cyclic-gmp and Hypertrophy

Cyclic guanosine monophosphate (cGMP) and its primary signaling kinase, protein kinase G, play an important role in counterbalancing stress remodeling in the heart. Growing evidence supports a positive impact on a variety of cardiac disease conditions from the suppression of cGMP hydrolysis. The latter is regulated by members of the phosphodiesterase (PDE) superfamily, of which cGMP-selective PDE5 has been best studied. Inhibitors such as sildenafil and tadalafil ameliorate cardiac pressure and volume overload, ischemic injury, and cardiotoxicity. Clinical trials have begun exploring their potential to benefit dilated cardiomyopathy and heart failure with a preserved ejection fraction. This review discusses recent developments in the field, highlighting basic science and clinical studies.

Topics: Carbolines; Cardiomyopathy, Dilated; Cyclic AMP; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Cyclic Nucleotide Phosphodiesterases, Type 5; Fibrosis; Heart; Heart Failure; Humans; Hypertrophy; Myocardium; Phosphodiesterase 5 Inhibitors; Phosphoric Diester Hydrolases; Piperazines; Purines; Sildenafil Citrate; Sulfones; Tadalafil; Transforming Growth Factor beta; TRPC Cation Channels; Ventricular Remodeling

Biochemical studies have established the presence of a NO pathway in the heart, including sources of NO and various effectors. Several cardiac ion channels have been shown to be modified by NO, such as L-type Ca(2+), ATP-sensitive K(+), and pacemaker f-channels. Some of these effects are mediated by cGMP, through the activity of three main proteins: the cGMP-dependent protein kinase (PKG), the cGMP-stimulated phosphodiesterase (PDE2) and the cGMP-inhibited PDE (PDE3). Other effects appear independent of cGMP, as for instance the NO modulation of the ryanodine receptor-Ca(2+) channel. In the case of the cardiac L-type Ca(2+) channel current (I(Ca,L)), both cGMP-dependent and cGMP-independent effects have been reported, with important tissue and species specificity. For instance, in rabbit sinoatrial myocytes, NO inhibits the beta-adrenergic stimulation of I(Ca,L) through activation of PDE2. In cat and human atrial myocytes, NO potentiates the cAMP-dependent stimulation of I(Ca,L) through inhibition of PDE3. In rabbit atrial myocytes, NO enhances I(Ca,L) in a cAMP-independent manner through the activation of PKG. In ventricular myocytes, NO exerts opposite effects on I(Ca,L): an inhibition mediated by PKG in mammalian myocytes but by PDE2 in frog myocytes; a stimulation attributed to PDE3 inhibition in frog ventricular myocytes but to a direct effect of NO in ferret ventricular myocytes. Finally, NO can also regulate cardiac ion channels by a direct action on G-proteins and adenylyl cyclase.

Topics: Adenylyl Cyclases; Animals; Calcium; Cats; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Heart Diseases; Heart Ventricles; Humans; Hypertrophy; Ion Channels; Ions; Muscle Cells; Myocardium; Myocytes, Cardiac; Nitric Oxide; Potassium; Rabbits; Signal Transduction; Tissue Distribution

In pathological conditions associated with persistent increases in hemodynamic workload (old myocardial infarction, high blood pressure, valvular heart disease), a number of signalling pathways are activated in the heart, all of which promote hypertrophic growth of the heart, characterised at the cellular level by increases in individual cardiac myocyte size. Some of these pathways are required for a successful adaptation to cardiac injury. Other pathways are maladaptive, however, as they lead to progressive contractile dysfunction and heart failure. The free radical gas nitric oxide and natriuretic peptides, both of which are produced in the heart, have emerged as endogenous inhibitors of maladaptive hypertrophy signalling. Overall, it appears that cardiac hypertrophy is controlled by an interplay of pro- and antihypertrophic signalling networks. This delicate balance can tip towards adaptation or heart failure. In the future, patients living with cardiac disease may benefit from therapeutic strategies targeting maladaptive hypertrophy signalling pathways.

Topics: Animals; Calcineurin; Cells, Cultured; Cyclic GMP; Humans; Hypertrophy; Models, Biological; Natriuretic Peptides; Nitric Oxide; Signal Transduction

The natriuretic peptides (NPs) constitute a family of polypeptide hormones that regulate mammalian blood volume and blood pressure. The ability of the NPs to modulate cardiac hypertrophy and cell proliferation as well is now beginning to be recognized. The NPs interact with three membrane-bound receptors, all of which contain a well-characterized extracellular ligand-binding domain. The R1 subclass of NP receptors (NPR-A and NPR-B) contains a C-terminal guanylyl cyclase domain and is responsible for most of the NPs downstream actions through their ability to generate cGMP. The R2 subclass lacks an obvious catalytic domain and functions primarily as a clearance receptor. This review focuses on the signal transduction pathways initiated by ligand binding and other factors that help to determine signalling specificities, including allosteric factors modulating cGMP generation, receptor desensitization, the activation and function of cGMP-dependent protein kinase (PKG), and identification of potential nuclear or cytoplasmic targets such as the mitogen-activated protein kinase signalling (MAPK) cascade. The inhibition of cardiac growth and hypertrophy may be an important but underappreciated action of the NP signalling system.

Topics: Amino Acid Sequence; Animals; Atrial Natriuretic Factor; Catalytic Domain; Cell Division; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Cytoplasm; Guanylate Cyclase; Humans; Hypertrophy; Ligands; MAP Kinase Signaling System; Models, Biological; Molecular Sequence Data; Natriuretic Peptide, Brain; Protein Binding; Protein Structure, Tertiary; Receptors, Atrial Natriuretic Factor; Signal Transduction

Topics: Adaptation, Physiological; Animals; Calcium; Cell Cycle; Cells, Cultured; Cyclic AMP; Cyclic GMP; Diet; Glomerular Filtration Rate; Growth Inhibitors; Hormones; Humans; Hyperplasia; Hypertrophy; Ion Channels; Kidney; Nephrectomy; Nephrons; Phospholipids; Proteins; RNA

Topics: Adenosine Triphosphatases; Animals; Calcium; Cardiomegaly; Cyclic AMP; Cyclic GMP; Electrophysiology; Heart; Heart Diseases; Humans; Hypertrophy; In Vitro Techniques; Microsomes; Mitochondria; Muscle Proteins; Myocardium; Myofibrils; Oxygen Consumption; Protein Biosynthesis; Protein Kinases; Sarcoplasmic Reticulum

This study investigated the effect of the phosphodiesterase 5 inhibitor sildenafil on the pulmonary vascular response to hypoxia in humans and mice.. In a randomized, double-blind study, sildenafil 100 mg or placebo was given orally to 10 healthy volunteers 1 hour before breathing 11% O(2) for 30 minutes. Pulmonary artery pressure (PAP) was measured with an indwelling right heart catheter. The acute 56% increase in mean PAP produced by hypoxia during placebo treatment (mean PAP [mean+/-SD mm Hg]: normoxia 16.0+/-2.1 versus hypoxia 25.0+/-4.8) was almost abolished by sildenafil (normoxia 16.0+/-2.1 versus hypoxia 18.0+/-3.6), with no significant effect on systemic blood pressure. In the isolated perfused lung of wild-type and endothelial nitric oxide synthase (eNOS)-deficient mice, sildenafil markedly blunted acute hypoxic pulmonary vasoconstriction. Wild-type mice dosed orally with the drug (25 mg. kg(-1). d(-1)) throughout 3 weeks of exposure to hypoxia (10% O(2)) exhibited a significant reduction in right ventricular systolic pressure (placebo versus sildenafil: 43.3+/-9.9 versus 29.9+/-9.7 mm Hg, P<0.05) coupled with a small reduction in right ventricular hypertrophy and inhibition of pulmonary vascular remodeling. In eNOS mutant mice, sildenafil attenuated the increase in right ventricular systolic pressure but without a significant effect on right ventricular hypertrophy or vascular remodeling.. Sildenafil attenuates hypoxia-induced pulmonary hypertension in humans and mice and offers a novel approach to the treatment of this condition. The eNOS-NO-cGMP pathway contributes to the response to sildenafil, but other biochemical sources of cGMP also play a role. Sildenafil has beneficial pulmonary hemodynamic effects even when eNOS activity is impaired.

