cyclic-gmp and Constriction--Pathologic

At birth, a marked decrease in pulmonary vascular resistance allows the lung to establish gas exchange. Persistent pulmonary hypertension of the newborn (PPHN) occurs when this normal adaptation of gas exchange does not occur. We review animal models used to study the pathogenesis and treatment of PPHN. Both acute models, such as acute hypoxia and infusion of vasoconstrictors, and chronic models of PPHN created both before and immediately after birth are described. Inhaled nitric oxide is an important emerging therapy for PPHN. We review nitric oxide receptor mechanisms, including soluble guanylate cyclase, which produces cGMP when stimulated by nitric oxide, and phosphodiesterases, which control the intensity and duration of cGMP signal transduction. A better understanding of these mechanisms of regulation of vascular tone may lead to safer use of nitric oxide and improved clinical outcomes.

Topics: Animals; Constriction, Pathologic; Cyclic GMP; Disease Models, Animal; Humans; Hypertension, Pulmonary; Hypoxia; Infant, Newborn; Ligation; Nitric Oxide Synthase; Persistent Fetal Circulation Syndrome; Pulmonary Artery; Vasodilation

Augmentation of NP (natriuretic peptide) receptor and cyclic guanosine monophosphate (cGMP) signaling has emerged as a therapeutic strategy in heart failure (HF). cGMP-specific PDE9 (phosphodiesterase 9) inhibition increases cGMP signaling and attenuates stress-induced hypertrophic heart disease in preclinical studies. A novel cGMP-specific PDE9 inhibitor, CRD-733, is currently being advanced in human clinical studies. Here, we explore the effects of chronic PDE9 inhibition with CRD-733 in the mouse transverse aortic constriction pressure overload HF model.. CRD-733 treatment reversed existing LV hypertrophy compared with vehicle (. The PDE9 inhibitor, CRD-733, improves key hallmarks of HF including LV hypertrophy, LV dysfunction, left atrial dilation, and pulmonary edema after pressure overload in the mouse transverse aortic constriction HF model. Additionally, elevated plasma cGMP may be used as a biomarker of target engagement. These findings support future investigation into the therapeutic potential of CRD-733 in human HF.

Topics: 3',5'-Cyclic-AMP Phosphodiesterases; Animals; Aorta; Carrier Proteins; Collagen; Constriction, Pathologic; Cyclic GMP; Cyclic GMP-Dependent Protein Kinase Type I; Fibrosis; Heart; Heart Atria; Heart Failure; Heart Ventricles; Hypertrophy, Left Ventricular; Lung; Male; Mice; Organ Size; Phosphodiesterase Inhibitors; Phosphorylation; Pulmonary Edema; Stroke Volume; Ventricular Remodeling

Decreased cardiac contractility and beta-adrenergic responsiveness have been observed in cirrhosis, but the etiology remains unclear. We aimed to test the role of nitric oxide (NO), a negative inotropic agent, in the pathogenesis of cirrhotic cardiomyopathy in a rat model.. Cirrhosis was induced by bile duct ligation. Four weeks after ligation or sham operation, cardiac levels of tumor necrosis factor (TNF)-alpha, guanosine 3,5'-cyclic monophosphate (cGMP), inducible NOS (NOS2), and endothelial constitutive NOS (NOS3) messenger RNA (mRNA) and protein were determined. Serum nitrite/nitrate level was measured. Cardiac contractile function was evaluated in isolated left ventricular papillary muscles in the absence and presence of the NOS inhibitor nitro-L-arginine methyl ester (L-NAME).. Cardiac TNF-alpha, NOS2 mRNA and protein, cGMP, and serum interleukin (IL)-1beta and nitrite/nitrate levels were significantly higher in cirrhotic rats than sham controls. No significant differences in NOS3 mRNA or protein were found between cirrhotic and sham control rats. Baseline isoproterenol-stimulated papillary muscle contractile force was significantly lower in the cirrhotic group; with L-NAME incubation, contractile force increased significantly in cirrhotic rats but was unaffected in the controls. In normal papillary muscles, IL-1beta attenuated the contractility, but coincubation with L-NAME again reversed this attenuation. Incubation with the exogenous NO donor S-nitroso-N-acetyl-penicillamine also blunted papillary muscle contractility.. These results suggest that cytokine-induced stimulation of NOS2 plays a significant role in the pathogenesis of cirrhotic cardiomyopathy.

Topics: Animals; Bile Ducts; Blotting, Western; Cardiomyopathies; Constriction, Pathologic; Cyclic GMP; Cytokines; Enzyme Inhibitors; Heart Ventricles; Immunohistochemistry; Ligation; Liver Cirrhosis, Experimental; Male; Myocardial Contraction; Myocardium; Nitrates; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Nitrites; Rats; Rats, Sprague-Dawley; Ventricular Function, Left

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

We have studied the effect of methylprednisolone on endotoxin-induced depression of contractile function in human gastroepiploic arteries. Endotoxin diminished the contractile response to noradrenaline in both the presence and absence of endothelium. This attenuation began after 4 h and reached a maximum after 10 h of endotoxin exposure. The cGMP content of endotoxin-treated rings was approximately seven-fold higher than in control rings. These endotoxin-mediated responses were blocked by L-NAME and methylene blue. These data indicate that the main cause of vascular hyposensitivity to noradrenaline was massive generation of nitric oxide. Pretreatment with methyl-prednisolone at concentrations (2.0-20.0 micrograms ml-1) similar to those achieved in plasma after therapeutic administration dose-dependently inhibited these endotoxin-mediated responses. These data support the concept that pharmacological administration of methylprednisolone has the potential to prevent endotoxin-induced depression of the contractile response to noradrenaline seen in endotoxaemic shock.

