cyclic-gmp and Arterial-Occlusive-Diseases

The FDA approval of Viagra (sildenafil) for the on demand treatment of erectile dysfunction (ED) through relaxation of the corporal and cavernosal vascular smooth muscle that results in an increase in blood flow to the corporal tissues stemmed from 2 decades of research, mainly at academic centers. This culminated in the finding of the nitric oxide/cGMP pathway as the mediator of penile erection, followed by some years of basic studies and clinical validation at Pfizer. Further on, new translational laboratory and animal research from our group initiated a second phase when we proposed an alternative therapeutic schedule and mechanism of action for PDE5 inhibitors (PDE5i) in both corporal veno-occlusive dysfunction (CVOD) and Peyronie's disease (PD), specifically, continuous long-term administration (CLTA) to achieve sustained levels of cGMP within the penis. Due to the extended half-life of the long-acting PDE5i, tadalafil, this new alternative encompasses preferentially daily administration, although shorter half-life PDE5i, like sildenafil and vardenafil work too, depending on the duration, dose, and frequency of their administration This novel use was initially supported by showing the antifibrotic/antioxidant effects of nitric oxide and cGMP, produced by the induction of iNOS, as a mechanism of defense against collagen deposition in the localized fibrotic plaque of PD in an avascular tissue, the tunica albuginea. Our studies on iNOS and the progressive diffuse fibrosis occurring in the smooth muscle in CVOD, led to proposing the CLTA of PDE5i for maintaining sustained cGMP levels both in PD and in CVOD in order to halt or regress the penile fibrosis. In CVOD, we showed that PDE5i protect the corporal smooth muscle and reduce myofibroblast activation and number, counteracting the underlying corporal tissue pathology that causes CVOD, and potentially ameliorating long-term CVOD or even curing it. This review is focused on this novel PDE5i anti-fibrotic therapeutic concept.

Topics: Animals; Arterial Occlusive Diseases; Cyclic GMP; Disease Models, Animal; Drug Evaluation, Preclinical; Erectile Dysfunction; Humans; Male; Muscle, Smooth; Nitric Oxide Synthase Type II; Penile Induration; Phosphodiesterase 5 Inhibitors; Sildenafil Citrate; Translational Research, Biomedical

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

Topics: Animals; Arterial Occlusive Diseases; Arteries; Arteriovenous Fistula; Carcinoma, Hepatocellular; Cardiomegaly; Chemical Phenomena; Chemistry; Cyclic GMP; Humans; Hydrogen-Ion Concentration; Liver Neoplasms; Metals; Protein Kinases; Proteins; Substrate Specificity; Veins

Administration of L-arginine improves nitric oxide (NO) formation and endothelium-dependent vasodilation in atherosclerotic patients.. We investigated in this double-blind, controlled study whether prolonged intermittent infusion therapy with L-arginine improves the clinical symptoms of patients with intermittent claudication, as compared with the endothelium-independent vasodilator prostaglandin E1, and control patients.. Thirty-nine patients with intermittent claudication were randomly assigned to receive 2 x 8 g L-arginine/day, or 2 x 40 microg prostaglandin E1 (PGE1)/day or no hemodynamically active treatment, for 3 weeks. The pain-free and absolute walking distances were assessed on a walking treadmill at 3 km/h, 12% slope, and NO-mediated, flow-induced vasodilation of the femoral artery was assessed by ultrasonography at baseline, at 1, 2 and 3 weeks of therapy and 6 weeks after the end of treatment. Urinary nitrate and cyclic guanosine-3', 5'-monophosphate (GMP) were assessed as indices of endogenous NO production.. L-Arginine improved the pain-free walking distance by 230+/-63% and the absolute walking distance by 155+/-48% (each p < 0.05). Prostaglandin E1 improved both parameters by 209+/-63% and 144+/-28%, respectively (each p < 0.05), whereas control patients experienced no significant change. L-Arginine therapy also improved endothelium-dependent vasodilation in the femoral artery, whereas PGE1 had no such effect. There was a significant linear correlation between the L-arginine/asymmetric dimethylarginine (ADMA) ratio and the pain-free walking distance at baseline (r=0.359, p < 0.03). L-Arginine treatment elevated the plasma L-arginine/ADMA ratio and increased urinary nitrate and cyclic GMP excretion rates, indicating normalized endogenous NO formation. Prostaglandin E1 therapy had no significant effect on any of these parameters. Symptom scores assessed on a visual analog scale increased from 3.51+/-0.18 to 83+/-0.4 (L-arginine) and 7.0+/-0.5 (PGE1; each p < 0.05), but did not significantly change in the control group (4.3+/-0.4).. Restoring NO formation and endothelium-dependent vasodilation by L-arginine improves the clinical symptoms of intermittent claudication in patients with peripheral arterial occlusive disease.

