Effectiveness and Safety of Phosphodiesterase 5 Inhibitors in Patients with Cardiovascular Disease and Hypertension

Pentaclethra macrophylla leaves reduce blood glucose level, improve sexual behavior and modulate critical enzymes associated with diabetes-erectile dysfunction morbidity in rats

OBJECTIVES

This research work studied the phenolic composition of Pentaclethra macrophylla (PM), the inclusion of dietary supplementation of PM leaves on sexual functions and its connection to inhibit enzymes (arginase and phosphodiesterase-5) and nitric oxide level, linked to type 2 diabetes-induced erectile dysfunction in rats.

METHODS

Gallic acid, chlorogenic and ellagic acids, Kaempferol, and epicatechin etc. was spotted with High performance liquid chromatography-diode array detector from PM extract. Twenty-five (25) rats were used for the study. Five rats were placed with basal diet; diets not supplemented with PM leaves (normal rat group) while twenty rats were made diabetic by feeding them with high fat diet for two weeks, prior to single injection with 35 mg/kg of streptozotocin (STZ). After checking with glucometer, experimental animals with blood glucose level >250 mg/dL were accepted as diabetic. The diabetic rats were subsequently divided into four groups of five rats each (n=5). The diabetic rats were placed on basal diet, or diets supplemented with PM leaves (10 % or 5 % inclusion) or sildenafil citrate (SC).

RESULTS

The result revealed that PM supplemented diets caused significant (p<0.05) reduction in blood glucose level, and augmented erectile function by inhibiting arginase and PDE5 activities as well as enhancing nitric oxide level.

CONCLUSIONS

In conclusion, dietary inclusion of PM leaves could serve as a potent nutraceutical source in hyperglycemia induced erectile dysfunction management.

Spectroscopic determination of hydrophobic adulterant tadalafil by aptasensor based ellipsometry

Tadalafil is one of the selective phosphodiesterase type 5 inhibitors (PDE5) and serves as the active compound in drugs used for the treatment of erectile dysfunction. These PDE5 inhibitors are prescribed under medical supervision. However, cases of adulteration of dietary supplements with PDE5 inhibitors or their unapproved analogs have been reported worldwide. The presence of the PDE5 inhibitors in such supplements poses a serious health risk to consumers, particularly when combined with certain nitrate-containing drugs, as their toxic effects have not been thoroughly assessed and may result in unpredictable adverse reactions. Therefore, it is crucial to detect adulteration in these dietary supplements. However, current methods for PDE5 inhibitor detection rely on time-consuming and expensive analytical techniques, although they are sensitive. In this study, we propose an aptasensor based on ellipsometry for the detection of PDE5 inhibitors. To enhance the detection specificity for PDE5 inhibitors, we designed an aptamer with a hydrophobic pocket that incorporates a guanine base-rich region and a three-way junction. This design is particularly effective considering the poor aqueous solubility of PDE5 inhibitors. Preliminary results demonstrate that tadalafil detection in various media can be achieved within the range of 1-2000 ng/mL. The limit of detection for the active compound of tadalafil is as low as 1.82 ng/mL.

Fluorescence "turn-on" sensing for five PDE5 inhibitors in functional food based on bimetallic nanoclusters

Some phosphodiesterase type-5 (PDE5) inhibitors are active ingredients of prescription drugs that are widely used in the treatment of erectile dysfunction (ED). Recently, a large number of substances with this activity have been developed. Illegal addition of PDE5 inhibitors to foods could lead to cardiovascular diseases and even death, which poses a serious threat to food safety, therefore an on-site rapid screening method is urgently needed. Herein, a host functionalized bimetallic nanoclusters, CD/Au Ag NCs, were synthesized through self-assembly of 6-Aza-2-thiothymine gold nanoclusters (ATT-Au NCs), Arginine silver nanoclusters (Arg-Ag NCs) and carboxymethyl β-cyclodextrin (β-CMCD). The introduction of Rhodamine 6G (R6G) could quench the fluorescence of CD/Au Ag NCs based on the inner filter effect (IFE) and fluorescence resonance energy transfer effect (FRET). Importantly, it was discovered that several PDE5 inhibitors exhibited a higher binding affinity to β-CMCD and could displace R6G binding with CD cavity, which disrupted the fluorescence quenching effects and resulted in the fluorescence recovery of CD/Au Ag NCs. This fluorescence turn-on signal could be utilized for the detection of PDE5 inhibitors. At present, emerging PDE5 inhibitor analogues pose a great challenge to food safety due to their unknown efficacy and safety. The proposed method holds the advantages of high sensitivity, simple probe synthesis, easy operation, and simultaneous detection of multiple PDE5 inhibitors. Meanwhile, the successful application in functional food sample demonstrated its high application potential in multiple PDE5 inhibitors screening.