Topics: Adolescent; Adult; Animals; Cyclic GMP; Double-Blind Method; Genotype; Heart Ventricles; Humans; Hypertension, Pulmonary; Hypertrophy; Hypoxia; In Vitro Techniques; Lung; Mice; Mice, Inbred C57BL; Mice, Knockout; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Phosphodiesterase Inhibitors; Piperazines; Pulmonary Artery; Purines; Sildenafil Citrate; Sulfones; Ventricular Function, Right

Topics: Angiotensin-Converting Enzyme Inhibitors; Captopril; Cell Enlargement; Cell Line; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Enalapril; Enzyme Activation; Glycation End Products, Advanced; Humans; Hypertrophy; Kidney Tubules, Proximal; MAP Kinase Signaling System; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase Type II; S-Nitroso-N-Acetylpenicillamine; Signal Transduction; Thionucleotides

The present study was aimed to determine whether stimulating Npr1 gene activity using Valporic acid (VA), a small short chain fatty acid molecule can enhance ANP mediated anti-hypertrophic activity in isoproterenol (ISO) - treated H9c2 cells in vitro. H9c2 cells were treated with ISO (10

Topics: Animals; Atrial Natriuretic Factor; Biomarkers; Cell Line; Cyclic GMP; Drug Synergism; Gene Expression Regulation; Histone Deacetylase 1; Histone Deacetylase 2; Hypertrophy; Myocardium; Rats; Receptors, Atrial Natriuretic Factor; RNA, Messenger; Transcription, Genetic; Valproic Acid

Nitric oxide (NO) plays important, but incompletely defined roles in skeletal muscle. NO exerts its regulatory effects partly though S-nitrosylation, which is balanced by denitrosylation by enzymes such as S-nitrosoglutathione reductase (GSNOR), whose functions in skeletal muscle remain to be fully deciphered.. GSNOR null (GSNOR. GSNOR may act as a "brake" on skeletal muscle contractile performance under physiological conditions by modulating nitrosylation/denitrosylation balance.. GSNOR may play important roles in skeletal muscle contractility, RyR1 S-nitrosylation, fiber type specification, and sGC activity. Antioxid. Redox Signal. 26, 165-181.

Topics: Alcohol Dehydrogenase; Animals; Calcium; Cyclic GMP; Genotype; Hypertrophy; Male; Mice; Mice, Knockout; Mitochondria, Muscle; Muscle Fatigue; Muscle Strength; Muscle, Skeletal; Neovascularization, Physiologic; Ryanodine Receptor Calcium Release Channel

We sought to determine the effect of chronic activation of β-adrenergic receptor (β-AR) on the left ventricular (LV) expression profile of Npr1 and Npr2 (coding for NPR-A and NPR-B, respectively) genes, and the functional activity of these receptors in adult Wistar rat hearts. The Npr1 gene expression was markedly reduced (3.5-fold), while the Npr2 gene expression was up regulated (4-fold) in Isoproterenol (ISO)-treated heart as compared with controls. A gradual reduction in NPR-A protein (3-fold), cGMP levels (75%) and a steady increased expression of NPR-B protein (4-fold), were noticed in ISO hearts. Further, in-vitro membranes assay shows that NPR-A dependent guanylyl cyclase (GC) activity was down-regulated (2-fold), whereas NPR-B dependent GC activity was increased (5-fold) in ISO treated hearts. Atenolol treatment normalized the altered expression of Npr1 and Npr2 genes. In conclusion, the chronic β-AR activation differentially regulates Npr1 and Npr2 genes in the heart. Npr1 down regulation is positively associated with the development of left ventricular hypertrophy (LVH) in ISO rats.

Topics: Animals; Atrial Natriuretic Factor; Cyclic GMP; Down-Regulation; Guanylate Cyclase; Heart; Hypertrophy; Male; Rats; Rats, Wistar; Receptors, Adrenergic, beta; Receptors, Atrial Natriuretic Factor; Signal Transduction; Up-Regulation

β1-2-adrenergic receptors (AR) are key regulators of cardiac contractility and remodeling in response to catecholamines. β3-AR expression is enhanced in diseased human myocardium, but its impact on remodeling is unknown.. Mice with cardiac myocyte-specific expression of human β3-AR (β3-TG) and wild-type (WT) littermates were used to compare myocardial remodeling in response to isoproterenol (Iso) or Angiotensin II (Ang II). β3-TG and WT had similar morphometric and hemodynamic parameters at baseline. β3-AR colocalized with caveolin-3, endothelial nitric oxide synthase (NOS) and neuronal NOS in adult transgenic myocytes, which constitutively produced more cyclic GMP, detected with a new transgenic FRET sensor. Iso and Ang II produced hypertrophy and fibrosis in WT mice, but not in β3-TG mice, which also had less re-expression of fetal genes and transforming growth factor β1. Protection from Iso-induced hypertrophy was reversed by nonspecific NOS inhibition at low dose Iso, and by preferential neuronal NOS inhibition at high-dose Iso. Adenoviral overexpression of β3-AR in isolated cardiac myocytes also increased NO production and attenuated hypertrophy to Iso and phenylephrine. Hypertrophy was restored on NOS or protein kinase G inhibition. Mechanistically, β3-AR overexpression inhibited phenylephrine-induced nuclear factor of activated T-cell activation.. Cardiac-specific overexpression of β3-AR does not affect cardiac morphology at baseline but inhibits the hypertrophic response to neurohormonal stimulation in vivo and in vitro, through a NOS-mediated mechanism. Activation of the cardiac β3-AR pathway may provide future therapeutic avenues for the modulation of hypertrophic remodeling.

Topics: Angiotensin II; Animals; Cells, Cultured; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Disease Models, Animal; Heart Ventricles; Humans; Hypertrophy; In Vitro Techniques; Isoproterenol; Male; Mice; Mice, Transgenic; Myocytes, Cardiac; Neurotransmitter Agents; Nitric Oxide Synthase; Receptors, Adrenergic, beta-3; Signal Transduction; Ventricular Remodeling

The objective of this study was to examine whether genetically determined differences in the guanylyl cyclase/natriuretic peptide receptor-A gene (Npr1) affect cardiac expression of proinflammatory cytokines, hypertrophic markers, nuclear factor-κB (NF-κB), and activating protein-1 (AP-1) in am Npr1 gene-dose-dependent manner. In the present studies, adult male Npr1 gene-disrupted (Npr1(-/-)), wild-type (Npr1(+/+)), and gene-duplicated (Npr1(++/++)) mice were used. The Npr1(-/-) mice showed 41 mm Hg higher systolic blood pressure and 60% greater heart weight to body weight (HW/BW) ratio; however, Npr1(++/++) mice exhibited 15 mm Hg lower systolic blood pressure and 12% reduced HW/BW ratio compared with Npr1(+/+) mice. Significant upregulation of gene expression of proinflammatory cytokines and hypertrophic markers along with enhanced NF-κB/AP-1 binding activities were observed in the Npr1(-/-) mouse hearts. Conversely, hypertrophic markers and proinflammatory cytokines gene expression as well as NF-κB/AP-1 binding activities were markedly decreased in Npr1(++/++) mouse hearts compared with wild-type mice. The ventricular guanylyl cyclase activity and cGMP levels were reduced by 96% and 87%, respectively, in Npr1(-/-) mice; however, these parameters were amplified by 2.8-fold and 3.8-fold, respectively, in Npr1(++/++) mice. Echocardiographic analysis revealed significantly increased fractional shortening in Npr1(++/++) mice (P < .05) but greatly decreased in Npr1(-/-) mice (P < .01) hearts compared with Npr1(+/+) mice. The present findings suggest that Npr1 represses the expression of cardiac proinflammatory mediators, hypertrophic markers, and NF-κB/AP-1-mediated mechanisms, which seem to be associated in an Npr1 gene-dose-dependent manner.

Topics: Animals; Body Weight; Cell Nucleus; Cyclic GMP; Cytokines; Cytosol; Fibrosis; Guanylate Cyclase; Heart; Heart Ventricles; Hypertrophy; Inflammation; Male; Mice; Mice, Transgenic; Myocardium; NF-kappa B; Organ Size; Receptors, Atrial Natriuretic Factor; Systole; Transcription Factor AP-1

Atrial and brain natriuretic peptides (ANP and BNP, respectively) exert antihypertrophic effects in the heart via their common receptor, guanylyl cyclase (GC)-A, which catalyzes the synthesis of cGMP, leading to activation of protein kinase (PK)G. Still, much of the network of molecular mediators via which ANP/BNP-GC-A signaling inhibit cardiac hypertrophy remains to be characterized.. We investigated the effect of ANP-GC-A signaling on transient receptor potential subfamily C (TRPC)6, a receptor-operated Ca(2+) channel known to positively regulate prohypertrophic calcineurin-nuclear factor of activated T cells (NFAT) signaling.. In cardiac myocytes, ANP induced phosphorylation of TRPC6 at threonine 69, the PKG phosphorylation site, and significantly inhibited agonist-evoked NFAT activation and Ca(2+) influx, whereas in HEK293 cells, it dramatically inhibited agonist-evoked TRPC6 channel activity. These inhibitory effects of ANP were abolished in the presence of specific PKG inhibitors or by substituting an alanine for threonine 69 in TRPC6. In model mice lacking GC-A, the calcineurin-NFAT pathway is constitutively activated, and BTP2, a selective TRPC channel blocker, significantly attenuated the cardiac hypertrophy otherwise seen. Conversely, overexpression of TRPC6 in mice lacking GC-A exacerbated cardiac hypertrophy. BTP2 also significantly inhibited angiotensin II-induced cardiac hypertrophy in mice.. Collectively, these findings suggest that TRPC6 is a critical target of antihypertrophic effects elicited via the cardiac ANP/BNP-GC-A pathway and suggest TRPC6 blockade could be an effective therapeutic strategy for preventing pathological cardiac remodeling.

