sildenafil-citrate and Fibrosis

Patients with fibrotic interstitial lung disease have symptom control and quality of life (QoL) needs. This review aims to evaluate the evidence for the use of interventions in improving dyspnoea, other symptoms and QoL.. Eleven databases, relevant websites and key journals were hand-searched. Studies were assessed and data extracted independently by two researchers using standardised proformas. Meta-analyses were performed where possible with 95% CI.. 34 papers with 19 interventions in 3635 patients were included. Meta-analyses showed no significant effect of interferon γ-1b or sildenafil on 6-minute walking distance (6MWD) or dyspnoea. Pulmonary rehabilitation and pirfenidone had a positive effect on 6MWD (mean difference (95% CI) 27.4 (4.1 to 50.7)) and 24.0 (4.3 to 43.7), respectively), and pulmonary rehabilitation had a mixed effect on dyspnoea. Both pulmonary rehabilitation and sildenafil showed a trend towards significance in improving QoL. There was weak evidence for the improvement of 6MWD using oxygen; dyspnoea using prednisolone, diamorphine, D-pencillamine and colchicine; cough using interferon α and thalidomide; anxiety using diamorphine; fatigue using pulmonary rehabilitation; and QoL using thalidomide and doxycycline. A wide range of outcome scales was used and there were no studies with economic evaluation.. There is strong evidence for the use of pulmonary rehabilitation and pirfenidone to improve 6MWD and moderate evidence for the use of sildenafil and pulmonary rehabilitation to improve QoL. Future recommendations for research would include careful consideration of the dichotomy of radical and palliative treatments when deciding on how symptom and QoL outcome measures are used and data presented.

Topics: Anti-Bacterial Agents; Anti-Inflammatory Agents, Non-Steroidal; Colchicine; Cough; Dyspnea; Exercise Test; Fibrosis; Glucocorticoids; Heroin; Humans; Immunologic Factors; Lung; Lung Diseases, Interstitial; Narcotics; Oxygen Inhalation Therapy; Piperazines; Prednisolone; Purines; Pyridones; Quality of Life; Sildenafil Citrate; Sulfones; Thalidomide; Tubulin Modulators

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

Topics: Alprostadil; Carbolines; Causality; Clinical Protocols; Erectile Dysfunction; Fibrosis; Humans; Male; Nurse's Role; Penile Prosthesis; Penis; Phosphodiesterase Inhibitors; Piperazines; Postoperative Care; Prostatectomy; Purines; Sildenafil Citrate; Sulfones; Tadalafil; Time Factors; Vasodilator Agents

The therapy of systemic sclerosis (SSc) remains a challenge for dermatology, rheumatology, internal medicine, and other disciplines. Organ involvement, above all kidney and lungs, is a key therapeutic issue. The current developments in organ-specific therapy are the main topic of the article. Finally, possibilities of disease-modifying drugs and value of HSCT are discussed.

Topics: Angiotensin-Converting Enzyme Inhibitors; Cardiovascular Diseases; Fibrosis; Fingers; Gastrointestinal Agents; Hematopoietic Stem Cell Transplantation; Humans; Hypertension, Pulmonary; Iloprost; Kidney Transplantation; Piperazines; Purines; PUVA Therapy; Raynaud Disease; Recurrence; Scleroderma, Systemic; Sildenafil Citrate; Skin Ulcer; Sulfones; Ultraviolet Therapy; Vasodilator Agents

Myocardial relaxation and stiffness are influenced by fibrillar collagen content. Cyclic nucleotide signaling regulators have been investigated targeting more effective modulation of collagen deposition during myocardial healing process. To assess the effects of phosphodiesterase type 3 and phosphodiesterase type 5 inhibitors on cardiac function and left ventricular myocardial fibrosis in catecholamine-induced myocardial injury, sildenafil and pimobendan were administered to male Wistar rats 24 hours after isoproterenol injection. Echocardiography and electrocardiogram were performed to assess kinetic and rhythm changes during 45 days of drug administration. At the end of study, type I and type III collagen were measured through immunohistochemistry analysis, and left ventricular pressure was assessed through invasive method. Echocardiography assessment showed increased relative wall thickness at 45 days in pimobendan group with significant diastolic dysfunction and increased collagen I deposition compared with nontreated positive group (3.03 ± 0.31 vs. 2.73 ± 0.28%, P < 0.05). Diastolic pressure correlated positively with type I collagen (r = 0.54, P < 0.05). Type III collagen analysis did not demonstrate difference among the groups. Sildenafil administration attenuated type I collagen deposition (2.15 ± 0.51 vs. positive group, P < 0.05) and suggested to be related to arrhythmic events. Arrhythmic events were not related to the quantity of fibrillar collagen deposition. Although negative modulation of collagen synthesis through cyclic nucleotides signaling have shown promising results, in this study, pimobendan postconditioning resulted in increased collagen type I formation and severe diastolic dysfunction while sildenafil postconditioning reduced collagen type I deposition and attenuated diastolic dysfunction.

Topics: Animals; Arrhythmias, Cardiac; Collagen Type I; Collagen Type III; Disease Models, Animal; Fibrosis; Isoproterenol; Male; Myocardium; Phosphodiesterase 3 Inhibitors; Phosphodiesterase 5 Inhibitors; Pyridazines; Rats, Wistar; Risk Assessment; Sildenafil Citrate; Ventricular Dysfunction, Left; Ventricular Function, Left; Ventricular Remodeling

The erectile dysfunction drug sildenafil has cardiopulmonary protective actions, and a nephroprotective action in cisplatin and ischemia-reperfusion-induced acute kidney injury. Here, we assessed its possible ameliorative action in a model of chronic kidney disease (CKD) using adenine feeding. Eight groups of rats were treated with saline (controls), adenine (0.25% w/w in feed daily for 5 weeks), and oral sildenafil (0.1, 0.5 or 2.5 mg/kg), either alone, or concomitantly with adenine. Urine was collected 24 h after the end of the treatments from all rats and blood pressure measured, followed by collection of blood and kidneys for the measurement of several functional, biochemical and histopathological parameters. Adenine treatment reduced body weight, creatinine renal clearance, and increased water intake and urine output, as well as the plasma concentrations of urea and creatinine, neutrophil gelatinase-associated lipocalin, and N-acetyl-β-D-glucosaminidase activity, and albumin in urine. Adenine also increased the concentrations of the uremic toxins indoxyl sulfate, uric acid and phosphate, and a number of proteins and inflammatory cytokines, and decreased that of several anti - oxidant indices. Renal histopathological markers of damage (inflammation and fibrosis) were significantly increased by adenine. Sildenafil, given simultaneously with adenine, induced a dose - dependent improvements in most of the above parameters, suggesting its possible use as adjunct treatment for CKD in humans.

