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Objectives To evaluate the effect of phosphodiesterase-5 (PDE-5) inhibitors on uteroplacental and fetal cerebral perfusion in pregnancies complicated with fetal growth restriction (FGR). Material and methods Relevant databases were searched from inception up to June 2021. The random-effects model was used to pool the weighted mean differences (WMDs) and the corresponding 95% confidence intervals (CIs). The primary outcomes were the effect of PDE-5 inhibitors on uterine (UtA-PI), umbilical (UA-PI) and middle cerebral artery (MCA-PI) pulsatility indices. Subgroup analyses were also performed based on the type of PDE-5 inhibitor medication, the dosage of medication, duration of treatment, sample size and onset of FGR. Results Seven clinical trials were eligible, 6 trials using sildenafil, and one using tadalafil. The random-effects models indicated PDE-5 inhibitors significantly decrease UtA-PI (WMD= -0.28, 95% CI= -0.46,-0.11) and UA-PI (WMD= -0.07, 95% CI= -0.13, -.01); however it failed to show a significant effect on MCA-PI (WMD= 0.24, 95% CI=-0.63, 1.11). Subgroup analyses showed similar significant effects of sildenafil on UtA-PI and UA-PI; however, no significant effect was observed after treatment with tadalafil. Conclusion PDE-5 inhibitors administration, especially sildenafil, may improve uteroplacental, but not fetal cerebral blood perfusion in pregnancies complicated by FGR.

Made available in DSpace on 2022-04-29T08:33:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-10-30 Acute kidney injury pathogenesis in envenoming by snakes is multifactorial and involves immunologic reactions, hemodynamic disturbances, and direct nephrotoxicity. Sildenafil (SFC), a phosphodiesterase 5 inhibitor, has been reported to protect against pathological kidney changes. Objective: This study aimed to investigate the protective effect of sildenafil against Bothrops alternatus snake venom (BaV)-induced nephrotoxicity. Methods: Kidneys from Wistar rats (n = 6, weighing 260–300 g) were isolated and divided into four groups: (1) perfused with a modified Krebs-Henseleit solution (MKHS) containing 6 g% of bovine serum albumin; (2) administered 3 μg/mL SFC; (3) perfused with 3 μg/mL BaV; and (4) administered SFC + BaV, both at 3 μg/mL. Subsequently, the perfusion pressure (PP), renal vascular resistance (RVR), urinary flow (UF), glomerular filtration rate (GFR), and percentage of electrolyte tubular sodium and chloride transport (%TNa+, %TCl−, respectively) were evaluated. The cyclic guanosine monophosphate (cGMP) levels were analyzed in the perfusate, and the kidneys were removed to perform oxidative stress and histopathological analyses. Results: All renal parameters evaluated were reduced with BaV. In the SFC + BaV group, SFC restored PP to normal values and promoted a significant increase in %TNa+ and %TCl−. cGMP levels were increased in the SFC + BaV group. The oxidative stress biomarkers, malondialdehyde (MDA) and glutathione (GSH), were reduced by BaV. In the SFC + BaV group, a decrease in MDA without an increase in GSH was observed. These findings were confirmed by histological analysis, which showed improvement mainly in tubulis. Conclusion: Our data suggest the involvement of phosphodiesterase-5 and cGMP in BaV-induced nephrotoxicity since its effects were attenuated by the administration of SFC. Department of Physiology and Pharmacology School of Medicine Federal University of Ceara, Coronel Nunes de Melo St., 1127 Drug Research and Development Center (NPDM) Federal University of Ceara, Coronel Nunes de Melo St., 1000 Department of Dental Clinic School of Pharmacy Dentistry and Nursing Federal University of Ceara, Monsenhor Furtado St. Center for the Study of Venoms and Venomous Animals Fazenda Experimental Lageado São Paulo State University, José Barbosa de Barros St. 1780 Center for the Study of Venoms and Venomous Animals Fazenda Experimental Lageado São Paulo State University, José Barbosa de Barros St. 1780

Aims: Therapy with phosphodiesterase-5 inhibitors (PDE5Is) after left ventricular assist device (LVAD) implantation has been associated with lower mortality and device thrombosis but increased risk for post-operative and gastrointestinal bleeding. We aimed to evaluate the impact of long-term PDE5Is on the overall bleeding risk after LVAD implantation. Methods and results: We retrospectively included patients who received a continuous-flow LVAD at our site and were prescribed with long-term oral PDE5Is after discharge from the index hospitalization. The primary endpoint was the occurrence of bleeding at 12 month follow-up. Secondary endpoints were all-cause death and the combination of bleeding and all-cause death. Our analysis included 109 patients of whom 75 (69%) received long-term PDE5Is. Mean age was 56 years, and 85% were male. At 12 months, 19 (17%) patients experienced at least one bleeding event. Patients on PDE5Is had higher bleeding rates (23% vs. 6%, P = 0.03) and more bleeding events per patient-year (0.32 vs. 0.06, P = 0.03) compared with patients not on PDE5Is. While overall bleeding incidence was excessively higher in the PDE5I group, there were no significant differences in the incidence of major bleeding (19% vs. 6%, P = 0.08) and gastrointestinal bleeding (11% vs. 3%, P = 0.18). Kaplan–Meier analysis revealed higher cumulative incidence of bleeding for the PDE5I group (log rank = 0.04) with no difference on all-cause death (log rank = 0.67) and the combination of bleeding and all-cause death (log rank = 0.13). Hospitalizations for bleeding and their duration were numerically higher in the PDE5I group (0.28 vs. 0.03, P = 0.07 and 2.4 vs. 0.2, P = 0.07, respectively). Conclusions: Phosphodiesterase-5 inhibitor treatment after LVAD implantation is associated with increased bleeding risk after LVAD implantation. The safety of long-term PDE5Is in LVAD patients remains unclear and needs to be further clarified in prospective studies with randomized study design. OA Förderung 2021

Supplemental Digital Content is available in the text., Rationale: PDE5 (phosphodiesterase 5) inhibition reduces the occurrence of ventricular arrhythmias following myocardial ischemia. However, the mechanisms of the antiarrhythmic effects of PDE5 inhibition are unknown. Diastolic calcium (Ca2+) waves lead to arrhythmias by inducing delayed afterdepolarizations (DADs). Ca2+ waves are initiated when sarcoplasmic reticulum (SR) Ca2+ content reaches a threshold level and the SR releases Ca2+ spontaneously and generates a depolarizing inward sodium-calcium exchange current. Objective: To determine the effects of PDE5 inhibition on the propensity for ventricular arrhythmias in a proarrhythmic large animal model and establish the role of alterations of intracellular Ca2+ cycling/SR Ca2+ content. Methods and Results: Arrhythmia burden, monophasic action potentials, and beat-to-beat variability of repolarization were measured in a sheep model using the IKr inhibitor dofetilide to induce QT prolongation and arrhythmia. Ca2+ transients, Ca2+ waves, and SR Ca2+ content were measured in isolated ventricular myocytes. PDE5 inhibition was achieved using acute application of sildenafil, and PKG (protein kinase G) was inhibited with KT5823. PDE5 inhibition reduced beat-to-beat variability of repolarization and suppressed afterdepolarizations, premature ventricular complexes, and torsade de pointes in vivo. In single cells, dofetilide-induced delayed afterdepolarizations and triggered action potentials were suppressed by PDE5 inhibition. PDE5 inhibition decreased Ca2+ wave frequency in all cells and abolished waves in 12 of 22 cells. A decrease in SR Ca2+ uptake, increased trans-sarcolemmal Ca2+ efflux, and reduced trans-sarcolemmal Ca2+ influx led to a reduction of SR Ca2+ content and Ca2+ wave abolition. These effects were dependent on PKG activation. Conclusions: PDE5 inhibition acutely suppresses triggered ventricular arrhythmias in vivo, and cellular data suggests this occurs via suppression of cellular Ca2+ waves. These novel antiarrhythmic properties of PDE5 inhibition are mediated by a reduction of SR Ca2+ content and are PKG dependent.

