at least partially through a CoA-independent transacylase activity (Kramer and Deykin, 1983; Sugiura and Waku, 1985). Although the physiological relevance of phospholipid remodelling is still to be fully elucidated, a possible coupling to the production of eicosanoids, as well as of other bioactive lipids (Sugiura et al, 1984;Sugiura and Waku, 1985; Bachelet et al, 1986;Brown et al, 1987), has been suggested. In consideration of the potential role played by certain eicosanoids in tumor growth (Spector and Burns, 1987), the question arises as to whether the pattern of arachidonic acid incorporation and redistribution among phospholipids in tumor cells is different from that observed in nontumoral cell systems.…”

mentioning

confidence: 99%

Arachidonic Acid Incorporation and Redistribution in Human Neuroblastoma (SK‐N‐BE) Cell Phospholipids

Spinedi

Pacini

Piacentini

et al. 1990

Journal of Neurochemistry

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The incorporation and redistribution of [1-14C]arachidonic acid in SK-N-BE human neuroblastoma cell phospholipids were investigated. By continuous labelling in serum-enriched medium, a rapid radioactivity incorporation into phosphatidylcholine (PtdCho), phosphatidylinositol, and phosphatidylserine was observed; initially, phosphatidylethanolamine (PtdEtn) was poorly labelled, but at later stages it displayed the highest level of arachidonic acid incorporation, in comparison with other phospholipid classes. Labelling of triacylglycerols was also observed. When cells were pulse-labelled with [1-14C]arachidonic acid and then reincubated in label-free medium, a decrease of the radioactivity in triacylglycerols was observed initially, paralleled by an increase of phospholipid labelling; thereafter, arachidonic acid redistribution was consistent with a net decrease of the radioactivity associated with PtdCho acid-stable forms (i.e., diacyl plus alkylacyl forms), concomitantly with a net labelling increase of both acid-stable PtdEtn and alkenylacyl-PtdEtn. Data indicate the following: (a) neuroblastoma cells incorporate arachidonic acid into phospholipids through complex kinetics involving transfer of the fatty acid from acid-stable PtdCho to both alkenylacyl-PtdEtn and acid-stable PtdEtn; and (b) triacylglycerols act as storage molecules for arachidonic acid which is subsequently incorporated into phospholipids. The possibility that arachidonic acid transfer to PtdEtn subclasses is driven by distinct mechanisms is discussed.

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Ionophore-induced metabolism of phospholipids and eicosanoid production in porcine aortic endothelial cells: selective release of arachidonic acid from diacyl and ether phospholipids

Cited by 39 publications

References 22 publications

Plasmenylethanolamine is the major storage depot for arachidonic acid in rabbit vascular smooth muscle and is rapidly hydrolyzed after angiotensin II stimulation.

Plasmenylethanolamine is the major storage depot for arachidonic acid in rabbit vascular smooth muscle and is rapidly hydrolyzed after angiotensin II stimulation.

Passage state affects arachidonic acid content and eicosanoid release in porcine aortic endothelial cells.

Arachidonic Acid Incorporation and Redistribution in Human Neuroblastoma (SK‐N‐BE) Cell Phospholipids

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