Topics: Adenine; Animals; Biomarkers; Blood Pressure; Body Weight; Creatinine; Cytokines; Fibrosis; Inflammation; Rats; Rats, Sprague-Dawley; Renal Insufficiency, Chronic; Sildenafil Citrate; Urea

Transforming growth factor-β1 (TGF-β1) plays important roles in penile corporal fibrosis and veno-occlusive dysfunction (CVOD). Angiotensin II (Ang II) is critically involved in erectile dysfunction, and blocking of Ang II is more important than inhibition of TGF-β in non-penile tissue fibrosis. However, the role of Ang II in corporal fbrosis and CVOD in a diabetic condition has not been investigated.. Diabetic rats were treated with sildenafil or losartan (an Ang II antagonist) alone or in combination. Intracavernosal pressure, dynamic infusion cavernosometry, and histological and molecular alterations of the corpus cavernosum were examined.. Diabetic rats exhibited decreases in erectile response, severe CVOD, apoptosis, fibrosis, and activation of the TGF-β1 pathway. Treatment with sildenafil had a modest effect on erectile response and an insignificant suppressive effect on CVOD, apoptosis, fibrosis, and the TGF-β1 pathway. Although losartan greatly improved the histological and molecular changes and CVOD as compared with sildenafil, its effect on erectile response was low. The combination of sildenafil and losartan had superior effects on these parameters than did either compound alone.. Ang II activation may be involved in apoptosis and fibrosis of the corpus cavernosum through Smad and non-Smad pathways, resulting in CVOD and ED. The low efficacy of sildenafil in a diabetic ED rat model was at least partly due to its inadequate effects on apoptosis, fibrosis, and CVOD.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Apoptosis; Collagen; Cyclic GMP; Diabetes Mellitus, Experimental; Fibrosis; Losartan; Male; Muscle, Smooth; Nitrites; Penile Erection; Rats; Rats, Sprague-Dawley; Signal Transduction; Sildenafil Citrate; Smad Proteins; Transforming Growth Factor beta1

Duchenne muscular dystrophy (DMD) is the most common inherited muscular dystrophy. Patients experience DMD in their 20s from cardiac or respiratory failure related to progressive muscle wasting. Currently, the only treatments for the symptoms of DMD are available. Muscle fibrosis, a DMD feature, leads to reduced muscle function and muscle mass, and hampers pharmaceutical therapeutic efficacy. Although antifibrotic agents may be useful, none is currently approved. Phosphodiesterase 4 (PDE4) inhibitors have exhibited antifibrotic effects in human and animal models. In this study, we showed beneficial effects of the PDE4 inhibitor piclamilast in the DMD mdx mouse. Piclamilast reduced the mRNA level of profibrotic genes, including collagen 1A1, in the gastrocnemius and diaphragm, in the mdx mouse, and significantly reduced the Sirius red staining area. The PDE5 inhibitors sildenafil and tadalafil ameliorated functional muscle ischemia in boys with DMD, and sildenafil reversed cardiac dysfunction in the mdx mouse. Single-treatment piclamilast or sildenafil showed similar antifibrotic effects on the gastrocnemius; combination therapy showed a potent antifibrotic effect, and piclamilast and combination therapy increased peroxisome proliferator-activated receptor γ coactivator-1α mRNA in mouse gastrocnemius. In summary, we confirmed that piclamilast has significant antifibrotic effects in mdx mouse muscle and is a potential treatment for muscle fibrosis in DMD.-Nio, Y., Tanaka, M., Hirozane, Y., Muraki, Y., Okawara, M., Hazama, M., Matsuo, T. Phosphodiesterase 4 inhibitor and phosphodiesterase 5 inhibitor combination therapy has antifibrotic and anti-inflammatory effects in mdx mice with Duchenne muscular dystrophy.

Topics: Animals; Anti-Inflammatory Agents; Benzamides; Fibrosis; Male; Mice; Mice, Inbred C57BL; Mice, Inbred mdx; Muscle Contraction; Muscle, Skeletal; Muscular Dystrophy, Animal; Muscular Dystrophy, Duchenne; Phosphodiesterase 4 Inhibitors; Phosphodiesterase 5 Inhibitors; PPAR gamma; Pyridines; RNA, Messenger; Sildenafil Citrate

Stimulators of the soluble guanylate cyclase (sGC) have recently been shown to inhibit transforming growth factor-β signalling. Here, we aimed to demonstrate that riociguat, the drug candidate for clinical trials in systemic sclerosis (SSc), is effective in experimental fibrosis and to compare its efficacy to that of phosphodiesterase V inhibitors that also increase the intracellular levels of cyclic guanosine monophosphate.. The antifibrotic effects of riociguat and sildenafil were compared in the tight-skin 1 model, in bleomycin-induced fibrosis and in a model of sclerodermatous chronic graft-versus-host-disease (cGvHD). Doses of 0.1-3 mg/kg twice a day for riociguat and of 3-10 mg/kg twice a day for sildenafil were used.. Riociguat dose-dependently reduced skin thickening, myofibroblast differentiation and accumulation of collagen with potent antifibrotic effects at 1 and 3 mg/kg. Riociguat also ameliorated fibrosis of the gastrointestinal tract in the cGvHD model. The antifibrotic effects were associated with reduced phosphorylation of extracellular signal-regulated kinases. Sildenafil at doses of 3 and 10 mg/kg exerted mild antifibrotic effects that were significantly less pronounced compared with 1 and 3 mg/kg riociguat.. These data demonstrated potent antifibrotic effects of riociguat on experimental skin and organ fibrosis. These findings suggest a role for riociguat for the treatment of fibrotic diseases, especially for the treatment of SSc. A phase II study with riociguat in patients with SSc is currently starting.

Topics: Animals; Disease Models, Animal; Dose-Response Relationship, Drug; Fibrosis; Guanylate Cyclase; Mice; Mice, Inbred Strains; Phosphodiesterase 5 Inhibitors; Pyrazoles; Pyrimidines; Scleroderma, Systemic; Sildenafil Citrate; Skin

Analyses of several mouse models imply that the phosphodiesterase 5 (PDE5) inhibitor sildenafil (SIL), via increasing cGMP, affords protection against angiotensin II (Ang II)-stimulated cardiac remodeling. However, it is unclear which cell types are involved in these beneficial effects, because Ang II may exert its adverse effects by modulating multiple renovascular and cardiac functions via Ang II type 1 receptors (AT1Rs). To test the hypothesis that SIL/cGMP inhibit cardiac stress provoked by amplified Ang II/AT1R directly in cardiomyocytes (CMs), we studied transgenic mice with CM-specific overexpression of the AT1R under the control of the α-myosin heavy chain promoter (αMHC-AT1R(tg/+)). The extent of cardiac growth was assessed in the absence or presence of SIL and defined by referring changes in heart weight to body weight or tibia length. Hypertrophic marker genes, extracellular matrix-regulating factors, and expression patterns of fibrosis markers were examined in αMHC-AT1R(tg/+) ventricles (with or without SIL) and corroborated by investigating different components of the natriuretic peptide/PDE5/cGMP pathway as well as cardiac functions. cGMP levels in heart lysates and intact CMs were measured by competitive immunoassays and Förster resonance energy transfer. We found higher cardiac and CM cGMP levels and upregulation of the cGMP-dependent protein kinase type I with AT1R overexpression. However, even a prolonged SIL treatment regimen did not limit the progressive CM growth, fibrosis, or decline in cardiac functions in the αMHC-AT1R(tg/+) model, suggesting that SIL does not interfere with the pathogenic actions of amplified AT1R signaling in CMs. Hence, the cardiac/noncardiac cells involved in the cross-talk between SIL-sensitive PDE activity and Ang II/AT1R still need to be identified.

