cyclic-gmp and Arteriosclerosis

Topics: Animals; Arteriosclerosis; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Endothelium, Vascular; Genetic Therapy; Humans; Natriuretic Peptides; Regeneration

Topics: Achondroplasia; Animals; Arteriosclerosis; Cell Division; Chondrogenesis; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Endothelium, Vascular; Guanylate Cyclase; Humans; Natriuretic Peptide, C-Type; Receptors, Atrial Natriuretic Factor; Regeneration; Vasoconstriction

Topics: Animals; Arteriosclerosis; Calcium; Caveolin 1; Caveolins; Cyclic GMP; Endothelial Cells; Gene Expression; Guanylate Cyclase; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Mutation; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Receptors, Cytoplasmic and Nuclear; Soluble Guanylyl Cyclase; Transcription, Genetic

Topics: Animals; Apoptosis; Arteriosclerosis; Biomechanical Phenomena; Calcium; Caveolae; Cyclic GMP; Endothelial Cells; Gene Expression; Guanylate Cyclase; Humans; Neovascularization, Physiologic; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Oxidative Stress; Platelet-Derived Growth Factor; Protein-Tyrosine Kinases; Receptors, Cytoplasmic and Nuclear; Soluble Guanylyl Cyclase; Stress, Mechanical; Vascular Cell Adhesion Molecule-1; Vasodilation

Topics: Animals; Apoptosis; Arteriosclerosis; Cell Division; Cyclic GMP; Depression, Chemical; Humans; Muscle, Smooth, Vascular; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III

Topics: 3',5'-Cyclic-GMP Phosphodiesterases; Adrenergic alpha-Antagonists; Arteriosclerosis; Blood Pressure; Carbolines; Contraindications; Coronary Disease; Cyclic GMP; Cyclic Nucleotide Phosphodiesterases, Type 5; Drug Interactions; Endothelium, Vascular; Erectile Dysfunction; Heart Rate; Humans; Hypotension; Imidazoles; Isosorbide Dinitrate; Male; Molecular Structure; Myocardial Infarction; Nitric Oxide Donors; Nitroglycerin; Phosphodiesterase Inhibitors; Phosphoric Diester Hydrolases; Piperazines; Purines; Randomized Controlled Trials as Topic; Sildenafil Citrate; Sulfones; Tadalafil; Triazines; Vardenafil Dihydrochloride; Vasodilation; Vasodilator Agents

Platelet thrombosis, intimal hyperplasia, and the progression of atherosclerosis are the most important factors determining the patency of vein grafts for arterial occlusive disease. Interactions between aggregating platelets and the vessel wall play an important role in all of these processes. The endothelium modulates the underlying vascular smooth muscle by releasing nitric oxide (NO), a potent vasodilator and anti-aggregating substance. This review focuses on vascular modulation by NO in vein grafts.

Topics: Animals; Arterial Occlusive Diseases; Arteriosclerosis; Cyclic GMP; Endothelium, Vascular; Genetic Therapy; Hemodynamics; Humans; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Transplantation, Autologous; Veins

The use of low doses of aspirin on a daily basis has increased greatly in the past 20 years, based on observations that it can significantly reduce the risk of heart attacks and strokes. However, aspirin can also cause severe damage to the stomach. A modified version of aspirin that releases nitric oxide has been developed that seems to offer important advantages over its 103-year-old parent--namely, improved protection for the heart without the unwanted effects on the stomach.

Topics: Animals; Apoptosis; Arteriosclerosis; Aspirin; Caspase Inhibitors; Cell Adhesion; Cyclic GMP; Cytokines; Heart; Humans; Hypertension; Myocardial Infarction; Stroke

The production of reactive oxygen and nitrogen species has been implicated in atherosclerosis principally as means of damaging low-density lipoprotein that in turn initiates the accumulation of cholesterol in macrophages. The diversity of novel oxidative modifications to lipids and proteins recently identified in atherosclerotic lesions has revealed surprising complexity in the mechanisms of oxidative damage and their potential role in atherosclerosis. Oxidative or nitrosative stress does not completely consume intracellular antioxidants leading to cell death as previously thought. Rather, oxidative and nitrosative stress have a more subtle impact on the atherogenic process by modulating intracellular signaling pathways in vascular tissues to affect inflammatory cell adhesion, migration, proliferation, and differentiation. Furthermore, cellular responses can affect the production of nitric oxide, which in turn can strongly influence the nature of oxidative modifications occurring in atherosclerosis. The dynamic interactions between endogenous low concentrations of oxidants or reactive nitrogen species with intracellular signaling pathways may have a general role in processes affecting wound healing to apoptosis, which can provide novel insights into the pathogenesis of atherosclerosis.

Topics: Animals; Antioxidants; Arteriosclerosis; Blood Vessels; Cell Communication; Cyclic GMP; Extracellular Matrix; Guanylate Cyclase; Humans; Lipoxygenase; Nitric Oxide; Prostaglandin-Endoperoxide Synthases; Reactive Oxygen Species; Second Messenger Systems; Signal Transduction; Sulfhydryl Compounds; Superoxide Dismutase; Superoxides

The vascular endothelium is a source of substances particularly nitric oxide that act in a paracrine fashion either to contract or relax smooth muscle cells and this function is disturbed in atherosclerotic arteries. The endothelium derived nitric oxide contribute in the basal vasomotor tone of epicardial normal and atheromatous coronary coronary arteries, and of atheromatous coronary stenoses in patients with stable angina. Nitrates, by acting indirectly to increase cGMP in smooth muscle cells, dilate most coronary stenoses and normal coronary segments, decrease left ventricular afterload and diastolic filling pressure and improve the distribution of coronary flow to subendocardial zone. Large and small epicardial coronary vessels responded differently to endothelium-dependent and independent vasodilators.

Topics: Arteriosclerosis; Biological Factors; Cardiovascular Agents; Clinical Trials as Topic; Coronary Vessels; Cyclic GMP; Humans; Muscle Contraction; Muscle, Smooth, Vascular; Nitrates; Nitric Oxide; Vasoconstrictor Agents; Vasodilator Agents

Nitric oxide (NO), the biologically active component of endothelium-derived relaxing factor, has critical roles in the maintenance of vascular homeostasis. Decreased endothelial NO production, as a result of endothelial dysfunction, occurs in the early phases of atherosclerosis. NO appears to inhibit atherogenesis by inhibiting leukocyte and platelet activation and by inhibiting smooth muscle cell proliferation. Endothelial denudation is a prominent feature of vascular injury associated with percutaneous angioplasty, and decreased NO production appears to contribute to the restenosis process. Manipulation of the NO/cGMP signal transduction system may provide novel therapeutic approaches for limiting atherogenesis and neointimal proliferation in the future.

Topics: Angioplasty, Balloon; Animals; Arteriosclerosis; Cyclic GMP; Endothelium, Vascular; Fibromuscular Dysplasia; Humans; Nitric Oxide; Recurrence; Signal Transduction

This review considers the hypothesis that the endothelium-derived vasodilator agents, prostacyclin and nitric oxide, also function physiologically to inhibit vascular smooth muscle cell (VSMC) proliferation. The underlying biochemical mechanisms are also discussed. Prostacyclin and other agents that increase intracellular cAMP concentration are potent and effective inhibitors of the proliferation of isolated VSMC in culture. Such agents inhibit the initiation of proliferation in quiescent cells and the proliferation of logarithmically growing cells from a variety of sources, including man. The data implicate prostacyclin as an important regulator of VSMC proliferation, although there is little direct in vivo evidence. Nitric oxide-releasing drugs (and atriopeptins which increase intracellular cGMP concentration by a different mechanism) also inhibit proliferation of cultured VSMC. The effects are, however, partial and obtained at higher concentrations than those required for vasodilatation. Even allowing for the instability of the agents under tissue culture conditions, cGMP-elevating agents appear to be poorer at inhibiting proliferation than cAMP-elevating agents, despite similar or greater vasodilator potency. These data imply that nitric oxide is less likely than prostacyclin to be a physiological regulator of VSMC proliferation, although definitive experiments in vivo are again lacking. It also follows that nitrovasodilators are less attractive as therapy for VSMC proliferation than prostacyclin analogues or other cAMP-elevating agents, such as phosphodiesterase inhibitors. By analogy with the mechanisms of vasodilatation, inhibition of calcium mobilization and the subsequent activation of protein kinase C are considered as possible mechanisms underlying inhibition of proliferation.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Arteriosclerosis; Cell Division; Cyclic AMP; Cyclic GMP; Endothelium, Vascular; Epoprostenol; Humans; Muscle, Smooth, Vascular; Nitric Oxide; Vasodilation

Topics: Animals; Arteriosclerosis; Cell Communication; Cell Division; Cells, Cultured; Cyclic GMP; Endothelial Growth Factors; Endothelium; Growth Substances; Humans; Lipoproteins; Macrophages; Monocytes; Muscle, Smooth, Vascular

Topics: 3',5'-Cyclic-AMP Phosphodiesterases; Adenylyl Cyclases; Arteriosclerosis; Calcium; Catecholamines; Cyclic AMP; Cyclic GMP; Endocrine System Diseases; Enzyme Activation; Humans; Hypertension; Psoriasis; Receptors, Cell Surface; Vascular Resistance

To demonstrate that nitroglycerin improves biological markers of arterial inflammation in patients with peripheral vascular disease.. Atherosclerosis is an inflammatory disease in which there is an increase in active inflammation markers such as C-reactive protein and other factors released by endothelial cells. Nitroglycerin acts by a chemical liberation of nitric oxide. We have previously published the results from several controlled clinical trials confirming an anti-inflammatory action of nitroglycerin.. Forty patients with peripheral vascular disease entered a randomized, double-blind, placebo-controlled pilot study for 6 weeks. Twenty-one patients were treated with continuous application of a transdermal nitroglycerin patch (15 mg/24 hours) on the anterior face of the thigh. Venous blood samples were obtained before treatment and 2 and 6 weeks after. We measured plasma levels of C-reactive protein, cGMP (also intraplatelet cGMP), E-selectin, ICAM, VCAM-1, IL-6, and nitrites/nitrates.. No biological parameter was modified in the placebo group. On the contrary, nitroglycerin significantly reduced plasma levels of C-reactive protein and sE-selectin and increased the levels of intraplatelet cGMP.. The results of this preliminary study show that nitroglycerin has an anti-inflammatory action in patients with peripheral vascular disease. This may provide a new therapeutic approach to understanding the efficacy of nitrovasodilators in the improvement of atherosclerotic syndromes.

Topics: Administration, Cutaneous; Adult; Aged; Anti-Inflammatory Agents; Arteriosclerosis; Biomarkers; C-Reactive Protein; Cyclic GMP; Double-Blind Method; E-Selectin; Female; Humans; Intercellular Adhesion Molecule-1; Interleukin-6; Male; Middle Aged; Nitrates; Nitrites; Nitroglycerin; Peripheral Vascular Diseases; Pilot Projects; Statistics, Nonparametric; Vascular Cell Adhesion Molecule-1; Vasculitis; Vasodilator Agents

Topics: Allografts; Animals; Aorta; Arteriosclerosis; Carotenoids; Cell Proliferation; Cyclic GMP; Down-Regulation; Intercellular Adhesion Molecule-1; Lycopene; Male; Models, Biological; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Nitric Oxide; Nitric Oxide Synthase Type III; Rats, Inbred BN; Rats, Inbred Lew; rho-Associated Kinases; Signal Transduction; Transplantation, Homologous

The abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) leads to intimal thickening of the aorta and is, therefore, important in the development of arteriosclerosis. As a result, the use of antiproliferative and antimigratory agents for VSMCs offers promise for the treatment of vascular disorders. Although several studies have demonstrated that ligustrazine may be used to treat heart and blood vessel diseases, the detailed mechanism underlying its actions remain to be elucidated. In the present study, the inhibitory effect of ligustrazine on platelet-derived growth factor (PDGF)-BB-stimulated VSMC proliferation and migration, and the underlying mechanisms were investigated. The findings demonstrated that ligustrazine significantly inhibited PDGF-BB-stimulated VSMC proliferation. VSMCs dedifferentiated into a proliferative phenotype under PDGF-BB stimulation, which was effectively reversed by the administration of ligustrazine. In addition, ligustrazine also downregulated the production of nitric oxide and cyclic guanine monophosphate, induced by PDGF-BB. Additionally, ligustrazine significantly inhibited PDGF-BB-stimulated VSMC migration. Mechanistic investigation indicated that the upregulation of cell cycle-associated proteins and the activation of the extracellular signal-regulated kinase (ERK) and P38 mitogen-activated protein kinase (MAPK) signaling induced by PDGF-BB was suppressed by the administration of ligustrazine. In conclusion, the present study, demonstrated for the first time, to the best of our knowledge, that ligustrazine downregulated PDGF-BB-induced VSMC proliferation and migration partly, at least, through inhibiting the activation of the ERK and P38 MAPK signaling.