Topics: Anilides; Animals; Atrial Natriuretic Factor; Calcium Channels; Cells, Cultured; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Disease Models, Animal; Humans; Hypertrophy; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Myocardium; Myocytes, Cardiac; Natriuretic Peptide, Brain; NFATC Transcription Factors; Patch-Clamp Techniques; Rats; Receptors, Atrial Natriuretic Factor; Signal Transduction; Thiadiazoles; TRPC Cation Channels; TRPC6 Cation Channel

Natriuretic peptides (NPs) inhibit cardiomyocyte hypertrophy through a cyclic GMP (cGMP)-dependent process, although these effects are associated with substantial vasodilatation. In this study, we used CU-NP, a non-vasodilatating novel NP synthesized from the ring structure of human C-type NP (CNP) and both C- and N-termini of urodilatin, and investigated whether it can directly modulate cardiomyocyte hypertrophy.. Experiments were carried out in cultured neonatal rat ventricular myocytes exposed to phenylephrine, angiotensin II, or endothelin-1 in the absence or presence of CU-NP. CU-NP produced a concentration- and time-dependent increase in intracellular cGMP levels. The hypertrophic responses to all agonists were abrogated by 10 nM CU-NP. CU-NP treatment also prevented increased activity, gene and protein expression of sodium-hydrogen exchanger-1 (NHE-1) as well as elevations in intracellular Na(+) concentrations caused by hypertrophic agents. In addition, these effects were associated with a more than two-fold increase in activity of the Ca(2+)-dependent protein phosphatase calcineurin that peaked 6 h after addition of hypertrophic stimuli. Early (1-3 h) calcineurin activation was unaffected by CU-NP, although activation at 6 and 24 h was prevented by CU-NP as was the resultant translocation of the transcriptional factor NFAT into nuclei.. Our study demonstrates a direct anti-hypertrophic effect of the chimeric peptide CU-NP via NHE-1 inhibition, thereby preventing calcineurin activation and NFAT nuclear import. Thus, CU-NP represents a novel fusion peptide of CNP and urodilatin that has the potential to be developed into a therapeutic agent to treat cardiac hypertrophy and heart failure.

Topics: Animals; Atrial Natriuretic Factor; Calcineurin; Cell Nucleus; Cells, Cultured; Cyclic GMP; Dose-Response Relationship, Drug; Hypertrophy; Mitogen-Activated Protein Kinase Kinases; Models, Animal; Myocytes, Cardiac; Peptide Fragments; Rats; Rats, Sprague-Dawley; Recombinant Fusion Proteins; Signal Transduction; Sodium; Sodium-Hydrogen Exchangers

Upregulating the heme oxygenase (HO) system removes the prooxidant heme, and thus is cytoprotective. Additionally, the products from the HO pathway including, carbon monoxide, bilirubin, and biliverdin, scavenge reactive oxygen species, inhibit lipid peroxidation, and suppress tissue inflammation, while the iron formed enhances the synthesis of the antioxidant ferritin. Deoxycorticosterone acetate (DOCA)-salt hypertension, a model of human primary aldosteronism, causes oxidative stress and impairs renal function by stimulating inflammatory/oxidative transcription factors such as NF-kappaB and activating protein (AP-1). The effect of the HO system in end-organ damage in mineralocorticoid-induced hypertension has not been fully characterized. In this study, the administration of the HO inducer hemin lowered blood pressure (191 vs. 135 mmHg; n = 22, P < 0.01), increased creatinine clearance, and reduced kidney hypertrophy proteinuria, albuminuria, and histopathological lesions, including glomerular hypertrophy, glomerulosclerosis, tubular dilation, tubular cast formation, and interstitial mononuclear cell infiltration in nephrectomy/DOCA-high-salt-hypertension. The renoprotection was accompanied by reduced levels of NF-kappaB, AP-1, fibronectin, transforming growth factor (TGF)-beta, and 8-isoprostane, a marker of oxidative stress. Correspondingly, a robust increase in total antioxidant capacity, HO activity, cGMP, and an antioxidant like ferritin was observed in hemin-treated animals. Our findings suggest that suppression of oxidative/inflammatory insults alongside the corresponding decline of fibronectin and TGF-beta, an activator of extracellular matrix proteins, may account for the attenuation of renal histopathological lesions and the antihypertrophic effects of hemin. The multifaceted interaction among the HO system, TGF-beta, fibronectin, AP-1, and NF-kappaB may be explored to design new drugs against end-stage-organ damage.

Topics: Animals; Blood Pressure; Cyclic GMP; Desoxycorticosterone; Ferritins; Heme Oxygenase (Decyclizing); Hemin; Hypertension; Hypertrophy; Kidney; Kidney Diseases; Male; Nephrectomy; NF-kappa B; Oxidative Stress; Rats; Rats, Sprague-Dawley; Transcription Factor AP-1; Up-Regulation

The negative functional effects of cyclic GMP are controlled by the sarcoplasmic reticulum calcium-ATPase (SERCA). The effects of cyclic GMP are blunted in cardiac hypertrophy. We tested the hypothesis that the interaction between cyclic GMP and SERCA would be reduced in hypertrophic cardiac myocytes. Myocytes were isolated from 7 control and 7 renal-hypertensive hypertrophic rabbits. Control and hypertrophic myocytes received 8-bromo-cGMP (8-Br-cGMP; 10(-7), 10(-6), 10(-5) mol/l), the SERCA blocker thapsigargin (10(-8) mol/l) followed by 8-Br-cGMP, or the SERCA blocker, cyclopiazonic acid (CPA; 10(-7) mol/l) followed by 8-Br-cGMP. Percent shortening and maximal rate of shortening and relaxation were recorded using a video edge detector. Changes in cytosolic Ca2+ were assessed in fura 2-loaded myocytes. In controls, 8-Br-cGMP caused a significant 36% decrease in percent shortening from 5.8 +/- 0.4 to 3.7 +/- 0.3%. Thapsigargin and CPA did not affect basal control or hypertrophic myocyte function. When 8-Br-cGMP was given following thapsigargin or CPA, the negative effects of 8-Br-cGMP on control myocyte function were reduced. In hypertrophic myocytes, 8-Br-cGMP caused a smaller but significant 17% decrease in percent shortening from 4.7 +/- 0.2 to 3.9 +/- 0.1%. When 8-Br-cGMP was given following thapsigargin or CPA, no significant changes occurred in hypertrophic cell function. Intracellular Ca2+ transients responded in a similar manner to changes in cell function in control and hypertrophic myocytes. These results show that the effects of cyclic GMP were reduced in hypertrophic myocytes, but this was not related to SERCA. In presence of SERCA inhibitors, the responses to cyclic GMP were blunted in hypertrophic as well as control myocytes.

Topics: Animals; Calcium; Cyclic GMP; Heart Ventricles; Hypertension, Renal; Hypertrophy; In Vitro Techniques; Indoles; Myocytes, Cardiac; Rabbits; Sarcoplasmic Reticulum Calcium-Transporting ATPases; Thapsigargin

The accumulation of advanced glycation end products (AGE) is a key mediator of renal tubular hypertrophy in diabetic nephropathy (DN). Reactive oxygen species and nitric oxide (NO) were involved in the progression of DN. In this study, the molecular mechanisms of NO and antioxidants responsible for inhibition of AGE-induced renal tubular hypertrophy were examined. We found that AGE (but not nonglycated bovine serum albumin) significantly suppressed the NO/cGMP/PKG signaling in human renal proximal tubular cells. NO donors S-nitroso-N-acetylpenicillamine (SNAP)/sodium nitroprusside (SNP) and antioxidants N-acetylcysteine (NAC)/taurine treatments significantly attenuated AGE-inhibited NO production, cGMP synthesis, and inducible NO synthase/cGMP-dependent protein kinase (PKG) activation. Moreover, AGE-induced extracellular signal-regulated kinase/c-Jun N-terminal kinase/p38 mitogen-activated protein kinase activation was markedly blocked by antireceptor for AGE (RAGE), SNAP, SNP, NAC, and taurine. The abilities of NO and antioxidants to inhibit AGE/RAGE-induced hypertrophic growth were verified by the observation that SNAP, SNP, NAC, and taurine inhibited fibronectin, p21(Waf1/Cip1), and RAGE expression. Therefore, antioxidants significantly attenuated AGE/RAGE-enhanced cellular hypertrophy partly through induction of the NO/cGMP/PKG signaling.