Topics: Adaptor Proteins, Signal Transducing; Angiotensin II; Animals; Cardiomegaly; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Fibrosis; Mice; Mice, Inbred C57BL; Mice, Transgenic; Myocytes, Cardiac; Piperazines; Purines; Receptor, Angiotensin, Type 1; Signal Transduction; Sildenafil Citrate; Sulfonamides; Up-Regulation

Systemic sclerosis (SSc) is a multi-organ fibrotic disease that affects the skin and various internal organs. Therapeutic strategies for tissue fibrosis have not been established; however, aberrantly activated fibroblasts in affected lesions are key targets for modulating fibrosis. Recently, increased intracellular cyclic GMP (cGMP) levels were demonstrated to improve fibrosis levels in various diseases. The purpose of this study was to assess the anti-fibrotic properties of cGMP in cultured fibroblasts from patients with SSc. The phosphodiesterase (PDE) 5 inhibitor sildenafil increased the intracellular cGMP levels in skin fibroblasts in a dose-dependent manner. Sildenafil treatment also significantly decreased the expression of several pro-fibrotic factors that were upregulated by TGF-β1 treatment in SSc skin fibroblasts. These inhibitory effects occurred via non-canonical TGF-β signaling. Our findings revealed that sildenafil might be a novel strategy to treat tissue fibrosis and vasculopathy in SSc.

Topics: Adult; Aged; Blotting, Western; Cells, Cultured; Collagen Type I; Collagen Type I, alpha 1 Chain; Connective Tissue Growth Factor; Cyclic GMP; Dose-Response Relationship, Drug; Female; Fibroblasts; Fibrosis; Humans; Male; Middle Aged; Phosphodiesterase 5 Inhibitors; Reverse Transcriptase Polymerase Chain Reaction; Scleroderma, Systemic; Sildenafil Citrate; Skin; Transforming Growth Factor beta1

Our previous studies support the protective effect of cGMP and cGMP-dependent protein kinase I (PKG-I) pathway on the development of renal fibrosis. Therefore, in the present studies, we determined whether pharmacologically or genetically increased PKG activity attenuates renal fibrosis in a unilateral ureteral obstruction (UUO) model and also examined the mechanisms involved. To increase PKG activity, we used the phosphodiesterase 5 inhibitor sildenafil and PKG transgenic mice. UUO model was induced in wild-type or PKG-I transgenic mice by ligating the left lateral ureteral and the renal fibrosis was observed after 14 days of ligation. Sildenafil was administered into wild-type UUO mice for 14 days. In vitro, macrophage and proximal tubular cell function was also analyzed. We found that sildenafil treatment or PKG transgenic mice had significantly reduced UUO-induced renal fibrosis, which was associated with reduced TGF-β signaling and reduced macrophage infiltration into kidney interstitial. In vitro data further demonstrated that both macrophages and proximal tubular cells were important sources of UUO-induced renal TGF-β levels. The interaction between macrophages and tubular cells contributes to TGF-β-induced renal fibrosis. Taken together, these data suggest that increasing PKG activity ameliorates renal fibrosis in part through regulation of macrophage and tubular cell function, leading to reduced TGF-β-induced fibrosis.

Topics: Actins; Angiotensin II; Animals; Cadherins; Cells, Cultured; Culture Media, Conditioned; Cyclic GMP-Dependent Protein Kinase Type I; Cytokines; Disease Models, Animal; Fibrosis; Inflammation Mediators; Kidney Diseases; Kidney Tubules, Proximal; Macrophages; Male; Mice; Mice, Transgenic; Phosphodiesterase 5 Inhibitors; Phosphorylation; Piperazines; Purines; Signal Transduction; Sildenafil Citrate; Smad2 Protein; Sulfones; Time Factors; Transforming Growth Factor beta1; Up-Regulation; Ureteral Obstruction

The aim of this study was to compare the effects of sildenafil and trimetazidine on bilateral cavernosal nerve injury-induced oxidative damage and fibrotic changes in cavernosal tissue in rat model.. A total of 32 male Sprague-Dawley rats were randomly divided into 4 groups; each group consist 8 rats (control, BCI, BCI + TMZ, and BCI + sildenafil groups). Tissue superoxide dismutase (SOD), malondialdehyde (MDA), and protein carbonyl (PC) levels were determined biochemically and distribution of cavernosal fibrosis density among groups was performed histopathologically.. Tissue SOD levels in BCI group were significantly lower than the control group (P < 0.05). Tissue MDA and PC levels in BCI group were significantly higher than the control group (P < 0.05). TMZ and sildenafil administration significantly increased tissue SOD levels (P < 0.05) and reduced tissue MDA and PC levels (P < 0.05). Histologically, the degree of cavernosal fibrosis and collagen density was higher in BCI group in comparison to control, TMZ-treated, and sildenafil-treated groups.. BCI caused oxidative damage and increased cavernosal fibrosis in rat penis. TMZ and sildenafil treatment decreased oxidative damage and reduced the degree of fibrosis in penile tissue due to BCI.