Topics: Arteriosclerosis; Becaplermin; Cell Movement; Cell Proliferation; Cyclic GMP; Gene Expression Regulation; Humans; Mitogen-Activated Protein Kinase 3; Muscle, Smooth, Vascular; Nitric Oxide; p38 Mitogen-Activated Protein Kinases; Proto-Oncogene Proteins c-sis; Pyrazines; Signal Transduction

Occlusive vascular changes, characterized by the formation of a neointima with lumen obstruction, are key histologic findings of allograft arteriosclerosis. Vascular integrity of the graft is critically dependent on nitric oxide (NO), synthesized by NO synthases (NOS), of which three isoforms have been located in the arterial wall: endothelial NOS (eNOS), inducible NOS, and neuronal NOS (nNOS). We have studied the role of NOS in a murine model of aortic allograft rejection.. The descending thoracic aorta of donor mice (BALB/c mice) was transplanted into two groups of recipients: (a) C57BL/6J and (b) C57BL/6J mice homozygous (-/-) for a knockout of the eNOS gene (eNOS(-/-)).. After 4 weeks, pronounced neointima formation, upregulated expression of adhesion molecules, and increased infiltration by inflammatory cells were demonstrated in wild-type recipient mice, whereas eNOS(-/-) recipient mice were protected from neointima development by a significantly increased synthesis of NO, as shown by increased formation of cGMP; this was mainly explained by upregulation of inducible NOS and nNOS.. Upregulation of inducible NOS and nNOS isoforms may be beneficial in preventing allograft arteriosclerosis in the early posttransplant period.

Topics: Animals; Aorta, Thoracic; Arteriosclerosis; Cell Adhesion; Cell Division; Cyclic GMP; DNA Primers; Homozygote; Kidney; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Knockout; Myocardium; Nitric Oxide; Nitric Oxide Synthase Type I; Nitric Oxide Synthase Type III; Postoperative Complications; Reverse Transcriptase Polymerase Chain Reaction; RNA; Tunica Intima

The objective of this study was to evaluate the influence of ingested l-arginine, l-citrulline, and antioxidants (vitamins C and E) on the progression of atherosclerosis in rabbits fed a high-cholesterol diet. The fatty diet caused a marked impairment of endothelium-dependent vasorelaxation in isolated thoracic aorta and blood flow in rabbit ear artery in vivo, the development of atheromatous lesions and increased superoxide anion production in thoracic aorta, and increased oxidation-sensitive gene expression [Elk-1 and phosphorylated cAMP response element-binding protein]. Rabbits were treated orally for 12 weeks with l-arginine, l-citrulline, and/or antioxidants. l-arginine plus l-citrulline, either alone or in combination with antioxidants, caused a marked improvement in endothelium-dependent vasorelaxation and blood flow, dramatic regression in atheromatous lesions, and decrease in superoxide production and oxidation-sensitive gene expression. These therapeutic effects were associated with concomitant increases in aortic endothelial NO synthase expression and plasma NO(2)(-)+NO(3)(-) and cGMP levels. These observations indicate that ingestion of certain NO-boosting substances, including l-arginine, l-citrulline, and antioxidants, can abrogate the state of oxidative stress and reverse the progression of atherosclerosis. This approach may have clinical utility in the treatment of atherosclerosis in humans.

Topics: Animals; Antioxidants; Aorta, Thoracic; Arginine; Arteriosclerosis; Ascorbic Acid; Citrulline; Cyclic AMP Response Element-Binding Protein; Cyclic GMP; Diet, Atherogenic; DNA-Binding Proteins; Endothelium, Vascular; ets-Domain Protein Elk-1; Humans; Male; Nitrates; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Nitrites; Oxidation-Reduction; Proto-Oncogene Proteins; Rabbits; Superoxides; Transcription Factors; Vasodilation; Vitamin E

Increased production of reactive oxygen species and loss of endothelial nitric oxide (NO) bioactivity are key features of vascular disease states such as atherosclerosis. Tetrahydrobiopterin (BH4) is a required cofactor for NO synthesis by endothelial nitric oxide synthase (eNOS); pharmacologic studies suggest that reduced BH4 availability may be an important mediator of endothelial dysfunction in atherosclerosis. We aimed to investigate the importance of endothelial BH4 availability in atherosclerosis using a transgenic mouse model with endothelial-targeted overexpression of the rate-limiting enzyme in BH4 synthesis, GTP-cyclohydrolase I (GTPCH).. Transgenic mice were crossed into an ApoE knockout (ApoE-KO) background and fed a high-fat diet for 16 weeks. Compared with ApoE-KO controls, transgenic mice (ApoE-KO/GCH-Tg) had higher aortic BH4 levels, reduced endothelial superoxide production and eNOS uncoupling, increased cGMP levels, and preserved NO-mediated endothelium dependent vasorelaxations. Furthermore, aortic root atherosclerotic plaque was significantly reduced in ApoE-KO/GCH-Tg mice compared with ApoE-KO controls.. These findings indicate that BH4 availability is a critical determinant of eNOS regulation in atherosclerosis and is a rational therapeutic target to restore NO-mediated endothelial function and reduce disease progression.

Topics: Animals; Aorta; Aortic Diseases; Apolipoproteins E; Arteriosclerosis; Biopterins; Coenzymes; Crosses, Genetic; Cyclic GMP; Diet, Atherogenic; Endothelium, Vascular; GTP Cyclohydrolase; Humans; Hyperlipoproteinemia Type II; Hyperlipoproteinemia Type IV; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Nitric Oxide; Organ Specificity; Receptor, TIE-2; Recombinant Fusion Proteins; Superoxides; Vasodilation

cGMP regulates vascular smooth muscle tone and arterial wall response to proliferative signals. We determined plasma cGMP and carotid artery intima-media thickness (IMT) and diameter in 84 asymptomatic men submitted to investigation of their cardiovascular risk profiles. Plasma cGMP was positively associated with IMT (P<0.01) and diameter (P<0.05), independently of coexisting risk factors. These associations were reinforced in the subgroup of subjects with high-sensitivity C-reactive protein level or multiple atherosclerotic plaques. A positive relationship existed between diameter and IMT (P<0.01) and disappeared after cGMP adjustment. This suggests a link between cGMP pathway and arterial wall geometry that is revealed by vascular injury conditions and may participate in early large artery remodeling.

Topics: Arteriosclerosis; C-Reactive Protein; Carotid Arteries; Cyclic GMP; Humans; Male; Middle Aged; Multivariate Analysis; Risk Factors; Tunica Intima; Ultrasonography

Atherosclerosis is associated with alterations in nitric oxide (NO)/cGMP signaling. In early stages of the disease, inflammatory and possibly other cells produce reactive oxygen species that scavenge vasoprotective NO. In addition to the oxidative stress, expression and activity of enzymes downstream to NO formation may also be affected. Here, we show in the aortas of chronically hypercholesterolemic rabbits (a model of late-stage atherosclerosis), both subunits and specific activity of the NO receptor soluble guanylyl cyclase (sGC) were significantly reduced, whereas overall NO synthase activity was unaffected. These changes were most prominent in the neointimal layer, wherein cGMP-dependent protein kinase I (cGK) levels also were reduced. Additionally, a protein (p38(nt)) that was constitutively tyrosine-nitrated was detected, and its expression was significantly reduced in atherosclerotic aorta. Phosphorylation of the cGK substrate vasodilator-stimulated phosphoprotein (VASP) at Ser-239, an established biochemical endpoint of NO/cGMP signaling, also was reduced. Thus, late-stage atherosclerosis is associated not only with enhanced NO breakdown but also with altered NO reception and cGMP signaling. Preferential down-regulation in neointima suggests a direct connection of these changes to neointimal proliferation and vascular dysfunction and provides a rationale for future pharmacotherapy using classical and novel sGC activators.

Topics: Animals; Aorta, Thoracic; Arteriosclerosis; Cell Adhesion Molecules; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Guanylate Cyclase; Lipids; Microfilament Proteins; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Peroxynitrous Acid; Phosphoproteins; Phosphoric Diester Hydrolases; Phosphorylation; Rabbits; Signal Transduction; Superoxide Dismutase

In cultured endothelial cells, the antioxidant, L-ascorbic acid (vitamin C), increases nitric oxide synthase (NOS) enzyme activity via chemical stabilization of tetrahydrobiopterin. Our objective was to determine the effect of vitamin C on NOS function and tetrahydrobiopterin metabolism in vivo. Twenty-six to twenty-eight weeks of diet supplementation with vitamin C (1%/kg chow) significantly increased circulating levels of vitamin C in wild-type (C57BL/6J) and apolipoprotein E (apoE)--deficient mice. Measurements of NOS enzymatic activity in aortas of apoE-deficient mice indicated a significant increase in total NOS activity. However, this increase was mainly due to high activity of inducible NOS, whereas eNOS activity was reduced. Significantly higher tetrahydrobiopterin levels were detected in aortas of apoE-deficient mice. Long-term treatment with vitamin C restored endothelial NOS activity in aortas of apoE-deficient mice, but did not affect activity of inducible NOS. In addition, 7,8-dihydrobiopterin levels, an oxidized form of tetrahydrobiopterin, were decreased and vascular endothelial function of aortas was significantly improved in apoE-deficient mice. Interestingly, vitamin C also increased tetrahydrobiopterin and NOS activity in aortas of C57BL/6J mice. In contrast, long-term treatment with vitamin E (2000 U/kg chow) did not affect vascular NOS activity or metabolism of tetrahydrobiopterin. In vivo, beneficial effect of vitamin C on vascular endothelial function appears to be mediated in part by protection of tetrahydrobiopterin and restoration of eNOS enzymatic activity.

Topics: Animals; Aorta; Apolipoproteins E; Arteriosclerosis; Ascorbic Acid; Biopterins; Cyclic AMP; Cyclic GMP; Dietary Supplements; Disease Models, Animal; Endothelium, Vascular; Enzyme Activation; In Vitro Techniques; Lipids; Male; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Superoxides; Time; Tyrosine; Vasomotor System; Vitamin E

Carbon monoxide (CO), one of the products of heme oxygenase action on heme, prevents arteriosclerotic lesions that occur following aorta transplantation; pre-exposure to 250 parts per million of CO for 1 hour before injury suppresses stenosis after carotid balloon injury in rats as well as in mice. The protective effect of CO is associated with a profound inhibition of graft leukocyte infiltration/activation as well as with inhibition of smooth muscle cell proliferation. The anti-proliferative effect of CO in vitro requires the activation of guanylate cyclase, the generation of cGMP, the activation of p38 mitogen-activated protein kinases and the expression of the cell cycle inhibitor p21Cip1. These findings demonstrate a protective role for CO in vascular injury and support its use as a therapeutic agent.

Topics: Angioplasty, Balloon, Coronary; Animals; Arteriosclerosis; Carbon Monoxide; Cyclic GMP; Cyclin-Dependent Kinase Inhibitor p21; Cyclins; Enzyme Activation; Graft Rejection; Guanylate Cyclase; Male; Mice; Mice, Inbred C57BL; Mitogen-Activated Protein Kinases; Nitric Oxide Synthase; p38 Mitogen-Activated Protein Kinases; Rats; Rats, Sprague-Dawley

We studied the effect of chronic ischemia on prostatic smooth muscle contraction in the rabbit.. New Zealand male rabbits weighing 3 to 3.5 kg were assigned to 2 groups. Group 1 (10 rabbits) underwent balloon endothelial injury of the iliac arteries and received a 0.5% cholesterol diet for 4 weeks and then a regular diet for 8 weeks. Control group 2 (10 rabbits) received a regular diet. After 12 weeks the animals were anesthetized. Iliac artery and prostate blood flow was recorded. Prostate tissues were prepared for isometric tension measurement, enzyme immunoassay to determine cyclic guanosine monophosphate (cGMP) release and histological examination.. In group 1 atherosclerosis as well as a significant decrease in iliac artery and prostate blood flow were observed. Ischemia significantly increased prostatic tissue contraction, decreased cGMP release and led to capsular and stromal thickening, and epithelial atrophy. The alpha1-adrenoceptor blocker doxazosin and the phosphodiesterase-5 inhibitor sildenafil citrate significantly decreased the contraction of control and ischemic tissues. Doxazosin was more effective in decreasing contractions when it was combined with sildenafil or the nitric oxide (NO) precursor L-arginine. In contrast, doxazosin was less effective when it was combined with the NO synthase inhibitor N omega-nitro-L-arginine or with the guanylate cyclase inhibitor methylene blue. Doxazosin significantly increased cGMP release in control tissues but not in ischemic tissues. Sildenafil significantly increased cGMP release in control and ischemic tissues.. Ischemia increased prostatic smooth muscle contraction and led to marked structural damage. Stimulators of NO synthesis and cGMP production enhanced the efficacy of doxazosin in decreasing prostatic tissue contraction. Sildenafil decreased contractility and increased cGMP release. Increased smooth muscle tone and structural changes in the ischemic prostate may suggest a role for prostate ischemia in resistance to urinary flow independent of prostate size.