Background/aim Phosphodiesterase 5 (PDE5) holds clinical relevance in several pathological states, including lung, breast, and prostate cancer. In this study, we examined PDE5 expression in oral squamous cell carcinoma (OSCC)-derived cell lines and tissues, and the anti-tumour effect of PDE5 inhibitor, sildenafil citrate (SC). Materials and methods Cell proliferation, cell invasion, and gap closure assays were performed in six OSCC-derived cell lines upon treatment with varying concentrations of SC. PDE5 expression was determined in primary OSCC tissues by western blotting and immunohistochemistry. Results Elevated PDE5 expression was observed in all cell lines. A concentration-dependent decrease in cell viability, invasion rate, and migration was observed after SC treatment. A significant correlation (p=0.05) was observed between elevated PDE5 expression and lymphatic infiltration in OSCC tissues. Conclusion PDE5 plays an important role in carcinogenesis of OSCC, and the specific inhibition of PDE5 may be an effective chemotherapeutic strategy.

This study determined the configuration of the isomers of tadalafil, nortadalafil, and homotadalafil in dietary supplements. The products purchased over the Internet studied included a honey product and a tablet, which contained tadalafil, and a candy, which contained nortadalafil and homotadalafil. Each of the pharmaceutical ingredients isolated from the products was measured with circular dichroism (CD).As a result, the CD spectrum of each isolated pharmaceutical ingredient was found to align with the standard CD spectrum of the 6R,12aR isomer, confirmed that each isolated tadalafil or tadalafil analogue included in a 6R,12aR isomer. According to a report, among the stereoisomers of tadalafil, the 6R,12aR isomers have the most potent inhibitory activities of phosphodiesterase-type-5. From the report, the potential strength of the inhibitory activity of the 6R,12aR isomers of nortadalafil and homotadalafil was suggested. Therefore, it seemed that the 6R,12aR isomer often used in the product.

INTRODUCTION Pulmonary arterial hypertension (PAH) is associated with high medical and pharmaceutical costs. Phosphodiesterase type 5 (PDE5) inhibitors have been found to be beneficial but costly. They are not subsidised in Singapore except via the Medication Assistance Fund (MAF) Plus scheme. In this study, we described the help-seeking behaviour of patients and funding strategies for Singaporean patients on PDE5 inhibitors in our registry. METHODS We consecutively recruited all patients with PAH who presented to our pulmonary hypertension specialty centre between 1 January 2003 and 29 December 2016. Singaporean patients on PDE5 inhibitors were included. Data recorded and analysed for this study included baseline demographics, whether the patients received MAF Plus funding, percentage of funding, and any additional source of subsidies. RESULTS 114 (77.0%) of 148 patients in the registry were Singapore citizens on PDE5 inhibitors. 75 (65.8%) of these 114 patients had been seen by a medical social worker, of whom 16 were on MAF Plus funding. 14 of the remaining 59 patients were subsidised by MediFund, whereas the remainder were self-paying. 30 (26.3%) patients in total were on some form of subsidy, and 28 (24.6%) patients were on combination therapy. Of this group, nine were receiving MAF Plus subsidies. CONCLUSION Fewer than expected patients were found to be receiving drug subsidies for PAH. This was partly due to insufficient referrals and lack of requests for financial assistance. Patients on combination therapy had greater financial challenges. This study should spur us on to study funding gaps further and address them.

Background Phosphodiesterase-5 inhibitors (PDE5i) have been used to treat pulmonary hypertension and right ventricular failure in patients with left ventricular assist devices (LVAD). The effects of PDE5i on post-LVAD outcomes including hemocompatibility-related adverse events are not well-established. This systematic review and meta-analysis aims to evaluate the effects of PDE5i on post-LVAD outcomes. Methods and Results A comprehensive literature search was conducted using Pubmed and Embase databases from inception through November 25, 2020, to compare post-LVAD outcomes in patients with or without PDE5i use. Pooled odds ratio (OR) with 95% confidence intervals (CI) and I2 statistic were calculated. Thirteen observational studies were included in this analysis. The use of PDE5i was not significantly associated with lower postoperative right ventricular failure (OR 0.38, 95% CI 0.02–5.96, P = .41). There was no significant association between PDE5i and gastrointestinal bleeding (OR 1.23, 95% CI 0.76–1.98, P = .2), overall stroke (OR 0.60, 95% CI 0.21–1.68, P = .17), ischemic stroke (OR 0.61, 95% CI 0.09–4.07, P = .38), or pump thrombosis (OR 0.71, 95% CI 0.14–3.54, P = .46). Conclusions Our meta-analysis showed no significant association between PDE5i and post-LVAD right ventricular failure. Despite the antiplatelet effects of PDE5i, there was no significant association between PDE5i and gastrointestinal bleeding, overall stroke, ischemic stroke, or pump thrombosis. Randomized controlled studies are warranted to evaluate the net benefits or harms of PDE5i in the LVAD population.

OBJECTIVE: To investigate the impact of penile rehabilitation on the recovery of erectile function after robot-assisted radical prostatectomy. METHODS: Patients who underwent robot-assisted radical prostatectomy in our department from 2010 to 2019 were included. For penile rehabilitation, a phosphodiesterase-5 inhibitor (tadalafil 20 mg) was administered twice a week for 1-6 months postoperatively. The International Index of Erectile Function questionnaire (question 1 and erectile function domain) and the Expanded Prostate Cancer Index Composite questionnaire (sexual function) were used. RESULTS: After propensity score matching, there were 79 patients in the penile rehabilitation group and 79 patients in the non-penile rehabilitation group. There was no significant difference in baseline characteristics between the two groups. Significantly higher scores were seen in the penile rehabilitation group compared with the non-penile rehabilitation group at postoperative 3, 6 and 9 months in the International Index of Erectile Function questionnaire-question 1, at 3, 6, 9 and 12 months in erectile function domain, and at 3, 6, 12 and 24 months in Expanded Prostate Cancer Index Composite questionnaire sexual function (P

Cardiac rupture is a fatal complication of acute myocardial infarction (MI), associated with increased inflammation and damaged extracellular matrix. C57BL/6 J wild type (WT) and Pde5a knockout (Pde5a−/−) mice were selected to establish MI model. The rupture rate of Pde5a−/− mice was significantly reduced (P

Vascular aging leads to structural and functional changes. Iliac arteries (IA) provide blood flow to lower urinary tract and pelvic ischemia has been reported as an important factor for bladder remodeling and overactivity. Dysfunction of the nitric oxide (NO)-cyclic guanosine monophosphate pathway (cGMP) is one factor involved in the development of lower urinary tract (LUT) disorders. Therefore, we hypothesized that ageing-associated LUT disorders is a consequence of lower cGMP productions due to an oxidation of soluble guanylate cylase (sGC) that results in local ischemia. In the present study IA from middle-aged and young rats were isolated and the levels of NO, reactive oxygen species (ROS), the gene expression of the enzymes involved in the NO-pathway and concentration-response curves to the soluble guanylate (sGC) stimulator (BAY 41-2272), sGC activator (BAY 58-2667), tadalafil, acetylcholine (ACh) and sodium nitroprusside (SNP) were determined. In IA from middle-aged rats the gene expression for endothelial nitric oxide synthase and the ROS were lower and higher, respectively than the young group. The relaxations induced by ACh and SNP were significantly lower in IA from middle-aged rats. In IA from middle-aged rats the mRNA expression of PDE5 was 55% higher, accompanied by lower relaxation induced by tadalafil. On the other hand, the gene expression for sGCα1 were similar in IA from both groups. Both BAY 41-2272 and BAY 58-2667 produced concentration-dependent relaxations in IA from both groups, however, the latter was 9-times more potent than BAY 41-2272 and produced similar relaxations in IA in both middle-aged and young groups. Yet, the sGC oxidant, ODQ increased the relaxation and the cGMP levels induced by BAY 58-2667. On the other hand, in tissues stimulated with SNP, tadalafil and BAY-2272, the intracellular levels of cGMP were lower in IA from middle-aged than young rats. In conclusion, our results clearly showed that the relaxations induced by the endothelium-dependent and -independent agents, by the PDE5 inhibitor and by sGC stimulator were impaired in IA from aged rats, while that induced by sGC activator was preserved. It suggests that sGC activator may be advantageous in treating ischemia-related functional changes in the lower urinary tract organs in situations where the NO levels are reduced.