Modulation of the nitric oxide/cGMP pathway in cardiac contraction and relaxation: Potential role in heart failure treatment

Evidence exists that heart failure (HF) has an overall impact of 1-2 % in the global population being often associated with comorbidities that contribute to increased disease prevalence, hospitalization, and mortality. Recent advances in pharmacological approaches have significantly improved clinical outcomes for patients with vascular injury and HF. Nevertheless, there remains an unmet need to clarify the crucial role of nitric oxide/cyclic guanosine 3',5'-monophosphate (NO/cGMP) signalling in cardiac contraction and relaxation, to better identify the key mechanisms involved in the pathophysiology of myocardial dysfunction both with reduced (HFrEF) as well as preserved ejection fraction (HFpEF). Indeed, NO signalling plays a crucial role in cardiovascular homeostasis and its dysregulation induces a significant increase in oxidative and nitrosative stress, producing anatomical and physiological cardiac alterations that can lead to heart failure. The present review aims to examine the molecular mechanisms involved in the bioavailability of NO and its modulation of downstream pathways. In particular, we focus on the main therapeutic targets and emphasize the recent evidence of preclinical and clinical studies, describing the different emerging therapeutic strategies developed to counteract NO impaired signalling and cardiovascular disease (CVD) development.

Inhibition of phosphodiesterase 5A by tadalafil improves SIRT1 expression and activity in insulin-resistant podocytes

A decrease in intracellular levels of 3',5'-cyclic guanosine monophosphate (cGMP) has been implicated in the progression of diabetic nephropathy. Hyperglycemia significantly inhibits cGMP-dependent pathway activity in the kidney, leading to glomerular damage and proteinuria. The enhancement of activity of this pathway that is associated with an elevation of cGMP levels may be achieved by inhibition of the cGMP specific phosphodiesterase 5A (PDE5A) using selective inhibitors, such as tadalafil. Hyperglycemia decreased the insulin responsiveness of podocytes and impaired podocyte function. These effects were associated with lower protein amounts and activity of the protein deacetylase sirtuin 1 (SIRT1) and a decrease in the phosphorylation of adenosine monophosphate-dependent protein kinase (AMPK). We found that PDE5A protein levels increased in hyperglycemia, and PDE5A downregulation improved the insulin responsiveness of podocytes with reestablished SIRT1 expression and activity. PDE5A inhibitors potentiate nitric oxide (NO)/cGMP signaling, and NO modulates the activity and expression of SIRT1. Therefore, we investigated the effects of tadalafil on SIRT1 and AMPK in the context of improving the insulin sensitivity in podocytes and podocyte function in hyperglycemia. Our study revealed that tadalafil restored SIRT1 expression and activity and activated AMPK by increasing its phosphorylation. Tadalafil also restored stimulating effect of insulin on glucose transport in podocytes with high glucose-induced insulin resistance. Additionally, tadalafil improved the function of podocytes that were exposed to high glucose concentrations. Our results display novel mechanisms involved in the pathogenesis of glomerulopathies in diabetes, which may contribute to the development of more effective treatment strategies for diabetic nephropathy.

An overview of the history, current strategies, and potential future treatment approaches in erectile dysfunction: a comprehensive review

INTRODUCTION

Erectile dysfunction (ED) is one of the most common urologic problems in men worldwide, with an approximately high incidence rate, significantly affecting patients' quality of life and their sexual partners.

OBJECTIVES

Due to the association of this disorder with essential diseases such as cardiovascular disease and diabetes, its prevention and treatment are vital for overall human physiologic and psychological health. Along with reviewing the history of treatment and current methods, we seek new approaches to curb this issue in the future.

METHODS

In this review, investigations were based on the focus of each section's content or conducted on an ad hoc basis. Searches were performed in Scopus and PubMed.