Topics: Adrenergic alpha-Antagonists; Animals; Arginine; Arteriosclerosis; Blood Flow Velocity; Cyclic GMP; Doxazosin; Electric Stimulation; Iliac Artery; In Vitro Techniques; Ischemia; Laser-Doppler Flowmetry; Male; Muscle Contraction; Muscle, Smooth; Nitric Oxide; Phosphodiesterase Inhibitors; Piperazines; Prostate; Purines; Rabbits; Sildenafil Citrate; Sulfones

We sought to determine whether hypercholesterolemia impacts on the NO-stimulated activity of platelet soluble guanylyl cyclase (sGC). We investigated two groups of nine New Zealand white rabbits receiving either a standard (NC) or a cholesterol chow (HC, 0.75%) for 15 weeks. The plasma content of cGMP and the specific activity of sGC in intact platelets were measured by a cGMP-specific radioimmunoassay. In HC, 47.9+/-3.1% of the aortic intimal area was covered with atherosclerotic lesions, and plasma cGMP levels (pmol/ml) were increased from 12.6+/-1.2 to 27.9+/-3.5 (P<.0001). In striking contrast, hypercholesterolemia had no effect on sGC activity stimulated by the NO donor SNAP. At 100 microM SNAP, the specific activities of sGC (pmol/10(9) platelets/min) were 81.8+/-14.5 in NC and 86.2+/-8.1 in HC. Basal sGC activity (pmol/10(9) platelets/min) was also similar in NC (0.21+/-0.04) and HC (0.460+/-0.11, P=.7813). In accordance, washed platelets from both groups showed a similar SNAP-induced inhibition of aggregation. These data suggest that an impaired response of platelets to NO is most likely not involved in platelet hyperreactivity in hypercholesterolemia.

Topics: Animals; Aorta, Abdominal; Aorta, Thoracic; Arteriosclerosis; Blood Platelets; Cyclic GMP; Guanylate Cyclase; Hypercholesterolemia; Nitric Oxide; Nitric Oxide Donors; Penicillamine; Platelet Aggregation; Platelet Count; Rabbits; Receptors, Cytoplasmic and Nuclear; Solubility; Soluble Guanylyl Cyclase; Tunica Intima

Inflammatory mediators secreted by leukocytes are implicated in atherogenesis. Chlamydia (C.) pneumoniae infection has been suggested as a trigger of this process. We investigated relationships between C. Pneumoniae serology, inflammatory mediators and symptomatic cardiovascular disease in old age.. In a cross-sectional study at baseline with a prospective 4 year follow-up, intraplatelet cyclic 3'-5'adenosine monophosphate (cAMP) and cyclic 3'-5'guanosine monophosphate (cGMP), plasma neutrophil gelatinase associated lipocalin (NGAL), plasma soluble tumor necrosis factor receptor-1 (TNFR-1) plasma neopterin and plasma endothelin-1 (ET-1) were analysed together with IgG and IgA antibodies for C. Pneumoniae in an elderly reference population (n=140, median age 71 years, 71 females). Twenty-one subjects had clinical manifestations of cardiovascular disease at baseline and another 21 were diagnosed with cardiovascular disease during follow-up.. In age adjusted logistic regression, subjects with cardiovascular disease showed higher plasma levels of neopterin (p=0.02), NGAL (p=0.04), and ET-1 (p<0.01). If subjects with cardiovascular disease at baseline were excluded from the analysis, higher plasma neopterin (p=0.01) and lower serum HDL cholesterol (p=0.03) predicted cardiovascular disease during follow-up. The presence of IgG or IgA against C. pneumoniae was not associated with cardiovascular disease. Neither were there any associations between inflammatory or endothelial parameters and C. pneumoniae serology.. The inflammatory mediators neopterin and NGAL and endothelial derived vasoconstrictive ET-1 were increased in elderly subjects with symptomatic cardiovascular disease. Increased plasma neopterin predicted cardiovascular disease during follow-up. No relationships were found between C. Pneumoniae serology and cardiovascular disease.

Topics: Acute-Phase Proteins; Aged; Arteriosclerosis; Carrier Proteins; Chlamydophila Infections; Chlamydophila pneumoniae; Cross-Sectional Studies; Cyclic AMP; Cyclic GMP; Endothelin-1; Female; Humans; Lipocalin-2; Lipocalins; Logistic Models; Male; Neopterin; Oncogene Proteins; Proto-Oncogene Proteins

Estriol (E3) has little effect on the female genitals. E3 is used in hormone replacement therapy, particularly in Europe and Japan, since it obviates the need for progestin administration. However, the effect of E3 on atherosclerosis has not been elucidated. In this study, we evaluated the effect of E3 on the progression of atherosclerosis in a rabbit model. Thirty-six rabbits total were used. Twenty-eight were bilaterally oophorectomized, and 8 were not. The rabbits were divided into 5 groups and treated for 12 weeks as follows. Gp I (n = 8) was fed a high cholesterol diet (HCD; standard diet plus 0.5% cholesterol); Gp II (n = 8) was fed a HCD with E3 (0.3 mg/kg/day); Gp III (n = 8) was fed a HCD with 17beta estradiol (E2) (0.1 mg/kg/day); Gp IV (n = 8), the non oophorectomized group, was fed a HCD; and Gp NC was oophorectomized (n = 4), and fed a regular diet. E3 treatment increased the plasma E2 and E3 levels in Gp II. The plasma lipid levels were not altered by the E2 or E3 treatment. A HCD diminished the acetylcholine-induced NO mediated relaxation in the thoracic aorta. The E2 treatment (Gp III) and E3 treatment (Gp II) restored the aortic basal NO release and the aortic cyclic GMP levels, particularly effectively in the E3 group. E3 treatment also decreased the atherosclerotic area, and its effect was comparable with E2 (surface involvement: 41.2 +/- 5.1% in Gp I; 10.1 +/- 2.7% in Gp II; and 6.5 +/- 1.3% in Gp III). All four hyperlipidemic groups showed an increase of eNOS mRNA in the aortae, and this was especially pronounced in Gps II and III. The level of peroxynitrite, as determined by immunohistochemical nitrotyrosine staining, was lower in Gps II and III than in Gp I. E3 strongly activates NO-mediated systems, and could play a role in retarding the progression of atherosclerosis and in stabilizing atheroma.

Topics: Acetylcholine; Animals; Aorta, Thoracic; Arteriosclerosis; Cyclic GMP; Endothelium, Vascular; Estriol; Female; Immunohistochemistry; In Vitro Techniques; Isometric Contraction; Muscle, Smooth, Vascular; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Nitroglycerin; omega-N-Methylarginine; Rabbits; RNA, Messenger

Nitric oxide (NO), an endothelium-dependent relaxing factor, regulates relaxation, proliferation, and migration of smooth muscle cells (SMCs) and most likely attenuates developing vascular disease such as atherosclerosis. We investigated whether or not NO is associated with regulation of aortic elasticity. S-Nitrosoglutathione (GSNO), a NO donor, stimulated tropoelastin synthesis in cultured SMCs during both the quiescent and proliferating phases. The stimulation of tropoelastin synthesis was dose-dependent within 1-100 nM. Maximum stimulation was detected by treatment with 100 nM GSNO for 24 h. 8-Bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP), an exogenous cyclic GMP analog, also upregulated tropoelastin synthesis. Tropoelastin and lysyl oxidase mRNA expression, as assessed by Northern blot analysis, was also stimulated by GSNO. Administration of KT5823, a cyclic GMP-dependent protein kinase inhibitor, inhibited the GSNO-induced tropoelastin synthesis. These results indicate that the stimulatory effects of GSNO are due to cyclic GMP dependent protein kinase (PKG) activation by NO. In conclusion, NO seems to enhance aortic elasticity via tropoelastin and lysyl oxidase upregulation.

Topics: Animals; Aorta; Arteriosclerosis; Cell Division; Chick Embryo; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Elastin; Glutathione; Muscle, Smooth, Vascular; Nitric Oxide; Nitroso Compounds; Protein-Lysine 6-Oxidase; RNA, Messenger; S-Nitrosoglutathione; Tropoelastin

Endothelium-dependent relaxations mediated by NO are impaired in a mouse model of human atherosclerosis. Our objective was to characterize the mechanisms underlying endothelial dysfunction in aortas of apolipoprotein E (apoE)-deficient mice, treated for 26 to 29 weeks with a lipid-rich Western-type diet. Aortic rings from apoE-deficient mice showed impaired endothelium-dependent relaxations to acetylcholine (10(-)(9) to 10(-)(5) mol/L) and Ca(2+) ionophore (10(-)(9) to 10(-)(6) mol/L) and endothelium-independent relaxations to diethylammonium (Z)-1-(N,N-diethylamino)diazen-1-ium-1,2-diolate (DEA-NONOate, 10(-)(10) to 10(-)(5) mol/L) compared with aortic rings from C57BL/6J mice (P<0.05). By use of confocal microscopy of an oxidative fluorescent probe (dihydroethidium), increased superoxide anion (O(2)(-)) production was demonstrated throughout the aortic wall but mainly in smooth muscle cells of apoE-deficient mice. CuZn-superoxide dismutase (SOD) and Mn-SOD protein expressions were unaltered in the aorta exposed to hypercholesterolemia. A cell-permeable SOD mimetic, Mn(III) tetra(4-benzoic acid) porphyrin chloride (10(-)(5) mol/L), reduced O(2)(-) production and partially normalized relaxations to acetylcholine and DEA-NONOate in apoE-deficient mice (P<0.05). [(14)C]L-Citrulline assay showed a decrease of Ca(2+)-dependent NOS activity in aortas from apoE-deficient mice compared with C57BL/6J mice (P<0.05), whereas NO synthase protein expression was unchanged. In addition, cGMP levels were significantly reduced in the aortas of apoE-deficient mice (P<0.05). Our results demonstrate that in apoE-deficient mice on a Western-type fat diet, impairment of endothelial function is caused by increased production of O(2)(-) and reduced endothelial NO synthase enzyme activity. Thus, chemical inactivation of NO with O(2)(-) and reduced biosynthesis of NO are key mechanisms responsible for endothelial dysfunction in aortas of atherosclerotic apoE-deficient mice.

Topics: Animals; Aorta; Apolipoproteins E; Arteriosclerosis; Blotting, Western; Calcium; Culture Techniques; Cyclic AMP; Cyclic GMP; Endothelium, Vascular; Male; Metalloporphyrins; Mice; Mice, Inbred C57BL; Mice, Knockout; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Superoxide Dismutase; Superoxides; Vasoconstriction; Vasodilation

Topics: Animals; Arteriosclerosis; Cyclic AMP; Cyclic GMP; Endothelium, Vascular; Glycolysis; Humans; Research; Swine; Tunica Intima

Dehydroepiandrosterone (DHEA) is speculated to have an antiatherosclerotic effect, although the mechanism of action remains unclear. The objective of the current study was to determine whether the antiatherosclerotic effect of DHEA is related to its conversion to estrogen and to define the role of nitric oxide (NO) in the antiatherosclerotic effect of DHEA. Forty-eight oophorectomized rabbits were divided into 5 groups and fed the following diets for 10 weeks: group 1, a regular rabbit diet plus 1% cholesterol (a high-cholesterol diet [HCD]); group 2, an HCD plus 0.3% DHEA; group 3, an HCD plus 0.3% DHEA and fadrozole (2.0 mg x kg(-1) x d(-1)), a specific aromatase inhibitor; group 4, an HCD plus 17beta-estradiol (20 microg x kg(-1) x d(-1)); and group 5, a regular diet. Atherosclerotic lesions, lipid deposition in aortic vessels, and basal and stimulated NO release were measured in the aforementioned groups of rabbits. NO release was measured by using an NO-selective electrode as well as by measuring vascular responses and the plasma NO metabolites nitrite and nitrate. The plasma total cholesterol level was increased, but there were no significant differences in lipid profile in the 4 groups of rabbits that were fed the HCD. The area occupied by atherosclerosis in the thoracic aorta was diminished by approximately 60% in the DHEA-treated rabbits (group 2) compared with the HCD group of rabbits (group 1); there was a corresponding 80% decrease in the estradiol group (group 4) but only a 30% decrease in the DHEA plus fadrozole group (group 3). In the aortas of rabbits from groups 1 and 3, the acetylcholine-induced and tone-related basal NO-mediated relaxations were diminished compared with those of the controls (group 5). However, these relaxations were restored in the aortas of group 2 and 4 rabbits, and an increase in NO release was observed in groups 2 and 4 compared with groups 1 and 3, as measured by an NO-selective electrode. Injection of neither solvent (20% ethanol/distilled water) nor fadrozole significantly affected the atherosclerotic area or the NO-related responses described above. We conclude that approximately 50% of the total antiatherosclerotic effect of DHEA was achieved through the conversion of DHEA to estrogen. NO may also play a role in the antiatherosclerotic effect of DHEA and 17beta-estradiol.