Topics: Antioxidants; Blotting, Western; Cell Line; Cell Size; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Fibronectins; Flow Cytometry; Glycation End Products, Advanced; Humans; Hypertrophy; Kidney Tubules; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase Type II; Oncogene Protein p21(ras); Receptor for Advanced Glycation End Products; Receptors, Immunologic; S-Nitroso-N-Acetylpenicillamine

Vascular fibrosis is a major complication of hypertension and atherosclerosis, yet it is largely untreatable. Natriuretic peptides (NPs) repress fibrogenic activation of vascular smooth muscle cells (VSMCs), but the intracellular mechanism mediating this effect remains undetermined. Here we show that inhibition of RhoA through phosphorylation at Ser188, the site targeted by the NP effector cyclic GMP (cGMP)-dependent protein kinase I (cGK I), is critical to fully exert antifibrotic potential. cGK I(+/-) mouse blood vessels exhibited an attenuated P-RhoA level and concurrently increased RhoA/ROCK signaling. Importantly, cGK I insufficiency caused dynamic recruitment of ROCK into the fibrogenic programs, thereby eliciting exaggerated vascular hypertrophy and fibrosis. Transgenic expression of cGK I-unphosphorylatable RhoA(A188) in VSMCs augmented ROCK activity, vascular hypertrophy, and fibrosis more prominently than did that of wild-type RhoA, consistent with the notion that RhoA(A188) escapes the intrinsic inhibition by cGK I. Additionally, VSMCs expressing RhoA(A188) became refractory to the antifibrotic effects of NPs. Our results identify cGK I-mediated Ser188 phosphorylation of RhoA as a converging node for pro- and antifibrotic signals and may explain how diminished cGMP signaling, commonly associated with vascular malfunction, predisposes individuals to vascular fibrosis.

Topics: Angiotensin II; Animals; Blood Vessels; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Enzyme Activation; Fibrosis; Gene Expression Regulation; Humans; Hypertrophy; Mice; Mice, Transgenic; Muscle, Smooth, Vascular; Mutant Proteins; Organ Specificity; Phosphorylation; Phosphoserine; Protein Biosynthesis; rho-Associated Kinases; rhoA GTP-Binding Protein; Serum Response Element; Signal Transduction; Transcription, Genetic

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a ligand-activated transcription factor that plays a critical role in metabolism. Thiazolidinediones, high-affinity PPARgamma ligands used clinically to treat type II diabetes, have been reported to lower blood pressure and provide other cardiovascular benefits. Some mutations in PPARgamma (PPARG) cause type II diabetes and severe hypertension. Here we tested the hypothesis that PPARgamma in vascular muscle plays a role in the regulation of vascular tone and blood pressure. Transgenic mice expressing dominant-negative mutations in PPARgamma under the control of a smooth-muscle-specific promoter exhibit a loss of responsiveness to nitric oxide and striking alterations in contractility in the aorta, hypertrophy and inward remodeling in the cerebral microcirculation, and systolic hypertension. These results identify PPARgamma as pivotal in vascular muscle as a regulator of vascular structure, vascular function, and blood pressure, potentially explaining some of the cardioprotective effects of thiazolidinediones.

Topics: Animals; Aorta, Thoracic; Blood Pressure; Cerebral Arteries; Circadian Rhythm; Cyclic GMP; Dose-Response Relationship, Drug; Female; Humans; Hypertension; Hypertrophy; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Muscle, Smooth, Vascular; Mutation; Myosin Heavy Chains; Nitric Oxide; PPAR gamma; Promoter Regions, Genetic; Rats; Systole; Vasoconstriction; Vasoconstrictor Agents; Vasodilation; Vasodilator Agents

In the infarcted rat heart, the increase of NO occurs in the hypertrophied myocardium of non-infarcted areas and its antihypertrophic efficacy has been well established. As another endogenous regulator and the reliable index of heart pathology, B-type natriuretic peptide also exhibits the antihypertrophic properties in many tissues by elevating intracellular cGMP. Several studies indicate that natriuretic peptides family may exert some actions in part via a nitric oxide pathway following receptor-mediated stimulation of iNOS. Therefore, it raises our great interest to ask what role NO plays in the antihypertrophic actions of B-type natriuretic peptide in cardiomyocytes. Incubation of cardiomyocytes under mild hypoxia for 12 h caused a significant increase in cellular protein content, protein synthesis and cell surface sizes. This growth stimulation was suppressed by exogenous B-type natriuretic peptide in a concentration dependent manner. Furthermore, the generation of intracellular cGMP, the upregulation of iNOS mRNA expression, the increase of iNOS activity and subsequent nitrite generation in hypertrophic cardiomyocytes was also increased by B-type natriuretic peptide. AG, a selective iNOS inhibitor, inhibited the upregulation of iNOS expression and the increase of iNOS activity by the combination of B-type natriuretic peptide/mild hypoxia or by the combination of 8-bromo-cGMP/mild hypoxia. Rp-8-br-cGMP, cGMP dependent protein kinase inhibitor, attenuated the actions of B-type natriuretic peptide and 8-bromo-cGMP which increases intracellular cGMP independent of B-type natriuretic peptide. In conclusion, our present data suggest that B-type natriuretic peptide exerted the antihypertrophic effects in cardiomyocytes, which was partially attributed to induction of iNOS-derived NO by cGMP pathway.

Topics: Animals; Animals, Newborn; Cell Hypoxia; Cell Proliferation; Cells, Cultured; Culture Media; Cyclic GMP; Gene Expression Regulation, Enzymologic; Hypertrophy; Myocytes, Cardiac; Natriuretic Peptide, Brain; Nitric Oxide; Nitric Oxide Synthase Type II; Nitrites; Rats; Rats, Sprague-Dawley; RNA, Messenger

Nitric oxide (NO), in addition to its vasodilator action, has also been shown to antagonize the mitogenic and hypertrophic responses of growth factors and vasoactive peptides such as endothelin-1 (ET-1) in vascular smooth muscle cells (VSMCs). However, the mechanism by which NO exerts its antimitogenic and antihypertrophic effect remains unknown. Therefore, the aim of this study was to determine whether NO generation would modify ET-1-induced signaling pathways involved in cellular growth, proliferation, and hypertrophy in A-10 VSMCs. Treatment of A-10 VSMCs with S-nitroso-N-acetylpenicillamine (SNAP) or sodium nitroprusside (SNP), two NO donors, attenuated the ET-1-enhanced phosphorylation of several key components of growth-promoting and hypertrophic signaling pathways such as ERK1/2, PKB, and Pyk2. On the other hand, inhibition of the endogenous NO generation with N(G)-nitro-L-arginine methyl ester, a nitric oxide synthase inhibitor, increased the ET-1-induced phosphorylation of these signaling components. Since NO mediates its effect principally through a cGMP-soluble guanylyl cyclase (sGC) pathway, we investigated the role of these molecules in NO action. 8-Bromoguanosine 3',5'-cyclic monophosphate, a nonmetabolizable and cell-permeant analog of cGMP, exhibited a effect similar to that of SNAP and SNP. Furthermore, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), an inhibitor of sGC, reversed the inhibitory effect of NO on ET-1-induced responses. SNAP treatment also decreased the protein synthesis induced by ET-1. Together, these data demonstrate that NO, in a cGMP-dependent manner, attenuated ET-1-induced phosphorylation of ERK1/2, PKB, and Pyk2 and also antagonized the hypertrophic effects of ET-1. It may be suggested that NO-induced generation of cGMP contributes to the inhibition of ET-1-induced mitogenic and hypertrophic responses in VSMCs.