RESULTS

In recent years, many treatments for ED have been reported besides oral administration of phosphodiesterase 5 inhibitors such as sildenafil and tadalafil (approved by the Food and Drug Administration). Common oral medications, intracavernous injections, herbal therapies (eg, herbal phosphodiesterase 5 inhibitors), and topical/transdermal medications are routine ED treatment approaches. Moreover, some novel medications are innovative candidates for completing ED's treatment protocols: stem cell injection, low-intensity extracorporeal shock wave therapy, platelet-rich plasma injection, gene therapy, amniotic fluid matrices, rho-kinase inhibitors, melanocortin receptor antagonists, maxi-K channel activators (ie, large-conductance calcium-activated potassium channels), guanylate cyclase activators, and nitric oxide donors.

CONCLUSION

Due to the importance of this complicated problem in men's society, a faster course of treatment trends toward new methods is needed to increase efficiency. Combining the mentioned treatments and attentively examining their efficacy through programmed clinical trials can be a big step toward solving this global problem.

Effects of Erectile Dysfunction Drugs Use on T-cells and Immune Markers on Men Who Have Sex with Men

Objective

Examine prospective relationships between erectile dysfunction (ED) drugs EDand CD4 and CD8 T-cells, and immune markers among men who have sex with men (MSM).

Methods

Data from Multicenter AIDS Cohort Study, an observational prospective cohort study, with semi-annual follow-ups conducted in four U.S. centers from 1998 onwards was used. Marginal structural models using g-computation was fitted to estimate the mean differences for the effects of self-reported ED drug use on CD4 and CD8 T-cell outcomes and immune biomarkers.

Results

Total of 1,391 men with HIV (MWH) and 307 men without HIV (MWOH) was included. Baseline mean CD4 cell count among MWH and MWOH was 499.9 cells/μL and 966.7 cells/μL, respectively. At baseline, 41.8% of MWH were virally suppressed. ED drug users reported a mean of 44.4 months of exposure to ED drugs. ED drug use was associated with increased CD4 cell outcomes among MWH but not MWOH. Mean differences in CD4 cell counts after 1 year of ED drug use was 57.6 cells/μL and increased to 117.7 after 10 years among MWH. CD8 counts were higher in ED drug users among MWH over 10 years than non-users; no consistent differences were found among MWOH. ED drug use appeared to reduce immune marker levels, such as IL-6 and increase markers, such as IL-10. We observed similar effects of ED drug use on biomarker levels among MWOH.

Conclusion

Long-term use of ED drugs do not adversely affect immune function among MWH or MWOH. Future studies on the relationships between different types of ED drugs and effects on T-cell subtypes are warranted.

Redox Switches Controlling Nitric Oxide Signaling in the Resistance Vasculature and Implications for Blood Pressure Regulation: Mid-Career Award for Research Excellence 2020

The arterial resistance vasculature modulates blood pressure and flow to match oxygen delivery to tissue metabolic demand. As such, resistance arteries and arterioles have evolved a series of highly orchestrated cell-cell communication mechanisms between endothelial cells and vascular smooth muscle cells to regulate vascular tone. In response to neurohormonal agonists, release of several intracellular molecules, including nitric oxide, evokes changes in vascular tone. We and others have uncovered novel redox switches in the walls of resistance arteries that govern nitric oxide compartmentalization and diffusion. In this review, we discuss our current understanding of redox switches controlling nitric oxide signaling in endothelial and vascular smooth muscle cells, focusing on new mechanistic insights, physiological and pathophysiological implications, and advances in therapeutic strategies for hypertension and other diseases.

Impacts of caffeine on resistant chicken's performance and cardiovascular gene expression

We previously reported a study on 288 broiler (Gallus gallus) chicks who received caffeine in water between days 3 and 42, at levels of 0, 6.25, 12.5, 25, 50 and 100 mg/kg body weight (BW)/day. In the previous report, we found that caffeine caused pulmonary hypertension (PH)-associated mortality in a significant minority (20%-30%) of birds, including right ventricular hypertrophy and ascites. We have also shown a significant upregulation of the serotonin transporter (SERT), troponin T2, adenosine A₁ receptor (ADORA1) and phosphodiesterase 5A (PDE5) in chicken suffering from PH. Here, we examine the resistant (survived) chicks from the first study that had not died due to acute heart failure and did not have clinical signs of pulmonary hypertension. Our goal was to determine whether birds who lacked overt signs of disease had subclinical manifestations, including similar changes in gene expression, growth rates and altered systemic haemodynamics. We found that growth was significantly increased by caffeine consumption (p < 0.01) at low doses; however, dosage over 50 mg/BW/d had remarkable adverse effects on growth (p < 0.01). Blood pressure, troponin T2 and PDE5 gene expression were not significantly altered by caffeine administration (p > 0.05). However, SERT gene expression linearly increased with increasing caffeine dosage (p < 0.01). The impact of caffeine on ADORA1 gene expression was dose dependent and nonlinear. In conclusion, despite the significant effects of caffeine on birds' growth, no significant negative effects of caffeine were observed on the cardiovascular function of resistant chickens. This work provides valuable information for further study on different dosage of caffeine in an animal model.

