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

Although 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) can restore endothelial function in coronary disease, in vitro and murine studies have shown their effects on myocardial angiogenesis to be biphasic and dose dependent. We investigated the functional and molecular effects of high-dose atorvastatin on the endogenous angiogenic response to chronic myocardial ischemia in hypercholesterolemic swine.. Yucatan pigs were fed either a normal (NORM group; n=7) or high-cholesterol diet, with (CHOL-ATR group; n=7) or without (CHOL group; n=6) atorvastatin (3 mg/kg per day) for 13 weeks. Chronic ischemia was induced by ameroid constrictor placement around the circumflex artery. Seven weeks later, microvessel relaxation responses, myocardial perfusion, and myocardial protein expression were assessed. The CHOL group demonstrated impaired microvessel relaxation to adenosine diphosphate (29+/-3% versus 61+/-6%, CHOL versus NORM; P<0.05), which was normalized in the CHOL-ATR group (67+/-2%; P=NS versus NORM). Collateral-dependent myocardial perfusion, adjusted for baseline, was significantly reduced in the CHOL group (-0.27+/-0.07 mL/min per gram versus NORM; P<0.001) as well as the CHOL-ATR group (-0.35+/-0.07 mL/min per gram versus NORM; P<0.001). Atorvastatin treatment was associated with increased phosphorylation of Akt (5.7-fold increase versus NORM; P=0.001), decreased vascular endothelial growth factor expression (-68+/-8%; P<0.001 versus NORM), and increased expression of the antiangiogenic protein endostatin (210+/-48%; P=0.004 versus NORM).. Atorvastatin improves hypercholesterolemia-induced endothelial dysfunction without appreciable changes in collateral-dependent perfusion. Increased myocardial expression of endostatin, decreased expression of vascular endothelial growth factor, and chronic Akt activation associated with atorvastatin treatment may account for the diminished angiogenic response.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Adenosine Diphosphate; Angiostatins; Animals; Apoptosis; Apoptosis Inducing Factor; Arterioles; Atorvastatin; Caspase 3; Caspases; Cholesterol; Coronary Circulation; Coronary Vessels; Drug Evaluation, Preclinical; Endostatins; Endothelium, Vascular; Female; Fibroblast Growth Factor 2; Gene Expression Regulation; Heptanoic Acids; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hypercholesterolemia; Male; Matrix Metalloproteinase 9; Myocardial Ischemia; Neovascularization, Physiologic; Nitric Oxide; Nitric Oxide Synthase Type III; Nitroprusside; Phosphorylation; Protein Processing, Post-Translational; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-bcl-2; Pyrroles; Receptor, TIE-2; Swine; Swine, Miniature; Vascular Endothelial Growth Factor A; Vasodilation

Hypercholesterolemia (HC) is characterized by increased circulating 8-epi-prostaglandin-F(2alpha) (isoprostane), a vasoconstrictor, marker, and mediator of increased oxidative stress, whose vascular effects might be augmented in HC. Anesthetized pigs were studied in vivo with electron beam computed tomography after a 12-wk normal (n = 8) or HC (n = 8) diet. Mean arterial pressure (MAP), single-kidney perfusion, and glomerular filtration rate (GFR) were quantified before and during unilateral intrarenal infusions of U46619 (10 ng x kg(-1) x min(-1)) or isoprostane (1 microg x kg(-1) x min(-1)). Basal renal perfusion and function were similar, and isoprostane infusion elevated its systemic levels similarly in normal and HC (333 +/- 89 vs. 366 +/- 48 pg/ml, respectively, P < 0.01 vs. baseline). Both drugs markedly and comparably decreased cortical perfusion and GFR in both groups, whereas medullary perfusion decreased significantly only in HC. Moreover, MAP increased significantly only in HC (+9 +/- 3 and +11 +/- 3 mmHg, respectively, P

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Blood Pressure; Dinoprost; Dose-Response Relationship, Drug; Drug Administration Routes; F2-Isoprostanes; Female; Glomerular Filtration Rate; Hemodynamics; Hypercholesterolemia; Isoprostanes; Kidney; Regional Blood Flow; Swine; Tomography, X-Ray Computed; Vasoconstrictor Agents; Vasomotor System