Topics: Animals; Aorta, Thoracic; Cell Proliferation; Cells, Cultured; Cyclic GMP; Dose-Response Relationship, Drug; Endothelin-1; Enzyme Inhibitors; Focal Adhesion Kinase 2; Guanylate Cyclase; Hypertrophy; Leucine; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase; Nitroprusside; Oxadiazoles; Phosphorylation; Protein Biosynthesis; Proto-Oncogene Proteins c-akt; Quinoxalines; Rats; Receptors, Cytoplasmic and Nuclear; S-Nitroso-N-Acetylpenicillamine; Signal Transduction; Soluble Guanylyl Cyclase

The antiproliferative action of nitric oxide (NO) has been well established and increased production was reported in the infarcted rat heart. Concomitantly, increased DNA synthesis and hyperplasia of cardiac myocytes were documented in the hypertrophied myocardium. Despite these observations, the effect of NO on DNA synthesis in hypertrophied cardiac myocytes remains unexamined. Hypertrophy of the non-infarcted left ventricle (NILV) in 1-week post-MI rats was characterized by the increased prepro-ANP and reduction of alpha-myosin heavy chain protein expression. Inducible NO synthase was expressed in the NILV and associated with a concomitant attenuation of MnSuperoxide dismutase protein content. The latter data suggest that an antiproliferative action of NO in the hypertrophied NILV may proceed via either a cyclic GMP-dependent pathway and/or facilitated by a peroxynitrite-dependent mechanism. In neonatal rat ventricular myocytes (NNVM), the NO donor S-nitroso-N-acetyl-penicillamine (SNAP) promoted a dose-dependent attenuation of DNA synthesis via a cyclic GMP-independent pathway. The permeable superoxide dismutase mimetic and peroxynitrite scavenger MnTBAP abrogated SNAP-dependent attenuation of DNA synthesis in NNVM. MnTBAP failed to inhibit SNAP-mediated recruitment of extracellular signal regulated kinase 1/2 (ERK1/2) but partially attenuated p38 phosphorylation. In hypertrophied NNVM induced by norepinephrine, SNAP-mediated peroxynitrite-dependent inhibition of DNA synthesis, ERK1/2 and p38 phosphorylation were significantly attenuated. Collectively, these data suggest that despite a favourable environment for NO and subsequent peroxynitrite generation in the NILV, hypertrophied cardiac myocytes may be partially refractory to their biological actions.

Topics: Animals; Animals, Newborn; Cyclic GMP; DNA; Heart Ventricles; Hypertrophy; Hypertrophy, Left Ventricular; Mitogen-Activated Protein Kinases; Muscle Cells; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase; p38 Mitogen-Activated Protein Kinases; Penicillamine; Peroxynitrous Acid; Rats; Rats, Sprague-Dawley; Superoxide Dismutase; Ventricular Myosins

We tested the hypothesis that the negative inotropic effects of C-type natriuretic peptide (CNP) would be diminished in renal hypertensive (one-kidney-one-clip, 1K1C) hypertrophic rabbit hearts and that this attenuated effect would be due either to decreased cyclic GMP production or to reduced signaling.. Using isolated control and 1K1C ventricular myocytes, cell shortening data (video edge detection) were collected: (1) at baseline and after CNP 10(-8,-7) M, followed by KT5823 (KT), a cyclic GMP-dependent protein kinase inhibitor; or (2) at baseline, following KT pre-treatment and subsequent CNP 10(-8,-7) M. In addition, cyclic GMP levels were determined by radioimmunoassay at baseline and CNP 10(-7) M.. In control myocytes, CNP decreased percent shortening (5.7 +/- 0.4 versus 4.0 +/- 0.4% at 10(-7) M), maximal rate of shortening (58.7 +/- 5.1 versus 45.2 +/- 3.6 microm/sec) and maximal rate of relaxation (57.1 +/- 4.9 versus 44.1 +/- 3.4 microm/sec) in a concentration-dependent manner. These effects were attenuated by subsequent KT administration. CNP failed to produce these negative functional effects in 1K1C myocytes. When pre-treated with KT, CNP had no negative functional effect in either normal and 1K1C myocytes. Basal levels of cyclic GMP were similar in control versus 1K1C myocytes; however, CNP produced a significant rise in cyclic GMP level in control (63.6 +/- 7.8 versus 83.5 +/- 11.3 pmol/10(5) myocytes) but not in 1K1C (49.2 +/- 2.6 versus 52.7 +/- 5.6) myocytes.. Thus, CNP acted through the cyclic GMP protein kinase in control myocytes. We conclude that in hypertrophic cardiac myocytes, the decreased effect of CNP was because of decreased production of cyclic GMP.

Topics: Animals; Carbazoles; Cardiomegaly; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Disease Models, Animal; Guanylate Cyclase; Heart Ventricles; Hypertension, Renal; Hypertrophy; Indoles; Myocardial Contraction; Myocytes, Cardiac; Natriuretic Peptide, C-Type; Protein Kinase Inhibitors; Rabbits; Signal Transduction; Surgical Instruments

Topics: Animals; Cyclic GMP; Cyclic GMP-Dependent Protein Kinase Type I; Cyclic GMP-Dependent Protein Kinases; Heart; Humans; Hypertrophy; Mice; Myocardium; Phosphodiesterase Inhibitors; Piperazines; Purines; Sildenafil Citrate; Sulfones

The crucial functions of atrial natriuretic peptide (ANP) and endothelial nitric oxide/NO in the regulation of arterial blood pressure have been emphasized by the hypertensive phenotype of mice with systemic inactivation of either the guanylyl cyclase-A receptor for ANP (GC-A-/-) or endothelial nitric-oxide synthase (eNOS-/-). Intriguingly, similar levels of arterial hypertension are accompanied by marked cardiac hypertrophy in GC-A-/-, but not in eNOS-/-, mice, suggesting that changes in local pathways regulating cardiac growth accelerate cardiac hypertrophy in the former and protect the heart of the latter. Our recent observations in mice with conditional, cardiomyocyte-restricted GC-A deletion demonstrated that ANP locally inhibits cardiomyocyte growth. Abolition of these local, protective effects may enhance the cardiac hypertrophic response of GC-A-/- mice to persistent increases in hemodynamic load. Notably, eNOS-/- mice exhibit markedly increased cardiac ANP levels, suggesting that increased activation of cardiac GC-A can prevent hypertensive heart disease. To test this hypothesis, we generated mice with systemic inactivation of eNOS and cardiomyocyte-restricted deletion of GC-A by crossing eNOS-/- and cardiomyocyte-restricted GC-A-deficient mice. Cardiac deletion of GC-A did not affect arterial hypertension but significantly exacerbated cardiac hypertrophy and fibrosis in eNOS-/- mice. This was accompanied by marked cardiac activation of both the mitogen-activated protein kinase (MAPK) ERK 1/2 and the phosphatase calcineurin. Our observations suggest that local ANP/GC-A/cyclic GMP signaling counter-regulates MAPK/ERK- and calcineurin/nuclear factor of activated T cells-dependent pathways of cardiac myocyte growth in hypertensive eNOS-/- mice.

Topics: Animals; Atrial Natriuretic Factor; Blood Pressure; Blotting, Northern; Blotting, Western; Cyclic GMP; Gene Deletion; Genotype; Heart Ventricles; Hypertension; Hypertrophy; Mice; Mice, Knockout; Mice, Transgenic; Myocardium; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Phenotype; Phosphorylation; RNA, Messenger; Signal Transduction

In DOCA-salt hypertension, renal kallikrein levels are increased and may play a protective role in renal injury. We investigated the effect of enhanced kallikrein levels on kidney remodeling of DOCA-salt hypertensive rats by systemic delivery of adenovirus containing human tissue kallikrein gene. Recombinant human kallikrein was detected in the urine and serum of rats after gene delivery. Kallikrein gene transfer significantly decreased DOCA- and salt-induced proteinuria, glomerular sclerosis, tubular dilatation, and luminal protein casts. Sirius red staining showed that kallikrein gene transfer reduced renal fibrosis, which was confirmed by decreased collagen I and fibronectin levels. Furthermore, kallikrein gene delivery diminished myofibroblast accumulation in the interstitium of the cortex and medulla, as well as transforming growth factor (TGF)-beta1 immunostaining in glomeruli. Western blot analysis and ELISA verified the decrease in immunoreactive TGF-beta1 levels. Kallikrein gene transfer also significantly reduced kidney weight, glomerular size, proliferating tubular epithelial cells, and macrophages/monocytes. Reduction of proliferation and hypertrophy was associated with reduced levels of the cyclin-dependent kinase inhibitor p27(Kip1), and the phosphorylation of c-Jun NH2-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK). The protective effects of kallikrein were accompanied by increased urinary nitrate/nitrite and cGMP levels, and suppression of superoxide formation. These results indicate that kallikrein protects against mineralocorticoid-induced renal fibrosis glomerular hypertrophy, and renal cell proliferation via inhibition of oxidative stress, JNK/ERK activation, and p27(Kip1) and TGF-beta1 expression.