Development of a group-specific antibody-based immunoassay method for simultaneously detecting sildenafil-like adulterants in herbal spirit drinks

Phosphodiesterase type 5 (PDE-5) inhibitors are commonly used to treat erectile dysfunction. There is a problem with synthesis and illegal use of a wide range of analogues of the licenced drugs and a simple class-wide analytical method is required. In this work, based on structural modelling, we developed an immunological method using norneovardenafil as a hapten as it contains only the general sub-structure and the common features of sildenafil-like adulterants, such as hydrophobic centres, hydrogen-bond donor atoms and hydrogen-bond acceptor atoms. Thus theoretically it could induce production of antibody which could recognise multiple sildenafil-like adulterants. By immunising rabbits, a group-specific polyclonal antibody was obtained with the desired broad-spectrum molecular recognition performance against sildenafil-like adulterants. Then, an indirect competitive enzyme-linked immunosorbent assay (icELISA) was developed for the detection of sildenafil-like adulterants in herbal spirit drinks. Under the optimised conditions, the icELISA method showed broad linear ranges for acetildenafil, sildenafil and vardenafil respectively of 0.7 to 27.7 μg/kg, 1.0 to 70.7 μg/kg and 1.5 to 22.7 μg/kg, with half-maximal inhibition concentration (IC₅₀) values of 4.5 μg/kg, 8.3 μg/kg and 5.7 μg/kg, respectively. For eleven herbal spirit drinks, there was good agreement between total levels of sildenafil-like adulterants measured by icELISA and levels of each of four individual adulterants determined by LC-MS/MS. In short, the developed icELISA can be employed for rapid and simple screening for adulteration of herbal spirit drinks with sildenafil-like compounds.

Effects of chronic type 5 phosphodiesterase inhibition on penile microvascular reactivity in hypertensive patients with erectile dysfunction: a randomized crossover placebo-controlled trial

This randomized crossover and placebo-controlled trial evaluated the effects of daily use of sildenafil citrate (SIL, 1-month 50 mg twice daily) on penile and systemic endothelial microvascular function in hypertensive patients presenting with erectile dysfunction. The effects of SIL on arterial pressure were evaluated using ambulatory blood pressure monitoring (ABPM). Fifty patients diagnosed with primary arterial hypertension and erectile dysfunction (aged 57.4 ± 5.6 years), recruited in a tertiary public hospital, were treated with SIL (50 mg twice daily) or placebo (PLA) for two 30-day periods with a 30-day washout between them. Laser speckle contrast imaging coupled with acetylcholine skin iontophoresis was used to evaluate penile and systemic (forearm) cutaneous microvascular reactivity. SIL treatment increased penile basal microvascular flow (P = 0.002) and maximal endothelial-dependent peak response to skin iontophoresis of acetylcholine (ACh, P = 0.006). The area under the curve of microvascular vasodilation induced by ACh was also significantly increased (P = 0.02). Lastly, SIL treatment did not modify systemic microvascular reactivity. Twenty-four-hour ABPM (P = 0.0002) and daytime (P = 0.002) and nighttime (P = 0.001) mean diastolic blood pressure values were significantly reduced after SIL treatment. The scores of the Simplified International Index of Erectile Function (P < 0.0001) and the number of patients with positive responses to Sexual Encounter Profile question 3 (P < 0.0001) also increased after SIL treatment. Penile endothelium-dependent microvascular reactivity improved after continuous use of sildenafil in hypertensive patients with erectile dysfunction; the treatment also reduced blood pressure, suggesting that, in addition to improving erectile function, daily use of sildenafil could improve blood pressure control.

