15-hydroxy-11-alpha-9-alpha-(epoxymethano)prosta-5-13-dienoic-acid and Arteriosclerosis

In a randomized pilot study we compared the antiplatelet effects of aspirin and BM 13.177 in two groups of 7 patients each undergoing PTCA. As compared with the pretreatment values template bleeding time was prolonged and collagen induced aggregation was inhibited in PRP and WB in all patients. In the course of angiography and PTCA a rise in platelet factor 4 and beta thromboglobulin was observed in both groups, followed by a decrease below the baseline levels. Thromboxane B2 in plasma and serum decreased in the aspirin group but remained unchanged during BM 13.177 treatment. In PRP and WB aggregation induced by U 46 619 was inhibited after ingestion of BM 13.177 but not following ASA. After three months a control coronary angiography was done. There was no difference in regard to the degree of restenosis between both groups. Medication was well tolerated, compliance was good and no side effects were noted.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Angioplasty, Balloon; Arteriosclerosis; Aspirin; Bleeding Time; Blood Platelets; Clinical Trials as Topic; Collagen; Cyclooxygenase Inhibitors; Female; Fibrinolytic Agents; Humans; Male; Middle Aged; Platelet Aggregation; Prostaglandin Endoperoxides, Synthetic; Receptors, Cell Surface; Receptors, Prostaglandin; Receptors, Thromboxane; Sulfonamides; Thromboxane B2; Thromboxanes

Current consensus suggests that lysophosphatidylcholine is the major detrimental factor in oxidized low-density lipoprotein that may contribute to the alterations of vasomotor responses associated with atherosclerosis. This study investigated the influences of lysophosphatidylcholine and major lipid components in oxidized low-density lipoprotein on vascular relaxation. We also determine if there was any interaction between these phospholipid components on relaxation. Porcine coronary artery rings were incubated with lysophosphatidylcholine, phosphatidylcholine or sphingomyelin. After contraction by the thromboxane A2 mimetic U46619, rings were relaxed with bradykinin and calcium ionophore A23187. Lysophosphatidylcholine with a higher proportion of stearoyl-lysophosphatidylcholine to palmitoyl-lysophosphatidylcholine ratio caused greater reduction of relaxational responses. While phosphatidylcholine and sphingomyelin had no effect on vascular relaxation, they reduced the ability of lysophosphatidylcholine to impair vascular relaxation. Our results thus suggested that the effectiveness of oxidized low-density lipoprotein at inhibiting vasodilatory responses may be determined by the relative proportion of different types of lysophosphatidylcholine as well as the amount of other phospholipid components: phosphatidylcholine and sphingomyelin.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Arteriosclerosis; Bradykinin; Calcimycin; Calcium; Cattle; Coronary Vessels; Dose-Response Relationship, Drug; Endothelium, Vascular; Ionophores; Lipoproteins, LDL; Liver; Lysophosphatidylcholines; Oxygen; Phosphatidylcholines; Phospholipids; Sphingomyelins; Swine; Thromboxane A2; Vasoconstrictor Agents

We examined the hypothesis that contraction of the carotid arteries to serotonin is normally inhibited by endothelial NO synthase (eNOS) and is enhanced in mice lacking the gene for eNOS. Because the influence of eNOS may vary with the sex of the mouse, we also tested whether responses to serotonin were dependent on sex. We studied carotid arteries in vitro from littermate control (eNOS(+/+)) mice, heterozygous (eNOS(+/-)) mice, and homozygous eNOS-deficient (eNOS(-/-)) mice (male and female). Contraction to serotonin was greater in male eNOS(+/+) mice than in female eNOS(+/+) mice. In male mice, contraction to serotonin increased by approximately 40% and 2.5-fold in male eNOS(+/-) and eNOS(-/-) mice, respectively. Contraction to serotonin was more than doubled in female eNOS(+/-) mice and increased >5-fold in arteries from eNOS(-/-) mice. In contrast, maximum vasoconstriction to U46619 was similar in male and female eNOS(+/+), eNOS(+/-), and eNOS(-/-) mice. Relaxation to acetylcholine was not different in male and female eNOS(+/+) or eNOS(+/-) mice but was absent in eNOS(-/-) mice. These findings suggest that the contraction of carotid arteries to serotonin is influenced by the sex of the animal. eNOS deficiency in gene-targeted mice is associated with enhanced contraction to serotonin, particularly in female mice, providing direct evidence that eNOS is a major determinant of vascular effects of serotonin. The results with eNOS(+/-) mice suggest a "gene-dosing" effect for vascular responses to serotonin.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Arteriosclerosis; Blotting, Southern; Carotid Arteries; Endothelium, Vascular; Female; Male; Mice; Mice, Knockout; Muscle, Smooth, Vascular; Nitric Oxide Synthase; Serotonin; Sex Factors; Vasoconstriction; Vasodilation