Topics: Animals; Cell Cycle Proteins; Cell Division; Cyclic GMP; Cyclin-Dependent Kinase Inhibitor p27; Desoxycorticosterone; Disease Models, Animal; Extracellular Matrix; Extracellular Signal-Regulated MAP Kinases; Fibrosis; Gene Transfer Techniques; Genetic Therapy; Hypertension, Renal; Hypertrophy; JNK Mitogen-Activated Protein Kinases; Kallikreins; Male; Nitrates; Oxidative Stress; Proteinuria; Rats; Rats, Sprague-Dawley; Sodium Chloride, Dietary; Transforming Growth Factor beta; Transforming Growth Factor beta1; Tumor Suppressor Proteins

To investigate the effect of long-term l-arginine supplementation on phenotype and proliferative status of vascular smooth muscle cells (VSMCs) from spontaneously hypertensive rats (SHR) as well as the possible changes in nitric oxide (NO) availability.. Male SHR, 22 weeks of age, received l-arginine (660 mg/kg per day) in their drinking water for 12 weeks. VSMCs from untreated (C-VSMC) and l-arginine-treated (l-Arg-VSMC) SHR were isolated from the common carotid artery, cultured and used until passage five. Size, protein content, cell proliferation and ploidy were evaluated in carotid VSMCs in culture, as well as the possible association of NO in these changes.. Relative cell size, total protein content per cell, and number of polyploid cells were significantly lower in l-Arg-VSMC compared to C-VSMC. Fetal calf serum stimulation (10% FCS) increased cell number only in l-Arg-VSMC. DNA synthesis, assessed by [H]methylthymidine incorporation after 10% FCS stimulation, was higher in l-Arg-VSMC than in C-VSMC. Cell cycle analysis revealed a significant increase of the number of l-Arg-VSMC at the G1 phase, together with a reduction at the G2 + M phase. In contrast, C-VSMC were arrested at the G2 + M phase of the cell cycle. Nitrite/nitrate levels, as well as intracellular cyclic guanosine monophosphate (cGMP) content, were significantly higher in l-Arg-VSMC. This was accompanied by enhanced inducible nitric oxide synthase (iNOS) expression and activity and a decreased constitutive nitric oxide synthase (cNOS) activity in these cells.. The results suggest that chronic treatment with l-arginine induces changes in VSMC size, ploidy and cell cycle. These changes are accompanied by iNOS induction and stimulation of the NO-cGMP pathway.

Topics: Animals; Arginine; Carotid Arteries; Cell Cycle; Cell Division; Cells, Cultured; Cyclic GMP; Endothelium, Vascular; Enzyme Induction; G1 Phase; Hypertrophy; Male; Muscle, Smooth, Vascular; Nitrates; Nitric Oxide Synthase; Nitrites; Ploidies; Rats; Rats, Inbred SHR; Time Factors

Evidence from several rodent models has suggested that a reduction of either atrial natriuretic peptide or its receptor in the heart affects cardiac remodeling by promoting the onset of cardiac hypertrophy. The atrial natriuretic peptide receptor mediates signaling at least in part via the generation of intracellular cyclic GMP. To directly test whether accumulation of intracellular cyclic GMP conveys protection against cardiac hypertrophy, we engineered transgenic mice that overexpress a catalytic fragment of constitutively active guanylate cyclase domain of the atrial natriuretic peptide receptor in a cardiomyocyte-specific manner. Expression of the transgene increased the intracellular concentration of cyclic GMP specifically within cardiomyocytes and had no detectable effect on cardiac performance under basal conditions. However, expression of the transgene attenuated the effects of the pharmacologic hypertrophic agent isoproterenol on cardiac wall thickness and prevented the onset of the fetal gene expression program normally associated with cardiac hypertrophy. Likewise, expression of the transgene inhibited the hypertrophic effects of abdominal aortic constriction, since it abolished its effects on ventricular wall thickness and greatly attenuated its effects on cardiomyocyte size. Altogether, our results suggest that cyclic GMP is a cardioprotective agent against hypertrophy that acts via a direct local effect on cardiomyocytes.

Topics: Adenylyl Cyclases; Animals; Aorta; Blood Pressure; Blotting, Northern; COS Cells; Cyclic GMP; DNA, Complementary; Echocardiography; Guanylate Cyclase; Hypertrophy; Isoproterenol; Male; Mice; Mice, Inbred C3H; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Myocardium; Peptides; Protein Structure, Tertiary; Rats; Receptors, Atrial Natriuretic Factor; RNA, Messenger; Tissue Distribution; Transfection; Transgenes

1. We tested the hypothesis that the cGMP-dependent protein kinase has major negative functional effects in cardiac myocytes and that the importance of this pathway is reduced in thyroxine (T4; 0.5 mg/kg per day for 16 days) hypertrophic myocytes. 2. Using isolated ventricular myocytes from control (n = 7) and T4-treated (n = 9) rabbit hypertrophic hearts, myocyte shortening was studied with a video edge detector. Oxygen consumption was measured using O2 electrodes. Protein phosphorylation was measured autoradiographically. 3. Data were collected following treatment with: (i) 8-(4-chlorophenylthio)guanosine-3',5'-monophosphate (PCPT; 10-7 or 10-5 mol/L); (ii) 8-bromo-cAMP (10-5 mol/L) followed by PCPT; (iii) beta-phenyl-1,N2-etheno-8-bromoguanosine-3',5'-monophosphorothioate, SP-isomer (SP; 10-7 or 10-5 mol/L); or (iv) 8-bromo-cAMP (10-5 mol/L) followed by SP. 4. There were no significant differences between groups in baseline percentage shortening (Pcs; 4.9 +/- 0.2 vs 5.6 +/- 0.4% for control and T4 groups, respectively) and maximal rate of shortening (Rs; 64.8 +/- 5.9 vs 79.9 +/- 7.1 micro m/ s for control and T4 groups, respectively). Both SP and PCPT decreased Pcs (-43 vs-21% for control and T4 groups, respectively) and Rs (-36 vs-22% for control and T4 groups, respectively), but the effect was significantly reduced in T4 myocytes. 8-Bromo-cAMP similarly increased Pcs (28 vs 23% for control and T4 groups, respectively) and Rs (20 vs 19% for control and T4 groups, respectively). After 8-bromo-cAMP, SP and PCPT decreased Pcs (-34%) and Rs (-29%) less in the control group. However, the effects of these drugs were not altered in T4 myocytes (Pcs -24%; Rs -22%). Both PCPT and cAMP phosphorylated the same five protein bands. In T4 myocytes, these five bands were enhanced less. 5. We conclude that, in control ventricular myocytes, the cGMP-dependent protein kinase exerted major negative functional effects but, in T4-induced hypertrophic myocytes, the importance of this pathway was reduced and the interaction between cAMP and the cGMP protein kinase was diminished.

Topics: 8-Bromo Cyclic Adenosine Monophosphate; Animals; Body Weight; Cyclic AMP; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Drug Administration Schedule; Drug Synergism; gamma-Aminobutyric Acid; Guanosine; Heart Ventricles; Hypertrophy; Injections, Intramuscular; Myocardial Contraction; Myocytes, Cardiac; Organ Size; Oxygen Consumption; Phosphoproteins; Phosphorylation; Rabbits; Stimulation, Chemical; Thyroxine; Time Factors

We investigated the expression and activity of nitric oxide synthase (NOS) and the localization of cyclic guanosine monophosphate (cGMP) in hypertrophied rat bladder. We also examined whether nitric oxide (NO) has a growth inhibitory effect in bladder smooth muscle cells.. The urethra was partly ligated and the bladder was removed 3 days, 3 or 6 weeks after obstruction. NOS activity was determined as the conversion of L-[14C]citrulline from L-[14C]arginine (Amersham Life Science, Solna, Sweden). Neuronal NOS (nNOS) expression was studied with Western blot analysis and immunohistochemistry. The expression of inducible NOS (iNOS) and cGMP was evaluated by immunohistochemistry. The effect of NO on isolated bladder smooth muscle cell growth was assessed as protein and DNA synthesis by [3H]-leucine and [3H]-thymidine (NEN Life Science Products, Zaventem, Belgium) incorporation, respectively.. Ca independent iNOS activity increased after short-term obstruction. Immunohistochemical studies in obstructed bladders demonstrated iNOS expression primarily in urothelial and inflammatory cells. Ca dependent nNOS activity decreased after obstruction, as confirmed by Western blot analysis. The cGMP immunoreactive cells were mainly found within the serosal layer of obstructed bladders. The NO donor DETA-NONOate (Alexis Biochemicals, Lausen, Switzerland) (300 microM.) reduced [3H]-leucine and [ H]-thymidine incorporation by a mean of 29% +/- 2% and 95% +/- 2%, respectively, in cultured bladder smooth muscle cells.. Bladder obstruction caused a small increase in iNOS activity and a decrease in nNOS activity. NO was found to have a growth inhibitory effect in bladder smooth muscle cells, suggesting that changes in NOS activity may influence the progress of bladder hypertrophy.