Topics: Acetylcholine; Adjuvants, Immunologic; Animals; Aorta, Thoracic; Aromatase; Arteriosclerosis; Calcimycin; Cholesterol, Dietary; Cyclic GMP; Dehydroepiandrosterone; Diet, Atherogenic; Electrodes; Endothelium, Vascular; Estrogens; Female; Ionophores; Nitrates; Nitric Oxide; Nitrites; Rabbits; Triglycerides; Vasodilation; Vasodilator Agents

Nitric oxide (NO) is involved in the regulation of blood pressure and local blood flow. Its biological activity is impaired in hypertension and atherosclerosis. Because blood pressure undergoes a circadian rhythm, we investigated whether systemic NO production is dependent on a circadian variability, and whether the phasing of diurnal rhythm in NO production corresponds to the one in blood pressure in humans.. We studied three groups of human subjects: 8 healthy volunteers (HV), 8 patients with essential hypertension (HT), and 8 patients with peripheral arterial occlusive disease (PAOD). Twenty-four-hour ambulatory blood pressure monitoring was performed simultaneously with eight consecutive 3-hour urine collection periods. Urinary nitrate excretion was measured by gas chromatography-mass spectrometry; urinary cyclic GMP excretion was assessed by RIA.. Twenty-four-hour mean arterial blood pressure was 119.8 +/- 2.0/75.8 +/- 1.5 mm Hg in HV, 145.0 +/- 6.4/94.9 +/- 2.8 mm Hg in HT (P < 0.05 vs HV), and 137.0 +/- 7.3/81.5 +/- 1.9 mm Hg in PAOD (P = NS vs HV). There was significant circadian variation in blood pressure in all groups, but daily amplitude was lower in HT and PAOD than in HV (P < 0.05); 24-hour mean urinary nitrate excretion was 183.4 +/- 27.2 mumol/mmol creatinine in HV, 102.9 +/- 18.1 mumol/mmol creatinine in HT, and 162.1 +/- 22.2 mumol/mmol creatinine in PAOD (P < 0.05 vs HV and HT). Urinary cyclic GMP excretion was 211.8 +/- 19.0 nmol/mmol creatinine in HV, 108.6 +/- 12.4 nmol/mmol creatinine in HT, and 97.9 +/- 13.4 nmol/mmol creatinine in PAOD (P < 0.05 for HT and PAOD vs HV). Circadian variation was present in urinary nitrate and cyclic GMP excretion in HV but was significantly diminished in HT and PAOD, respectively; 24-hour mean nitrate-to-cyclic GMP ratio was 0.89 +/- 0.05 in HV and 1.10 +/- 0.10 in HT (P = NS). It was increased to 2.02 +/- 0.17 in PAOD (P < 0.05 vs HV and HT).. There is significant circadian variation in urinary nitrate and cyclic GMP excretion rates, two marker molecules for systemic NO production, in healthy humans. NO production is increased in the morning, concomitantly with the morning increase in blood pressure, indicating that NO may buffer blood pressure increase. Diurnal variation in nitrate and cyclic GMP excretion is absent in HT, pointing to impaired NO formation. The major change in PAOD is increased nitrate/cyclic GMP ratio, which points to increased oxidative inactivation of NO in this disease. Disturbed formation and activity of NO may contribute to blood pressure alterations in cardiovascular disease.

Topics: Adult; Arterial Occlusive Diseases; Arteriosclerosis; Blood Pressure; Case-Control Studies; Circadian Rhythm; Cyclic GMP; Female; Humans; Hypertension; Male; Middle Aged; Nitrates; Nitric Oxide

Topics: Arginine; Arteriosclerosis; Biomarkers; Carotid Arteries; Chromatography, High Pressure Liquid; Cyclic GMP; Enzyme Inhibitors; Humans; Nitrates; Nitric Oxide Synthase; Regression Analysis; Stereoisomerism; Tunica Intima

Endothelin-converting enzyme-1 (ECE-1) processes big endothelin-1 (ET-1) to ET-1, a peptide implicated in atheroma formation. ECE-1 exists in 2 isoforms (ECE-1alpha and ECE-1beta), the result of alternative splicing of a common gene. Neutral endopeptidase (NEP) is a genetically distinct metallopeptidase that degrades the natriuretic peptides. These peptides mediate antiproliferative and vasodilating actions. We sought to demonstrate the distribution of the 2 ECE-1 isoforms in experimental atherosclerosis, to determine the effects of chronic NEP-I on plasma cGMP concentrations, vascular wall ECE-1 activity, and ET-1 concentration, and to correlate these actions with atheroma formation. Our hypothesis was that chronic NEP-I, in association with augmented cGMP, would inhibit ECE-1 conversion of big ET-1 to active ET-1, thus reducing tissue ET-1 concentrations and associated atheroma formation.. Cholesterol-fed New Zealand White rabbits (n=8, 1% cholesterol diet) and NEP-I-treated cholesterol-fed New Zealand White rabbits (n=8; candoxatril, 30 mg/kg per day, Pfizer) were euthanized after 8 weeks of feeding. ECE-1alpha and ECE-1beta immunoreactivity was present in the aortas of both groups. Compared with control values, plasma cGMP concentrations were increased (2.8+/-0.6 versus 8.4+/-1.2 pmol/mL, P<0.05), ECE-1 activity was attenuated (68+/-3% versus 32+/-8%, P<0. 05), aortic tissue ET-1 concentrations were reduced (4.6+/-0.5 versus 3.2+/-0.3 pg/mg protein, P<0.05), and atheroma formation was attenuated (62+/-6% versus 34+/-5%, P<0.01) by NEP-I.. These studies suggest that ECE-1 is present and functionally active in the vascular wall in atherosclerosis. Inhibition of ECE-1 by NEP-I represents a novel approach to interruption of the endothelin system in this cardiovascular disease state.

Topics: Animals; Aorta; Arteriosclerosis; Aspartic Acid Endopeptidases; Atrial Natriuretic Factor; Chronic Disease; Cyclic GMP; Diet, Atherogenic; Disease Models, Animal; Endothelin-1; Endothelin-Converting Enzymes; Endothelins; In Vitro Techniques; Isoenzymes; Male; Metalloendopeptidases; Neprilysin; Protein Precursors; Rabbits; Time Factors; Vasoconstriction

The molecular mechanisms of the antiatherosclerotic effects of estrogen are not yet known. We evaluated the effects of 17beta-estradiol (E(2)) on high cholesterol diet- (HCD; standard diet and 1% cholesterol) and balloon injury-induced atherosclerosis in female New Zealand White rabbits. The abdominal aortas of 40 oophorectomized (Groups 1 through 5) and 8 nonoophorectomized (Group 6) rabbits were injured by balloon catheter, and the animals were then divided into the following groups and treated for 10 weeks: Group 1, standard diet; Group 2, standard diet plus a moderate dose of E(2) (100 microg x kg(-1) x d(-1)); Group 3, HCD; Group 4, HCD plus a moderate dose of E(2); Group 5, HCD plus a low dose of E(2) (20 microg x kg(-1) x d(-1)); and Group 6, HCD in nonoophorectomized rabbits. After the treatment phase, plasma E(2) was increased up to 282.2+/-45.5 pg/mL in Group 2, 263.0+/-41.5 pg/mL in Group 4, 87. 9+/-18.8 pg/mL in Group 5, and 45.6+/-7.3 pg/mL in Group 6. HCD-mediated increases in plasma lipid levels were not changed by E(2) treatment, whereas E(2) decreased the aortic intimal thickening in Group 2 animals compared with those in Group 1 and reduced atherosclerosis in the thoracic and abdominal aortas of Group 4, 5, and 6 rabbits compared with those in Group 3. E(2) restored the impaired abdominal aortic endothelium-dependent relaxation of balloon-injured and HCD-supplemented rabbits, and E(2) increased basal nitric oxide (NO) release. The basal NO-releasing effect showed a significant, inverse relation with the severity of atherosclerosis. Plasma E(2) concentration also showed a significant, inverse relation with atherosclerotic area. In conclusion, physiological concentrations of E(2) can retard the progression of severe atherosclerosis and stabilize atheromas induced by HCD and balloon injury. The retardation may be partially mediated by endothelial NO function in vessels treated with E(2).

Topics: Animals; Aorta, Abdominal; Arteriosclerosis; Catheterization; Cholesterol; Cholesterol, Dietary; Cyclic GMP; Endothelium, Vascular; Estradiol; Female; Immunohistochemistry; Lipids; Muscle Relaxation; Muscle, Smooth, Vascular; Nitrates; Nitric Oxide; Nitrites; Ovariectomy; Rabbits

Recently, intravascular low-power red laser light (LPRLL) therapy has been proposed for the prevention of postangioplasty restenosis due to the observed inhibition of experimental neointimal formation. The objective of this study was to determine the impact of endoluminal LPRLL on vascular levels of inducible nitric oxide synthase (iNOS) and cyclic guanosine monophosphate (cGMP) to help define the mechanism of this effect. Eight atherosclerotic male adult New Zealand White rabbits weighing 4-6 kg were used in these studies. The iliac arteries were treated in separate zones with: (1) balloon inflation only; (2) laser illumination only; and (3) balloon inflation + laser illumination. An uninjured zone of the iliac artery served as a control. Laser irradiation (630 nm) was delivered to the vessel wall via a Cold laser Illuminator (Cook, Inc., Bloomington, IN), with a 3 mm-diameter balloon. Experiments demonstrated that vascular cGMP levels obtained immediately following treatment in the balloon only group was the lowest (0.29 +/- 0.05 pmol/mg protein) and significantly lower compared with the uninjured controls (1.01 +/- 0.07 pmol/ mg protein) (P < 0.001). In the laser only treated group cGMP levels were significantly increased (2.87 +/- 0.12 pmol/mg protein) compared with the uninjured control (P < 0.001) and the balloon only group (P < 0.001). Vascular cGMP levels in the balloon + laser group (2.09 +/0.07 pmol/mg protein) was also increased compared to the balloon only (P < 0.001) and control (P < 0.001) groups. Qualitative analysis of Western blot demonstrated that laser illumination induces iNOS. In contrast balloon dilatation did not induce iNOS. Balloon + laser treatment, however, tended to restore the expression of iNOS. Our study demonstrated that intravascular low dose laser irradiation induces iNOS and elevates vascular cGMP in an in vivo atherosclerotic rabbit model.