Serotonin [5-hydroxytryptamine (5-HT)] has been implicated in platelet activation and vasoconstriction, two processes that contribute to arterial thrombosis in atherosclerotic diseases. In the present study, Japanese White rabbits fed 1% cholesterol for 5 weeks were used to investigate the response of hypercholesterolemic vascular arteries and platelets to 5-HT. Contractions of the thoracic aorta induced by 5-HT were comparable between the cholesterol-fed group and the age-matched control group. However, acetylcholine-induced vasodilation in arteries preconstricted with 5-HT was moderately but significantly attenuated in the cholesterol-fed rabbits. Platelet aggregation responses to 5-HT (0.1-3 micromol/l) in combination with epinephrine (5 micromol/l), adenosine diphosphate (ADP) (0.3-10 micromol/l), 9,11-dideoxy-9alpha,11alpha-methanoepoxy-prostaglandin F2alpha (U-46619) (1-30 micromol/l) or collagen (3 microg/ml) were significantly enhanced in cholesterol-fed rabbits. In contrast, platelet 5-HT content determined with a high-performance liquid chromatography-electrochemical detector (HPLC-ECD) was significantly decreased in cholesterol-fed rabbits. These results suggest a possible association among the endothelial dysfunction, platelet aggregation and platelet 5-HT content in rabbits with dietary hypercholesterolemia.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Acetylcholine; Adenosine Diphosphate; Animals; Blood Platelets; Cholesterol, Dietary; Free Radical Scavengers; Hypercholesterolemia; Platelet Aggregation; Rabbits; Serotonin; Vasoconstrictor Agents; Vasodilation; Vasodilator Agents

The F2-isoprostanes are a family of novel prostaglandin isomers and a stable product of in vivo oxidative stress. 8-epi-prostaglandinF2 alpha, a member of this isoprostane family, is a vasoconstrictor and its local release may contribute to the abnormal vasomotor tone associated with hypercholesterolemia. We therefore aimed to outline the role of 8-epi-prostaglandinF2 alpha as a coronary vasoconstrictor in experimental hypercholesterolemia.. Pigs were randomized to two experimental groups (each n = 9): normal (N) and high cholesterol (HC) diet. To determine the vasoconstrictive effects of 8-epi-prostaglandinF2 alpha in vitro, doses from 10(-9) to 10(-5) M were used to constrict coronary epicardial rings. Plasma total and LDL cholesterol levels were significantly higher in the HC group compared with the N group (P < 0.005) as were plasma 8-epi-prostaglandinF2 alpha levels (P < 0.001). 8-epi-prostaglandinF2 alpha immunoreactivity was present in the vessel wall in both groups. Normal vessels with intact endothelium (n = 8 rings) contracted to 8-epi-prostaglandinF2 alpha (maximal contraction 15.5 +/- 8.74%). In the HC group, rings with intact endothelium had a greater contractile response to 8-epi-prostaglandinF2 alpha compared to normals (72.3 +/- 7.9%; n = 8; P < 0.0001). This was reversed by preincubation with NOR-3, a NO donor (maximal contraction 6.7 +/- 1.56%; n = 5; P < 0.0001). Enhanced contraction in normal vessels occurred with endothelial denudation (98.4 +/- 3.56%; n = 6; P < 0.0001) and with preincubation of the endothelium-intact rings with L-NMMA (N-monomethyl-L-arginine), an NO synthase inhibitor (85.5 +/- 10.3%, n = 6, P < 0.001). The enhanced contraction seen with hypercholesterolemia did not occur with other prostanoid vasoconstrictors.. Experimental hypercholesterolemia leads to a significant increase in 8-epi-prostaglandinF2 alpha levels in addition to enhanced 8-epi-prostaglandinF2 alpha-induced coronary vasoconstriction, in vitro. These findings support a role for the F2-isoprostanes in the regulation of coronary vasomotor tone in pathophysiologic states.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Analysis of Variance; Animals; Arginine; Arteries; Bridged Bicyclo Compounds, Heterocyclic; Cholesterol; Cholesterol, HDL; Cholesterol, LDL; Coronary Vessels; Dinoprost; Dinoprostone; Endothelium, Vascular; Enzyme Inhibitors; Fatty Acids, Unsaturated; Female; Hydrazines; Hypercholesterolemia; Immunohistochemistry; In Vitro Techniques; Muscle, Smooth, Vascular; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase; Nitro Compounds; omega-N-Methylarginine; Oxidative Stress; Random Allocation; Swine; Thromboxane A2; Vasoconstriction; Vasoconstrictor Agents