Topics: Animals; Blotting, Western; Calcium; Cell Division; Cells, Cultured; Cyclic GMP; Female; Hydrazines; Hypertrophy; Immunohistochemistry; Muscle, Smooth; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase; Nitric Oxide Synthase Type I; Nitric Oxide Synthase Type II; Nitroso Compounds; Rats; Rats, Sprague-Dawley; Urinary Bladder; Urinary Bladder Neck Obstruction

The management of sick newborn infants who have sustained a hypoxic insult is a common clinical problem but relatively little is known about the recovery process. The aim of this study was to investigate this process in newborn piglets.. Thirty five newborn piglets were exposed to chronic hypobaric hypoxia for three days, either from birth, three or 14 days of age, and were allowed to recover for one, three, or six days. Control animals of relevant age were also studied. The heart weight ratio and pulmonary arterial muscularity were measured. Endothelial dependent and independent relaxation of the isolated intrapulmonary conduit arteries was determined in classical organ chamber studies, together with measurement of basal and stimulated cGMP accumulation.. After six days of recovery the hypoxia induced right ventricular hypertrophy and pulmonary arterial medial hypertrophy had decreased in all animals but values were still abnormal in the two younger age groups. Relaxation was still impaired during the first three days of recovery in all groups, had normalised by six days in the two youngest groups, but relaxation (both endothelium dependent and independent) remained impaired in older animals. In these older animals basal nitric oxide (NO) production and basal and stimulated cGMP accumulation was normal.. The recovery of the smooth muscle cells lags behind that of the endothelial cells. A normal stimulated increase in cGMP with reduced relaxation suggests an altered threshold for cGMP effected relaxation. These findings help to explain why some hypoxic infants require protracted NO therapy.

Topics: Acetylcholine; Animals; Animals, Newborn; Calcimycin; Cyclic GMP; Enzyme Inhibitors; Hypertension, Pulmonary; Hypertrophy; Hypertrophy, Right Ventricular; Hypoxia; Nitric Oxide; omega-N-Methylarginine; Phosphodiesterase Inhibitors; Pulmonary Artery; Purinones; Swine; Tunica Intima; Vasoconstriction; Vasodilator Agents

Kallikrein gene delivery has been shown to attenuate hypertension, cardiac hypertrophy, and renal injury in hypertensive animal models. The aim of this study was to investigate the potential protective effects of kallikrein gene delivery in salt-induced stroke and cerebrovascular disorders.. Adenovirus harboring the human tissue kallikrein gene (AdCMV-cHK) was delivered intravenously into Dahl salt-sensitive (DS) rats after 4 weeks of high salt loading, and blood pressure was monitored weekly for 9 weeks.. A single injection of AdCMV-cHK caused a significant reduction of systolic blood pressure compared with that in control rats, with or without an injection of adenovirus carrying the LacZ (control) gene (AdCMV-LacZ). A maximal blood pressure reduction of 21 mm Hg was observed 2 weeks after gene delivery. The stroke mortality rate of DS rats (AdCMV-LacZ group versus the AdCMV-cHK group) was significantly decreased: 38% versus 9% at 3 weeks and 54% versus 27% at 5 weeks after gene delivery. Kallikrein gene delivery significantly attenuated salt-induced aortic hypertrophy, as evidenced by reduced thickness of the aortic wall. Recombinant human tissue kallikrein was detected in rat serum and urine after gene transfer. Kinin-releasing activities in the brain as well as urinary kinin and cGMP levels were significantly increased in rats receiving the kallikrein gene.. This is the first study to demonstrate the protective effect of kallikrein gene delivery in reducing salt-induced stroke mortality and vascular dysfunction.

Topics: Adenoviridae; Animals; Aorta; Blood Pressure; Brain; Cerebrovascular Disorders; Cyclic GMP; Gene Transfer Techniques; Humans; Hypertrophy; Injections, Intravenous; Kallikreins; Kinins; Male; Rats; Rats, Inbred Dahl; Recombinant Proteins; Sodium Chloride; Time Factors

Bladder outlet obstruction (BOO) is a common disorder that is associated with altered bladder structure and function. For example, it is well established that BOO results in hypertrophy and hyperplasia of the bladder smooth muscle as well as detrusor instability. Since prostaglandins (PGs) and cyclic nucleotides (cyclic AMP [cAMP] and cyclic GMP [cGMP]) mediate both smooth muscle tone and proliferation, it is reasonable to suggest that changes in their levels may be involved in the pathophysiology of BOO-associated bladder disorders. Hence, the objective of this study was to investigate cyclic AMP, cyclic GMP and prostaglandins in the bladder of a rabbit model of BOO. BOO was induced in adult male New Zealand White rabbits. After 3 weeks, urinary bladders were excised, weighed and cut into segments. They were then incubated with stimulators of PGs, cAMP and cGMP and the formation of PGs, cAMP and cGMP were measured using radioimmunoassays. There was a significant increase in the obstructed bladder weights (P=0.002). The formation of PGE2, PGI2, cAMP and cGMP was significantly diminished in the detrusor (P<0.05) and bladder neck (P<0.05) in the BOO bladders compared to age-matched controls. Since PGE2, PGI2, cAMP and cGMP are known to inhibit the proliferation of smooth muscle cells (SMCs), the decreased synthesis of these factors, in BOO, may play a role in bladder SMC hypertrophy/hyperplasia. Our study points to the possible use of drugs that modulate the NO-cGMP and/or PG-cAMP axes in BOO-associated bladder pathology.

Topics: Acetylcholine; Animals; Calcimycin; Cyclic AMP; Cyclic GMP; Dinoprostone; Disease Models, Animal; Epoprostenol; Hyperplasia; Hypertrophy; In Vitro Techniques; Male; Muscle, Smooth; Organ Size; Phorbol 12,13-Dibutyrate; Prostaglandins; Rabbits; Urinary Bladder; Urinary Bladder Neck Obstruction

Guanylate cyclase (GC) activity was measured in the cytosolic fraction of sebaceous gland-enriched skin samples obtained from alopecic and non-alopecic areas of subjects affected by male pattern baldness. GC activity was significantly higher in alopecic scalp (7.13 +/- 2.7 pmol/min/mg prot; n = 22) than in non-alopecic samples (3.91 +/- 0.48 pmol/min/mg prot; n = 8). 3-beta-androstanediol was able to increase GC activity up to 15% when added to the incubation medium (1 x 10(-5) M). The regional differences observed should be due to the larger size of the sebaceous glands in alopecic areas. The higher production of dihydrotestosterone and 3-beta-androstanediol in alopecic areas may also contribute to determine the level of GC in scalp skin. The role of second messenger systems in sebaceous glands to understand certain aspects of the action mechanism of androgens is discussed.

Topics: Alopecia; Androstane-3,17-diol; Cyclic AMP; Cyclic GMP; Cytosol; Dihydrotestosterone; Guanylate Cyclase; Humans; Hypertrophy; Kinetics; Male; Scalp; Sebaceous Glands; Second Messenger Systems; Stimulation, Chemical

Male and female rats were given oestradiol benzoate (1 mg s.c. twice a week for 3 weeks) and/or sodium nitroprusside (SN), a donor of nitric oxide (NO), which was administered in their food in amounts of 0.2 or 0.6 mg/rat/day. Neither oestradiol-induced hypertrophy of the hypophysis, nor the serum prolactin (PRL) level, was affected by the simultaneous administration of SN. The PRL content of the hypophysis rose after oestradiol in the males, but the increase was again uninfluenced by the simultaneous administration of SN and the cAMP content of the hypophysis--raised after oestradiol--was likewise unaffected. The amount of cGMP in the hypophysis after oestradiol rose only in males. Both the serum and the hypophyseal prolactin level were found to be correlated to the cAMP and the cGMP content of the hypophysis. It was found that the simultaneous administration of SN together with oestradiol slightly reduced the increase in the cGMP content of the hypophysis elicited with oestradiol treatment only.