Hypoxic coronary vasospasm may lead to myocardial ischaemia and cardiac dysfunction. Inosine 3′,5′‐cyclic monophosphate (cIMP) is a putative second messenger to mediate this pathological process. Nevertheless, it remains unclear as to whether levels of cIMP can be regulated in living tissue such as coronary artery and if so, what is the consequence of this regulation on hypoxia‐induced vasoconstriction. In the present study, we found that cIMP was a key determinant of hypoxia‐induced constriction but not that of the subsequent relaxation response in porcine coronary arteries. Subsequently, coronary arteries were treated with various phosphodiesterase (PDE) inhibitors to identify PDE types that are capable of regulating cIMP levels. We found that inhibition of PDE1 and PDE5 substantially elevated cIMP content in endothelium‐denuded coronary artery supplemented with exogenous purified cIMP. However, cGMP levels were far lower than their levels in intact coronary arteries and lower than cIMP levels measured in endothelium‐denuded coronary arteries supplemented with exogenous cIMP. The increased cIMP levels induced by PDE1 or PDE5 inhibition further led to augmented hypoxic constriction without apparently affecting the relaxation response. In intact coronary artery, PDE1 or PDE5 inhibition up‐regulated cIMP levels under hypoxic condition. Concomitantly, cGMP level increased to a comparable level. Nevertheless, the hypoxia‐mediated constriction was enhanced in this situation that was largely compromised by an even stronger inhibition of PDEs. Taken together, these data suggest that cIMP levels in coronary arteries are regulated by PDE1 and PDE5, whose inhibition at a certain level leads to increased cIMP content and enhanced hypoxic constriction.

Our study aims to explore changes in bladder contractility and the phosphodiesterase type 5 (PDE5) signalling pathway in response to partial bladder outlet obstruction (PBOO). A surgically induced male rat PBOO model and human obstructed bladder tissues were used. Histological changes were examined by H&E and Masson's trichrome staining. Bladder strip contractility was measured via organ bath. The expressions of nitric oxide synthase (NOS) isoforms, PDE5, muscarinic cholinergic receptor (CHRM) isoforms and PDE4 isoforms in bladder were detected by RT‐PCR and Western blotting. The immunolocalization of the PDE5 protein and its functional activity were also determined. PBOO bladder tissue exhibited significant SM hypertrophy and elevated responsiveness to KCl depolarization and the muscarinic receptor agonist carbachol. NOS isoforms, PDE5, CHRM2, CHRM3 and PDE4A were up‐regulated in obstructed bladder tissue, whereas no change in PDE4B and PDE4D isoform expression was observed. With regard to PDE5, it was expressed in the SM bundles of bladder. Interestingly, obstructed bladder exhibited less relaxation responsiveness to sodium nitroprusside (SNP), but an exaggerated PDE5 inhibition effect. The up‐regulation of PDE5 could contribute to the lack of effect on Qmax for benign prostatic hyperplasia/lower urinary tract symptom (BPH/LUTS) patients treated with PDE5 inhibitors. Moreover, PDE5 (with presence of NO) and PDE4 may serve as new therapeutic targets for bladder diseases such as BPH‐induced LUTS and overactive bladder (OAB).

Diabetic nephropathy (DN) is a leading cause of end-stage renal disease (ESRD). Hypertension increases kidney stress, which deteriorates function, and leads to peripheral renal vascular resistance. Long-term hypoperfusion promotes interstitial fibrosis and glomerular sclerosis, resulting in nephrosclerosis. Although hypertension and DN are frequent ESRD complications, relevant animal models remain unavailable. We generated a deoxycorticosterone acetate (DOCA)-salt hypertensive uni-nephrectomized (UNx) KKAy mouse model demonstrating hypertension, hyperglycemia, cardiac hypertrophy, kidney failure, increased urinary albumin creatinine ratio (UACR), and increased renal PDE4D and cardiac PDE5A mRNA levels. We hypothesized that the novel PDE4 selective inhibitor, compound A, and PDE5 inhibitor, sildenafil, exhibit nephroprotective, and cardioprotective effects in this new model. Compound A, sildenafil, and the angiotensin II receptor blocker, irbesartan, significantly reduced ventricular hypertrophy and pleural effusion volume. Meanwhile, compound A and sildenafil significantly suppressed the UACR, urinary kidney injury molecule-1, and monocyte chemoattractant protein-1 levels, as well as that of renal pro-fibrotic marker mRNAs, including collagen 1A1, fibronectin, and transforming growth factor-beta (TGF-β). Moreover, compound A significantly suppressed TGF-β-induced pro-fibrotic mRNA expression in vitro in all major kidney lesions, including within the glomerular mesangial region, podocytes, and epithelial region. Hence, PDE4 and PDE5 inhibitors may be promising treatments, in combination with irbesartan, for DN with hypertension as they demonstrate complementary mechanisms.

The nitric oxide (NO)-cyclic guanosine monophosphate (cGMP)-protein kinase G (PKG) pathway plays a critical role in skeletal homeostasis. Preclinical data using NO and its donors and genetically modified mice demonstrated that NO was required in bone remodeling and partly mediated the anabolic effects of mechanical stimuli and estrogen. However, the off-target effects and tachyphylaxis of NO limit its long-term use, and previous clinical trials using organic nitrates for osteoporosis have been disappointing. Among the other components in the downstream pathway, targeting cGMP-specific phosphodiesterase to promote the NO-cGMP-PKG signal is a viable option. There are growing in vitro and in vivo data that, among many other PDE families, PDE5A is highly expressed in skeletal tissue, and inhibiting PDE5A using currently available PDE5A inhibitors might increase the osteoanabolic signal and protect the skeleton. These preclinical data open the possibility of repurposing PDE5A inhibitors for treating osteoporosis. Further research is needed to address the primary target bone cell of PDE5A inhibition, the contribution of direct and indirect effects of PDE5A inhibition, and the pathophysiological changes in skeletal PDE5A expression in aging and hypogonadal animal models.

Background Testosterone (T) deficiency is associated with erectile dysfunction (ED). The relaxant response of T on the corporal smooth muscle through a non-genomic pathway has been reported; however, the in vitro modulating effects of T on human corpus cavernosum (HCC) have not been studied. Objectives To compare the effects of various concentrations of T on nitric oxide (NO)-dependent and nitric oxide-independent relaxation in organ bath studies and elucidate its mode of action, specifically targeting the cavernous NO/cyclic guanosine monophosphate (cGMP) pathway. Materials and methods Human corpus cavernosum (HCC) samples were obtained from men undergoing penile prosthesis implantation (n = 9). After phenylephrine (Phe) precontraction, the effects of various relaxant drugs of HCC strips were performed using organ bath at low (150 ng/dL), eugonadal (400 ng/dL), and hypergonadal (600 ng/dL) T concentrations. The penile tissue measurements of endothelial nitric oxide synthase (eNOS), neuronal (n)NOS, and phosphodiesterase type 5 (PDE5) were evaluated via immunostaining, Western blot, cGMP and nitrite/nitrate (NOx) assays. Results Relaxation responses to ACh and EFS in isolated HCC strips were significantly increased at all T levels compared with untreated tissues. The sildenafil-induced relaxant response was significantly increased at both eugonadal and hypergonadal T levels. Normal and high levels of T are accompanied by increased eNOS, nNOS, cGMP, and NOx levels, along with reduced PDE5 protein expression. Conclusion This study reveals an important role of short-term and modulatory effects of different concentrations of T in HCC. T positively regulates functional activities, inhibition of PDE5 expression, and formation of cGMP and NOx in HCC. These results demonstrate that T indirectly contributes to HCC relaxation via downstream effects on nNOS, eNOS, and cGMP and by inhibiting PDE5. This action provides a rationale for normalizing T levels in hypogonadal men with ED, especially when PDE5 inhibitors are ineffective. T replacement therapy may improve erectile function by modulating endothelial function in hypogonadal men.