Effects of shRNA-mediated silencing of PDE5A3 on intracellular cGMP and free Ca2+ levels and human prostate smooth muscle cell proliferation from benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) with lower urinary tract symptoms (LUTS) is a common disease among elderly men, for which safe and effective treatment strategies remain limited. The aim of the present study was to explore the potential effects of phosphodiesterase 5A3 (PDE5A3) silencing on human prostate smooth muscle cells (HPSMCs). HPSMCs were initially obtained from patients with BPH/LUTS. Short hairpin RNA (shRNA) targeting the PDE5A3 gene was subsequently transfected into cultured HPSMCs. The expression of PDE5A3 was measured using reverse transcription-quantitative PCR and western blotting. cGMP levels were then measured using western blotting and immunocytochemical staining and intracellular Ca²⁺ concentration was measured using rhod2-AM in HPSMCs after transfection. HPSMC proliferation was also observed within 4 days. Cells transfected with PDE5A3-shRNA2 exhibited the most notable decline in PDE5A3 expression compared with that in the Control or NC groups. cGMP levels in HPSMCs transfected with PDE5A3-shRNA2 was significantly increased compared with those in the Control or NC groups, whereas intracellular Ca²⁺ concentrations in cells in the PDE5A3-shRNA2 group were decreased compared with that in the Control or NC groups. The proliferation of HPSMCs in the PDE5A3-shRNA2 group was also inhibited compared with that in the Control or NC groups after 72 h of culture. In conclusion, shRNA-mediated silencing of PDE5A3 was able to increase the levels of cGMP whilst reducing the concentration of Ca²⁺ in HPSMCs, in turn suppressing their proliferation. These findings may potentially provide a novel therapeutic target for treating BPH/LUTS.

Tadalafil alleviates cisplatin-induced reproductive toxicity through the activation of the Nrf2/HO-1 pathway and the inhibition of oxidative stress and apoptosis in male rats

Male reproductive toxicity is a well-known adverse effect of cisplatin (CIS), an important antineoplastic agent used to control several types of cancers. Tadalafil (TDF), is a long-acting phosphodiesterase-5 (PDE5) inhibitor commonly used as treatment for erectile dysfunction. The aim of this work was to study the possible protective effect of TDF against CIS-induced testicular toxicity in rats and the possible involvement of Nrf2/HO-1 pathway, which demonstrates antioxidant and inflammatory activities utilizing zinc protoporphyrin-IX (ZnPP) as HO-1 inhibitor. Results revealed that TDF attenuated the CIS-induced disturbances in sperm count and activities, normalized the serum testosterone level, improved the CIS-induced changes in epididymal and testicular weights and restored the normal structure of testicular tissues. In addition, TDF upregulated the gene expression levels of Nrf2 and HO-1 and the activity of HO-1 whereas, it reduced the CIS-induced changes in testicular oxidative stress markers and the levels of inflammatory mediators (TNF-α and iNOS). Furthermore, TDF antagonized the CIS-induced increase in testicular gene expression of apoptotic markers caspase-3 and Bax, and the decrease in Bcl-2. However, ZnPP co-administration significantly attenuated all TDF-mediated improvements in CIS-induced testicular toxicity, biochemical changes, and apoptosis. In conclusion, TDF exerts a protective effect against CIS-induced reproductive toxicity in males, through different mechanisms, besides its inhibitory action to PDE5, possibly mediated by the upregulation of Nrf2/HO-1, along with its antioxidant, anti-inflammatory, and anti-apoptotic effects. Hence, the use of TDF represents a promising therapeutic approach to protect the male reproductive system from the harmful toxic effects of CIS.

Efficacy and Side Effects of Drugs Commonly Used for the Treatment of Lower Urinary Tract Symptoms Associated With Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is the most common benign disease of the prostate gland and is caused by benign hyperplasia of the smooth muscle cells and stromal cells in this important gland. BPH is also the most common disease underlying lower urinary tract symptoms (LUTS). The incidence of BPH increases with age and affects more than half of all men 50 years or older. BPH mainly exerts effects on urinary function and can seriously reduce a patient's quality of life. At present, treatment for BPH aims primarily to improve the quality of life and reduce the risk of BPH-related complications. Pharmacological therapy is recommended for moderate-to-severe cases of LUTS that are suggestive of BPH. A range of drugs is currently available to treat this condition, including α1-adrenoceptor antagonists, 5α-reductase inhibitors (5-ARIs), phosphodiesterase type 5 inhibitors (PDE5Is), muscarinic receptor antagonists (MRAs), β3-adrenoceptor agonists, and plant extracts. Of these, the most commonly used drugs in the clinic are α1-adrenoceptor antagonists, 5-ARIs, and combination therapy. However, these drugs exert their effects via various mechanisms and are associated with adverse reactions. The purpose of this review is to provide current comprehensive perspectives on the mechanisms of action, efficacy, and adverse reactions associated with the drugs most commonly used for the treatment of BPH.