Topics: Animals; Cyclic AMP; Cyclic GMP; Estradiol; Female; Hypertrophy; Male; Nitroprusside; Organ Size; Pituitary Gland; Prolactin; Rats; Rats, Wistar

Seven-month-old, lean male SHHF/Mcc-cp rats, a model of spontaneous hypertension, progressive renal dysfunction, and congestive heart failure (CHF), were treated with either clonidine (CL) or enalapril (EN) or received no treatment (CON) for 20 weeks. CL significantly decreased systolic blood pressure (SBP), kidney weights, and severity of renal lesions as compared with untreated CON. EN produced a decrease in SBP comparable to that in CL. Kidney weights and severity of renal histologic changes in the EN group were intermediate between those of the CL and CON groups. Despite similar plasma atrial natriuretic peptide (ANP) concentrations, CL treatment resulted in a significant increase in the density of guanylate cyclase-linked glomerular ANP receptors, whereas EN treatment resulted in a significant decrease in the total number of ANP receptors and in the number of nonguanylate cyclase-linked receptors and an increase in overall binding affinity. These findings demonstrate that antihypertensive agents will slow progression of renal injury in SHHF/Mcc-cp rats and that CL is more effective than EN in alleviating progressive kidney damage in this model. Furthermore, different classes of antihypertensive drugs may alter the density or ratio of biologically active and clearance ANP receptor sites in the glomerulus.

Topics: Animals; Atrial Natriuretic Factor; Binding Sites; Clonidine; Cyclic GMP; Enalapril; Hypertension; Hypertrophy; Kidney; Kidney Diseases; Kidney Glomerulus; Male; Rats; Rats, Inbred Strains; Receptors, Atrial Natriuretic Factor; Receptors, Cell Surface

Vascular remodeling is central to the pathophysiology of hypertension and atherosclerosis. Recent evidence suggests that vasoconstrictive substances, such as angiotensin II (AII), may function as a vascular smooth muscle growth promoting substance. To explore the role of the counterregulatory hormone, atrial natriuretic polypeptide (ANP) in this process, we examined the effect of ANP (alpha-rat ANP [1-28]) on the growth characteristics of cultured rat aortic smooth muscle (RASM) cells. ANP (10(-7) M) significantly suppressed the proliferative effect of 1% and 5% serum as measured by 3H-thymidine incorporation and cell number, confirming ANP as an antimitogenic factor. In quiescent RASM cells, ANP (10(-7), 10(-6) M) significantly suppressed the basal incorporations of 3H-uridine and leucine by 50 and 30%, respectively. ANP (10(-7), 10(-6) M) also suppressed AII-induced RNA and protein syntheses (by 30-40%) with the concomitant reduction of the cell size. Furthermore, ANP also significantly attenuated the increase of 3H-uridine and leucine incorporations caused by transforming growth factor-beta (4 x 10(-11), 4 x 10(-10) M), a potent hypertrophic factor. These results indicate that ANP possesses an antihypertrophic action on vascular smooth muscle cells. Down-regulation of protein kinase C by 24-h treatment with phorbol 12,13-dibutyrate did not inhibit ANP-induced suppression on 3H-uridine incorporation. Based on the observation that ANP was more potent than a ring-deleted analogue of ANP on inhibiting 3H-uridine incorporation, we conclude that the ANP's inhibitory effect is primarily mediated via the activation of a guanylate cyclase-linked ANP receptor(s). Indeed 8-bromo cGMP mimicked the antihypertrophic action of ANP. Accordingly, we speculate that in addition to its vasorelaxant and natriuretic effects, the antihypertrophic action of ANP observed in the present study may serve as an additional compensatory mechanism of ANP in hypertension.

Topics: Angiotensin II; Animals; Aorta; Atrial Natriuretic Factor; Cell Division; Cell Line; Cyclic GMP; Down-Regulation; Hypertrophy; Muscle, Smooth, Vascular; Protein Kinase C; Rats; Receptors, Atrial Natriuretic Factor; Receptors, Cell Surface; Transforming Growth Factor beta

Lipid methylation has been studied in homogenized dog kidney cortical tubules. At pH 9, using S-adenosyl-L-methionine as methyl donor, most of the methyl groups appeared incorporated into phosphatidylcholine, the activity showing an apparent Km of 16 microM. This enzymatic activity was unchanged by the presence of the divalent cations Ca2+ or Mg2+, cAMP or cGMP. In addition, lipid methylation was also unchanged after treatment of intact tubules with angiotensin II, parathyroid hormone or vasopressin. An increased phosphatidylcholine synthesis was observed in the remnant kidney cortical tubules after uninephrectomy through an activation of phosphocholine transferase without detectable modification of lipid methylation. These findings suggest that lipid methylation is not regulated by these biochemical or functional stimuli tested in canine renal cortical tubules.

Topics: Animals; Calcium; Cyclic AMP; Cyclic GMP; Dogs; Hormones; Hypertrophy; Kidney Cortex; Kidney Tubules; Lipid Metabolism; Magnesium; Methylation; Phosphatidylcholines; Signal Transduction

Topics: 3',5'-Cyclic-AMP Phosphodiesterases; 3',5'-Cyclic-GMP Phosphodiesterases; Animals; Butylated Hydroxytoluene; Cresols; Cyclic AMP; Cyclic GMP; Hypertrophy; Lung; Male; Mice; Mice, Inbred C57BL; Nucleotides, Cyclic; Protein Kinases

1. Cyclic adenosine 3', 5'-monophosphate (cyclic AMP) and cyclic guanosine 3', 5'-monophosphate (cyclic GMP) have been estimated in the kidneys of rats.2. Ten minutes after unilateral nephrectomy there was a threefold increase of cyclic GMP in the remaining kidney, which was accompanied by a moderate fall of cyclic AMP.3. The changes in cyclic nucleotides in the remaining kidney after unilateral nephrectomy were of short duration.4. When an anephric rat was cross-circulated with a normal litter-mate, there was an increase of cyclic GMP concentration in the kidneys of the latter, which reached its maximum 10 min after the establishment of the cross circulation.5. In experiments where one kidney of a litter-mate was transplanted to the neck of another rat, unilateral nephrectomy was not followed by changes of the level of cyclic nucleotides in either the transplanted or the remaining kidney. Bilateral nephrectomy, however, resulted in a marked increase of cyclic GMP in the transplanted kidney.6. The clamping of the blood vessels to one kidney for periods up to 10 min had the same effect as unilateral nephrectomy on the concentration of cyclic GMP in the remaining kidney. When the clamp was removed and the circulation restored, the concentrations of cyclic nucleotides returned to preoperative levels in both kidneys.

Topics: Animals; Cross Circulation; Cyclic AMP; Cyclic GMP; Hypertrophy; Kidney; Kidney Transplantation; Male; Nephrectomy; Rats; Transplantation, Homologous

1. After hypophysectomy, both body and kidney weights fall, but at different rates. The rate at which the kidney decreases in weight is faster than that of the whole body.2. Seven days after unilateral nephrectomy, the dry weight of the remaining kidney of hypophysectomized rats, with the exception of rats which had been hypophysectomized for 2 days only, was always heavier than the kidney of control hypophysectomized rats of similar body weight.3. The difference between the dry weight of kidneys of unilaterally nephrectomized hypophysectomized and control hypophysectomized rats increased from 15% in early hypophysectomized (9 days) to about 35% in late hypophysectomized animals (23 days).4. The implantation of renal cortical cells from 2 day hypophysectomized rats into unilaterally nephrectomized control litter-mates inhibited compensatory renal hypertrophy in the latter. When a similar operation was made using kidney cells from animals which had been hypophysectomized for 23 days, there was no significant inhibition of compensatory renal hypertrophy.5. The renal contents of adenosine-3',5'-monophosphate (cyclic AMP) and of guanosine-3',5'-monophosphate (cyclic GMP) in rats hypophysectomized for 2 days were of the same order as those in normal rats, but were markedly lower in rats hypophysectomized for 23 days.6. In contrast to what had been observed in normal rats, in hypophysectomized (2 or 23 days) rats, unilateral nephrectomy did not affect significantly the levels of cyclic nucleotides in the remaining kidney.7. Cross-circulating anephric normal rats with 2 day hypophysectomized animals resulted in an increase of cyclic GMP content in their kidneys. The cross-circulation between anephric normal rats and 23 days hypophysectomized rats had no effect on the level of renal cyclic GMP of the latter.8. When rats hypophysectomized for either 2 or 23 days and which had been nephrectomized were cross-circulated with normal rats, there were no changes in the content of cyclic GMP in the kidneys of the latter.

Topics: Animals; Body Weight; Cross Circulation; Cyclic AMP; Cyclic GMP; Hypertrophy; Hypophysectomy; Kidney; Kidney Cortex; Male; Nephrectomy; Organ Size; Pituitary Gland; Rats; Time Factors; Transplantation, Homologous

Topics: Animals; Cyclic AMP; Cyclic GMP; Hypertrophy; Kidney; Male; Rats