Low-intensity shockwave therapy (Li-ESWT) has been shown to be an effective and safe treatment for vasculogenic erectile dysfunction (ED). We aim to evaluate the effectiveness and safety of LiESWT in treating patients affected from vasculogenic ED who did not respond to oral treatment with Phosphodiesterase 5 inhibitors (PDE5-i). It is a multicentric open-label prospective study, in a cohort of patients non-responders to PDE-5i. Li-ESWT was performed in an outpatient setting by using the following schedule: 3000 shockwaves with an energy of 0.25 mJ/mm2 and a frequency of 4–6 Hz, twice a week for 3 weeks. International Index of Erectile Function, Erection Hardness Score and Sexual Quality of Life-Male questionnaires, and penile doppler ultrasound (PDU) are the outcome measurements. The Student t-test or Wilcoxon signed-rank test were applied to compare variables, with results considered statistically significant at p < 0.05. 106 (97.2%) completed treatment and performed follow-up visit after 4 weeks. At follow up visit, the mean IIEF-EF increased by 8.6 points (13.47 ± 4.61 vs 22.07 ± 5.27; p < 0.0001). A clinically significant improvement of IIEF-EF was achieved in 75 patients (70.7%). An EHS score ≥ 3, sufficient for a full intercourse, was reported by 72 patients (67.9%) at follow-up visit. 37 (34.9%) patients reported a full rigid penis (EHS = 4) after treatment. Li-ESWT treatment was also able to improve quality of life (SQOL-M: 45.56 ± 8.00 vs 55.31 ± 9.56; p < 0.0001). Li-ESWT significantly increased mean PSV (27.79 ± 5.50 vs 41.66 ± 8.59; p < 0.0001) and decreased mean EDV (5.66 ± 2.03 vs 1.93 ± 2.11; p < 0.0001) in PDU. Combination of Li-ESWT and PDE5-i represents an effective and safe treatment for patients affected from ED who do not respond to first line oral therapy.

Phosphodiesterase 5A1 (PDE5) is a key target for treating cardiovascular diseases and erectile dysfunction. Here, we report the crystal structure of PDE5 complexed with the sole second generation drug avanafil. Analysis of protein-drug interactions revealed the structural basis of avanafil's superior isoform selectivity. Moreover, a halogen bonding was observed between avanafil and a backbone carbonyl oxygen of an adjacent α-helix, whose contribution to inhibitory potency illustrates the feasibility of exploiting α-helix backbone in structure-based drug design.

The need of circumventing life-threatening cardiovascular disorders (CVDs) and pulmonary hypertension (PHT) worldwide prompts researchers to develop effective therapeutic agents. Crucial role of cyclic nucleotide phosphodiesterase-5 (PDE5A) and cyclic nucleotide phosphodiesterase-3 (PDE3A) in cardiovascular signaling makes them potential drug targets for the treatment of CVDs and PHT. In this study, one-drug-multiple-target strategy has been employed to screen inhibitors exhibiting dual specificity through Phase-generated and statistically validated e-pharmacophore models of PDE5A and PDE3A. An extensive CoCoCo database of 7 million compounds with ∼150,000,000 conformations was virtually screened by sequential e-pharmacophore mapping followed by Lipinski Rule of Five (RO5) evaluation and hierarchical docking simulations. Finally, docked hits were subjected to rigorous MMGBSA analysis to estimate the relative spatial affinity of the drug-like compounds. The hits (354 and 366 ligands against PDE5A and PDE3A, respectively) were further optimized through 2D clustering followed by a comprehensive 2D and 3D interaction analysis. Five structurally diverse hits mapped equally well with the e-pharmacophore models and showed promising inhibitory interactions with conserved four catalytic features of PDE5A and PDE3A, thus exhibiting dual specificity. Proposed lead compounds exhibited the lowest MMGBSA binding energies and were found to be in agreement with Lipinski Rule of Five (RO5) and ADME/Tox criteria as compared to sildenafil. The proposed dual inhibitors could thus provide promising outcomes for the discovery of dual as well as multipotent drug like compounds after lead optimization and primary therapeutic interventions. Communicated by Ramaswamy H. Sarma

Introduction: Priapism is prolonged penile erection in the absence of sexual arousal or desire and is a devastating condition affecting millions of patients with sickle cell disease (SCD) globally. Available drug treatments for SCD-related priapism remain limited and have been primarily reactive rather than preventive. Hence, there is an unmet need for new drug targets and pharmacologic therapies.Areas covered: We examine the molecular mechanisms underlying SCD-associated priapism evaluated mostly in animal models. In mouse models of SCD, molecular defects of priapism operating at the cavernous tissue level include reduced tonic NO/cGMP signaling, elevated oxidative/nitrosative stress, vascular adhesion molecule derangements, excessive adenosine and opiorphin signaling, dysregulated vasoconstrictive RhoA/ROCK signaling, and testosterone deficiency. We discuss the consequences of downregulated cGMP-dependent phosphodiesterase type 5 (PDE5) activity in response to these molecular signaling derangements, as the main effector mechanism causing unrestrained cavernous tissue relaxation that results in priapism.Expert opinion: Basic science studies are crucial for understanding the underlying pathophysiology of SCD-associated priapism. Understanding the molecular mechanisms could unearth new therapeutic targets for this condition based on these mechanisms. Treatment options should aim to improve deranged erection physiology regulatory signaling to prevent priapism and potentially restore or preserve erectile function.

Aims The urethral dysfunction produced by a rat model of peripheral neurogenic detrusor underactivity (DU) using pelvic nerve crush (PNC) injury was characterized and then tested with the administration of tadalafil, a phosphodiesterase type 5 (PDE 5) inhibitor. Methods Ten days after producing PNC rats, awake cystometrograms (CMGs) and isovolumetric cystometrograms with urethral perfusion pressure (IC-UPP) measurements were performed. Also, in control rats, IC-UPP was recorded before and after intravenous atropine administration to determine if the reduction of bladder contraction pressure affects urethral relaxation during voiding. Then, CMG and IC-UPP measurements in PNC rats were recorded after intravenous administration of tadalafil. Lastly, real-time polymerase chain reaction was used to measure transcript levels of neuronal nitric oxide synthases (nNOS), endothelial nitric oxide synthases, and PDE 5 in urethral specimens from PNC and control rats. Results PNC rats demonstrated the characteristics of DU in CMG. Also, PNC rats exhibited significant decreases in isovolumetric bladder contraction amplitudes and urethral relaxation. Atropine attenuated the amplitude of isovolumetric bladder contractions; however, atropine did not affect urethral relaxation in control rats. Tadalafil decreased postvoid residual and increased voiding efficiency without changing bladder contraction amplitude in PNC rats. Also, tadalafil improved the amplitude of urethral relaxation during bladder contraction in PNC rats. Urethral nNOS transcript levels were upregulated in PNC rats compared to control rats. Conclusions PNC rats revealed both DU and impaired urethral relaxation. PDE 5 inhibition in PNC rats enhanced urethral relaxation during voiding, resulting in improved voiding efficiency. Thus, urethral dysfunction could be a potential target for the treatment of inefficient voiding associated with neurogenic DU.

Some illegal dietary supplements contain phosphodiesterase type 5 (PDE5) inhibitors, such as sildenafil, for exerting "therapeutic" effects in erectile dysfunction. This is apparently dangerous, and thus, should be appropriately regulated. Identification of descarbonsildenafil was first reported in Singapore in a coffee sample labeled to exert male sexual performance enhancement effects. However, it is unclear whether the compound possesses PDE5 inhibitory activity. We encountered during our survey of dietary supplements, a sexual enhancement product commercially available in Tokyo, in which a peak presumed to be of descarbonsildenafil was detected by LC-UV and electrospray ionization-tandem MS (ESI-MS/MS). The compound was isolated and identified as descarbonsildenafil with liquid chromatography-quadrupole time-of-flight-mass spectrometry (LC-QTOF-MS), NMR, and X-ray crystal structural analysis. In addition, descarbonsildenafil showed PDE5 inhibitory activity in PDE5 inhibition assay, and its IC50 value for PDE5A1 was found to be 30 nmol/L. The results of INADEQUATE NMR and X-ray crystal structural analysis in this study provide information for the identification of descarbonsildenafil. Since this study indicates that this compound is a PDE5 inhibitor having adequate activity, it is regulated as a drug component in Japan.

Some medicinal mushrooms have effects on sexual dysfunctions. Nitric oxide synthase (NOS)-cyclic gua-nosine monophosphate (cGMP)-phosphodiesterase 5 enzyme (PDE5) pathway is one of the pathophysiological basis of erectile dysfunction (ED). The normal erectile function involves the synthesis of nitric oxide (NO), and the subsequent accumulation of cGMP, whereas cGMP degradation is specifically controlled by PDE5, which promotes corporal smooth muscle cell (SMC) tone and terminates erection. The antioxidant activities of Inonotus obliquus (chaga) water extracts (IO1) and water extraction and alcohol precipitation extracts (IO2) were compared using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assay and oxygen radical absorbance capacity (ORAC) method. Three subtypes of NOS (nNOS, iNOS, and eNOS) and PDE5 protein expressions were tested by Western blotting, and cGMP was determined by ELISA on a rat corporal primary SMC. The results revealed that IO2, which had a significantly higher polysaccharide content than IO1, showed a significantly higher ORAC value and a significantly lower half inhibitory concentration for DPPH scavenging activity than IO1. We observed that both IO1 and IO2 increased the expression of eNOS and iNOS significantly compared with the control. Furthermore, when compared with the control, IO1 increased PDE5 expression significantly, while IO2 showed no effect. The different impacts on PDE5 might be the reason that IO2, not IO1, showed significant inducible effect on cGMP compared with the control. This is to our knowledge, the first study exploring the effect of I. obliquus on NOS-cGMP-PDE5 pathway on SMC. The results provide a possible selection of I. obliquus for the treatment of ED.