Topics: Animals; Fibrosis; Male; Malondialdehyde; Oxidative Stress; Penis; Piperazines; Purines; Random Allocation; Rats, Sprague-Dawley; Sildenafil Citrate; Sulfones; Superoxide Dismutase; Trauma, Nervous System; Treatment Outcome; Trimetazidine; Vasodilator Agents

Right ventricular (RV) function is an important determinant of prognosis in congenital heart diseases, pulmonary hypertension, and heart failure. Preventive sildenafil treatment has been shown to enhance systolic RV function and improve exercise capacity in a model of fixed RV pressure load. However, it is unknown whether sildenafil has beneficial effects when treatment is started in established RV dysfunction, which is clinically more relevant. Our aim was to assess the effects of sildenafil treatment on RV function and fibrosis in a model of established RV dysfunction due to fixed afterload. Rats were subjected to pulmonary artery banding (PAB), which induced RV dysfunction after 4 wk, characterized by reduced exercise capacity, decreased tricuspid annular plane systolic excursion, and RV dilatation. From week 4 onward, 50% of rats were treated with sildenafil (100 mg·kg(-1)·day(-1), n = 9; PAB-SIL group) or vehicle (n = 9; PAB-VEH group). At 8 wk, exercise capacity was assessed using cage wheels, and RV function was assessed using invasive RV pressure-volume measurements under anesthesia. Sildenafil treatment, compared with vehicle, improved RV ejection fraction (44 ± 2% vs. 34 ± 2%, P < 0.05, PAB-SIL vs. PAB-VEH groups), reduced RV end-diastolic pressure (2.3 ± 0.5 vs. 5.1 ± 0.9 mmHg, P < 0.05), and RV dilatation (end-systolic volume: 468 ± 45 vs. 643 ± 71 μl, P = 0.05). Sildenafil treatment also attenuated RV fibrosis (30 ± 6 vs. 17 ± 3‰, P < 0.05) but did not affect end-systolic elastance, exercise capacity, or PKG or PKA activity. In conclusion, sildenafil improves RV diastolic function and attenuates interstitial fibrosis in rats with established RV dysfunction, independent from afterload. These results indicate that sildenafil treatment has therapeutic potential for established RV dysfunction.

Topics: Animals; Cardiotonic Agents; Diastole; Disease Models, Animal; Exercise Tolerance; Fibrosis; Heart Ventricles; Hypertrophy, Right Ventricular; Male; Piperazines; Purines; Rats, Wistar; Recovery of Function; Sildenafil Citrate; Stroke Volume; Sulfones; Time Factors; Ventricular Dysfunction, Right; Ventricular Function, Right; Ventricular Pressure

Conflicting results have been reported for the roles of cGMP and cGMP-dependent protein kinase I (cGKI) in various pathological conditions leading to cardiac hypertrophy and fibrosis. A cardioprotective effect of cGMP/cGKI has been reported in whole animals and isolated cardiomyocytes, but recent evidence from a mouse model expressing cGKIβ only in smooth muscle (βRM) but not in cardiomyocytes, endothelial cells, or fibroblasts has forced a reevaluation of the requirement for cGKI activity in the cardiomyocyte antihypertrophic effects of cGMP. In particular, βRM mice developed the same hypertrophy as WT controls when subjected to thoracic aortic constriction or isoproterenol infusion. Here, we challenged βRM and WT (Ctr) littermate control mice with angiotensin II (AII) infusion (7 d; 2 mg ⋅ kg(-1) ⋅ d(-1)) to induce hypertrophy. Both genotypes developed cardiac hypertrophy, which was more pronounced in Ctr animals. Cardiomyocyte size and interstitial fibrosis were increased equally in both genotypes. Addition of sildenafil, a phosphodiesterase 5 (PDE5) inhibitor, in the drinking water had a small effect in reducing myocyte hypertrophy in WT mice and no effect in βRM mice. However, sildenafil substantially blocked the increase in collagen I, fibronectin 1, TGFβ, and CTGF mRNA in Ctr but not in βRM hearts. These data indicate that, for the initial phase of AII-induced cardiac hypertrophy, lack of cardiomyocyte cGKI activity does not worsen hypertrophic growth. However, expression of cGKI in one or more cell types other than smooth muscle is necessary to allow the antifibrotic effect of sildenafil.

Topics: Angiotensin II; Animals; Cardiomegaly; Cyclic GMP; Cyclic GMP-Dependent Protein Kinase Type I; Cyclic Nucleotide Phosphodiesterases, Type 5; Fibrosis; Genetic Markers; Hypertension; Mice; Muscle, Smooth; Myocardial Contraction; Myocytes, Cardiac; Nitric Oxide; Phosphodiesterase 5 Inhibitors; Piperazines; Purines; Sildenafil Citrate; Sulfones; Vasoconstrictor Agents

Recent evidences suggested that cyclic guanosine monophosphate-specific phosphodiesterase 5 (PDE5) inhibitor represents an important therapeutic target for cardiovascular diseases. Whether and how it ameliorates cardiac fibrosis, a major cause of diastolic dysfunction and heart failure, is unknown. The purpose of this study was to investigate the effects of PDE5 inhibitor on cardiac fibrosis. We assessed cardiac fibrosis and pathology in mice subjected to transverse aortic constriction (TAC). Oral sildenafil, a PDE5 inhibitor, was administered in the therapy group. In control mice, 4 weeks of TAC induced significant cardiac dysfunction, cardiac fibrosis, and cardiac fibroblast activation (proliferation and transformation to myofibroblasts). Sildenafil treatment markedly prevented TAC-induced cardiac dysfunction, cardiac fibrosis and cardiac fibroblast activation but did not block TAC-induced transforming growth factor-β1 (TGF-β1) production and phosphorylation of Smad2/3. In isolated cardiac fibroblasts, sildenafil blocked TGF-β1-induced cardiac fibroblast transformation, proliferation and collagen synthesis. Furthermore, we found that sildenafil induced phosphorylated cAMP response element binding protein (CREB) and reduced CREB-binding protein 1 (CBP1) recruitment to Smad transcriptional complexes. PDE5 inhibition prevents cardiac fibrosis by reducing CBP1 recruitment to Smad transcriptional complexes through CREB activation in cardiac fibroblasts.

Topics: Animals; Blotting, Western; Cells, Cultured; Cyclic Nucleotide Phosphodiesterases, Type 5; Enzyme-Linked Immunosorbent Assay; Fibroblasts; Fibrosis; Guanosine Monophosphate; Heart; Male; Mice; Mice, Inbred C57BL; Phosphodiesterase 5 Inhibitors; Piperazines; Purines; Rats; Rats, Sprague-Dawley; Signal Transduction; Sildenafil Citrate; Smad Proteins; Smad2 Protein; Smad3 Protein; Sulfonamides; Transforming Growth Factor beta

Patients with diabetes exhibit more severe erectile dysfunction (ED) and are less responsive to first-line oral phosphodiesterase type 5 inhibitor (PDE5i). It has been suggested that increased collagen deposition and reduced smooth muscle content in the corpus cavernosum are important mechanisms for diabetes-associated ED and that transforming growth factor-β1 (TGF-β1) is a potent fibrotic factor responsible for the structural alterations in the corpus cavernosum.. The aims of this study are to determine whether activation of TGF-β1 and its downstream pathways is responsible for the reduced efficacy of the PDE5is in diabetic ED via abnormalities in cavernosal structures and to investigate the synergistic effects of the TGF-β1 antagonist P144 and sildenafil on erectile response.. Six weeks after inducting diabetes with streptozotocin in male Sprague-Dawley rats, age-matched control and diabetic rats were treated with vehicle, sildenafil, or P144 alone or in combination for 4 weeks, respectively.. Intracavernous pressure, dynamic infusion cavernosometry, and histological and molecular alterations of the corpus cavernosum were analyzed.. Diabetic rats exhibited a decreased erectile response, severe corporal veno-occlusive dysfunction (CVOD), and structural alterations including cavernosal fibrosis and decreased smooth muscle content. Expression and activation of TGF-β1 and its downstream Smad and non-Smad pathways increased in diabetic rats. Treatment with sildenafil showed modest effect on erectile response and a less suppressive effect on CVOD, cavernosal fibrosis, and molecular alterations. Treatment with P144 had lower effect on erectile response, even greatly improved the histological and molecular alterations and CVOD than sildenafil. The combined treatment with P144 and sildenafil effectively restored erectile response, CVOD, and histological and molecular alterations.. An insufficient suppressive effect of sildenafil on cavernosal fibrosis, severe CVOD, and TGF-β1 pathways was implicated in reduced efficacy of the PDE5i in diabetic ED. Treatment with P144 synergized sildenafil and significantly increased erectile response by the potential antifibrotic activity.

