These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Eicosanoid metabolism in cholesterol-enriched arterial smooth muscle cells: reduced arachidonate release with concomitant decrease in cyclooxygenase products.
    Author: Pomerantz KB, Hajjar DP.
    Journal: J Lipid Res; 1989 Aug; 30(8):1219-31. PubMed ID: 2504863.
    Abstract:
    A biochemical correlation between vascular cholesterol metabolism and eicosanoid biosynthesis has not been fully elucidated. To assess the effects of cholesteryl ester (CE) accretion on eicosanoid synthesis, we studied eicosanoid metabolism in cultured rabbit aortic smooth muscle cells (SMC) following lipid-enrichment by incubation with cationized LDL (cLDL). SMC exposed to cLDL synthesized 50% less immunoreactive 6-keto-PGF1 alpha than untreated cells when exposed to the calcium ionophore, A-23187. In addition, cLDL-treatment reduced arachidonate acid (AA)-induced prostacyclin (PGI2) production sevenfold. Components of cLDL decreased eicosanoid biosynthesis in the following rank-order: linoleate greater than cholesterol greater than apo-cLDL. Lipid-enriched cells incorporated amounts of [1-14C]AA into phosphatidylcholine and phosphatidylethanolamine equal to control cells, but subsequent exposure to ionophore released significantly less radioactivity as free arachidonate (AA), with proportionally less conversion to eicosanoids. Ionophore released equivalent amounts of AA from all phospholipids, suggesting specificity for uptake, but not release of AA by cellular phospholipases. Cells enriched in CE had an eightfold decrease in percentage of phospholipid-derived AA relative to linoleate as compared to controls. Taken together, our data demonstrate that SMC metabolism of cLDL leads to cholesterol and CE accretion concomitant with diminished production of eicosanoids. Potential mechanisms for this effect include competitive inhibition of eicosanoid production by linoleate derived from LDL, direct inhibition of phospholipase A2 activity by cholesterol, and decrease in cyclooxygenase activity. These findings may have pathophysiological significance in that a reduction in PGI2 synthetic capacity of arterial SMC may exacerbate CE deposition since PGI2 promotes intracellular CE hydrolysis.
    [Abstract] [Full Text] [Related] [New Search]