We characterized the acute effects of oxidized low-density lipoproteins (oxidized-LDL) on vascular reactivity in isolated aorta from wild-type C57BL/6J mice, and compared these with the chronic alterations in vascular function observed in apolipoprotein-E gene knockout [ApoE(-/-)] mice fed a high-fat diet, which results in hyperlipidemia and atherosclerosis. In the abdominal (but not thoracic) aorta, oxidized-LDL (100 microg/ml) reduced relaxations induced by acetylcholine (10(-9) M-10(-5) M), which are mediated entirely by nitric oxide (NO). The relaxations induced by the NO donor S-nitroso-N-acetylpenicillamine (SNAP, 10(-8) M-10(-4) M), the cyclic GMP analogue 8-bromo cyclic GMP (100 microM) and the nonspecific vasodilator papaverine (100 microM) were not changed by oxidized-LDL. Native LDL had no effect on vasorelaxations. The attenuation of endothelium-dependent relaxations caused by oxidized-LDL mimicked the endothelial dysfunction found in ApoE(-/-) mice. These results are consistent with the suggestion that oxidized-LDL has an important role in the pathogenesis of endothelial NO dysfunction associated with hyperlipidemia and atherosclerosis in these mice.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Acetylcholine; Animals; Aorta, Abdominal; Aorta, Thoracic; Apolipoproteins E; Arteriosclerosis; Cholesterol, Dietary; Dose-Response Relationship, Drug; Endothelium, Vascular; Genotype; Hyperlipidemias; In Vitro Techniques; Lipoproteins, LDL; Mice; Mice, Inbred C57BL; Mice, Knockout; Nitric Oxide Donors; Penicillamine; Potassium; Serotonin; Vasoconstriction; Vasoconstrictor Agents; Vasodilation; Vasodilator Agents

Atherosclerosis involves a complex array of factors, including leukocyte adhesion and platelet vasoactive factors. Aspirin, which is used to prevent secondary complications of atherosclerosis, inhibits platelet production of thromboxane (Tx) A(2). The actions of TxA(2) as well as of other arachidonic acid products, such as prostaglandin (PG) H(2), PGF(2alpha), hydroxyeicosatetraenoic acids, and isoprostanes, can be effectively antagonized by blocking thromboxane (TP) receptors. The purpose of this study was to determine the role of platelet-derived TxA(2) in atherosclerotic lesion development by comparing the effects of aspirin and the TP receptor antagonist S18886. The effect of 11 weeks of treatment with aspirin (30 mg. kg(-1). d(-1)) or S18886 (5 mg. kg(-1). d(-1)) on aortic root atherosclerotic lesions, serum levels of intercellular adhesion molecule-1 (ICAM-1), and the TxA(2) metabolite TxB(2) was determined in apolipoprotein E-deficient mice at 21 weeks of age. Both treatments did not affect body or heart weight or serum cholesterol levels. Aspirin, to a greater extent than S18886, significantly decreased serum TxB(2) levels, indicating the greater efficacy of aspirin in preventing platelet synthesis of TxA(2). S18886, but not aspirin, significantly decreased aortic root lesions as well as serum ICAM-1 levels. S18886 also prevented the increased expression of ICAM-1 in cultured human endothelial cells stimulated by the TP receptor agonist U46619. These results indicate that inhibition of platelet TxA(2) synthesis with aspirin has no significant effect on atherogenesis or adhesion molecule levels. The effects of S18886 suggest that blockade of TP receptors inhibits atherosclerosis by a mechanism independent of platelet-derived TxA(2), perhaps by preventing the expression of adhesion molecules whose expression is stimulated by eicosanoids other than TxA(2).