Topics: Acetylcholine; Arteries; Constriction, Pathologic; Culture Techniques; Cyclic GMP; Depression, Chemical; Dose-Response Relationship, Drug; Endotoxins; Glucocorticoids; Humans; Methylprednisolone; Muscle Contraction; Norepinephrine; Omentum

We tested the hypothesis that dismutation of superoxide anion increases endogenous levels of nitric oxide, resulting in inhibition of cyclic variations in blood flow in arteries that are injured and stenotic.. Platelet adhesion and aggregation leading to cyclic flow variations might result, in part, from generation of superoxide anion that can deplete endogenously produced nitric oxide.. Spontaneous cyclic flow variations, monitored with a proximal Doppler probe, were induced in the carotid artery of anesthetized rabbits by clamping the vessel with forceps and placing a high grade stenosis at the site of injury. Bovine copper/zinc superoxide dismutase (12 mg/kg body weight, n = 5), a synthetic low molecular weight mimetic (12 mg/kg, n = 8) or buffer vehicle (n = 8) was administered intravenously as divided boluses over 45 min, and the frequency of cyclic flow variations was monitored for 4 h.. Cyclic flow variations remained stable for 4 h in vehicle-treated animals (15 +/- 1 [mean +/- SEM]/30 min at baseline and 16 +/- 1/30 min after 4 h, n = 8) but exhibited a marked and persistent reduction in animals given copper/zinc superoxide dismutase (from 14 +/- 1/30 min at baseline to 4 +/- 1/30 min after 4 h) or the mimetic (from 15 +/- 1/30 min at baseline to 3 +/- 1/30 min after 4 h, p < 0.005). They were restored in three of four mimetic-treated animals during infusion of NG-monomethyl- L-arginine (100 mg/kg), an inhibitor of nitric oxide production. In addition, levels of cyclic guanosine 5'-monophosphate in platelets were elevated after administration of the mimetic (from 2.4 +/- 0.5 fmol/10(6) platelets at baseline to 4.9 +/- 0.6 fmol/10(6) platelets 45 min after the mimetic, p < 0.03, n = 6), whereas mean arterial blood pressure was decreased and flow velocity in the carotid artery was increased consistent with mediation of the effect on cyclic flow variations by increased endogenous nitric oxide.. Dismutation of superoxide anion appears to attenuate platelet thrombus formation at a site of vessel injury by potentiation of endogenously produced nitric oxide. This approach may have utility to inhibit platelet-rich thrombosis in injured and stenotic arteries where production of superoxide anion is increased.

Topics: Animals; Arteries; Aspirin; Blood Platelets; Cardiovascular Agents; Constriction, Pathologic; Cyclic GMP; Drug Evaluation, Preclinical; Drug Synergism; Nitric Oxide; Nitroglycerin; Organometallic Compounds; Rabbits; Random Allocation; Superoxide Dismutase; Thrombosis; Time Factors

The present studies examined adenosine and guanosine 3',5'-cyclic monophosphate (cAMP and cGMP) levels in left ventricular tissue of neonatal and adult rats subjected to 3-10 days of abdominal aortic constriction. Left ventricular cAMP levels were elevated after 3 days of pressure overloading in neonatal rats (2,274 +/- 430 pmol/g; mean +/- SE) compared with composite control values (1,280 +/- 124) obtained from sham-operated neonates, sham-operated adults, and aortic-constricted adult groups. cAMP levels declined progressively until, at 10 days after aortic constriction, values were lower (681 +/- 25 pmol/g) than control (1,621 +/- 107). Left ventricular cGMP level was higher in sham-operated neonatal (38 +/- 3 pmol/g) than in sham-operated adult rats (17 +/- 1) at 3 and 10 days postsurgery, but pressure overloading exerted no effect on cGMP measurements. Adenylate cyclase activity in left ventricular tissue homogenate was higher in 3-day sham-operated neonatal (58 +/- 3 pmol X mg protein-1 X min-1) compared with sham-operated adult (10 +/- 1) rats as the result of augmented nonmuscle cell activity. Elevated cAMP values in 3-day, pressure-overloaded neonates occurred despite lower adenylate cyclase activity (44 +/- 2), via degradative modulation (cAMP phosphodiesterase). Guanylate cyclase activity in left ventricular tissue was consistent with prevailing cGMP levels and was not influenced by aortic constriction. The present experiments show that neonatal cardiac enlargement is associated with biphasic alterations in cAMP level which are modulated, at least in part, via degradative reactions.

Topics: Adenylyl Cyclases; Animals; Animals, Newborn; Aortic Diseases; Constriction, Pathologic; Cyclic AMP; Cyclic GMP; Guanylate Cyclase; Heart Ventricles; Hemodynamics; Male; Myocardium; Organ Size; Rats; Rats, Inbred Strains; Time Factors