Topics: Angioplasty, Balloon; Angioplasty, Balloon, Laser-Assisted; Animals; Arteriosclerosis; Cyclic GMP; Disease Models, Animal; Enzyme Activation; Iliac Artery; Male; Muscle Relaxation; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Rabbits

We have recently found that administration of L-arginine to hypercholesterolemic rabbits induces regression of preexisting lesions. Others have previously shown that activation of the L-arginine/nitric oxide (NO) synthase pathway can induce apoptosis of vascular cells in vitro. Accordingly, the current study was designed to determine if dietary supplementation of L-arginine induces apoptosis of intimal lesions and if this effect is mediated through the NO synthase pathway.. Male New Zealand White rabbits were fed a 0.5% cholesterol diet for 10 weeks and subsequently placed on 2.5% L-arginine HCl in the drinking water, and the cholesterol diet was continued for 2 weeks, at which time the aortas were harvested for histological studies. L-Arginine treatment increased the number of apoptotic cells (largely macrophages) in the intimal lesions by 3-fold (11.9+/-3.9 vs 3.9+/-1. 4 apoptotic cells/mm2, P<0.01). In subsequent studies, aortas were harvested for ex vivo studies. Aortic segments were incubated in cell culture medium for 4 to 24 hours with modulators of the NO synthase pathway. The tissues were then collected for histological studies and the conditioned medium collected for measurement of nitrogen oxides by chemiluminescence. Addition of sodium nitroprusside (10(-5) mol/L) to the medium caused a time-dependent increase in apoptosis of vascular cells (largely macrophages) in the intimal lesion. L-Arginine (10(-3) mol/L) had an identical effect on apoptosis, which was associated with an increase in nitrogen oxides released into the medium. These effects were not mimicked by D-arginine, and they were antagonized by the NO synthase inhibitor L-nitro-arginine (10(-4) mol/L). The effect of L-arginine was not influenced by an antagonist of cGMP-dependent protein kinase, nor was the effect mimicked by the agonist of protein kinase G or 8-BR cGMP.. These results indicate that supplemental L-arginine induces apoptosis of macrophages in intimal lesions by its metabolism to NO, which acts through a cGMP-independent pathway. These studies are consistent with our previous observation that supplementation of dietary arginine induces regression of atheroma in this animal model. These studies provide a rationale for further investigation of the therapeutic potential of manipulating the NO synthase pathway in atherosclerosis.

Topics: Animals; Aorta, Abdominal; Apoptosis; Arginine; Arteriosclerosis; Cyclic GMP; Dietary Supplements; Male; Nitric Oxide; Nitric Oxide Synthase; Organ Culture Techniques; Rabbits

We investigated whether glutathione (GSH), a reduced thiol that modulates redox state and forms adducts of nitric oxide (NO), improves endothelium-dependent vasomotion and NO activity in atherosclerosis.. Endothelial dysfunction and reduced NO activity are associated with atherosclerosis and its clinical manifestations such as unstable angina.. In the femoral circulation of 17 patients with atherosclerosis or its risk factors, endothelium-dependent vasodilation with acetylcholine (ACH), and endothelium-independent vasodilation with nitroglycerin and sodium nitroprusside were studied before and after GSH. In 10 patients, femoral vein plasma cyclic guanylate monophosphate (cGMP) levels were measured during an infusion of ACH before and after GSH. Femoral artery flow velocity was measured using a Doppler flow wire and the resistance index (FVRI) calculated as mean arterial pressure divided by flow velocity.. Glutathione strongly potentiated ACH-mediated vasodilation; at the two doses, FVRI decreased by 47% and 56% before, and by 61% and 67% after GSH (p = 0.003). Glutathione also elevated cGMP levels in the femoral vein during ACH infusion from 17.6 +/- 3 to 23.3 +/- 3 pmol/ml (p = 0.006). Augmentation of ACH responses was only observed in patients with depressed endothelial function. Glutathione did not influence endothelium-independent vasodilation with either NO donor.. Thiol supplementation with GSH selectively improves human endothelial dysfunction by enhancing NO activity.

Topics: Acetylcholine; Arteriosclerosis; Blood Flow Velocity; Cyclic GMP; Endothelium, Vascular; Female; Femoral Artery; Glutathione; Humans; Male; Middle Aged; Nitric Oxide; Nitric Oxide Donors; Nitroglycerin; Nitroprusside; Vascular Resistance; Vasodilation; Vasodilator Agents

Tissue kallikrein cleaves kininogen substrate to produce vasoactive kinin peptides that have been implicated in the proliferation of vascular smooth muscle cells (VSMCs). To explore potential roles of the kallikrein-kinin system in vascular biology, we evaluated the effects of adenovirus-mediated human kallikrein gene delivery on the growth of primary cultured VSMCs and in balloon-injured rat artery in vivo. Kallikrein gene transfer into cultured rat VSMCs resulted in time-dependent secretion of recombinant human tissue kallikrein and inhibition of cell proliferation. Balloon angioplasty reduced endogenous rat tissue kallikrein mRNA and protein levels at the injured site. In rats that received adenovirus-mediated human kallikrein gene delivery, we observed a 39% reduction in intima/media ratio at the injured vessel after delivery compared with that of rats that received control virus (n=8, P<0.01). Icatibant, a specific bradykinin B(2) receptor antagonist, blocked the protective effect and reversed the intima/media ratio to that of the control rats (n=5, P<0.01). After gene delivery, human kallikrein mRNA was identified at the injured vessel and a 3-fold increase occurred in kininogenase activity. cAMP and cGMP levels in balloon-injured aorta increased significantly at 4, 7, and 14 days after kallikrein gene delivery, but icatibant abolished the increase. These results provide new insights into the role of the vascular kallikrein-kinin system and have significant implications for gene therapy to treat restenosis or atherosclerosis.

Topics: Angioplasty, Balloon; Animals; Aorta, Abdominal; Arteriosclerosis; Base Sequence; Blood Pressure; Blotting, Southern; Carotid Artery Injuries; Carotid Artery, Common; Cells, Cultured; Constriction, Pathologic; Cyclic AMP; Cyclic GMP; Data Interpretation, Statistical; Dogs; Gene Transfer Techniques; Genetic Therapy; Heart Rate; Humans; In Vitro Techniques; Kallikrein-Kinin System; Kallikreins; Male; Molecular Sequence Data; Muscle, Smooth, Vascular; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Time Factors; Tunica Intima; Tunica Media

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

To clarify relationships between the (endothelial vasodilatory and vasoconstrictive function) and leukocyte inflammatory mediators in subjects with asymptomatic atherosclerosis, we measured (intraplatelet cyclic 3',5'-guanosine monophosphate [cGMP] and cyclic 3',5'-adenosine monophosphate [cAMP]), plasma endothelin (ET-1), and plasma neopterin in 197 subjects with asymptomatic atherosclerosis (median age 63 years, range 49-69 years). We measured neutrophil protease 4 (NP4), tumor necrosis factor (TNFmu), soluble tumor necrosis factor receptor-1 (sTNFR-1), and neutrophil gelatinase associated lipocalin (NGAL) in 152 of the 197 subjects. Intraplatelet cGMP correlated inversely with plasma ET-1 (r=-0.22; p=0.01), which confirms earlier in vitro data of the inhibitory effect of ET-1 on NO production and/or the cGMP mediated inhibitory effect of NO on ET-1 production. Plasma neopterin as well as NP4 correlated directly with intraplatelet cGMP (r=0.24; p<0.01 and r=0.33; p<0.001, respectively). Intraplatelet cAMP correlated directly with plasma TNFmu (r=0.17; p<0.05) and sTNFR-1 (r=0.20; p<0.05). The relationship between leukocyte derived inflammatory mediators and intraplatelet cyclic nucleotides suggest an antiaggregating effect of leukocytes upon platelets, which may constitute a negative feedback mechanism that inhibits platelet activation during the atherosclerotic inflammatory process.

Topics: Aged; Arteriosclerosis; Blood Platelets; Carotid Artery, Common; Carotid Stenosis; Cyclic AMP; Cyclic GMP; Cytokines; Endothelin-1; Female; Humans; Inflammation; Leukocytes; Male; Middle Aged; Myeloblastin; Neopterin; Platelet Aggregation; Prospective Studies; Risk Factors; Serine Endopeptidases; Ultrasonography

Cholesterol feeding results in impaired endothelium dependent vasorelaxation. The role of nitric oxide in this process is unclear. The aim of this study was to evaluate the role of nitric oxide in cholesterol-induced vasomotor dysfunction by examining the effect of overexpression of eNOS in the hypercholesterolemic rabbit aorta on vascular reactivity. Vascular rings from the thoracic aorta of hypercholesterolemic rabbits were exposed ex vivo either to an adenoviral vector encoding endothelial nitric oxide synthase (AdeNOS) or Escherichia coli beta Galactosidase (AdbetaGal). Transgene expression was examined by histochemistry for beta galactosidase, immunohistochemistry for eNOS and cyclic GMP measurements and vasomotor studies were performed. Transgene expression was found to localize to the endothelium and adventitia. cGMP levels were significantly greater in AdeNOS compared to AdbetaGal transduced rings. Acetylcholine mediated relaxation was significantly impaired in cholesterol fed rabbits and was markedly improved by overexpression of eNOS. These results suggest that reduced NO bioavailability observed in cholesterol-induced vascular dysfunction can be partially overcome by eNOS gene transfer.

Topics: Acetylcholine; Adenoviridae; Animals; Aorta, Thoracic; Arteriosclerosis; beta-Galactosidase; Cyclic GMP; Endothelium, Vascular; Escherichia coli; Gene Transfer Techniques; Genetic Vectors; In Vitro Techniques; Nitric Oxide; Nitric Oxide Synthase; Rabbits; Vasodilation; Vasodilator Agents

Local activation of polymorphonuclear leukocytes (PMNLs) is considered an important aspect of the pathogenesis of intermittent claudication, although concrete mechanisms of their effects on circulatory homeostasis in peripheral atherosclerotic disease remain unclear. This study evaluated the ability of PMNLs to deactivate nitric oxide (NO), a key regulator of regional circulation, as a possible factor determining PMNL involvement into ischemic disorders in patients who have intermittent claudication before and after vascular reconstruction.. A total of 57 patients who had peripheral occlusive disease in an aortofemoral segment before surgical treatment (group 1) and 65 patients who had similar occlusive lesions and other clinical and demographic data 6 to 12 months after undergoing inflow vascular reconstruction (group 2) were examined. All patients from group 2 had anatomically patent grafts; their satisfaction and level of function after surgical treatment were assessed by a five-point questionnaire. The sex- and age-matched control group included 35 subjects. NO activity was bioassayed by measuring its ability to increase cyclic guanosine monophosphate (cGMP) accumulation in rat fetal lung-cultured fibroblasts (RFL-6 cells). The ability of PMNLs to deactivate NO was characterized as the percent decrease in NO-induced cGMP accumulation in RFL-6 cells.. Stimulated PMNLs caused inhibition of the activity of authentic NO; accumulation of cGMP induced by sodium nitroprusside was not affected. PMNLs from patients with peripheral atherosclerotic disease either before or after vascular reconstruction had a more marked capacity of NO inactivating than the cells from healthy subjects. For both groups of patients, levels of PMNL-induced NO deactivation were higher for patients with diabetes, and especially both diabetes and arterial hypertension. For both groups of patients, there was no correlation between levels of PMNL-induced NO deactivation and resting ankle-brachial indexes (ABIs). In contrast, close correlation was revealed between levels of PMNL-induced NO deactivation and postexercise ABIs and percent decrease in resting ABIs after exercise in patients evaluated either before or after surgical treatment.. The ability of stimulated PMNLs to deactivate NO is elevated in peripheral occlusive disease and may be implicated in the pathogenesis of intermittent claudication. In patients who underwent successful recanalization of magistral arteries, levels of PMNL-induced NO deactivation remained higher than in control subjects. The increase in the ability of PMNL to deactivate NO positively correlated to ABI decreases after exercise in patients with peripheral occlusive disease either before or after surgical treatment.

Topics: Animals; Aortic Diseases; Arteriosclerosis; Blood Circulation; Blood Pressure; Case-Control Studies; Cells, Cultured; Cyclic GMP; Diabetes Mellitus; Female; Femoral Artery; Fibroblasts; Homeostasis; Humans; Hypertension; Intermittent Claudication; Ischemia; Lung; Male; Middle Aged; Neutrophil Activation; Neutrophils; Nitric Oxide; Nitroprusside; Patient Satisfaction; Peripheral Vascular Diseases; Rats; Vascular Patency

We investigated whether L-arginine induces regression of preexisting atheromatous lesions and reversal of endothelial dysfunction in hypercholesterolemic rabbits, whether similar effects can be obtained by cholesterol-lowering therapy with lovastatin, and which mechanism leads to these effects.. Rabbits were fed 1% cholesterol for 4 weeks and 0.5% cholesterol for an additional 12 weeks. Two groups of cholesterol-fed rabbits were treated with L-arginine (2.0% in drinking water) or lovastatin (10 mg/d) during weeks 5 through 16. Systemic nitric oxide (NO) formation was assessed as the urinary excretion rates of nitrate and cGMP in weekly intervals. Cholesterol feeding progressively reduced urinary nitrate excretion to approximately 40% of baseline (P<.05) and increased plasma concentrations of asymmetrical dimethylarginine (ADMA), an endogenous NO synthesis inhibitor. Dietary L-arginine reversed the reduction in plasma L-arginine/ADMA ratio and partly restored urinary excretion of nitrate and cGMP (each P<.05 vs cholesterol) but did not change plasma cholesterol levels. L-Arginine completely blocked the progression of carotid intimal plaques, reduced aortic intimal thickening, and preserved endothelium-dependent vasodilator function. Lovastatin treatment reduced plasma cholesterol by 32% but did not improve urinary nitrate or cGMP excretion or endothelium-dependent vasodilation. Lovastatin had a weaker inhibitory effect on carotid plaque formation and aortic intimal thickening than L-arginine. L-Arginine inhibited but lovastatin potentiated superoxide radical generation in the atherosclerotic vascular wall.. Dietary L-arginine improves NO-dependent vasodilator function in cholesterol-fed rabbits and completely blocks the progression of plaques via restoration of NO synthase substrate availability and reduction of vascular oxidative stress. Lovastatin treatment has a weaker inhibitory effect on the progression of atherosclerosis and no effect on vascular NO elaboration, which may be due to its stimulatory effect on vascular superoxide radical generation.