Topics: Aged; Aged, 80 and over; Alprostadil; Arginine; Arterial Occlusive Diseases; Blood Flow Velocity; Chronic Disease; Cyclic GMP; Double-Blind Method; Exercise Test; Female; Femoral Artery; Follow-Up Studies; Humans; Infusions, Intravenous; Intermittent Claudication; Leg; Male; Middle Aged; Nitrates; Nitric Oxide; Peripheral Vascular Diseases; Treatment Outcome; Ultrasonography, Doppler, Duplex; Vasodilation; Vasodilator Agents

To evaluate effect of controlled stent-based release of an NO donor to limit in-stent restenosis in rabbits.. Bioerodable microspheres containing NO donor or biodegradable polymer (polylactide-co-glycolide-polyethylene glycol) were prepared and loaded in channeled stents. Daily concentrations of NO release from NO-containing microspheres were assayed in vitro. NO- and polymer-containing (control) microsphere-loaded stents were deployed in aortas of New Zealand white rabbits (n = 8). Aortas with stents were harvested at 7 (n = 5) and 28 days (n = 3) and evaluated for cyclic guanosine monophosphate (cGMP) levels (7 days), number of proliferating cell nuclear antigen-positive cells (7 days), and intima-to-media ratio (7 and 28 days), with statistical significance evaluated by using one-way analysis of variance.. NO-containing microspheres released NO with an initial bolus in the 1st week, followed by sustained release for the remaining 3 weeks. Significant increase in cGMP levels and decrease in proliferating cell nuclear antigen-positive cells were found at 7 days for the NO-treated group relative to controls (P <.05). Intima-to-media ratio in the NO-treated group was reduced by 46% and 32% relative to controls at 7 and 28 days, respectively (mean, 0.14 +/- 0.01 [standard error] vs 0.26 +/- 0.02 at 7 days, P <.01; 1.34 +/- 0.05 vs 1.98 +/- 0.08 at 28 days, P <.01).. Stent-based controlled release of NO donor significantly reduces in-stent restenosis and is associated with increase in vascular cGMP and suppression of proliferation.

Topics: Angiography, Digital Subtraction; Animals; Aorta, Abdominal; Aortography; Arterial Occlusive Diseases; Cell Division; Coated Materials, Biocompatible; Cyclic GMP; Male; Microspheres; Muscle, Smooth, Vascular; Nitric Oxide Donors; Nitroso Compounds; Prosthesis Failure; Rabbits; Secondary Prevention; Stents

Adrenomedullin (AM) is a potent vasodilator expressed in tissues relevant to cardiovascular function. AM peptide has been shown to inhibit the proliferation and migration of vascular smooth muscle cells in vitro. However, the effect of AM on blood vessels after vascular injury in vivo has not been elucidated. In order to explore the potential roles of AM in vascular biology, we evaluated the effect of AM by local gene delivery on neointima formation in balloon-injured rat artery. Adenovirus carrying the human AM cDNA under the control of cytomegalovirus promoter/enhancer (Ad.CMV-hAM) was generated by homologous recombination. After delivery of Ad.CMV-hAM into rat left carotid artery, we identified the expression of human AM mRNA in the left carotid artery, but not in the right carotid artery, heart or kidney by reverse transcription-polymerase chain reaction (RT-PCR) followed by Southern blot analysis. Following local AM gene delivery, we observed a 51% reduction in intima/media ratio at the injured site as compared with that of control rats injected with the luciferase gene (n=7, P<0.01). AM gene transfer resulted in regeneration of endothelium as compared to the control. AM gene delivery significantly increased cGMP levels in balloon-injured arteries. These results indicate that AM contributes to reduction of neointima formation by promotion of re-endothelialization and inhibition of vascular smooth muscle cell proliferation via cGMP-dependent signaling pathway.