Topics: Animals; Diabetes Mellitus, Experimental; Drug Synergism; Erectile Dysfunction; Fibrosis; Humans; Male; Muscle, Smooth; Penile Erection; Penis; Phosphodiesterase 5 Inhibitors; Piperazines; Purines; Rats; Rats, Sprague-Dawley; Sildenafil Citrate; Sulfones; Transforming Growth Factor beta1

The rationale of this article is enhancing the therapeutic potential of stem cells in ischemic microenvironments by novel preconditioning strategies is critical for improving cellular therapy. We tested the hypothesis that inhibition of phosphodiesterase-5 (PDE-5) with sildenafil (Viagra) or knockdown with a silencing vector in adipose-derived stem cells (ASCs) would improve their survival and enhance cardiac function following myocardial implantation in vivo. ASCs were treated with sildenafil or PDE-5 silencing vector short hairpin RNA (shRNA(PDE-5)) and subjected to simulated ischemia/reoxygenation in vitro. Both sildenafil and shRNA(PDE-5) significantly improved viability, decreased necrosis, apoptosis, and enhanced the release of growth factors, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (b-FGF), and insulin-like growth factor. Inhibition of protein kinase G reversed these effects. To show the beneficial effect of preconditioned ASCs in vivo, adult male CD-1 mice underwent myocardial infarction. Preconditioned ASCs (4 × 10(5)) were directly injected intramyocardially. Preconditioned ASC-treated hearts showed consistently superior cardiac function when compared with nonpreconditioned ASCs after 4 weeks of treatment. This was associated with significantly reduced fibrosis, increased vascular density, and decreased resident myocyte apoptosis when compared with mice receiving nonpreconditioned ASCs. VEGF, b-FGF, and Angiopoietin-1 were also significantly elevated 4 weeks after cell therapy with preconditioned ASCs. We conclude that preconditioning by inhibition of PDE-5 can be a powerful novel approach to improve stem cell therapy following myocardial infarction.

Topics: Adipose Tissue; Animals; Apoptosis; Cardiotonic Agents; Cell Survival; Cells, Cultured; Combined Modality Therapy; Coronary Vessels; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Cyclic Nucleotide Phosphodiesterases, Type 5; Fibrosis; Humans; Intercellular Signaling Peptides and Proteins; Male; Mice; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Phosphodiesterase 5 Inhibitors; Piperazines; Purines; Signal Transduction; Sildenafil Citrate; Stem Cell Transplantation; Stem Cells; Sulfones

Duchenne muscular dystrophy (DMD) is the most common form of muscular dystrophy caused by mutations in the dystrophin gene. Loss of dystrophin initiates a progressive decline in skeletal muscle integrity and contractile capacity which weakens respiratory muscles including the diaphragm, culminating in respiratory failure, the leading cause of morbidity and mortality in DMD patients. At present, corticosteroid treatment is the primary pharmacological intervention in DMD, but has limited efficacy and adverse side effects. Thus, there is an urgent need for new safe, cost-effective, and rapidly implementable treatments that slow disease progression. One promising new approach is the amplification of nitric oxide-cyclic guanosine monophosphate (NO-cGMP) signalling pathways with phosphodiesterase 5 (PDE5) inhibitors. PDE5 inhibitors serve to amplify NO signalling that is attenuated in many neuromuscular diseases including DMD. We report here that a 14-week treatment of the mdx mouse model of DMD with the PDE5 inhibitor sildenafil (Viagra(®), Revatio(®)) significantly reduced mdx diaphragm muscle weakness without impacting fatigue resistance. In addition to enhancing respiratory muscle contractility, sildenafil also promoted normal extracellular matrix organization. PDE5 inhibition slowed the establishment of mdx diaphragm fibrosis and reduced matrix metalloproteinase-13 (MMP-13) expression. Sildenafil also normalized the expression of the pro-fibrotic (and pro-inflammatory) cytokine tumour necrosis factor α (TNFα). Sildenafil-treated mdx diaphragms accumulated significantly less Evans Blue tracer dye than untreated controls, which is also indicative of improved diaphragm muscle health. We conclude that sildenafil-mediated PDE5 inhibition significantly reduces diaphragm respiratory muscle dysfunction and pathology in the mdx mouse model of Duchenne muscular dystrophy. This study provides new insights into the therapeutic utility of targeting defects in NO-cGMP signalling with PDE5 inhibitors in dystrophin-deficient muscle.

Topics: Animals; Creatine Kinase; Cyclic GMP; Diaphragm; Disease Models, Animal; Evans Blue; Fibrosis; Male; Mice; Mice, Inbred C57BL; Mice, Inbred mdx; Muscle Contraction; Muscle Fatigue; Muscle Weakness; Muscular Dystrophy, Duchenne; Nitric Oxide; Phosphodiesterase 5 Inhibitors; Piperazines; Purines; Sildenafil Citrate; Sulfones

It has been shown that phosphodiesterase type 5 (PDE5) inhibitors preserve smooth muscle (SM) content and ameliorate the fibrotic degeneration normally seen in the corpora cavernosa after bilateral cavernosal nerve resection (BCNR). However, the downstream mechanisms by which these drugs protect the corpora cavernosa remain poorly understood.. To provide insight into the mechanism, we aimed to determine the gene expression profile of angiogenesis-related pathways within the penile tissue after BCNR with or without continuous sildenafil (SIL) treatment.. Five-month-old Fisher rats were subjected to BCNR or sham operation and treated with or without SIL (20 mg/kg/BW drinking water) for 3 days or 45 days (N = 8 rats per group). Total RNAs isolated from the denuded penile shaft and prostate were subjected to reverse transcription and to angiogenesis real-time-polymerase chain reaction arrays (84 genes). Changes in protein expression of selected genes such as epiregulin (EREG) and connective tissue growth factor (CTGF) were corroborated by Western blot and immunohistochemistry.. Genes modulated by BCNR and SIL treatment.. A decreased expression of genes related to SM growth factors such as EREG, platelet-derived growth factor (PDGF), extracellular matrix regulators such as metalloproteinases 3 and 9, endothelial growth factors, together with an upregulation of pro-fibrotic genes such as CTGF and transforming growth factor beta 2 were found at both time points after BCNR. SIL treatment reversed this process by upregulating endothelial and SM growth factors and downregulating pro-fibrotic factors. SIL did not affect the expression of EREG, VEGF, and PDGF in the ventral prostate of BCNR animals.. SIL treatment after BCNR activates genes related to SM preservation and downregulates genes related to fibrosis in the corpora cavernosa. These results provide a mechanistic justification for the use of SIL and other PDE5 inhibitors as protective therapy against corporal SM loss and fibrosis after radical prostatectomy.