Topics: Animals; Anticholesteremic Agents; Arginine; Arteriosclerosis; Cholesterol; Cholesterol, Dietary; Cyclic GMP; Diet, Atherogenic; Endothelium, Vascular; Hypercholesterolemia; Lovastatin; Male; Nitrates; Nitric Oxide; Rabbits; Superoxides

We evaluated the effects of nipradilol, a beta-adrenoreceptor antagonist which contains a nitroxy residue, for vascular response in atherosclerosis of rabbits. Four groups of rabbits received different diets (standard diet; standard diet plus 10 mg/kg/day nipradilol; atherogenic diet [standard diet plus 1% cholesterol]; atherogenic diet plus 10 mg/kg/day nipradilol) for 9 weeks. Plasma lipids, blood pressure, vascular function, nitric oxide (NO), activity of NO synthase, cGMP, and histological atherosclerotic changes were evaluated. Neither the atherogenic diet nor nipradilol treatment affected significantly the animals' body weight, blood pressure, or heart rate. The atherogenic diet increased total cholesterol and triglycerides, which were not altered by nipradilol. The atherogenic diet diminished the acetylcholine-induced NO mediated relaxation. Nipradilol treatment restored this relaxation. Analyses using a NO-sensitive selective electrode showed that nipradilol released NO in the presence of cells and that NO release was greater in atherosclerotic aorta with than without nipradilol treatment. Nipradilol treatment increased the basal NO release as evaluated by the aortic tissue cyclic GMP (cGMP) levels in atherosclerotic vessel, and reduced the esterified cholesterol levels in atherosclerotic vessel. Conclusively, NO released by nipradilol may protect endothelium derived relaxation in atherosclerotic vessels, and may partially inhibit the accumulation of cholesterol in the atherosclerotic lesions.

Topics: Adrenergic beta-Antagonists; Animals; Arteriosclerosis; Cattle; Cells, Cultured; Cholesterol; Cyclic GMP; Endothelium, Vascular; Immunohistochemistry; Male; Muscle Relaxation; Nitric Oxide; Nitric Oxide Synthase; Propanolamines; Rabbits

1. Experiments were performed to examine the effects of putative non-endothelial nitric oxide on the soluble guanylate cyclase activity of severe atherosclerotic aortae from hypercholesterolaemic rabbits fed a cholesterol rich diet for 45 weeks. 2. The guanosine 3':5'-cyclic monophosphate (cyclic GMP) content of aortae from rabbits fed either a control diet or a diet containing 0.3% cholesterol for 45 weeks was quantified in saline extracts or in trichloracetic acid/either extracts by use of a competitive immunoenzymatic assay. Rabbit anti-cyclic GMP immunoglobulin G was covalently linked to the solid phase, in order to avoid false positive results due to high rabbit immunoglobulin G concentrations in the atherosclerotic saline extracts. 3. Saline extracts of atherosclerotic aortae which were harvested immediately after death (intact aortae) contained about 6 fold more cyclic GMP than control aortae when expressed in pmol cyclic GMP mg-1 protein. The cyclic GMP concentrations in trichloracetic acid/ether extracts of atherosclerotic and control aortae expressed in pmol mg-1 fresh tissue were not significantly different. 4. Neointimal-medial explants from atherosclerotic and control aortae were placed in a physiological saline solution and incubated at 37 degrees C for six hours in an incubator gassed with 5% CO2. Before the incubation, the cyclic GMP concentrations in saline extracts of atherosclerotic explants (0.74 +/- 0.27 pmol mg-1) were found to be 17 fold higher than those of control explants (0.043 +/- 0.008 pmol mg-1). The cyclic GMP content of control explants decreased significantly after 6 h of incubation, while that of atherosclerotic explants remained elevated. 5. Chronic administration of NG-nitro-L-arginine methyl ester, a non selective inhibitor of nitric oxide synthases, at 12 mg kg-1 day-1 subcutaneously for one month did not reduce the cyclic GMP concentration of intact atherosclerotic aortae, while that of intact aortae from control rabbits decreased by 63.4 +/- 7.6%. 6. These data show that atherosclerotic aortae harvested immediately after death from hypercholesterolaemic rabbits contain higher concentrations of cyclic GMP than control aortae when measured in saline extracts. In vitro, the persistence of the cyclic GMP production in atherosclerotic neointimal medial explants suggests that the guanylate cyclase is activated by an endogenous mediator. This mediator could be NO, synthesized by non endothelial nitric oxide synthases. The

Topics: Animals; Aorta; Arteriosclerosis; Cyclic GMP; Guanylate Cyclase; Immunoglobulin G; Male; NG-Nitroarginine Methyl Ester; Nitric Oxide Synthase; Rabbits

Nitric oxide (NO) exerts its vasodilator and antiaggregatory effects through activation of soluble guanylate cyclase and the consequent increase in the concentration of cGMP in target cells. We conducted this study in order to evaluate relationships between intraplatelet cGMP levels and risk factors for atherosclerosis in middle aged subjects. Intraplatelet cGMP was determined by radioimmunoassay and related to age, BMI, blood pressure, antihypertensive treatment, total, LDL and HDL cholesterol, triglycerides, blood glucose, HbA1c, smoking habit and intimal thickness of the common carotid artery in 265 subjects participating in a health survey (age 59 +/- 6 years, range 48-68 years, 121 females, 144 males). Intraplatelet cGMP concentration was inversely correlated with total serum cholesterol (r = -0.18; p < 0.01) and HDL cholesterol (r = -0.14, p < 0.05) as well as with platelet count (r = -0.29; p < 0.001). When platelet count was adjusted for, only the correlation between total serum cholesterol and cGMP remained significant. No significant correlations could be demonstrated between intraplatelet cGMP levels and measurable parameters of atherosclerosis. Lower levels of the vasodilating and antiaggregating mediator cGMP in platelets are related to higher levels of serum total cholesterol. These results favour the hypothesis of a relationship between lipid levels and NO associated vasodilator and antiaggregating function in atherosclerosis.

Topics: Age Factors; Aged; Antihypertensive Agents; Arteriosclerosis; Blood Glucose; Blood Platelets; Blood Pressure; Body Mass Index; Cardiovascular Diseases; Cholesterol; Cholesterol, HDL; Cholesterol, LDL; Cyclic GMP; Diabetes Mellitus; Female; Glycated Hemoglobin; Humans; Male; Middle Aged; Platelet Count; Radioimmunoassay; Risk Factors; Smoking; Triglycerides

Disorders in arterial production of PGI2 and NO occur in atherosclerosis. Exogenous PGI2 and NO are capable of interacting pharmacologically. We claim that no such direct interactions occur between endogenous endothelial PGI2 and NO. Studying mechanisms of cardiac reactive hyperemia in guinea pigs and of thrombolysis in cats, we surmise that in vivo vascular intima releases PGI2 intraluminally while NO is secreted abluminally and thus these two ephemeral mediators do not see each other. Hence, in any disease, the disturbances in endothelial generation of PGI2 or NO have to be scrutinized separately. It may well be that endogenous PGI2 maintains endothelial thromboresistance while NO controls arterial myocytes and tissues in which microcirculation is embedded. These responsibilities remain unshared. Interactions between PGI2 and NO are confined to pharmacological domains.

Topics: Animals; Arteriosclerosis; Blood Pressure; Cats; Coronary Disease; Cyclic GMP; Epoprostenol; Guinea Pigs; Hyperemia; In Vitro Techniques; Male; Myocardium; Nitric Oxide; Thrombosis; Thromboxane B2

Platelets play important roles for hemostasis with activated platelets adhering to the injured vessel wall to initiate platelet aggregation. At the same time, our study revealed the cytotoxic effect on endothelial cells characterized by an increase of intracellular Ca++ and a decrease of EDRF production, which may cause plasmal infiltration including blood cells and lipids. Our clinical survey using a small dose of aspirin as an antiplatelet therapy clearly demonstrated its suppressive effect on platelet aggregation and its favorable effect on fibrinolysis. These data suggest that the therapeutic effect of aspirin in vascular disease could be applied to the prevention of thrombus formation and the protection of endothelial cells from the cytotoxic effect of activated platelets.

Topics: Adenylyl Cyclases; Animals; Arteriosclerosis; Aspirin; Blood Platelets; Calcium; Capillary Permeability; Cattle; Collagen; Cyclic AMP; Cyclic GMP; Endothelium, Vascular; Myocardial Ischemia; Nitric Oxide; Plasminogen Activator Inhibitor 1; Platelet Activation; Platelet Aggregation; Tissue Plasminogen Activator

The early atherosclerotic lesion is characterized by the migration of inflammatory cells, including monocytes, which may serve as a source of cytokines such as monocyte chemoattractant protein 1 (MCP-1), a homologue of mouse JE. We investigated the effect of MCP-1 on the growth of vascular smooth muscle cells (VSMC) isolated from rat aortae. In Northern blot analysis, MCP-1/JE transcripts were not observed in unstimulated VSMC, but its expression was clearly observed by exposure to lipopolysaccharide (1 micrograms/ml) for 6 h. Human recombinant MCP-1 inhibited the uptake of [3H]thymidine by VSMC cultured in 0.5% fetal bovine serum (FBS) containing Dulbecco's modified Eagle's medium (DMEM) in a dose-dependent manner. The inhibitory effect of MCP-1 on the growth of VSMC was also confirmed by a change in cell counts. The antiproliferative effect of MCP-1 was significantly blocked in the presence of an anti-MCP-1 antibody. MCP-1-induced inhibition of [3H]thymidine uptake was not affected in the presence of indomethacin (1 micrograms/ml) or NG-monomethyl-L-arginine (0.1 mM), and MCP-1 showed no effect on 6-ketoprostaglandin F1 alpha, guanosine 3',5'-cyclic monophosphate, and adenosine 3',5'-cyclic monophosphate syntheses in VSMC. These results indicate that MCP-1 inhibits the proliferation of VSMC in vitro and that its effect is independent of prostaglandin or nitric oxide generation.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Arginine; Arteriosclerosis; Cell Division; Cells, Cultured; Chemokine CCL2; Chemotactic Factors; Cyclic AMP; Cyclic GMP; DNA; Gene Expression; Humans; Indomethacin; Lipopolysaccharides; Muscle, Smooth, Vascular; omega-N-Methylarginine; Rats; Recombinant Proteins; Thymidine

To determine if endogenous local levels of nitric oxide (NO) modulate atherogenesis, we studied the effect of inhibiting NO with NG-nitro-L-arginine methyl ester (L-NAME) on early neointima formation in cholesterol-fed rabbits. Male rabbits were fed for 5 weeks with a 0.5% cholesterol diet alone or treated in addition during the last 4 weeks with L-NAME (12 mg/kg per day SC) via osmotic minipump. Endothelial cell function was assessed in isolated aortic rings by vascular reactivity and levels of cyclic GMP. In L-NAME-treated rabbits there was inhibition of endothelium-dependent relaxations to acetylcholine and the calcium ionophore A23187 as well as impaired cyclic GMP accumulation in response to acetylcholine. Neointima formation in the ascending thoracic aorta was assessed by determining media and intima cross-sectional areas with computerized image analysis. Compared with rabbits that consumed the cholesterol diet alone, L-NAME-treated rabbits had significant increases in lesion area (0.29 +/- 0.04 versus 0.15 +/- 0.03 mm2) and in lesion/media ratio (0.06 +/- 0.01 versus 0.03 +/- 0.01). Plasma levels of cholesterol and fluorescent lipid peroxide products were unchanged, suggesting no difference in cholesterol metabolism or oxidation. Because arterial blood pressure was not altered by L-NAME treatment, the increased atherogenesis could not be attributed to an increase in blood pressure. These results indicated that local inhibition of NO accelerates early neointima formation possibly because of modulating monocyte recruitment or foam cell lipid accumulation.