Introduction Testosterone deficiency is known to induce endothelial dysfunction, which can lead to erectile dysfunction and/or vascular dysfunction. In some basic and clinical reports, testosterone has been shown to regulate the nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway and thereby influence endothelial function and endothelial progenitor cells (EPCs), which are key for the endothelial repair system. Aim To review the association between testosterone and endothelial dysfunction focusing on NO and EPCs. Methods A review of relevant literature up to September 2018 was performed via PubMed. Main Outcome Measures We reviewed the association between testosterone and endothelial dysfunction focusing on NO derived from endothelial NO synthase, phosphodiesterase type 5 (PDE-5), asymmetric dimethylarginine (ADMA), inflammation, and EPCs. Results Numerous articles describing the association between testosterone deficiency and endothelial dysfunction have been published. Some reports have shown that testosterone deficiency decreases NO production by altering the expression and activity of NO synthase and by regulating ADMA expression. Testosterone also regulates the expression of phosphodiesterase type 5. In addition, some basic and clinical studies have shown that testosterone affects the function and number of EPCs. However, some inconsistencies among these reports have been noted. Conclusion Testosterone deficiency might cause endothelial dysfunction by decreasing NO levels through regulating the expression and activity of NO synthase and increasing ADMA expression. In addition, testosterone might affect the endothelial repair system by regulating the proliferation and migration of EPCs. Testosterone replacement therapy might be useful for treating endothelial dysfunction, considering that some reports have shown that this therapy improved NO bioavailability and EPC function. Hotta Y, Kataoka T, Kimura K. Testosterone Deficiency and Endothelial Dysfunction: Nitric Oxide, Asymmetric Dimethylarginine, and Endothelial Progenitor Cells. Sex Med Rev 2019;7:661–668.

Background: Erectile dysfunction is a disease commonly caused by diabetes mellitus (DMED) and cavernous nerve injury (CNIED). Bioinformatics analyses including differentially expressed genes (DEGs), enriched functions and pathways (EFPs), and protein-protein interaction (PPI) networks were carried out in DMED and CNIED rats in this study. The critical biomarkers that may intervene in nitric oxide synthase (NOS, predominantly nNOS, ancillary eNOS, and iNOS)-cyclic guanosine monophosphate (cGMP)-phosphodiesterase 5 enzyme (PDE5) pathway, an important mechanism in erectile dysfunction treatment, were then explored for potential clinical applications. Methods: GSE2457 and GSE31247 were downloaded. Their DEGs with a |logFC (fold change)| > 0 were screened out. Database for Annotation, Visualization and Integrated Discovery (DAVID) online database was used to analyze the EFPs in Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes networks based on down-regulated and up-regulated DEGs respectively. PPI analysis of 2 datasets was performed in Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) and Cytoscape. Interactions with an average score greater than 0.9 were chosen as the cutoff for statistical significance. Results: From a total of 1710 DEGs in GSE2457, 772 were down-regulated and 938 were up-regulated, in contrast to the 836 DEGs in GSE31247, from which 508 were down-regulated and 328 were up-regulated. The 25 common EFPs such as aging and response to hormone were identified in both models. PPI results showed that the first 10 hub genes in DMED were all different from those in CNIED. Conclusions: The intervention of iNOS with the hub gene complement component 3 in DMED and the aging process in both DMED and CNIED deserves attention.

Objectives: We aimed to analyze the trend change of the most popular Phosphodiesterase-5 Inhibitors (PDE5i) over time and geography by using Google Trends (GT) data in 10 years period and COVID-19 pandemic. Materials and methods: GT is able to generate a “line-graph”, showing how interest has increased or decreased over a period within specific territories. The search values for specific terms are indexed as relative search volume (RSV), which is presented on a scale from 0-100. Avarage annual percentage change (AAPC) and RSV were analyzed to evaluate gain or loss of interest in trends. Search terms were generated for Food and Drug Administration (FDA)-approved PDE5i; tadalafil, sildenafil, vardenafil, avanafil, and their most-used brand names. The data was within “worldwide” from 1 January 2010, to 31 December 2020, using the ‘‘global’’ query category. Results: The overall interest in PDE5i has doubled. Sildenafil has become the most trend PDE5i of today with a regular increase (AAPC: 0.016, p < 0.01). Although the search trend of tadalafil remained almost constant until 2014, the rate of increase in the last 6 years raised and tadalafil has become the 2nd most popular PDE5i recently (AAPC: 0.007, p < 0.01). For vardenafil there has been a decreased interest (AAPC: -0.009, p < 0.01). There is no significant change in avanafil trend (AAPC: 0.000, p: 0.5). All PDE5i interest on GT decreased notably from February to June 2020. But after June, search trends reached the level before the COVID-19 period in a month. Conclusions: These findings show us, with its increasing prevalence, erectile dysfunction (ED) has become a major public health problem. People from different geographies search the internet for ED treatment options. Patients should be informed that ED may be the first sign of many comorbid diseases, and patients with ED should be referred to a health institution for diagnosis and treatment.

Thrombotic diseases seriously threaten human life. Justicia, as a common Chinese medicine, is usually used for anti-inflammatory treatment, and further studies have found that it has an inhibitory effect on platelet aggregation. Therefore, it can be inferred that Justicia can be used as a therapeutic drug for thrombosis. This work aims to reveal the pharmacological mechanism of the anti-thrombotic effect of Justicia through network pharmacology combined with wet experimental verification. During the analysis, 461 compound targets were predicted from various databases and 881 thrombus-related targets were collected. Then, herb-compound-target network and protein–protein interaction network of disease and prediction targets were constructed and cluster analysis was applied to further explore the connection between the targets. In addition, Gene Ontology (GO) and pathway (KEGG) enrichment were used to further determine the association between target proteins and diseases. Finally, the expression of hub target proteins of the core component and the anti-thrombotic effect of Justicia’s core compounds were verified by experiments. In conclusion, the core bioactive components, especially justicidin D, can reduce thrombosis by regulating F2, MMP9, CXCL12, MET, RAC1, PDE5A, and ABCB1. The combination of network pharmacology and the experimental research strategies proposed in this paper provides a comprehensive method for systematically exploring the therapeutic mechanism of multi-component medicine.

International audience; Plasmodium falciparum gametocytes modify the mechanical properties of their erythrocyte host to persist for several weeks in the blood circulation and to be available for mosquitoes. These changes are tightly regulated by the plasmodial phosphodiesterase delta that decreases both the stiffness and the permeability of the infected host cell. Here, we address the effect of the phosphodiesterase inhibitor tadalafil on deformability and permeability of gametocyteinfected erythrocytes. We show that this inhibitor drastically increases isosmotic lysis of gametocyte-infected erythrocytes and impairs their ability to circulate in an in vitro model for splenic retention. These findings indicate that tadalafil represents a novel drug lead potentially capable of blocking malaria parasite transmission by impacting gametocyte circulation.

For years, guanylate cyclase seemed to be homogenic and tissue nonspecific enzyme; however, in the last few years, in light of preclinical and clinical trials, it became an interesting target for pharmacological intervention. There are several possible options leading to an increase in cyclic guanosine monophosphate concentrations. The first one is related to the uses of analogues of natriuretic peptides. The second is related to increasing levels of natriuretic peptides by the inhibition of degradation. The third leads to an increase in cyclic guanosine monophosphate concentration by the inhibition of its degradation by the inhibition of phosphodiesterase type 5. The last option involves increasing the concentration of cyclic guanosine monophosphate by the additional direct activation of soluble guanylate cyclase. Treatment based on the modulation of guanylate cyclase function is one of the most promising technologies in pharmacology. Pharmacological intervention is stable, effective and safe. Especially interesting is the role of stimulators and activators of soluble guanylate cyclase, which are able to increase the enzymatic activity to generate cyclic guanosine monophosphate independently of nitric oxide. Moreover, most of these agents are effective in chronic treatment in heart failure patients and pulmonary hypertension, and have potential to be a first line option.