Topics: Animals; Disease Models, Animal; Endothelium, Vascular; Epidermal Growth Factor; Epiregulin; Extracellular Matrix; Fibrosis; Gene Expression; Intercellular Signaling Peptides and Proteins; Male; Matrix Metalloproteinase 1; Matrix Metalloproteinase 3; Nerve Tissue; Penis; Phosphodiesterase 5 Inhibitors; Piperazines; Purines; Rats; Sildenafil Citrate; Sulfones; Transforming Growth Factor beta2

Portopulmonary hypertension (POPH), or pulmonary arterial hypertension associated with cirrhosis, carries a high mortality and often precludes liver transplantation. Many POPH patients have preserved or increased cardiac output; therefore, decreasing pulmonary artery pressure rather than improving cardiac output is more important in reducing liver transplant risk, and this makes sildenafil an attractive therapeutic option. We assessed the clinical response of patients with POPH treated with sildenafil monotherapy. We retrospectively reviewed the charts of 10 patients with POPH and sildenafil monotherapy. Eight of 10 patients had hepatitis C virus infection. Patients took 31 +/- 14 mg (mean +/- standard deviation) thrice daily and were followed for 21 +/- 16 months. The World Health Organization functional class improved from 3.0 +/- 0.0 to 2.3 +/- 0.5 at 1 year (P < 0.05). Four of 8 patients increased the 6-minute walk distance at 1 year by 30 m or more. Three patients became transplant-eligible, 1 of whom underwent successful transplantation, and 3 patients have been stable without progression of liver disease or POPH. The remainder were not transplant candidates because of refractory POPH (n = 2) or other comorbidities (n = 2). We conclude that sildenafil may be an effective therapy for POPH that can stabilize or improve hemodynamics in patients with POPH and thereby facilitate liver transplantation.

Topics: Female; Fibrosis; Hemodynamics; Hepacivirus; Hepatitis C; Humans; Hypertension, Pulmonary; Liver Transplantation; Male; Middle Aged; Piperazines; Purines; Retrospective Studies; Sildenafil Citrate; Sulfones; Time Factors; Treatment Outcome; Vasodilator Agents

Inhibition of phosphodiesterase 5 (PDE5) decreases pulmonary pressure and improves symptoms in patients with pulmonary arterial hypertension. It is unclear however, whether inhibition of PDE5 can prevent myocardial remodelling during right-ventricular pressure overload.. Right-ventricular pressure overload was produced in male rats in a pulmonary hypertension model (monocrotaline 60 mg/kg s.c.) or by surgical pulmonary artery banding. PDE5 inhibition using oral sildenafil (50 mg/kg/day in drinking water) or placebo was initiated 14 days after monocrotaline treatment and continued for 14 days until final examination. In the pulmonary artery banding groups, rats were treated with sildenafil (50 mg/kg/day) or placebo for 21 days following surgical pulmonary artery banding. At the final experiments, right-ventricular haemodynamics were measured and remodelling was analysed using histological, biochemical, and gene expression markers. Both monocrotaline and pulmonary artery banding increased right-ventricular systolic pressure to approximately 80 mmHg. In parallel, both interventions induced markers of hypertrophy (upregulation of natriuretic peptides, increase in myocyte diameter) and fibrosis (upregulation of collagen types 1A2 and 3A1) as well as mRNA expression of the tissue inhibitor of matrix metalloproteases 1 and osteopontin in the right ventricle. In monocrotaline model, sildenafil decreased pulmonary pressure, reduced right-ventricular hypertrophy, and prevented fibrosis marker gene upregulation. After pulmonary artery banding, in contrast, sildenafil increased markers of myocardial remodelling and right-ventricular myocyte diameter.. Sildenafil prevents myocardial remodelling in pulmonary hypertension through an indirect action via right-ventricular unloading.

Topics: Administration, Oral; Animals; Blood Pressure; Cyclic GMP; Cyclic Nucleotide Phosphodiesterases, Type 5; Disease Models, Animal; Fibrillar Collagens; Fibrosis; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Male; Monocrotaline; Myocardium; Natriuretic Peptides; Osteopontin; Phosphodiesterase 5 Inhibitors; Phosphodiesterase Inhibitors; Piperazines; Pulmonary Artery; Purines; Rats; Rats, Sprague-Dawley; Rats, Wistar; RNA, Messenger; Sildenafil Citrate; Stroke Volume; Sulfones; Time Factors; Tissue Inhibitor of Metalloproteinase-1; Ventricular Pressure; Ventricular Remodeling

Topics: Administration, Oral; Animals; Cyclic GMP; Cyclic Nucleotide Phosphodiesterases, Type 5; Extracellular Matrix Proteins; Fibrosis; Hemodynamics; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Myocardium; Phosphodiesterase 5 Inhibitors; Phosphodiesterase Inhibitors; Piperazines; Purines; Rats; Sildenafil Citrate; Sulfones; Ventricular Remodeling

Pulmonary arterial hypertension (PAH) is often treated with endothelin (ET) receptor blockade or phosphodiesterase-5 (PDE5) inhibition. Little is known about the specific effects on right ventricular (RV) function and metabolism. We determined the effects of single and combination treatment with Bosentan [an ET type A (ET(A))/type B (ET(B)) receptor blocker] and Sildenafil (a PDE5 inhibitor) on RV function and oxidative metabolism in monocrotaline (MCT)-induced PAH. Fourteen days after MCT injection, male Wistar rats were orally treated for 10 days with Bosentan, Sildenafil, or both. RV catheterization and echocardiography showed that MCT clearly induced PAH. This was evidenced by increased RV systolic pressure, reduced cardiac output, increased pulmonary vascular resistance (PVR), and reduced RV fractional shortening. Quantitative histochemistry showed marked RV hypertrophy and fibrosis. Monotreatment with Bosentan or Sildenafil had no effect on RV systolic pressure or cardiac function, but RV fibrosis was reduced and RV capillarization increased. Combination treatment did not reduce RV systolic pressure, but significantly lowered PVR, and normalized cardiac output, RV fractional shortening, and fibrosis. Only combination treatment increased the mitochondrial capacity of the RV, as reflected by increased succinate dehydrogenase and cytochrome c oxidase activities, associated with an activation of PKG, as indicated by increased VASP phosphorylation. Moreover, significant interactions were found between Bosentan and Sildenafil on PVR, cardiac output, RV contractility, PKG activity, and mitochondrial capacity. These data indicate that the combination of Bosentan and Sildenafil may beneficially contribute to RV adaptation in PAH, not only by reducing PVR but also by acting on the mitochondria in the heart.