Topics: Amino Acid Oxidoreductases; Animals; Aorta; Arginine; Arteriosclerosis; Cyclic GMP; Endothelium, Vascular; Hypercholesterolemia; Lipid Peroxidation; Male; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Rabbits; Vasodilation

We report the effects of isradipine and ramipril on regression of diet-induced atherosclerosis in rabbits. Regression of diet-induced atherosclerosis was not significantly affected by ramipril, but isradipine significantly retarded regression. Thirty rabbits in three groups were fed a 0.3% cholesterol diet for 4 weeks. After this induction period, group IIr received the 0.3% cholesterol diet, group IIIr received the 0.3% cholesterol diet with isradipine (0.33 mg/kg/day), and group IVr received the 0.3% cholesterol diet with ramipril (0.33 mg/kg/day) for 12 more weeks. The rabbits then received a standard diet and remained on their respective drug regimen for 12 more weeks. Group Ir (10 rabbits) received a standard diet for 28 weeks. Acetylcholine (ACh)-induced maximal endothelium-dependent relaxations (EDR) of aortic rings were significantly less in group IIr (22.8 +/- 3.2%) than in group Ir (66.4 +/- 4.0%; p < 0.05). Ramipril and isradipine did not improve EDR as compared with group IIr. Regression of atherosclerosis was accompanied by an improved endothelium-dependent releasing factor (EDRF) release from the endothelium, but ramipril and isradipine did not promote this process. In addition, regression was associated with increasing sensitivity of vascular smooth muscle to EDRF that was significantly retarded by isradipine but not ramipril. Basal cyclic GMP levels were significantly reduced in aortic rings from group IIr as compared with group Ir. Ramipril, but not isradipine, restored basal cyclic GMP levels to control values. Both isradipine and ramipril protect against endothelial degeneration in hypercholesterolemic rabbits. However, isradipine but not ramipril inhibits regression of diet-induced atherosclerosis in rabbits.

Topics: Acetylcholine; Animals; Aorta, Thoracic; Arteriosclerosis; Biomarkers; Cholesterol; Cholesterol, Dietary; Cyclic AMP; Cyclic GMP; Diet, Atherogenic; Endothelium, Vascular; In Vitro Techniques; Isradipine; Male; Muscle Relaxation; Nitric Oxide; Nitroprusside; Phospholipids; Rabbits; Ramipril; Triglycerides

Both atherosclerotic lesions and hypoxia alter the contractile properties of the arterial wall and, in particular, may interfere with the relaxation mechanisms dependent or not on the endothelium. The present study was designed to test the effect of severe hypoxia on the contractile behavior of the atherosclerotic rabbit aorta. Segments of aortas obtained from control, cholesterol-fed, or Watanabe hereditary hyperlipidemic rabbits were mounted in organ chambers for isometric tension recording. A change of the bath PO2 from "normoxic" conditions (95% O2-5% CO2) to "hypoxic" conditions (95% N2-5% CO2) caused relaxation in the precontracted control aortas (by approximately 85%) but a transient contraction (approximately 20% of the maximal contraction obtained with 30 mM KCl) followed by a relaxation in the precontracted atherosclerotic aortas. Both types of responses were observed in aortas contracted with aggregating platelets, 5-hydroxytryptamine (5-HT), norepinephrine, endothelin, and prostaglandin F2 alpha. The hypoxic contractions in atherosclerosis were not dependent on the presence of an intact endothelium. They could not be antagonized by blockers of alpha-adrenoceptors, 5-HT2 receptors, histamine receptors, thromboxane receptors, and muscarinic cholinoreceptors. Inhibitors of cyclooxygenase, lipoxygenase, Na+, K(+)-ATPase, and free radical scavengers or an activator of endothelium-derived relaxing factor did not significantly affect the hypoxic contraction; the absence of effect of some inhibitors of protein synthesis seems to rule out the involvement of endothelin, angiotensin II, and bradykinin. The hypoxic contraction was not influenced by omission of Ca2+ from the medium or by inhibition of Ca2+ influx but was prevented by blockade of intracellular Ca2+. The inhibitor of nitric oxide synthase (nitro-L-arginine, 100 microM) and the guanylyl cyclase inhibitor (methylene blue, 10 microM) both enhanced the initial contractile responses to 5-HT to a similar extent as hypoxia and completely prevented the hypoxic contraction in the atherosclerotic tissues. The cyclic nucleotide analogues 8-bromo-cGMP and dibutyryl cAMP also inhibited the hypoxic contraction in the atherosclerotic aorta. The cGMP levels were markedly decreased and the cAMP levels were moderately decreased in the aortas of the cholesterol-fed rabbits as compared with the control aortas. Hypoxia further decreased cGMP but not the cAMP levels in atherosclerotic aortas with and without endo

Topics: Animals; Aorta; Arginine; Arteriosclerosis; Calcium; Cell Hypoxia; Cyclic GMP; Disease Models, Animal; Endothelium, Vascular; Male; Methylene Blue; Nitric Oxide; Nitroarginine; Rabbits; Serotonin; Vasoconstriction

The differentiation-dependent expression of purinergic receptors for metabolically stable analogues of adenosine and ATP was studied in human mononuclear phagocytes (MNPs). Ligands of these receptors are able to modulate cellular cholesterol metabolism. In addition, the intracellular signal transduction pathways of the purinergic receptor system were examined. ATP gamma S, the metabolic stable analogue of ATP, was used as a P2 ligand, and 2-p-(2-carboxyethyl)phenylethylamino-5'-N-ethylcarboxamido adenosine (CGS 21680) and 5'-(N-ethylcarboxamido)adenosine (NECA) were used as P1 ligands in binding studies. Binding of [35S]ATP gamma S to MNPs at 4 degrees C revealed saturable low-affinity binding sites with a Kd of 868 +/- 52 nmol/L and Bmax of 7.3 +/- 0.4 pmol per 10(6) cells in 1-day cultured human MNPs and a Kd of 780 +/- 30 nmol/L and Bmax of 14.0 +/- 0.8 pmol per 10(6) cells in 7-day cultured human MNPs. The characterization of the P1 receptors on 1- and 7-day cultured human MNPs showed that they are expressed only on 7-day cultured human MNPs. The specific binding curve of the adenosine A2 receptor agonist [3H]CGS 21680 was biphasic, with a Kd1 of 33 +/- 15 nmol/L and a Kd2 of 90 +/- 10 nmol/L and with Bmax1 of 0.19 +/- 0.06 pmol per 10(6) cells and Bmax2 of 0.41 +/- 0.09 pmol per 10(6) cells, whereas NECA did not exhibit specific binding. The typical agonists for probing A1 receptor subtypes did not bind to 1- and 7-day cultured human MNPs, indicating that only A2 receptors are expressed on 7-day cultured human MNPs. ATP gamma S enhanced [Ca2+]i in 1- and 7-day cultured human MNPs in a concentration-dependent manner, whereas the P1 ligands, adenosine and CGS 21680, induced Ca2+ flux only in 7-day cultured MNPs. All three drugs increased intracellular cAMP levels in 7-day cultured human MNPs at a concentration of 10(-5) mol/L, whereas no effect was observed in 1-day cultured human MNPs. The uptake of fluorescently labeled acetylated low-density lipoprotein (LDL) in 7-day cultured human MNPs was inhibited by adenosine, CGS 21680, ATP, and ATP gamma S. No significant influence of these compounds was measured on the uptake of LDL, acetylated LDL, and high-density lipoprotein, in 1-day cultured MNPs. Our investigations indicate that the expression of P2y and A2 receptors is increased during differentiation of blood monocytes to macrophages.(ABSTRACT TRUNCATED AT 400 WORDS)

Topics: Adenosine Triphosphate; Arteriosclerosis; Calcium; Cell Differentiation; Cells, Cultured; Cyclic AMP; Cyclic GMP; Humans; Lipoproteins, LDL; Phagocytes; Receptors, Purinergic; Signal Transduction

This study was undertaken to examine the alterations in vascular relaxation responsiveness to endothelium-dependent or -independent vasodilators, including atrial natriuretic peptide (ANP) and acetylcholine, in aortas of Watanabe heritable hyperlipidemic (WHHL) rabbits during the progression of the atherosclerotic plaque. WHHL rabbits were divided into two groups according to age: group 1, 6-11 months, and group 2, 12-18 months. The isolated thoracic aortas obtained from both normal (control) and WHHL rabbits were suspended in a bath containing oxygenated Krebs' buffer for recording of isometric force. The endothelium-dependent relaxation evoked by acetylcholine was reduced in group 1 WHHL rabbits and decreased progressively in proportion to the degree of atherosclerosis progression when compared with age-matched control rabbits. ANP-induced relaxation was not significantly decreased in group 1 WHHL rabbits. However, ANP-induced relaxation was markedly impaired in group 2 WHHL rabbits. Thoracic aortas with severe atherosclerosis were less sensitive to ANP, with a significant increase in the median effective dose, although maximum relaxation induced by ANP was not reduced. Accumulation of cyclic GMP induced by ANP and acetylcholine was markedly reduced in atherosclerotic arteries obtained from group 2 WHHL rabbits compared with control rabbits. Vascular relaxation elicited by nitroglycerin or isoproterenol was not significantly impaired in atherosclerotic arteries from either group 1 or group 2 WHHL rabbits. From these results, we suggest that ANP-induced cyclic GMP formation and vascular relaxation via particulate guanylate cyclase in vascular smooth muscle cells are impaired in severely atherosclerotic arteries.

Topics: Acetylcholine; Animals; Aorta, Thoracic; Arteriosclerosis; Atrial Natriuretic Factor; Cholesterol; Cyclic GMP; Endothelium, Vascular; Female; Hyperlipidemias; Isoproterenol; Male; Nitroglycerin; Rabbits; Triglycerides; Vasodilation

The purpose of this study was to determine whether the generation of a neointima, an early step in the development of atherosclerosis, affects endothelium-dependent or -independent vasodilation. The neointima was induced, within 7 days, by positioning a nonocclusive silicone collar around one carotid artery in rabbits. After 1, 2, 7, or 14 days segments were cut from the collar-surrounded region of this artery as well as from the sham-operated contralateral artery and were used for isometric tension recording or for bioassay of nitric oxide (NO). The acetylcholine-induced release of NO was significantly reduced at 7 days. The tension recordings suggested that this already occurred at the earliest stages of neointima formation. Neither the capacity of the endothelial cells to form NO in response to the calcium ionophore A23187 nor the capacity of the underlying smooth muscle cells to relax in response to sources of exogenous NO (3-morpholinosydnonimine and nitroglycerin) was affected by the neointima. Therefore, the impaired endothelium-dependent relaxations to acetylcholine are presumably due to a defect at the level of the endothelial muscarinic receptors. The presence of a fully developed neointima did not alter the responsiveness to isoproterenol and forskolin but enhanced prostacyclin-mediated responses (assessed by iloprost and 13-hydroxyoctadecadienoic acid). These results illustrate selective alterations of endothelial and smooth muscle cell function in intima generation before fatty streak formation.

Topics: Animals; Arteriosclerosis; Carotid Arteries; Cyclic AMP; Cyclic GMP; Endothelium, Vascular; Epoprostenol; Female; In Vitro Techniques; Linoleic Acids; Male; Nitric Oxide; Phenylephrine; Rabbits; Receptors, Muscarinic; Vasoconstriction; Vasodilation

The present study was addressed to understand two specific issues: (a) whether atherogenic activity of smooth muscle cells could be initiated by incorporating cholesterol within their membranes through a LDL-receptor-independent pathway; and (b) whether trifluoperazine, which we had recently shown to prevent the cholesterol-induced atherogenesis in an experimental animal model system, could prevent such activity of these cells induced by cholesterol in vitro. The results of such a study revealed that trifluoperazine could prevent the cholesterol-induced stimulation of (a) DNA synthesis, (b) cholesterol synthesis, (c) intracellular cGMP levels, (d) intracellular free and esterified cholesterol accumulation, and (e) collagen secretion. Furthermore, the drug caused stimulation of cholesterol-induced suppression of LDL-receptor synthesis. On this basis, we suggest that acquisition of cholesterol by smooth muscle cells through the LDL-receptor-independent pathway may be the fundamental process responsible for atherogenic activity of these cells and that the drug trifluoperazine has the inherent capacity to prevent the membrane-cholesterol-modulated atherogenic activity of smooth muscle cells in vitro.