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

The coronary vasoconstrictor effects of endothelins, mediated by both endothelin ETA and ETB receptors, may be differentially altered in pathophysiological states associated with endothelial dysfunction and elevated endothelin levels. Experimental hypercholesterolemia is associated with coronary endothelial dysfunction and increased circulating endothelin concentrations. These studies were designed to test the hypothesis that experimental hypercholesterolemia is characterized by a differentially altered coronary contractile response to ETA- and ETB-receptor stimulation, in vitro. Pigs were fed either a normal or a high-cholesterol diet for 10 to 13 weeks. Changes in the intraluminal diameter of pressurized small coronary arteries (< 481 +/- 25 microns in diameter) to cumulative concentrations (10(-10) to 10(-6) mol/L) of endothelin-1 (ET-1), and sarafotoxin 6c (S6c), a specific ETB-receptor agonist, were measured using a video dimension analyzer. The maximal contraction attained with ET-1 was greater than with S6c in both normal (86 +/- 7% versus 47 +/- 7%, P = .001) and hypercholesterolemic (77 +/- 6% versus 37 +/- 7%, P < .001) pigs. At 10(-10) mol/L, vessels from hypercholesterolemic pigs manifested greater contraction to both ET-1 (23 +/- 6% versus 8 +/- 3%, P = .02) and S6c (17 +/- 5% versus 4 +/- 2%, P = .02). Incubation of arteries from hypercholesterolemic pigs with BQ-788 (ETB-receptor antagonist), but not FR-139317 (ETA-receptor antagonist), altered the contractile response to ET-1 at 10(-10) mol/L. Removal of the endothelium abolished the difference in response to S6c between normal and hypercholesterolemic pigs. These studies demonstrate that experimental hypercholesterolemia is characterized by enhanced coronary vasoconstriction to endothelins in vitro, the mechanism of which is mediated mainly through the ETB receptor. Thus, the ETB receptor has a role in regulation of coronary artery tone in both the steady-state and pathophysiological states.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Azepines; Cholesterol, Dietary; Coronary Vessels; Diet, Atherogenic; Endothelin Receptor Antagonists; Endothelin-1; Endothelins; Endothelium, Vascular; Female; Hypercholesterolemia; Indoles; Lipids; Oligopeptides; Piperidines; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; Swine; Vasoconstriction; Vasoconstrictor Agents; Viper Venoms

Studies in both animals and humans with raised lipid levels have demonstrated abnormalities in vascular function usually manifested by an impairment in endothelium-dependent vasorelaxation. This is believed to be an early event in atheroma formation. There are few data on the effects on vascular function in humans of lowering serum lipids. We conducted a study to investigate the effects of cholesterol reduction on the in vitro function of human peripheral small arteries in middle-aged patients with hypercholesterolemia.. Subcutaneous gluteal fat biopsies were taken from 18 hypercholesterolemic (HC) patients (mean +/- SEM serum total cholesterol, 9.7 +/- 0.57 mmol/L) and 16 age- and sex-matched control subjects (mean cholesterol, 4.69 +/- 0.18 mmol/L). Subcutaneous small arteries (internal diameter, < 330 microns) were dissected and mounted on a wire myograph for isometric tension measurements. The HC patients showed impaired relaxation to acetylcholine (10(-9) to 10(-6) mol/L) after preconstriction with the thromboxane A2 analogue U46619 (10(-6) mol/L, mean maximum relaxation, 42.9 +/- 5.4%) compared with control subjects (85.7 +/- 4.0%, P < .00001). Incubation with the nitric oxide substrate L-arginine (3 mmol/L) improved the endothelium-dependent vasorelaxation response to acetylcholine (70.9 +/- 6.0%, P < .01) in patients but not in control subjects. Also, there was a smaller but significant difference in responses to the endothelium-independent agent sodium nitroprusside (10(-9) to 10(-6) mol/L) between the HC group (mean maximum relaxation, 76.9 +/- 6.0%) and the control subjects (89.7 +/- 6%; P < .01). A total of 10 patients had a second gluteal skin biopsy and repeat functional studies after successful cholesterol-lowering therapy after a mean period of 9.9 +/- 4.7 months. A significant reduction in total and LDL cholesterol was achieved (5.29 +/- 0.2 and 3.23 +/- 0.21 mmol/L, respectively; P < .001). This restored vasorelaxation to control values in response to both acetylcholine (mean maximum relaxation, 83.3 +/- 3.8%; P < .0001) and sodium nitroprusside (87.9 +/- 4.8%, P < .01). Although both groups were normotensive, there were significantly higher blood pressures in the HC group compared with control subjects (139 +/- 4.1 versus 123 +/- 3.0 mm Hg systolic, P < .01; 84 +/- 1.3 versus 75 +/- 2.2 mm Hg diastolic, P < .01). There was no difference in initial blood pressures between the entire group of 18 and the 10 patients who had repeat biopsies. The blood pressures fell to control values after cholesterol reduction (129.33 +/- 4.93 mm Hg systolic and 72.33 +/- 2.93 diastolic mm Hg, P < .02 relative to pretreatment values).. These results demonstrate abnormalities of both endothelium-dependent and -independent relaxation in human peripheral small arteries that are normalized with effective lipid lowering. The changes in blood pressure may have been secondary to the improvement in vascular function.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Arginine; Arteries; Blood Pressure; Cholesterol; Female; Humans; Hypercholesterolemia; In Vitro Techniques; Lipoproteins; Male; Middle Aged; Nitroprusside; Norepinephrine; Prostaglandin Endoperoxides, Synthetic; Thromboxane A2; Vasoconstriction

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Adult; Blood Platelets; Female; Humans; Hypercholesterolemia; Immunosorbent Techniques; Lipoproteins, LDL; Male; Middle Aged; Plasmapheresis; Platelet Adhesiveness; Platelet Aggregation; Platelet Count; Prostaglandin Endoperoxides, Synthetic; Time Factors