Demethoxycurcumin: A naturally occurring curcumin analogue for treating non-cancerous diseases

Turmeric extracts contain three primary compounds, which are commonly referred to as curcuminoids. They are curcumin, demethoxycurcumin (DMC), and bisdemethoxycurcumin. While curcumin has been the most extensively studied of the curcuminoids, it suffers from low overall oral bioavailability due to extremely low absorption as a result of low water solubility and instability at acidic pH, as well as rapid metabolism and clearance from the body. However, DMC, which lacks the methoxy group on the benzene ring of the parent structure, has much greater chemical stability at physiological pH and has been recently reported to exhibit antitumor properties. However, the treatment of noncancerous diseases with DMC has not been comprehensively reviewed. Therefore, here we evaluate published scientific literature on the therapeutic properties of DMC. The beneficial pharmacological actions of DMC include anti-inflammatory, neuroprotective, antihypertensive, antimalarial, antimicrobial, antifungal, and vasodilatory properties. In addition, DMC's ability to ameliorate the effects of free radicals and an environment characterized by oxidative stress caused by the accumulation of advanced glycation end-products associated with diabetic nephropathy, as well as DMC's capacity to inhibit the migration and proliferation of vascular smooth muscle cells following balloon angioplasty are also addressed. This review collates the available literature regarding the therapeutic possibilities of DMC in noncancerous conditions.

PDE5A Suppresses Proteasome Activity Leading to Insulin Resistance in C2C12 Myotubes

OBJECTIVE

The involvement of phosphodiesterase type 5 (PDE5) in the development of insulin resistance has been reported recently. However, the underlying molecular mechanism remains unclear. The present study aims at investigating the potential impacts of PDE5A on insulin signaling in C2C12 skeletal muscle myotubes and uncover the related mechanism.

METHODS

C2C12 myoblasts were differentiated into myotubes. Western blot was performed to detect the levels of proteins and phosphorylated proteins. Glucose uptake was determined by a colorimetric kit. The overexpression or knockdown of specific protein was carried out by infecting the myotubes with adenoviruses carrying cDNA or shRNA corresponding to the targeted protein, respectively.

RESULTS

PDE5A was demonstrated to negatively regulate insulin signaling, evidenced by the opposite effects on the suppression or enhancement of the insulin-stimulated Akt phosphorylation and 2-deoxy-D-glucose (2-DG) uptake in C2C12 myotubes, when PDE5A was overexpressed or knockdown, respectively. Interestingly, PDE5A overexpression led to significantly enhanced, while its knockdown resulted in markedly reduced, endoplasmic reticulum (ER) stress. Inhibition of ER stress improved PDE5A overexpression-induced insulin resistance. In addition, PDE5A was found to suppress proteasome activity. Inhibition of PDE5 by its selective inhibitor icariin restored PDE5A overexpression-reduced proteasome activity and mitigated PDE5A overexpression-induced ER stress. Consistently, icariin administration also markedly attenuated the detrimental impacts of PDE5A overexpression on insulin signaling.

CONCLUSIONS

These results suggest that PDE5A suppresses proteasome activity, which results in ER stress and subsequent insulin resistance in C2C12 myotubes.

Penile microvascular endothelial function in hypertensive patients: effects of acute type 5 phosphodiesterase inhibition

The primary aim of this study was to evaluate penile endothelial microvascular function in patients with primary arterial hypertension and age-matched normotensive subjects using laser speckle contrast imaging (LSCI). Additionally, we analyzed the acute penile microvascular effects induced by oral phosphodiesterase type 5 inhibitor (sildenafil; SIL) administration. Endothelium-dependent microvascular reactivity was evaluated in the penises and forearms of hypertensive patients (aged 58.8±6.6 years, n=34) and age-matched healthy volunteers (n=33) at rest and 60 min following oral SIL (100 mg) administration. LSCI was coupled with cutaneous acetylcholine (ACh) iontophoresis using increasing anodal currents. Basal penile cutaneous vascular conductance (CVC) values were not significantly different between control subjects and hypertensive individuals. Penile CVC values increased significantly after SIL administration in control (P<0.0001) and hypertensive (P<0.0001) subjects. Peak CVC values were not different between the two groups during penile ACh iontophoresis before SIL administration (P=0.2052). Peak CVC values were higher in control subjects than in hypertensive subjects after SIL administration (P=0.0427). Penile endothelium-dependent microvascular function is, to some extent, preserved in patients presenting with primary arterial hypertension under effective anti-hypertensive treatment. LSCI may be a valuable non-invasive tool for the evaluation of penile vascular responses to phosphodiesterase type 5 inhibitor.