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Aorta; Apolipoproteins E; Arteriosclerosis; Aspirin; Body Weight; Cell Adhesion; Cholesterol; Endothelium, Vascular; Female; Humans; Intercellular Adhesion Molecule-1; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Naphthalenes; Platelet Aggregation Inhibitors; Propionates; Receptors, Thromboxane; Tetrahydronaphthalenes; Thromboxane A2; Thromboxane B2; U937 Cells; Umbilical Veins; Vasoconstrictor Agents

Advanced glyco-oxidation end products (AGEs) generate oxygen free radicals that potentiate the development of atherosclerosis. Thus, AGEs may potentiate the aggregation of human platelets through oxidative stress. AGE-bovine serum albumin (BSA) and AGE-poly-L-lysine were evaluated for aggregation of human platelets. Superoxide in platelet-rich plasma (PRP) was measured using lucigenin-derived chemiluminescence. The platelet aggregation induced by ADP or U46619 was potentiated by preincubation with AGE-BSA, by 40% and by 59%, P < .05, respectively, vs BSA. Aggregation was increased by AGEs in a dose-dependent manner. The production of superoxide was significantly greater in PRP incubated with AGE-BSA vs BSA. The other Maillard reaction products, such as Amadori-, pentosidine-, and carboxymethyl lysine (CML)-BSA had no effect. Superoxide dismutase or indomethacin abolished the enhancing effect of AGEs on the platelet aggregation. AGEs potentiate platelet aggregation possibly with superoxide anions and prostanoids. AGE-induced potentiation of platelet aggregation may be involved in the development of atherosclerosis.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Adenosine Diphosphate; Arginine; Arteriosclerosis; Cyclic AMP; Cyclic GMP; Female; Glycation End Products, Advanced; Humans; Indomethacin; Lysine; Male; Oxidative Stress; Platelet Aggregation; Polylysine; Prostaglandins; Reactive Oxygen Species; Serum Albumin, Bovine; Superoxide Dismutase; Superoxides

Vascular responses of human intramyocardial small arteries were examined in vitro to assess the influence of atherosclerosis and risk factors for coronary artery disease on endothelium-dependent relaxation. Recipient hearts were obtained from patients with ischemic (n = 14) and nonischemic (n = 13) cardiomyopathy undergoing heart transplantation. Small intramyocardial coronary arteries (mean internal diameter 313 +/- 11 micrometers) were mounted on a wire myograph for measurement of morphology and isometric tension. Vasodilation was examined after preconstriction with U-46619, a thromboxane A2 analog. Endothelium-dependent relaxation to acetylcholine and bradykinin was impaired in patients with ischemic compared with nonischemic cardiomyopathy (P < 0.01 and P < 0.001, respectively). Endothelium-independent relaxation to sodium nitroprusside was preserved. Incubation with L-arginine (3 mmol/l) did not improve endothelium-dependent relaxation to acetylcholine or bradykinin. With the use of stepwise multivariate analysis, hypercholesterolemia, but no other risk factor for atherosclerosis, was independently associated with impaired endothelium-dependent relaxation to acetylcholine (r = -0.50, P = 0.05) but not to bradykinin. Endothelial dysfunction in intramyocardial small arteries may predispose patients with nonobstructive epicardial atherosclerosis and hypercholesterolemia to myocardial ischemia.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Acetylcholine; Adult; Arteries; Arteriosclerosis; Bradykinin; Cardiomyopathies; Coronary Circulation; Endothelium, Vascular; Female; Heart; Heart Failure; Heart Transplantation; Humans; Hypercholesterolemia; In Vitro Techniques; Isometric Contraction; Male; Middle Aged; Nitroprusside; Substance P; Vasodilation

We examined the vascular structure and endothelium-dependent relaxation in two genetic models of hypercholesterolemia: apolipoprotein E (apoE)-knockout mice and combined apoE/LDL receptor-double-knockout mice. Intimal area was increased markedly in proximal segments of thoracic aortas from apoE/LDL receptor-knockout mice [0.13 +/- 0.03 (mean +/- SE) mm2] compared with normal (C57BL/6J) mice (0.002 +/- 0.002 mm2, P < .05). Despite intimal thickening, the vascular lumen was not smaller in the aortas of apoE/LDL receptor-knockout mice (0.52 +/- 0.03 mm2) than in normal mice (0.50 +/- 0.03 mm2). In apoE-deficient mice, intimal thickening was minimal or absent, even though the concentration of plasma cholesterol was only modestly less than that in the double-knockout mouse (14.9 +/- 1.1 vs 18.0 +/- 1.2 mmol/L, respectively, P < .05). Relaxation of the aorta was examined in vitro in vascular rings precontracted with U46619. In normal mice, acetylcholine produced relaxation, which was markedly attenuated by the nitric oxide synthase inhibitor NG-nitro-L-arginine (100 microM). Relaxation to acetylcholine and the calcium ionophore A23187 was normal in apoE-deficient mice (in which lesions were minimal) but greatly impaired in the proximal segments of thoracic aortas of apoE/LDL receptor-deficient mice, which contained atherosclerotic lesions. Vasorelaxation to nitroprusside was similar in normal and apoE-knockout mice, with modest but statistically significant impairment in atherosclerotic segments of apoE/LDL receptor-knockout mice. In distal segments of the thoracic aorta of apoE/LDL receptor-deficient mice, atherosclerotic lesions were minimal or absent, and the endothelium-dependent relaxation to acetylcholine and calcium ionophore was normal. Thus, in apoE/LDL receptor-knockout mice (a genetic model of hyperlipidemia), there is vascular remodeling with preservation of the aortic lumen despite marked intimal thickening, with impairment of endothelium-dependent relaxation to receptor- and nonreceptor-mediated agonists. Atherosclerosis may be accelerated in the apoE/LDL receptor-double-knockout mouse compared with the apoE-knockout strain alone. We speculate that other factors, such as the absence of LDL receptors, may contribute to the differences in the extent of atherosclerosis in these two models of hyperlipidemia.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Acetylcholine; Animals; Aorta, Thoracic; Aortic Diseases; Apolipoproteins E; Arteriosclerosis; Calcimycin; Calcium; Disease Models, Animal; Endothelium, Vascular; Enzyme Inhibitors; Female; Hypercholesterolemia; Ionophores; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Muscle Relaxation; Nitric Oxide Synthase; Nitroarginine; Receptors, LDL; Superoxide Dismutase; Vasoconstrictor Agents