Topics: Adenoviridae; Adrenomedullin; Angioplasty, Balloon; Animals; Arterial Occlusive Diseases; Carotid Arteries; Carotid Stenosis; Cyclic AMP; Cyclic GMP; Gene Expression; Genetic Vectors; Humans; Models, Biological; Peptides; Rats; RNA, Messenger; Tunica Intima

Nitric oxide (NO) has multiple important actions that contribute to the maintenance of vascular homeostasis. NO is synthesized by three different isoforms of NO synthase (NOS), all of which have been reported to be expressed in human atherosclerotic vascular lesions. Although the regulatory roles of endothelial NOS (eNOS) and inducible NOS (iNOS) on the development of atherosclerosis have been described, little is known about the role of neuronal NOS (nNOS). Here, we show that nNOS also exerts important vasculoprotective effects in vivo. In a carotid artery ligation model, nNOS gene-deficient (nNOS-KO) mice exhibited accelerated neointimal formation and constrictive vascular remodeling caused by blood flow disruption. In a rat balloon injury model, the selective inhibition of nNOS activity potently enhanced vasoconstrictor responses to a variety of calcium-mobilizing stimuli, suppressed tissue cGMP concentrations, a marker of vascular NO production, and exacerbated neointimal formation. In both models, nNOS was absent before injury and was up-regulated only after the injury, and was predominantly expressed in the neointima and medial smooth muscle cells. These results provide the first direct evidence that nNOS plays important roles in suppressing arteriosclerotic vascular lesion formation in vivo.

Topics: Angioplasty, Balloon; Animals; Arterial Occlusive Diseases; Calcium; Carotid Arteries; Cyclic GMP; Enzyme Inhibitors; Ligation; Mice; Mice, Knockout; Models, Biological; Nitric Oxide Synthase; Nitric Oxide Synthase Type I; Rats; Up-Regulation; Vasoconstriction

YC-1, a synthetic benzyl indazole derivative, is capable of stimulating endogenous vessel wall cyclic guanosine monophosphate (cGMP) production and attenuating the remodeling response to experimental arterial angioplasty. In an effort to investigate the mechanisms of this YC-1-mediated vasoprotection, we examined the influence of soluble YC-1 or YC-1 incorporated in a polyethylene glycol (PEG) hydrogel on cultured rat vascular smooth muscle cell (SMC) cGMP synthesis, SMC proliferation, and platelet function. Results demonstrate that soluble YC-1 stimulated SMC cGMP production in a dose-dependent fashion, while both soluble and hydrogel-released YC-1 inhibited vascular SMC proliferation in a dose-dependent fashion without effects on cell viability. Platelet aggregation and adherence to collagen were both significantly inhibited in a dose-dependent fashion by soluble and hydrogel-released YC-1. Arterial neointima formation following experimental balloon injury was significantly attenuated by perivascular hydrogel-released YC-1. These results suggest that YC-1 is a potent, physiologically active agent with major anti-proliferative and anti-platelet properties that may provide protection against vascular injury through cGMP-dependent mechanisms.

Topics: Angioplasty, Balloon; Animals; Arterial Occlusive Diseases; Blood Platelets; Carotid Stenosis; Cell Adhesion; Cell Division; Cells, Cultured; Cyclic GMP; Dose-Response Relationship, Drug; Hydrogels; Indazoles; Muscle, Smooth, Vascular; Platelet Aggregation Inhibitors; Polyethylene Glycols; Rats; Rats, Sprague-Dawley