Topics: Animals; Body Weight; Bosentan; Capillaries; Cyclic GMP-Dependent Protein Kinases; Diffusion; Endothelin Receptor Antagonists; Fibrosis; Hemodynamics; Hypertension, Pulmonary; In Vitro Techniques; Male; Mitochondria, Heart; Myocardial Contraction; Myocardium; Myocytes, Cardiac; Myoglobin; Organ Size; Oxygen Consumption; Phosphodiesterase 5 Inhibitors; Phosphodiesterase Inhibitors; Piperazines; Pulmonary Artery; Purines; Rats; Rats, Wistar; Sildenafil Citrate; Sulfonamides; Sulfones; Ultrasonography

To evaluate whether a dose of 50 mg preserved the architecture of the corpora cavernosa biopsy in man.. 21 patients (54-70 years old) who underwent radical prostatectomy for prostate cancer were treated with sildenafil citrate (50 mg, 3 times a week for 2 months) soon after surgery. They underwent cavernous biopsy before surgery and after 2 months of sildenafil treatment. Biopsy tissues were fixed in formalin, stained with Masson's trichrome method, and evaluated with the Eureka Interface system with a per-area analysis, and elastic fibers were counted on 10-12 fields (x400) of five serial sections.. Two months after surgery the percent of connective tissue in cavernosa samples in all patients did not differ from that before surgery, being between 30 and 40% in the per-area analysis. Similarly, the elastic fiber count did not differ significantly before and after surgery.. Sildenafil prevented the progression of fibrosis in prostatectomized patients. Its efficacy seems to result from an antiproliferative effect exerted on fibroblasts.

Topics: Aged; Fibrosis; Humans; Male; Middle Aged; Penile Diseases; Penis; Piperazines; Prostatectomy; Purines; Sildenafil Citrate; Sulfones

Aging-related erectile dysfunction is characterized by a loss of smooth muscle cells (SMCs) and fibrosis in the corpora cavernosa, and functionally by corporal veno-occlusive dysfunction (CVOD). Phosphodiesterase 5 (PDE5A) inhibitors, in part via upregulating inducible nitric oxide synthase (NOS2A), have antifibrotic properties in penile tissues. We aimed to determine whether in the aged rat the chronic long-term treatment with sildenafil ameliorates corporal SMC loss and fibrosis, stimulates NOS2A induction, and corrects the associated CVOD. Aged male rats (20 mo old) received sildenafil in their drinking water (20 mg/kg per day) or plain water for 45 days, and untreated young rats (5 mo old) served as controls (n = 8 per group). CVOD was assessed by dynamic infusion cavernosometry (DIC). Collagen:SMC (Masson trichrome) and collagen III:I (picrosirius red) ratios, SMC content (alpha-smooth muscle actin [ACTA2]), cell proliferation (proliferating nuclear antigen [PCNA]), apoptotic death (TUNEL), and NOS2A induction were measured by histochemistry and immunohistochemistry followed by quantitative image analysis. Collagen content was determined by hydroxyproline assay, and transforming growth factor beta-1 (TGFB1); xanthine oxidoreductase (XDH); ACTA2; NOS2A; and the Rho kinase inhibitor protein tyrosine phosphatase, nonreceptor type 11 (PTPN11), and activator, VAV, were measured by quantitative Western blot. In the aged rats treated with sildenafil, the erectile response by DIC was normalized, and the corporal SMC:collagen ratio and SMC number were increased. In addition, sildenafil reduced the corporal collagen content without affecting the collagen III:I ratio, increased the PCNA:apoptosis ratio, and stimulated NOS2A induction, although there was no effect on XDH, TGFB1, PTPN11, or VAV levels. These data show that long-term PDE5A treatment corrected CVOD in the aged rat and partially reversed the aging-related fibrosis and loss of SMC in the corpora cavernosa without affecting TGFB1 or PTPN11 levels, which are markers of oxidative stress. It may be speculated that similar effects may be achieved with this paradigm in men.

Topics: 3',5'-Cyclic-GMP Phosphodiesterases; Aging; Animals; Blotting, Western; Collagen; Cyclic Nucleotide Phosphodiesterases, Type 5; Erectile Dysfunction; Fibrosis; Genitalia, Male; Image Processing, Computer-Assisted; Immunohistochemistry; In Situ Nick-End Labeling; Male; Muscle, Smooth; Nitric Oxide Synthase Type II; Oxidative Stress; Penis; Phosphodiesterase Inhibitors; Piperazines; Proliferating Cell Nuclear Antigen; Purines; Rats; Rats, Inbred F344; Sildenafil Citrate; Sulfones; Up-Regulation

Pulmonary fibroblast to myofibroblast conversion is a pathophysiological feature of idiopathic pulmonary fibrosis and COPD. This conversion is induced by transforming growth factor (TGF)-beta derived from epithelial cells as well as activated macrophages that have infiltrated the lung. Preventing this conversion might be a favourable therapeutic approach. Within this study we examined the activity of different members of the phosphodiesterase (PDE) family in primary human lung fibroblasts and various lung fibroblast cell lines both before and after TGF-beta induced differentiation to myofibroblasts as reflected by the expression of alpha-smooth muscle actin. We showed that the predominant PDE activities in lung fibroblasts are attributed to PDE5, PDE1 and to a smaller extent to PDE4. cyclic GMP (cGMP)-hydrolyzing activity declines by about half after differentiation to myofibroblasts in all pulmonary fibroblasts investigated, which is accompanied by a down-regulation of PDE5 protein. Lung fibroblast to myofibroblast differentiation is blocked by treatment with the PDE4 inhibitor piclamilast alone, depending on the TGF-beta concentration applied, and in combination with prostaglandin E(2) (PGE(2)) in a synergistic manner. Despite the high PDE5 activity the PDE5 inhibitor sildenafil by itself as well as in combination with brain natriuretic peptide or the nitric oxide-donor DETA-NONOate shows no inhibiting effects. However, combining sildenafil with the guanylyl cyclase (GC) activator BAY58-2667 and ODQ (which sensitizes GC for activation by BAY58-2667) suppressed TGF-beta induced differentiation. In summary, our data indicate that drugs interfering with the cyclic AMP (cAMP)-as well as with the NO-cGMP-pathway offer the therapeutic opportunity to prevent the differentiation of pulmonary fibroblasts to myofibroblasts in lung fibrosis.