Improvement in erectile function in a rat model of high cholesterol diet-induced atherosclerosis by atorvastatin in a manner that is independent of its lipid-lowering property

The purpose of the present study is to explore the effects of a lipid-lowering drug atorvastatin, a three-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, in the treatment of erectile dysfunction (ED) in a rat model of atherosclerosis (AS) and the possible mechanisms underneath. A high-cholesterol diet was administrated to Sprague-Dawley rats in an attempt to induce an ASED model, which was later confirmed by abdominal aorta histopathology and erectile function evaluation. ASED rats were further assigned to non-treatment group, atorvastatin low-dose treatment group (5 mg kg^-1  day^-1 ), high-dose group (10 mg kg^-1  day^-1 ) and sildenafil (1.5 mg kg^-1  day^-1 ) treatment group. Lipid profile, erectile function, oxidative stress biochemical markers, endothelial nitric oxide synthase (eNOS) and extracellular superoxide dismutase (SOD_EX ) mRNA expression were evaluated after 8-week treatment duration. Erectile function was impaired in AS rat model, which was preserved in atorvastatin and sildenafil intervention groups. The oxidative stress biochemical markers were attenuated, while eNOS and SOD_EX mRNA expression were restored in atorvastatin and sildenafil groups, which were found to be involved in ED pathogenesis. However, the lipid profile remained unaltered in the treatment group, and it was elevated in ASED rats. This kind of lipid-lowering agent, or atorvastatin, has the utilisation potential in ASED treatment, even before lipid profiles altered. This effect on erectile function preservation of atorvastatin was attributed to its preservation of endothelial function, possibly through amelioration of oxidative stress and improvement in eNOS expression.

Cardiac safety profile of sildenafil: chronotropic, inotropic and coronary vasodilator effects in the canine isolated, blood-perfused heart preparations

Sildenafil is a phosphodiesterase type-5 inhibitor. We evaluated the effects of sildenafil on the sinoatrial rate, developed tension of the papillary muscle and coronary blood flow by using the canine isolated, blood-perfused sinoatrial node and papillary muscle preparations. The former preparation had a regular automaticity rate of 106 ± 1 beats/min (n = 4), whereas the latter showed a developed tension of 22 ± 4 mN (n = 4) and a coronary blood flow of 3.9 ± 0.1 mL/min (n = 4). Intracoronary injection of 10, 30 and 100 µg of sildenafil, which would provide about 20 to 200 times higher plasma drug concentrations than its therapeutic level, increased the automaticity rate by 4, 12 and 22%, the developed tension by 19, 55 and 118% and the coronary blood flow by 42, 95 and 142%, respectively. These results indicate that supratherapeutic concentration of sildenafil possesses direct positive chronotropic and inotropic effects together with a coronary vasodilator action, confirming that caution has to be paid on the use of sildenafil for patients with ischemic heart diseases, obstructive hypertrophic cardiomyopathy and/or ventricular arrhythmias. The information on sildenafil reported in this study may help establish a guidance on cardiac safety assessment of newer phosphodiesterase type-5 inhibitors.

Pharmacodynamics, pharmacokinetics and clinical efficacy of phosphodiesterase-5 inhibitors

INTRODUCTION

Phosphodiesterase type 5 inhibitors (PDE5Is) are the first-line drugs in the management of erectile dysfunction (ED). However, over the past two decades tremendous efforts have been made to identify new clinical uses of PDE5Is beyond their roles in ED. Areas covered: Basic science articles, clinical trials, reviews, and meta-analysis published between 1996 and 2015 were searched using MEDLINE (PubMed interface) to collect the most relevant and impactful studies from our perspectives as practicing urologists. This review mainly focuses on the level one evidence-based clinical efficacy and drug-related toxicity of oral PDE5Is. In addition, drug discovery, pharmacokinetics and pharmacodynamics, potential use in other diseases, and future directions are discussed. Expert opinion: On-demand PED5Is for the treatment of ED has shifted toward chronic administration in a broad spectrum of conditions that are thought to be associated with endovascular health. Several studies have shown that PDE5Is may play a cardioprotective or neuroprotective role. Further studies are under way to verify beneficial effects of PDE5I in non-urological conditions.