The cyclic guanosine monophosphate (cGMP) signaling system is one of the most prominent regulators of many physiopathological processes in humans and rodents. It has been strongly established as an accomplished cellular signal involved in the regulation of energy homeostasis and cell metabolism, and pharmacological enhancement of cGMP has shown beneficial effects in metabolic disorders models. cGMP intracellular levels are finely regulated by phosphodiesterases (PDEs). The main enzyme responsible for the degradation of cGMP is PDE5. Preclinical and clinical studies have shown that PDE5 inhibitors (PDE5i) have beneficial effects on improving insulin resistance and glucose metabolism representing a promising therapeutic strategy for the treatment of metabolic disorders. This review aims to describe the molecular basis underlying the use of PDE5i to prompt cell metabolism and summarize current clinical trials assessing the effects of PDE5i on glucose metabolism.

Bromodomain and extraterminal (BET) proteins are promising therapeutic targets for hematological and solid tumors. However, BET inhibitor monotherapy did not show a significant therapeutic benefit for hepatocellular carcinoma (HCC) in preclinical trials. Here, we identified YAP/TAZ genes, as determinants for sensitivity to BET inhibitors. YAP/TAZ expression, especially TAZ, promote resistance to BET inhibitor. In addition, we analyzed that the mRNA level of PDE5 was positively correlated with YAP/TAZ based on TCGA database and demonstrated tadalafil, a PDE5 inhibitor, could block YAP/TAZ protein expression by activating Hippo pathway. Cotreatment with tadalafil and JQ-1 synergistically reduced YAP/TAZ protein expression, suppressed proliferation and induced G0-G1 arrest of cultured HCC cells. JQ-1 alone does not show significant benefits in a mouse model of HCC induced by c-Myc/N-Ras plasmids. In contrast, the combination, tadalafil and JQ-1, successfully suppressed tumor progression, enhanced antitumor immunity by improving the ratio of activated CD8 and extended the survival time of mice. Our data define the key role of YAP/TAZ in mediating resistance to BET inhibitor, described the PDE5/PKG/Hippo/YAP/TAZ axis and identified a common clinical drug that can be developed as an effective combined strategy to overcome BET inhibitor resistance in MYC/Ras-driven HCC.

Pulmonary hypertension (PH), remains a challenging disease with a large impact on both humans and meat-type chickens. PH is characterized by the onset of idiopathic pulmonary arterial hypertension leading to right ventricular failure. In this experiment relative gene expression of adenosine A1 receptor (ADORA1), serotonin transporter (SERT), phosphodiesterase 5A (PDE5) and troponin T2 were compared in hearts from broilers with acute right ventricular failure and from healthy birds. There were major increases in adenosine A1 receptor (177%) and serotonin transporter (475%), and more modest but significant increases in PDE5 (146%) and troponin T2 (140%) gene expressions in broilers with right ventricular failure compared to healthy birds (P

Background The phosphodiesterase-5 inhibitor (PDE5) sildenafil has emerged as a promising treatment for preeclampsia (PE). However, a sildenafil trial was recently halted due to lack of effect and increased neonatal morbidity. Methods Ex vivo dual-sided perfusion of an isolated cotyledon and wire-myography on chorionic plate arteries were performed to study the effects of sildenafil and the non-selective PDE inhibitor vinpocetine on the response to the NO donor sodium nitroprusside (SNP) under healthy and PE conditions. Ex vivo perfusion was also used to study placental transfer of sildenafil in 6 healthy and 2 PE placentas. Furthermore, placental mRNA and protein levels of eNOS, iNOS, PDE5 and PDE1 were quantified. Findings Sildenafil and vinpocetine significantly enhanced SNP responses in chorionic plate arteries of healthy, but not PE placentas. Only sildenafil acutely decreased baseline tension in arteries of both healthy and PE placentas. At steady state, the foetal-to-maternal transfer ratio of sildenafil was 0·37 ± 0·03 in healthy placentas versus 0·66 and 0·47 in the 2 PE placentas. mRNA and protein levels of PDE5, eNOS and iNOS were comparable in both groups, while PDE1 levels were lower in PE. Interpretation The absence of sildenafil-induced NO potentiation in arteries of PE placentas, combined with the non-PDE-mediated effects of sildenafil and the lack of PDE5 upregulation in PE, argue against sildenafil as the preferred drug of use in PE. Moreover, increased placental transfer of sildenafil in PE might underlie the neonatal morbidity in the STRIDER trial. Fund This study was funded by an mRACE Erasmus MC grant.

Sildenafil is known to reduce cardiac hypertrophy through cGMP-dependent protein kinase (cGK) activation. Studies have demonstrated that cGK has a central switching role in modulating vascular smooth muscle cell (VSMC) phenotype in response to vascular injury. Here, we aimed to examine the effects of cGK activation by sildenafil on neointimal formation and platelet aggregation. After vascular injury, neointimal hyperplasia in rat carotid arteries was significantly reduced in the sildenafil-treated group. This effect of sildenafil was accompanied by the reduction of viability and migration of VSMCs. Further experiments showed that the increased cGK activity by sildenafil inhibited platelet-derived growth factor-induced phenotype change of VSMCs from a contractile form to a synthetic one. Conversely, the use of cGK inhibitor or gene transfer of dominant-negative cGK reversed the effects of sildenafil, increasing viability of VSMCs and neointimal formation. Interestingly, sildenafil significantly inhibited platelet aggregation induced by ADP or thrombin. This effect was reversed by cGK inhibitor, suggesting that sildenafil inhibits platelet aggregation via cGK pathway. This study demonstrated that sildenafil inhibited neointimal formation and platelet aggregation via cGK pathway. These results suggest that sildenafil could be a promising candidate for drug-eluting stents for the prevention of both restenosis and stent thrombosis.

Cerebral small vessel disease in deep penetrating arteries is a major cause of lacunar infarcts, white matter lesions and vascular cognitive impairment. Local cerebral blood flow in these small vessels is controlled by endothelial-derived nitric oxide, which exerts a primary vasodilator stimulus on vascular myocytes, via cytoplasmic cyclic GMP. Here, we investigated whether the cGMP-degrading enzyme phosphodiesterase-5 (PDE5) is present in small penetrating arteries in the deep subcortical white matter of older people. Frontal cortical tissue blocks were examined from donated brains of older people (n = 42, 24 male: 18 female, median age 81, range: 59-100 years). PDE5, detected by immunohistochemical labeling, was graded as absent, sparse, or abundant in vascular cells within small arteries in subcortical white matter (vessel outer diameter: 20-100 µm). PDE5 labeling within arterial myocytes was detected in all cases. Degree of PDE5 expression (absent, sparse, or abundant) was not associated with age or with neuropathological diagnosis of small vessel disease. In conclusion, PDE5 is present in vascular myocytes within small penetrating arteries in older people. This is a potential molecular target for pharmacological interventions.

Background Sildenafil, a phosphodiesterase 5 (PDE5) inhibitor, is known to increase the intracellular level of cyclic guanosine monophosphate (cGMP), which causes vasodilation. However, the effect of sildenafil on human hair follicles (hHFs) is unknown. Objective The purpose of this study was to determine the role of sildenafil in hair growth. Methods We investigated the expression of PDE5 in human dermal papilla cells (hDPCs) and hHFs. The effects of sildenafil on hDPC proliferation were evaluated using BrdU assays. The mRNA expression of growth factors and extracellular signal-regulated kinase (ERK) phosphorylation were investigated using real-time PCR and western blotting, respectively. Additionally, anagen induction and perifollicular vessel formation were evaluated using an in vivo mice model. Results We confirmed high expression of PDE5 in hDPCs and hHFs. Sildenafil enhances proliferation of hDPCs and up-regulates the mRNA expression of vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF), which are responsible for hair growth. Additionally, sildenafil up-regulates the levels of phosphorylated ERK and accelerates anagen induction by stimulating perifollicular vessel formation after topical application in mice. Conclusion Our study demonstrates for the first time, the significant therapeutic potential of sildenafil on hair growth and its potential use in treatment of alopecia.

