Hydroxyeicosatetraenoic acid metabolism in cultured human skin fibroblasts. Evidence for peroxisomal beta-oxidation.

To determine whether the peroxisome is responsible for hydroxyeicosatetraenoic acid (HETE) oxidation, 12- and 15-HETE oxidation was measured in normal and peroxisomal deficient skin fibroblasts from patients with Zellweger's (cerebrohepatorenal) syndrome. When incubated for 1 h with normal fibroblasts, reverse phase HPLC indicated that 24% of the 12-HETE radioactivity was converted to one major polar metabolite. Chemical derivatization followed by reverse phase HPLC and TLC indicated that this metabolite is 8-hydroxyhexadecatrienoic acid [16:3(8-OH)].

1-O-alkyl-2-acetyl-sn-glycerol: a platelet-activating factor metabolite with biological activity in vascular smooth muscle cells.

Platelet-activating factor (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine; PAF) is a potent vasoactive ether lipid produced by activated blood cells and endothelial cells. Vascular smooth muscle cells partially convert exogenous PAF to 1-O-alkyl-2-acetyl-sn-glycerol (AAG), a biologically active diacylglycerol analogue. AAG is formed rapidly (less than 15 s) after exposure of the smooth muscle cells and does not appear to be a substrate for diacylglycerol kinase in these cells.

Brain microvessels produce 12-hydroxyeicosatetraenoic acid.

Cerebral microvessels isolated from perfused, adult murine brain produce a compound with the chromatographic properties of a monohydroxyeicosatetraenoic acid when incubated with arachidonic acid or stimulated with calcium ionophore A23187. The formation of this arachidonic acid metabolite is not reduced in the presence of the cyclooxygenase inhibitor ibuprofen, but it is abolished by the lipoxygenase inhibitor nordihydroguaiaretic acid. Analysis by gas chromatography combined with chemical ionization and electron impact mass spectrometry of reduced and nonreduced derivatives of the metabolite, indicate that the compound is 12-hydroxyeicosatetraenoic acid.

Identification of the major metabolite of 12-HETE produced by renal tubular epithelial cells.

The identification and polarity of release of the major metabolite of 12-HETE produced by cultured canine renal tubular epithelial cells was determined. When incubated with 1.0 microM [3H]12-HETE for 1 h, cultured Madin Darby Canine Kidney (MDCK) cells converted 35% of the radiolabeled 12-HETE to a more polar metabolite.

Formation of 9-hydroxyoctadecadienoic acid from linoleic acid in endothelial cells.

Human umbilical vein endothelial cells convert linoleic acid to two monohydroxyoctadecadienoic (HODE) acids, 9- and 13-HODE. More 9-HODE than 13-HODE is formed under most conditions. The production of these metabolites is reduced substantially by acetylsalicylic acid, ibuprofen, or arachidonic acid, suggesting that cyclooxygenase may be involved in endothelial HODE synthesis.