Topics: Actins; Benzamides; Benzoates; Blotting, Western; Cell Differentiation; Cells, Cultured; Cyclic GMP; Dinoprostone; Drug Synergism; Enzyme Activators; Fibroblasts; Fibrosis; Guanylate Cyclase; Humans; Immunohistochemistry; Isoenzymes; Lung; Myocytes, Smooth Muscle; Natriuretic Peptide, Brain; Nitric Oxide Donors; Nitroso Compounds; Oxadiazoles; Phosphodiesterase Inhibitors; Piperazines; Purines; Pyridines; Quinoxalines; Receptors, Cytoplasmic and Nuclear; Sildenafil Citrate; Soluble Guanylyl Cyclase; Sulfones; Transforming Growth Factor beta

Recent evidence suggests that blocking inducible nitric oxide (NO) synthase in the penis may exacerbate fibrotic processes and that application of medications known to increase NO in tissues may prevent fibrosis.. To report the use of an antifibrotic regimen consisting of medications known to upregulate NO production in two patients with refractory priapism.. Two patients presented with priapism of greater than 48-hour duration. After corporal aspiration/irrigation and shunting procedures failed, both were prescribed a daily antifibrotic regimen comprising the phosphodiesterase inhibitors pentoxifylline and sildenafil, and the NO precursor, L-arginine.. At 1 year, both patients were found to have supple corpora without evidence of corporal fibrosis.. An antifibrotic regimen consisting of upregulators of NO production may ameliorate the corporal fibrosis associated with recalcitrant priapism.

Topics: Arginine; Enzyme Inhibitors; Fibrosis; Humans; Male; Middle Aged; Nitric Oxide; Nitric Oxide Synthase; Penis; Pentoxifylline; Phosphodiesterase Inhibitors; Piperazines; Priapism; Purines; Sildenafil Citrate; Sulfones; Treatment Outcome

Sildenafil is a selective inhibitor of the cGMP-specific phosphodiesterase type V (PDE-V) in the corpus cavernosum. PDE-V is also present in the mesenteric artery. Cirrhosis is complicated by a splanchnic vasodilation attributed to a local overproduction of nitric oxide (NO). As sildenafil potentiates the effects of NO, it may further decrease mesenteric vascular tone and increase portal venous blood flow. The aim is to evaluate the effects of sildenafil on the systemic and splanchnic haemodynamics in an experimental model of cirrhosis.. Secondary biliary cirrhosis was induced in male Wistar rats by common bile duct ligation (CBDL, n=8); control rats were sham-operated (sham, n=7). The mean arterial pressure (MAP), portal venous pressure (PVP) and arterial mesenteric blood flow (MBF) were measured after intramesenteric (0.01-10 mg/kg) and after intravenous (i.v.) (0.01-10 mg/kg) administration of sildenafil.. Baseline PVP was significantly higher in CBDL than in sham rats, whereas baseline MAP tended to be lower and MBF tended to be higher in CBDL compared with sham rats. Both intramesenteric and i.v. injection of sildenafil significantly decreased MAP and increased MBF and PVP in a dose-dependent way. The decrease in MAP was significantly less important in CBDL than in sham rats. The increase in MBF was importantly lower in CBDL than in sham rats. PVP tended to increase more significantly in sham rats than in CBDL.. Sildenafil increases MBF and PVP and induces systemic hypotension. The effects are less pronounced in cirrhosis, suggesting vascular hyporesponsiveness to sildenafil. Although the rise in PVP in cirrhotic animals is smaller than in controls, it may present a risk for haemorrhagic complications. Further studies are necessary before prescribing sildenafil to patients with cirrhosis.

Topics: Animals; Blood Pressure; Fibrosis; Hemodynamics; Hypertension, Portal; Male; Models, Animal; Phosphodiesterase Inhibitors; Piperazines; Portal Pressure; Purines; Rats; Rats, Wistar; Sildenafil Citrate; Splanchnic Circulation; Sulfones

Inducible nitric oxide synthase (iNOS) is expressed in both the fibrotic plaque of Peyronie's disease (PD) in the human, and in the PD-like plaque elicited by injection of TGFbeta1 into the penile tunica albuginea (TA) of the rat. Long-term inhibition of iNOS activity, presumably by blocking nitric oxide (NO)- and cGMP-mediated effects triggered by iNOS expression, exacerbates tissue fibrosis through an increase in: (a) collagen synthesis, (b) levels of reactive oxygen species (ROS), and (c) the differentiation of fibroblasts into myofibroblasts. We have now investigated whether: (a) phosphodiesterase (PDE) isoforms, that regulate the interplay of cGMP and cAMP pathways, are expressed in both the human and rat TA; and (b) L-arginine, that stimulates NOS activity and hence NO synthesis, and PDE inhibitors, that increase the levels of cGMP and/or cAMP, can inhibit collagen synthesis and induce fibroblast/myofibroblast apoptosis, thus acting as antifibrotic agents. We have found by immunohistochemistry, RT/PCR, and Western blot that PDE5A-3 and PDE4A, B, and D variants are indeed expressed in human and rat normal TA and PD plaque tissue, as well as in their respective fibroblast cultures. As expected, in the PD fibroblast cultures, pentoxifylline (non-specific cAMP-PDE inhibitor) increased cAMP levels without affecting cGMP levels, whereas sildenafil (PDE5A inhibitor) raised cGMP levels. Both agents and L-arginine reduced the expression of collagen I (but not collagen III) and the myofibroblast marker, alpha-smooth muscle actin, as determined by immunocytochemistry and quantitative image analysis. These effects were mimicked by incubation with 8-Br-cGMP, which in addition increased apoptosis, as measured by TUNEL. When L-arginine (2.25 g/kg/day), pentoxifylline (10 mg/kg/day), or sildenafil (10 mg/kg/day) was given individually in the drinking water for 45 days to rats with a PD-like plaque induced by TGF beta1, each treatment resulted in a 80-95% reduction in both plaque size and in the collagen/fibroblast ratio, as determined by Masson trichrome staining. Both sildenafil and pentoxiphylline stimulated fibroblast apoptosis within the TA. Our results support the hypothesis that the increase in NO and/or cGMP/cAMP levels by long-term administration of nitrergic agents or inhibitors of PDE, may be effective in reversing the fibrosis of PD, and more speculatively, other fibrotic conditions.

Topics: Animals; Apoptosis; Arginine; Blotting, Western; Cyclic GMP; Enzyme Inhibitors; Fibrosis; Humans; Male; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Penile Induration; Penis; Pentoxifylline; Phosphodiesterase Inhibitors; Phosphoric Diester Hydrolases; Piperazines; Purines; Rats; Rats, Inbred F344; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sildenafil Citrate; Sulfones