15-hydroperoxy-5-8-11-13-eicosatetraenoic-acid and Arteriosclerosis

Topics: Animals; Arteriosclerosis; Cardiovascular System; Cornea; Erythropoiesis; Leukotrienes; Linoleic Acids; Lipid Peroxides; Mammals; Skin; Vasoconstrictor Agents

Topics: Animals; Arachidonic Acids; Arteriosclerosis; Epoprostenol; Humans; Leukotrienes; Lipid Peroxides; Prostaglandins; Rabbits; Rats; SRS-A; Thromboxanes

Treatment of human artery wall cells with apolipoprotein A-I (apoA-I), but not apoA-II, with an apoA-I peptide mimetic, or with high density lipoprotein (HDL), or paraoxonase, rendered the cells unable to oxidize low density lipoprotein (LDL). Human aortic wall cells were found to contain 12-lipoxygenase (12-LO) protein. Transfection of the cells with antisense to 12-LO (but not sense) eliminated the 12-LO protein and prevented LDL-induced monocyte chemotactic activity. Addition of 13(S)-hydroperoxyoctadecadienoic acid [13(S)-HPODE] and 15(S)-hydroperoxyeicosatetraenoic acid [15(S)-HPETE] dramatically enhanced the nonenzymatic oxidation of both 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (PAPC) and cholesteryl linoleate. On a molar basis 13(S)-HPODE and 15(S)-HPETE were approximately two orders of magnitude greater in potency than hydrogen peroxide in causing the formation of biologically active oxidized phospholipids (m/z 594, 610, and 828) from PAPC. Purified paraoxonase inhibited the biologic activity of these oxidized phospholipids. HDL from 10 of 10 normolipidemic patients with coronary artery disease, who were neither diabetic nor receiving hypolipidemic medications, failed to inhibit LDL oxidation by artery wall cells and failed to inhibit the biologic activity of oxidized PAPC, whereas HDL from 10 of 10 age- and sex-matched control subjects did. We conclude that a) mildly oxidized LDL is formed in three steps, one of which involves 12-LO and each of which can be inhibited by normal HDL, and b) HDL from at least some coronary artery disease patients with normal blood lipid levels is defective both in its ability to prevent LDL oxidation by artery wall cells and in its ability to inhibit the biologic activity of oxidized PAPC.

Topics: Aorta; Arachidonate 12-Lipoxygenase; Arachidonate 15-Lipoxygenase; Arteriosclerosis; Aryldialkylphosphatase; Cells, Cultured; Chemotaxis, Leukocyte; Coculture Techniques; Coronary Disease; Endothelium, Vascular; Esterases; Female; Humans; Hydrogen Peroxide; Leukotrienes; Linoleic Acids; Lipid Peroxides; Lipoproteins, LDL; Male; Models, Cardiovascular; Monocytes; Muscle, Smooth, Vascular; Oligodeoxyribonucleotides, Antisense; Oxidation-Reduction; Phospholipids; Reference Values

The lipoxygenase product 15-hydroxyeicosatetraenoic acid (15-HETE) was shown to be the most important eicosanoid formed in the atherosclerotic rabbit aorta. The aim of the present study was to compare the effects of 15-HETE and its hydroperoxy precursor 15-HpETE with those of other vasoconstrictor and vasodilator agents in arteries from rabbits fed either a control or a cholesterol-rich diet for 16 and 30 weeks. 5-Hydroxytryptamine (5-HT) aggregated platelets and thrombin caused contractions of isolated rabbit aortas. The contractile responses elicited by platelets from control animals were similar to those evoked by platelets from atherosclerotic rabbits. After 16 weeks of hypercholesterolemia, the contractile responses were either augmented (5-HT), unchanged (platelets) or reduced (thrombin). After 30 weeks of hypercholesterolemia, the responses to all contractile agents used had decreased. In both aortas and pulmonary arteries the endothelium-dependent relaxations to the calcium ionophore, A23167, and to acetylcholine were progressively lost and the endothelium-independent relaxations to nitroglycerin were reduced by the progressing hypercholesterolemia. The 15-lipoxygenase metabolites contracted the isolated thoracic aorta and pulmonary artery from control rabbits and to a lesser extent those of the cholesterol-fed rabbits. After raising the tone in these vessels with prostaglandin F2 alpha PGF2 alpha) or noradrenaline, 15-HpETE induced relaxations which were not significantly influenced by the development of fatty streaks. Our data illustrate that the contractions of the blood vessel wall to 15-HETE, like those to other vasoconstrictors, are markedly reduced by developing atherosclerosis. In contrast, the relaxations to 15-HpETE in the rabbit arteries remain unaltered after 16 to 30 weeks of hypercholesterolemia. This is unlike the reactions to other vasodilators, which are markedly reduced.

Topics: Acetylcholine; Animals; Arachidonate 15-Lipoxygenase; Arteriosclerosis; Calcimycin; Dinoprost; Hydroxyeicosatetraenoic Acids; Hypercholesterolemia; In Vitro Techniques; Leukotrienes; Lipid Peroxides; Male; Muscle, Smooth, Vascular; Nitroglycerin; Platelet Aggregation; Rabbits; Thrombin; Vasoconstrictor Agents; Vasodilator Agents

A segment of fresh rabbit thoracic aorta (RbA) was turned inside out and superfused (1.5 ml/min) with citrated (3.8%) or heparinized (10 U/ml) blood of rabbit and the superfusate was discarded. RbA gained in weight due to deposition of thrombi on its endothelial surface. These thrombi were mainly composed of platelets. The interaction between platelets and endothelium was augmented in RbAs from animals with atherosclerosis and in RbAs pretreated with aspirin (110 microM) or 15-HPETE (150 microM) or by the enzymatic system generating oxygen free radicals (xanthine:xanthine oxidase - 100 microM: 0.1 U/ml). On the other hand, this interaction was impaired by superoxide dismutase (20 U/ml) or catalase (0.2 U/ml). Finally, the dissipation of thrombi by thromboxane A2-synthetase inhibitor--dazoxiben was found to be related to an increase in endothelial generation of prostacyclin.

Topics: Animals; Aorta, Thoracic; Arteriosclerosis; Aspirin; Blood Platelets; Endothelium, Vascular; Epoprostenol; Imidazoles; Indomethacin; Leukotrienes; Lipid Peroxides; Platelet Adhesiveness; Rabbits; Superoxide Dismutase; Thrombosis; Xanthine; Xanthine Oxidase; Xanthines