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Arteriosclerosis; Calcium; Calcium Channel Blockers; Diet, Atherogenic; Estradiol; Magnesium; Male; Myocardial Contraction; Prostaglandin Endoperoxides, Synthetic; Rabbits; Rats; Rats, Wistar; Swine; Thromboxane A2; Verapamil

Endothelium-dependent relaxations in response to substance P and bradykinin were lower in atherosclerotic than in normal human coronary arteries. The relaxation induced by substance P was inhibited by L-NG-monomethylarginine (L-NMMA), which shows that release of nitric oxide is involved in the mediation of endothelium-dependent relaxation in these arteries. L-NMMA also inhibited a basal component of endothelium-dependent relaxation. The basal secretion of nitric oxide was significantly lower in diseased than in normal arteries. These findings suggest that atherosclerotic human coronary arteries lack an important protective mechanism that normally guards against vasospasm and thrombosis.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Adolescent; Adult; Arginine; Arteriosclerosis; Bradykinin; Child; Child, Preschool; Coronary Vessels; Dose-Response Relationship, Drug; Drug Synergism; Endothelium, Vascular; Humans; Middle Aged; Nitric Oxide; omega-N-Methylarginine; Prostaglandin Endoperoxides, Synthetic; Substance P; Vasoconstriction; Vasodilation

Atherosclerosis impairs endothelium-dependent relaxation of large conduit arteries. Because coronary resistance vessels are spared from the development of overt atherosclerosis, endothelium-dependent responses were examined in these vascular segments. Malaysian cynomolgus monkeys (n = 6) were made atherosclerotic by being fed a 0.7% cholesterol diet for 18 months. Control monkeys (n = 6) were fed a standard diet. Coronary microvessels (122-220 microns) were studied in a pressurized (20 mm Hg), no-flow state using a video-imaging apparatus. Relaxations of microvessels, preconstricted with the thromboxane analogue U46619, were determined in response to acetylcholine, bradykinin, the calcium ionophore A23187, adenosine, and sodium nitroprusside. Microvascular relaxations to bradykinin and A23187 were reduced in atherosclerotic monkeys compared with controls, whereas acetylcholine produced additional contraction in atherosclerotic monkeys. Responses of preconstricted microvessels to adenosine and sodium nitroprusside were identical in atherosclerotic and control animals. Indomethacin did not alter responses in control or atherosclerotic animals. Histologic examination revealed neither intimal thickening nor plaque formation in microvessels of this size class despite marked changes in conduit arteries. Electron microscopy showed minor alterations of endothelial cell morphology in microvessels of atherosclerotic animals. In conclusion, long-term hypercholesterolemia markedly impairs endothelium-dependent vascular relaxation in the coronary microcirculation where overt atherosclerosis does not develop. These changes in endothelial cell function may significantly alter regulation of myocardial perfusion by neurohumoral stimuli.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Acetylcholine; Animals; Arteriosclerosis; Bradykinin; Calcimycin; Cholesterol, Dietary; Coronary Vessels; Endothelium, Vascular; Indomethacin; Macaca fascicularis; Male; Microcirculation; Microscopy, Electron; Prostaglandin Endoperoxides, Synthetic; Saponins; Vasodilation