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

The increased severity of the myocardial injury produced by coronary occlusion-reperfusion in models of atherosclerosis is associated with an increase in leukocyte accumulation in the ischemic myocardium. Expression of P-selectin, an adhesion molecule involved in the interaction between leukocytes and endothelium, is increased in atherosclerotic vessels. Long-term angiotensin-converting enzyme (ACE) inhibition has been shown to reduce atherosclerotic vascular change in experimental models.. We examined changes in the size of the infarct resulting from coronary occlusion/reperfusion in normally fed and cholesterol-fed rabbits that were chronically treated with quinapril. Infarct size was significantly larger in the cholesterol-fed versus normally fed rabbits. ACE activity in the ischemic and nonischemic myocardium was significantly reduced by quinapril. Chronic quinapril administration significantly ameliorated the increased myocardial injury in cholesterol-fed rabbits. Quinapril administration markedly increased the myocardial cGMP content and reduced the myeloperoxidase activity in the border region of the ischemic myocardium in cholesterol-fed rabbits. The enhanced expression of P-selectin in myocardial tissue of cholesterol-fed rabbits was also effectively reduced by quinapril treatment. The above effects of quinapril were eliminated by blockade of bradykinin B2 receptors or inhibition of nitric oxide synthesis.. Chronic quinapril treatment ameliorated the severity of myocardial injury produced by coronary occlusion/reperfusion in cholesterol-fed rabbits, possibly because of reversal of the enhanced interaction between leukocytes and endothelium in the ischemic myocardium via a bradykinin-related pathway.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Aorta; Arterial Occlusive Diseases; Coronary Artery Disease; Cyclic GMP; Disease Models, Animal; Enzyme Inhibitors; Hemodynamics; Isoquinolines; Leukocytes; Male; Myocardial Infarction; Myocardial Ischemia; Myocardial Reperfusion Injury; Myocardium; NG-Nitroarginine Methyl Ester; Nitric Oxide Synthase; P-Selectin; Peroxidase; Quinapril; Rabbits; Receptor, Bradykinin B2; Receptors, Bradykinin; Tetrahydroisoquinolines; Ventricular Fibrillation

Heme oxygenase-1 (HO-1, HSP32) is an early gene that is responsive to an array of pathological conditions including, but not limited to, hypoxia and cerebral ischemia. HO-1 cleaves the heme molecule and produces carbon monoxide (CO) and biliverdin (an antioxidant) and is essential for iron homeostasis. The purpose of this study was to investigate, using transgenic (Tg) mice, whether overexpression of HO-1 in the brain augments or attenuates cellular injury caused by ischemic stroke. Homozygous HO-1 Tg mice that overexpress HO-1 under the control of the neuron-specific enolase promoter (characterized previously) were used. Under halothane anesthesia and normothermic conditions, wild-type nontransgenic (nTg; n = 22) and HO-1 Tg (n = 24) mice were subjected to middle cerebral artery occlusion (MCAo). Six hours after induction of ischemia, Tg and nTg mice developed infarcts that were 39 +/- 6 and 63 +/- 9 mm3, respectively (p < 0.01). No significant difference between the two strains was observed in the values of brain edema (11.3 +/- 4% in Tg vs. 14.6 +/- 5% in nTg; p < 0.1). At 24 h after MCAo, Tg mice exhibited significant neuroprotection as determined by the stroke volumes (41 +/- 2 mm3 in Tg vs. 74 +/- 5 mm3 in nTg; p < 0.01) and values of ischemic cerebral edema (21 +/- 6% in Tg vs. 35 +/- 11% in nTg; p < 0.01). Data suggest that neuroprotection in Tg mice was, at least in part, related to the following findings: (a) constitutively up-regulated cyclic GMP and bcl-2 levels in neurons; (b) inhibition of nuclear localization of p53 protein; and (c) antioxidant action of HO-1, as detected by postischemic neuronal expression of ferritin, and decreases in iron staining and tissue lipid peroxidation. We suggest that pharmacological stimulation of HO-1 activity may constitute a novel therapeutic approach in the amelioration of ischemic injury during the acute period of stroke.

Topics: Animals; Arterial Occlusive Diseases; Behavior, Animal; Blotting, Northern; Brain Edema; Brain Ischemia; Cerebral Arterial Diseases; Cerebrovascular Circulation; Cyclic GMP; Ferritins; Gene Expression Regulation, Enzymologic; Heme Oxygenase (Decyclizing); Heme Oxygenase-1; Immunohistochemistry; Lipid Peroxidation; Membrane Proteins; Mice; Mice, Transgenic; NADPH Dehydrogenase; Neurons; Proto-Oncogene Proteins c-bcl-2; Stroke Volume; Tumor Suppressor Protein p53

Topics: Arterial Occlusive Diseases; Cyclic GMP; Humans; Nitric Oxide; Predictive Value of Tests