Cyclic GMP (cGMP) is an important intracellular regulator of endochondral bone growth and skeletal remodeling. Tadalafil, an inhibitor of the phosphodiesterase (PDE) type 5 (PDE5) that specifically hydrolyzes cGMP, is increasingly used to treat children with pulmonary arterial hypertension (PAH), but the effect of tadalafil on bone growth and strength has not been previously investigated. In this study, we first analyzed the expression of transcripts encoding PDEs in primary cultures of chondrocytes from newborn rat epiphyses. We detected robust expression of PDE5 as the major phosphodiesterase hydrolyzing cGMP. Time-course experiments showed that C-type natriuretic peptide increased intracellular levels of cGMP in primary chondrocytes with a peak at 2 min, and in the presence of tadalafil the peak level of intracellular cGMP was 37% greater ( P < 0.01) and the decline was significantly attenuated. Next, we treated 1-mo-old Sprague Dawley rats with vehicle or tadalafil for 3 wk. Although 10 mg·kg−1·day−1 tadalafil led to a significant 52% ( P < 0.01) increase in tissue levels of cGMP and a 9% reduction ( P < 0.01) in bodyweight gain, it did not alter long bone length, cortical or trabecular bone properties, and histological features. In conclusion, our results indicate that PDE5 is highly expressed in growth plate chondrocytes, and short-term tadalafil treatment of growing rats at doses comparable to those used in children with PAH has neither obvious beneficial effect on long bone growth nor any observable adverse effect on growth plate structure and trabecular and cortical bone structure.

AIM To investigate the potential effect of inhibitors of phosphodiesterase-5 (PDE-5) for therapy of portal hypertension in liver cirrhosis. METHODS In the rat model of thioacetamide-induced liver fibrosis/cirrhosis the nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathway was investigated. Expression and localization of PDE-5, the enzyme that converts vasodilating cGMP into inactive 5’-GMP, was in the focus of the study. Hepatic gene expression of key components of the NO-cGMP pathway was determined by qRT-PCR: Endothelial NO synthase (eNOS), inducible NO synthase (iNOS), soluble guanylate cyclase subunits α1 and β1 (sGCa1, sGCb1), and PDE-5. Hepatic PDE-5 protein expression and localization were detected by immunohistochemistry. Serum cGMP concentrations were measured using ELISA. Acute effects of the PDE-5 inhibitor Sildenafil (0.1 mg/kg or 1.0 mg/kg) on portal and systemic hemodynamics were investigated using pressure transducers. RESULTS Hepatic gene expression of eNOS (2.2-fold; P = 0.003), sGCa1 (1.7-fold; P = 0.003), sGCb1 (3.0-fold; P = 0.003), and PDE-5 (11-fold; P = 0.003) was increased in cirrhotic livers compared to healthy livers. Overexpression of PDE-5 (7.7-fold; P = 0.006) was less pronounced in fibrotic livers. iNOS expression was only detected in fibrotic and cirrhotic livers. In healthy liver, PDE-5 protein was localized primarily in zone 3 hepatocytes and to a lesser extent in perisinusoidal cells. This zonation was disturbed in cirrhosis: PDE-5 protein expression in perisinusoidal cells was induced approximately 8-fold. In addition, PDE-5-expressing cells were also found in fibrous septa. Serum cGMP concentrations were reduced in rats with cirrhotic livers by approximately 40%. Inhibition of PDE-5 by Sildenafil caused a significant increase in serum cGMP concentrations [+ 64% in healthy rats (P = 0.024), + 85% in cirrhotic rats (P = 0.018)]. Concomitantly, the portal venous pressure was reduced by 19% in rats with liver cirrhosis. CONCLUSION Overexpression and abrogated zonation of PDE-5 likely contribute to the pathogenesis of cirrhotic portal hypertension. PDE-5 inhibition may therefore be a reasonable therapeutic approach for portal hypertension.

Idiopathic pulmonary arterial hypertension (IPAH) is a rapidly progressive disease with several treatment options. Long-term mortality remains high with great heterogeneity in treatment response. Even though most of the pathology of IPAH is observed in the lung, there is systemic involvement. Platelets from patients with IPAH have characteristic metabolic shifts and defects in activation; therefore, we investigated whether they could be used to identify other disease-specific abnormalities. We used proteomics to investigate protein expression changes in platelets from patients with IPAH compared with healthy controls. Key abnormalities of nitric oxide pathway were tested in platelets from a larger cohort of unique patients with IPAH. Platelets showed abnormalities in the prostacyclin and nitric oxide pathways, which are dysregulated in IPAH and hence targets of therapy. We detected reduced expression of G protein αs and increased expression of the regulatory subunits of the cAMP-dependent protein kinase (PKA) type II isoforms, supporting an overall decrease in the activation of the prostacyclin pathway. We noted reduced levels of the soluble guanylate cyclase (sGC) subunits and increased expression of the phosphodiesterase type 5 A (PDE5A), conditions that affect the response to nitric oxide. Ensuing analysis of 38 unique patients with IPAH demonstrated considerable variation in the levels and specific activity of sGC, a finding with novel implications for personalized therapy. Platelets have some of the characteristic vasoactive signal abnormalities seen in IPAH and may provide comprehensive ex vivo mechanistic information to direct therapeutic decisions.

Context The leech and centipede granules have good curative effects on many diabetic vascular diseases, including diabetes-induced erectile dysfunction (DIED). Objective To explore the effect of leech and centipede on erectile function in rats with diabetes-induced erectile dysfunction and its possible mechanism. Materials and methods Thirty male Sprague–Dawley DIED rats were randomly divided into the model group (Group M), low-dose group (Group DD), high-dose group (Group DG) and tadalafil group (Group T) (n = 6); diabetic rats were induced by streptozotocin. Apomorphine was used to induce diabetic erectile dysfunction. The ‘leech-centipede’ granules (0.15 and 0.6 g/kg) were intragastrically administered in the DD and DG groups for 8 weeks. Blood glucose, serum insulin, testosterone, cGMP levels and protein expression changes were measured in each group. Results After 8 weeks, the erectile function of rats in the DG group significantly improved (1.26 ± 0.73). Penis tissue cGMP levels were higher in the DG group (1.48 ± 0.11) than in the M group (0.58 ± 0.15). Protein and mRNA expression levels of NOS were significantly higher (0.77 ± 0.05; 0.61 ± 0.02) but those of PDE5 (0.43 ± 0.05; 0.61 ± 0.03) were lower in the DG group than in the M group (0.37 ± 0.06; 0.51 ± 0.01; 0.78 ± 0.06; 0.81 ± 0.04). Conclusion The leech-centipede can improve erectile dysfunction in DIED rats by regulating the expression of cGMP, NOS, and PDE5-related molecules in the PDE5 pathway. This study provides a potential mechanism for the treatment of DIED with leech-centipede.

Skeletal muscle damage is a common clinical manifestation of systemic sclerosis (SSc). C-X-C chemokine ligand 10 (CXCL10) is involved in myopathy and cardiomyopathy development and is associated with a more severe SSc prognosis. Interestingly, the phosphodiesterase type 5 inhibitor (PDE5i) sildenafil reduces CXCL10 sera levels of patients with diabetic cardiomyopathy and in cardiomyocytes. Here, we analyzed the levels of CXCL10 in the sera of 116 SSc vs. 35 healthy subjects and explored differences in 17 SSc patients on stable treatment with sildenafil. CXCL10 sera levels were three-fold higher in SSc vs. healthy controls, independent of subset and antibody positivity. Sildenafil treatment was associated with lower CXCL10 sera levels. Serum CXCL10 strongly correlated with the clinical severity of muscle involvement and with creatine kinase (CK) serum concentration, suggesting a potential involvement in muscle damage in SSc. In vitro, sildenafil dose-dependently reduced CXCL10 release by activated myocytes and impaired cytokine-induced Signal transducer and activator of transcription 1 (STAT1), Nuclear factor-κB (NFκB) and c-Jun N-terminal kinase (JNK) phosphorylation. This was also seen in cardiomyocytes. Sildenafil-induced CXCL10 inhibition at the systemic and human muscle cell level supports the hypothesis that PDE5i could be a potential therapeutic therapy to prevent and treat muscle damage in SSc.