Topics: Animals; Aorta; Arteriosclerosis; Cell Division; Cholesterol; Collagen; Cyclic GMP; Male; Muscle, Smooth, Vascular; Rabbits; Receptors, LDL; Trifluoperazine

Cyclic AMP and cyclic GMP content was measured in intima media of unaffected and atherosclerotic areas of human aorta in a short-term organ culture. It was demonstrated that during short-term cultivation the content of both cyclic nucleotides in tissues is constant. The cyclic AMP content in fatty streaks and atherosclerotic plaques is significantly (2 to 7-fold) lower than in unaffected intima. The cyclic GMP level in atherosclerotic lesions is 1.5 to 3-fold higher than in normal. The content of both cyclic nucleotides in the media underlying fatty streaks and atherosclerotic plaques is the same as in the normal tissue. The obtained data indicate serious disorders in the system of cyclic nucleotides during atherosclerosis.

Topics: Adult; Aorta; Arteriosclerosis; Cyclic AMP; Cyclic GMP; Humans; Male; Middle Aged; Nucleotides, Cyclic; Organ Culture Techniques

We report here on the effect of an endothelium-dependent vascular smooth muscle relaxant, lysophosphatidylcholine (LPC) on rabbit aortic strips and on hemodynamic changes by LPC in atherosclerotic animals. Cyclic GMP changes induced by LPC in atherosclerotic vessels were also determined. Atherosclerosis was produced by feeding a high cholesterol and saturated fatty acid diet. LPC was injected into the left atrium and coronary flow was measured by radioactive microspheres; in vitro, relaxation of precontracted aortic strips by lysophosphatidylcholine was also recorded. LPC failed to increase coronary flow in the presence of atherosclerosis. In isolated aortic strips, dose-response curves with acetylcholine and LPC showed diminished relaxation in atherosclerotic preparations, and cyclic GMP production following LPC was reduced. The results demonstrate that vascular relaxation by LPC, together with its ability to activate guanylate cyclase is dependent on the functional and morphological integrity of the vascular wall.

Topics: Animals; Aorta; Arteriosclerosis; Coronary Circulation; Coronary Vessels; Cyclic GMP; Dose-Response Relationship, Drug; Endothelium, Vascular; Lysophosphatidylcholines; Male; Rabbits; Vascular Resistance; Vasodilation

The dependence of vascular relaxation on an intact endothelium and the relationship between relaxation and cyclic GMP accumulation were determined in coronary arteries isolated from cardiac transplantation patients with or without coronary atherosclerosis. In nonatherosclerotic arteries, the endothelium-dependent agent acetylcholine produced concentration-related relaxations. In atherosclerotic arteries, endothelium-dependent relaxations were abolished with acetylcholine, partly suppressed with substance P and histamine, and completely preserved with the ionophore A23187. In these arteries, the endothelium-independent agent nitroglycerin remained fully active. Accumulation of cyclic GMP in atherosclerotic strips was suppressed with acetylcholine but unattenuated with A23187 and nitroglycerin. In aortas from rabbits with diet-induced atherosclerosis, there was likewise an impaired cholinergic relaxation and cyclic GMP accumulation in the presence of preserved responses to A23187 and nitroglycerin. The results demonstrate that impaired cholinergic responses in atherosclerotic arteries reflect a muscarinic defect and not an inability of endothelium to release endothelial factor or smooth muscle to respond to it.

Topics: Acetylcholine; Animals; Aorta; Arteriosclerosis; Calcimycin; Coronary Vessels; Cyclic GMP; Endothelium; Histamine; Humans; Nitric Oxide; Nitroglycerin; Rabbits; Receptors, Muscarinic; Substance P; Vasodilation; Vasodilator Agents

The content of cAMP and cGMP was measured in the intima and media of unaffected and atherosclerotic areas of human aorta in a short-term organ and cell cultures. In an organ culture the cAMP content in fatty streaks and atherosclerotic plaques is significantly (2 to 7-fold) lower than in unaffected intima. The cGMP level in atherosclerotic lesions is 1.5 to 3-fold higher than normal. The content of both cyclic nucleotides in the media underlying fatty streaks and plaques is the same as in the normal tissue. Similar alterations of cAMP and cGMP levels were seen in the cells cultured from atherosclerotic lesions. Cholera toxin, methylisobutylxanthine and forskolin as well as dibutyryl cAMP inhibit by 2-7-fold[3H]thymidine uptake into intimal cells cultured from atherosclerotic human aorta. These agents also decrease cholesteryl ester and triglyceride levels and do not affect the content of phospholipids and free cholesterol in the cells cultured from atherosclerotic lesions.

Topics: 1-Methyl-3-isobutylxanthine; Aorta; Arteriosclerosis; Cells, Cultured; Cholera Toxin; Colforsin; Cyclic AMP; Cyclic GMP; Humans; Lipid Metabolism; Organ Culture Techniques

Cyclic AMP and cyclic GMP content and activities of cyclic nucleotide metabolic enzymes were determined in intima and media of atherosclerotic and unaffected human aorta obtained shortly after death due to myocardial infarction. Cyclic AMP content in fatty streaks and atherosclerotic plaques was lower by three- and five-fold, respectively, as compared with uninvolved intima. Cyclic GMP level in atherosclerotic lesions was estimated to be three-fold higher than in grossly normal area. Basal activity of adenylate cyclase in fatty streaks and plaques was two- to six-fold lower than in unaffected intima. Besides, the ability of adenylate cyclase to be stimulated by the stable analogue of prostacyclin, carbacyclin, was suppressed in plaques. Guanylate cyclase activity in fatty streaks was 1.5- to three-fold higher than in normal tissue. The thiol-reducing agent, dithiothreitol, decreased the enzyme activity to normal level, suggesting the oxidative nature of guanylate cyclase activation in the lesion zone. There were no significant changes in cyclic AMP phosphodiestease activity in the regions of the atherosclerotic lesion. Cyclic GMP phosphodiesterase activity in atherosclerotic plaques was two-fold lower than in the intima of unaffected areas. We did not find differences in the content of cyclic nucleotides or related enzyme activities in the media of uninvolved areas of human aorta nor in the media underlying atherosclerotic lesions. Our findings suggest that development of human atherosclerotic lesions is accompanied by dramatic changes in the cyclic nucleotide metabolism featuring gradual hormonal receptor uncoupling from adenylate cyclase, activation of guanylate cyclase in fatty streaks and inhibition of cyclic GMP phosphodiesterase in plaques.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adenylyl Cyclases; Adipose Tissue; Adult; Aorta; Arteriosclerosis; Cyclic AMP; Cyclic GMP; Guanylate Cyclase; Humans; Male; Middle Aged; Reference Values

The effect of several anti-atherogenic drugs (ticlopidine, nicotinic acid and etofibrate) on immune responses and immune complex anaphylaxis has been studied in mice. All the drugs enhanced the activation by concanavalin A, phytohemagglutinin, and lipopolysaccharide of lymphocytes taken from treated animals. Contact hypersensitivity to trinitrochlorobenzene was inhibited by similar treatments with the same drugs, possibly through inhibition of the efferent phase of the reaction. Nicotinic acid produced a slight enhancement of antibody responses to sheep erythrocytes, whereas etofibrate inhibited the response at the highest dose studied. In addition, treatment with these drugs variably protected the mice from anaphylactic shocks induced by immune complexes. Marked protection was also observed using the antiserotoninic, cyproheptadine. These results indicate that drugs used to prevent atherogenic processes modulate different proliferative and effector immunological reactions.

Topics: Anaphylaxis; Animals; Antibody Formation; Antigen-Antibody Complex; Arteriosclerosis; Clofibrate; Clofibric Acid; Cyclic AMP; Cyclic GMP; Female; Hypersensitivity, Delayed; Lymphocyte Activation; Mice; Mice, Inbred BALB C; Niacin; Thiophenes; Ticlopidine

Topics: Animals; Arteriosclerosis; Blood Vessels; Cell Communication; Cells, Cultured; Cyclic GMP; Endothelial Growth Factors; Endothelium; Growth Substances; Intercellular Junctions; Lipoproteins, LDL; Mice; Mice, Inbred BALB C; Models, Cardiovascular; Muscle, Smooth, Vascular; Nitric Oxide; Platelet-Derived Growth Factor; Rabbits; Rats; Vasodilator Agents

Length-tension relationships and contractile responses to agonists associated with cyclic nucleotide levels in aortas from atherosclerotic rabbits were studied. The same number of tissues from healthy rabbits was also studied. Diffuse lesions were produced by denudation of the vascular endothelium of rabbit aorta using a balloon catheter and then feeding these rabbits a high cholesterol diet for two months. Stretch-passive tension curves and length-active tension curves which developed in the presence of 60 mM KCl significantly shifted to the left. The altered length-tension relationships indicate a decreased distensibility in these strips and this is attributed to an enhanced accumulation of collagen. Dose-response curve analysis revealed a marked hypersensitivity to serotonin as indicated by greater pD2 values (negative logarithm of half maximum dose) than seen in the controls. In addition, the mean absolute values of the maximum contraction induced by serotonin and KCl were significantly higher than in the controls. Although cyclic AMP levels in the strips with a pathology were lower and cyclic GMP/cyclic AMP ratios were higher than the controls in the basal state, serotonin induced no marked alterations in the cyclic nucleotides levels in the strips from either the diseased or control rabbits. These mechanical and pharmacological alterations of atherosclerotic vessels may relate to clinical events such as coronary spasm.

Topics: Animals; Aorta, Thoracic; Arteriosclerosis; Cyclic AMP; Cyclic GMP; Male; Potassium Chloride; Rabbits; Serotonin; Vasoconstriction

Topics: Animals; Arteriosclerosis; Cyclic CMP; Cyclic GMP; Endothelium; Factor XII; Fibroblasts; Fibronectins; Guinea Pigs; Muscle, Smooth, Vascular; Rats; Thrombin

Topics: 3',5'-Cyclic-AMP Phosphodiesterases; 3',5'-Cyclic-GMP Phosphodiesterases; Animals; Aorta; Arteries; Arteriosclerosis; Chromatography, DEAE-Cellulose; Columbidae; Coronary Vessels; Cyclic AMP; Cyclic GMP; Electrophoresis, Polyacrylamide Gel; Phosphodiesterase Inhibitors

Although roles of roles of cyclic AMP and cyclic GMP in platelets are though to be important on platelet aggregation, little information on their phosphodiesterase (PDE) is available. Cyclic AMP and cyclic GMP hydrolytic activities of platelets (cAMPPDE and cGMPPDE in platelets) and platelet aggregation by ADP and adrenaline were measured in 22 healthy volunteers, 26 arteriosclerotic patients and other 20 miscellaneous patients excluding vascular diseases. Activities of cAMPPDE and cGMPPDE of platelets were 2.37 +/- 0.52, 7.23 +/- 1.84 in the healthy, 2.50 +/- 0.85, 7.53 +/- 2.60 in the arteriosclerotics and 2.38 +/- 1.02, 6.98 +/- 2.59 pmol/min/10(7) platelets in the miscellaneous patients, respectively. No significant difference was observed among these three groups. Platelet aggregabilities also showed no significant difference. However, there was a significant inverse correlation between the aggregability by 1 microgram/ml of adrenaline and the PDE activities only in the arteriosclerotic patients. The correlation coefficient were-0.61 between the primary aggregation and cAMPPDE,-0.65 between the primary aggregation and cGMPPDE,-0.58 between the 5 min aggregation and cAMPPDE and -0.76 between the 5 min aggregation and cGMPPDE. The inverse correlation between platelet aggregation and cyclic nucleotide metabolism in circulating platelts of the arteriosclerotic patients may suggest that interaction of platelets with arteriosclerotiv vessel walls would produce a certain change in platelets.

Topics: 2',3'-Cyclic-Nucleotide Phosphodiesterases; 3',5'-Cyclic-AMP Phosphodiesterases; Adenosine Diphosphate; Adult; Arteriosclerosis; Blood Platelets; Cyclic AMP; Cyclic GMP; Epinephrine; Female; Humans; Male; Middle Aged; Phosphoric Diester Hydrolases; Platelet Aggregation