We studied urinary nitrate and cGMP excretion rates, indices of systemic NO formation, and plasma concentrations of L-arginine and the endogenous NO synthase inhibitor asymmetrical dimethylarginine (ADMA) and its inactive stereoisomer, symmetrical dimethylarginine, in 77 patients with peripheral arterial occlusive disease (PAOD) in Fontaine stages IIb through IV and in 47 young and 37 elderly healthy control subjects.. Urinary nitrate excretion was 182.0+/-11.4 micromol/mmol creatinine and cGMP excretion was 186.2+/-13.0 nmol/mmol creatinine in young healthy control subjects. In elderly control subjects, both excretion rates were slightly lower (nitrate, 156.0+/-7.8 micromol/mmol creatinine; cGMP, 150.0+/-8.3 nmol/mmol creatinine; P=NS). In PAOD patients, there was a significant, progressive reduction of urinary nitrate (IIb, 138.4+/-11.9; III, 128.6+/-11.3; and IV, 91.9+/-8.0 micromol/mmol creatinine; P<.05) and cGMP (IIb, 139.9+/-25.2; III, 115.6+/-13.1; and IV, 76.9+/-7.9 nmol/mmol creatinine; P<.05) excretion rates related to the Fontaine stage of PAOD. These changes were independent of changes in renal excretory function. Plasma L-arginine concentrations were not significantly different between the groups, but ADMA concentrations were elevated in PAOD patients (young control subjects, 1.25+/-0.11; elderly control subjects, 1.01+/-0.05 micromol/L; IIb, 2.62+/-0.24; III, 3.06+/-0.48; and IV, 3.49+/-0.26 micromol/L; P<.05 for PAOD versus control subjects). There was a significant linear correlation between urinary nitrate and cGMP excretion rates and a significant negative linear correlation between plasma ADMA concentrations and urinary nitrate excretion.. In PAOD patients, there is a progressive reduction in urinary nitrate and cGMP excretion rates, which may be caused in part by accumulation of ADMA, an endogenous inhibitor of NO synthase.

Topics: Adult; Aged; Aged, 80 and over; Aging; Arginine; Arterial Occlusive Diseases; Cyclic GMP; Disease Progression; Enzyme Inhibitors; Female; Humans; Male; Middle Aged; Nitrates; Nitric Oxide; Nitric Oxide Synthase; Peripheral Vascular Diseases; Vasodilation

Nitric oxide has been implicated as a mediator of glutamate excitotoxicity in primary neuronal cultures.. A number of indicators of brain nitric oxide production (nitric and cyclic guanosine monophosphate [cGMP] concentrations and nitric oxide synthase activity) were examined after bilateral carotid ligation and right middle cerebral artery occlusion in adult rats.. Brain nitrite was significantly increased in the right versus left cortex 5, 10, and 20 minutes after middle cerebral artery occlusion (P < .05), with a return to baseline at 60 minutes. There were no significant changes in cerebellar concentrations. Cortical levels of cGMP were increased at 10, 20, and 60 minutes after occlusion, with significant right-to-left differences (P < .05). Cerebellar concentrations of cGMP were also increased but without significant side-to-side differences. Nitric oxide synthase activity increased approximately 10-fold from baseline 10 minutes after occlusion in the right cortex but decreased markedly by 60 minutes from its peak at 10 minutes. The right-to-left difference in nitric oxide synthase activity was significant at 20 minutes (P < .05). Pretreatment of rats with NG-nitro-L-arginine, a nitric oxide synthase inhibitor, abolished the rise in nitrite and cGMP.. These results suggest that a sharp transient increase in the activity of nitric oxide synthase occurs during the first hour of cerebral ischemia, which leads to a burst in nitric oxide production and activation of guanylate cyclase.

Topics: Amino Acid Oxidoreductases; Analysis of Variance; Animals; Arginine; Arterial Occlusive Diseases; Brain; Cerebellum; Cerebral Arterial Diseases; Cerebral Cortex; Cyclic GMP; Functional Laterality; Ischemic Attack, Transient; Male; Nitric Oxide; Nitric Oxide Synthase; Nitrites; Nitroarginine; Rats; Rats, Wistar

The functional rarefaction of small arterioles previously reported at 6 weeks of age in the SHR has been shown to be a structural decrease in arteriolar density as well. In addition, the high "occlusive tone" normally found in young normotensive rats is observed in the older SHR. This elevated tone contributes to a functional rarefaction in the older SHR arterioles. The mechanism for the rarefaction appears to be related to the cAMP/cGMP second messenger system.

Topics: Aging; Animals; Arterial Occlusive Diseases; Arterioles; Cyclic AMP; Cyclic GMP; Hypertension; Muscles; Rats