Phosphodiesterase inhibitors (PDE5i) are considered the first line therapy for erectile dysfunction. All PDE5i available on the market are structurally related; their main differences relate to their pharmacokinetic parameters. For these treatments to be effective and safe, it is necessary that these drugs are in the appropriate doses and that they reach adequate concentrations in the plasma. For this purpose, it is essential to perform therapeutic monitoring using bioanalytical methods. In this way, the present work aimed to develop and validate a new bioanalytical method, based on LC-MS/MS, for the simultaneous quantification of six commercially available PDE5i (avanafil, lodenafil, sildenafil, tadalafil, udenafil, and vardenafil). For this purpose, the human plasma was extracted with diethyl ether and sulfaquinoxaline was established as an internal standard. Separation was achieved using an Xbridge C18 column at 40 °C as the stationary phase, using water and acetonitrile as the mobile phase (both with formic acid and ammonium formate) in gradient mode. The method was validated according to the current guidelines and was found to be selective, linear (from 1 to 200 ng.mL−1 for all drugs except for tadalafil which is from 5 to 200 ng.mL−1), precise, accurate, and free of residual and matrix effects. The drugs were considered stable in plasma and in solution under different conditions. The method was applied to volunteerssamples, demonstrating that the method can be used routinely and may be useful in future studies on pharmacokinetics and therapeutic monitoring.

Lactic acid in tumor microenvironment inhibits iNKT cell functions and thus dampens their anti-tumor efficacy. The underlying mechanisms remain unclear. Here, we show that phosphodiesterase-5 inhibitors, sildenafil and tadalafil, promote IFN-γ and IL-4 production in iNKT cells in a cGMP-PKG pathway dependent manner. To favor their cytokine production, iNKT cells reduce Pde5a mRNA lever after activation. In line with the reduction of cytokines caused by lactic acid, lactic acid elevates Pde5a mRNA lever in activated iNKT cells. As a result, phosphodiesterase-5 inhibitor partially restores the cytokine production in lactic acid-treated cells. Our results demonstrate that phosphodiesterase-5 inhibits cytokine production in iNKT cells, and that contributes to the lactic acid-caused dysfunction of iNKT cells.

Renal arteriolar tone depends considerably on the dilatory action of nitric oxide (NO) via activation of soluble guanylyl cyclase (sGC) and cGMP action. NO deficiency and hypoxia/reoxygenation are important pathophysiological factors in the development of acute kidney injury. It was hypothesized that the NO-sGC-cGMP system functions differently in renal afferent arterioles (AA) compared with efferent arterioles (EA) and that the sGC activator cinaciguat differentially dilates these arterioles. Experiments were performed in isolated, perfused mouse glomerular arterioles. Hypoxia (0.1% oxygen) was achieved by using a hypoxia chamber. Phosphodiesterase 5 (PDE5) and sGC subunits were considerably expressed on the mRNA level in AA. PDE5 inhibition with sildenafil, which blocks cGMP degradation, diminished the responses to ANG II bolus application in AA, but not significantly in EA. Vasodilation induced by sildenafil in ANG II-preconstricted vessels was stronger in EA than AA. Cinaciguat, an NO- and heme-independent sGC activator, dilated EA more strongly than AA after NG-nitro-l-arginine methyl ester (l-NAME; NO synthase inhibitor) treatment and preconstriction with ANG II. Cinaciguat-induced dilatation of l-NAME-pretreated and ANG II-preconstricted arterioles was similar to controls without l-NAME treatment. Cinaciguat also induced dilatation in iodinated contrast medium treated AA. Furthermore, it dilated EA, but not AA, after hypoxia/reoxygenation. The results reveal an important role of the NO-sGC-cGMP system for renal dilatation and that EA have a more potent sGC activated dilatory system. Furthermore, AA seem to be more sensitive to hypoxia/reoxygenation than EA under these experimental conditions.

The kidneys are vital organs that play an important role in removing waste materials from the blood, electrolyte balance, blood pressure regulation, and red blood cell genesis. Kidney disease can be caused by various factors, including diabetes, ischemia/reperfusion injury, and nephrotoxic agents. Inflammation and oxidative stress play a key role in the progression and pathogenesis of kidney diseases. Acute kidney injury (AKI) and chronic kidney disease (CKD) are important health problems worldwide, as they are associated with a long-term hospital stay, and increased morbidity and mortality in high-risk patients. Current standard therapeutic options are not sufficient to delay or stop the loss of kidney function. Therefore, it is necessary to develop new therapeutic options. Phosphodiesterase 5 inhibitors (PDE5Is) are a currently available class of drugs that are used to treat erectile dysfunction and pulmonary hypertension in humans. However, recent evidence suggests that PDE5Is have beneficial renoprotective effects via a variety of mechanisms. In this review, the benefits of PDE5 inhibitors in clinical conditions associated with kidney disease, such as diabetic nephropathy, ischemia–reperfusion injury, and acute and chronic kidney injury, are summarized.

Erectile dysfunction is a common entity in clinical practice. Primary erectile dysfunction, not related to vasculopathy or psychiatric disorder, can be readily treated with phosphodiesterase inhibitors. These drugs have many physiologic effects that can alter a patient's hemodynamic profile considerably, especially in the presence of concomitant structural heart disease, specifically valvular heart disease. Although some contraindications to the use of PDE5 inhibitors in patients with cardiovascular disease are defined, the effect of these drugs in the presence of valvular heart disease is not well documented. The purpose of this review is to analyze the data regarding the safety of PDE5 inhibitors in patients with valvular heart disease.

Posttraumatic osteonecrosis of the femoral head (ONFH) affects patients at different ages and may lead to functional limitation and joint replacement, with total hip arthroplasty, which is a costly procedure. Proposed methods to optimize ischemic tissue regeneration have been reported. Phosphodiesterase-5 inhibitors act by inhibiting the degradation of guanosine 3',5'-cyclic monophosphate in the nitric oxide pathway, increasing its bioavailability and promoting vascular endothelial growth factor (VEGF)-mediated neovascular recruitment and the induction of tissue regeneration in the traumatized bone. Thirty male Sprague-Dawley rats (6 months old) were subjected to an experimental model of traumatic ONFH divided into two groups, according to the administration of 5 mg/kg sildenafil or water (control group). Rats were then killed at 7, 14, and 21 days. Histological (Goldner's trichrome), histochemical (periodic acid-Schiff [PAS]), and immunohistochemical (VEGF and osteopontin [OPN]) techniques were used to quantify bone and vascular responses. Higher levels of VEGF (p < 0.01) and OPN (p < 0.01) immunostaining in the epiphysis, the greater formation of osteoid tissue (p < 0.01 on Day 7; p < 0.05 on Day 14), and higher levels of PAS staining (p < 0.01 on Day 7) were observed in the sildenafil-treated group. The present study demonstrated that sildenafil optimized bone tissue regeneration by increasing VEGF signaling and OPN expression, with increased bone formation (osteoid and carbohydrate macromolecule deposition) in the early stages following traumatic ischemic insult. Thus, sildenafil treatment may improve the prognosis of patients with osteonecrosis.

Background. Erectile dysfunction has remained as one of the major global health issues. Since the discovery of phosphodiesterase type 5 inhibitors, a significant portion of the patients has solved the issue of erectile dysfunction. However, the wide distribution of phosphodiesterase type 5 enzymes at various sites of the body led phosphodiesterase type 5 inhibitors to cause various unnecessary outcomes. Hence, it is vital to look for and find optional agents that could solve these limitations. The people of Ethiopia depend heavily on medicinal plants to ease their ailments, including erectile dysfunction. Aim of the study. The current study was carried out to systematically review the traditional medicinal plants used for the management of erectile dysfunction in Ethiopia. Method. A systematic and manual search was conducted to retrieve relevant articles published from 2000 to August 2020. Electronic databases of PubMed (Medline), Google Scholar, and grey literature were employed to access the studies. Accordingly, fifty-four published articles and thesis papers were finally included in this study. Result. Seventy plant species have been reported for the management of erectile dysfunction in Ethiopia. The commonly recorded family was Fabaceae, followed by Asteraceae, Malvaceae, Convolvulaceae, and Solanaceae. The plant species that represented the highest number of citations were Asparagus africanus, succeeded by Ricinus communis and Carissa spinarum. The commonest plant part used was roots. Majority of the medicinal plants were administered orally. The growth forms of the reported species were primarily herbs followed by shrubs. Conclusion. The present review compiled medicinal plants utilized by the Ethiopian community to manage erectile dysfunction. The findings will serve as a reference for the selection of plants for further pharmacological, toxicological, and phytochemical investigations in developing new plant-based drugs used for the treatment of erectile dysfunction.