The goal of our study was to examine the effects of infusion of serotonin and the thromboxane A2 analogue U46619 into one carotid artery to stimulate their release from platelets during aggregation. We measured blood flow to the brain and eye using microspheres and cerebral microvascular pressure in the pial arteries of normal and atherosclerotic cynomolgus monkeys. Unilateral intracarotid infusion of 10-30 micrograms/min serotonin did not affect cerebral blood flow in normal or atherosclerotic monkeys; serotonin did not alter blood flow to the eye in normal monkeys but decreased flow to the retina and choroid in atherosclerotic monkeys by 39 +/- 11% and 44 +/- 10% (mean +/- SEM), respectively. Infusion of 30 ng/min U46619 did not alter cerebral blood flow but increased the pressure gradient from the aorta to the pial artery, which is an index of large-artery resistance, in atherosclerotic monkeys. U46619 had no effect on blood flow to the eye in normal monkeys but decreased blood flow to the retina and choroid by 71 +/- 14% and 53 +/- 13%, respectively, in atherosclerotic monkeys. Thus, atherosclerosis potentiates the constrictor responses of large cerebral arteries to thromboxane and the responses of blood vessels of the eye to thromboxane and serotonin.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Arteriosclerosis; Blood Pressure; Blood Vessels; Carotid Arteries; Cerebrovascular Circulation; Eye; Injections, Intra-Arterial; Macaca fascicularis; Platelet Aggregation; Prostaglandin Endoperoxides, Synthetic; Serotonin; Thromboxanes; Vasoconstriction

We examined the influence of stable prostacyclin analogues (carbacyclin) and thromboxane A2 (U46619) on atherosclerotic properties of cells: [3H]thymidine incorporation and intracellular cholesterol content. A primary culture of human aortic subendothelial cells derived from atherosclerotic plaques was used. Carbacyclin exerted a direct anti-atherosclerotic effect, significantly reducing atherosclerotic manifestations of cells, while agent U46619 stimulated proliferation and cholesterol accumulation, i.e. demonstrated atherogenic potency in culture. Calcium antagonists (verapamil and diltiazem) markedly enhanced anti-atherosclerotic properties of carbacyclin and restricted the atherogenicity of U46619.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Aorta; Arteriosclerosis; Cells, Cultured; Diltiazem; DNA Replication; Epoprostenol; Humans; Muscle, Smooth, Vascular; Prostaglandin Endoperoxides, Synthetic; Prostaglandins, Synthetic; Verapamil

We investigated the effects of stable analogues of prostacyclin (carbacyclin) and thromboxane A2 (U46619) and various calcium antagonists on atherosclerotic cellular indices, intracellular cholesterol content and [3H]thymidine incorporation. Primary culture of human subendothelial cells derived from atherosclerotic plaques of aorta was used. Carbacyclin reduced cholesterol accumulation and cell proliferation. U46619 in opposite to carbacyclin stimulated this processes. In general, carbacyclin exerted a direct antiatherosclerotic and U46619 - atherogenic action in culture. Calcium antagonists: dihydropyridines, verapamil derivatives and diltiazem demonstrated antiatherosclerotic properties themselves and potentiated carbacyclin effect but restricted atherogenicity of U46619.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Aorta; Arteriosclerosis; Calcium Channel Blockers; Cells, Cultured; Cholesterol; DNA Replication; Epoprostenol; Humans; Muscle, Smooth, Vascular; Prostaglandin Endoperoxides, Synthetic

The role of thromboxane in human, rabbit, dog, pig and sheep platelet aggregation has been studied. Each of these species showed a concentration-dependent relationship between collagen concentrations and the thromboxane B2 (TXB2) released from aggregating platelets, however sheep platelets produced only 17.5% of the amount of TXB2 released from human platelets under the same collagen stimulus. Indomethacin did not inhibit sheep platelet aggregation in the concentration range 0.114 mM - 0.114 muM, yet proved to be a potent inhibitor of human platelet aggregation. The prostaglandin endoperoxide analogue, U.46619, induced human platelet aggregation at a dose of 100 ng, however the analogue, at doses as high as 500 micrograms was much less active on sheep platelets when compared to human platelets. Thus we have demonstrated that there are differences in the extent of thromboxane involvement in platelet aggregation between different species, which must be considered with other criteria, before choosing an animal model for studying human atherosclerosis.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Arteriosclerosis; Blood Platelets; Collagen; Dogs; Humans; Indomethacin; Prostaglandin Endoperoxides, Synthetic; Rabbits; Sheep; Species Specificity; Swine; Thromboxane B2; Thromboxanes