Drug Use and Misuse in the Mountains: A UIAA MedCom Consensus Guide for Medical Professionals

Donegani, Enrico, Peter Paal, Thomas Küpper, Urs Hefti, Buddha Basnyat, Anna Carceller, Pierre Bouzat, Rianne van der Spek, and David Hillebrandt. Drug use and misuse in the mountains: a UIAA MedCom consensus guide for medical professionals. High Alt Med Biol. 17:157-184, 2016.-Aims: The aim of this review is to inform mountaineers about drugs commonly used in mountains. For many years, drugs have been used to enhance performance in mountaineering. It is the UIAA (International Climbing and Mountaineering Federation-Union International des Associations d'Alpinisme) Medcom's duty to protect mountaineers from possible harm caused by uninformed drug use. The UIAA Medcom assessed relevant articles in scientific literature and peer-reviewed studies, trials, observational studies, and case series to provide information for physicians on drugs commonly used in the mountain environment. Recommendations were graded according to criteria set by the American College of Chest Physicians.

RESULTS

Prophylactic, therapeutic, and recreational uses of drugs relevant to mountaineering are presented with an assessment of their risks and benefits.

CONCLUSIONS

If using drugs not regulated by the World Anti-Doping Agency (WADA), individuals have to determine their own personal standards for enjoyment, challenge, acceptable risk, and ethics. No system of drug testing could ever, or should ever, be policed for recreational climbers. Sponsored climbers or those who climb for status need to carefully consider both the medical and ethical implications if using drugs to aid performance. In some countries (e.g., Switzerland and Germany), administrative systems for mountaineering or medication control dictate a specific stance, but for most recreational mountaineers, any rules would be unenforceable and have to be a personal decision, but should take into account the current best evidence for risk, benefit, and sporting ethics.

Antihypertensive therapy causes erectile dysfunction

PURPOSE OF REVIEW

Erectile dysfunction is a common sexual disorder affecting 40% of men in the United States. However, the pathophysiologic mechanism involved in the causation of erectile dysfunction is multifactorial and not well delineated.

RECENT FINDINGS

Several recent studies disclose that erectile dysfunction is the result of multiple interrelated comorbid conditions that include hypertension, coronary artery disease (CAD), heart failure, and diabetes mellitus among them. In addition to comorbid conditions, certain cardiovascular and antihypertensive drugs are also involved in the development of erectile dysfunction, with the most prominent being the thiazide type diuretics, the aldosterone receptor blockers, and the β-adrenergic receptor blockers. Also, knowledge by the patient of the drug and its action on erectile dysfunction may increase the incidence of erectile dysfunction (Hawthorn effect). Before treatment is initiated, patients should be screened for the presence of erectile dysfunction, because this condition is associated with hypertension, CAD, heart failure, diabetes mellitus, and their treatment and an appropriate treatment regimen should be selected. If that fails, the addition of phosphodiesterase 5 inhibitors to the treatment regimen is recommended. The only exception is a patient with CAD treated with organic nitrates, in which the coadministration of phosphodiesterase 5 inhibitors is strictly prohibited.

SUMMARY

Knowledge of the various comorbid conditions and their treatment associated with the development of erectile dysfunction will help the caring physician to treat his patients appropriately and safely. All these aspects will be discussed in this review.

Histopathologic and Ultrastructural Changes in Seminiferous Tubules of Adult Male Albino Rats Following Daily Administration of Different Doses of Tadalafil

OBJECTIVE

To investigate the effect of chronic daily administration of different doses of tadalafil on the structure of the seminiferous tubules and on spermatogenesis.

MATERIALS AND METHODS

Sixty adult male Wistar rats were included; they were divided into four groups: a control group (group I) and groups II, III, and IV that received daily tadalfil in doses of 0.45, 0.9, and 1.8 mg/kg for 12 weeks (equivalent to human doses of 5, 10, and 20 mg daily), respectively. The epididymis was processed for evaluation of sperm parameters, serum testosterone was measured, Johnsen score for rats was calculated, and testicular histopathological and ultrastructural examinations were performed.

RESULTS

Serum testosterone was significantly lower in group IV than in groups I and II. Moreover, posttreatment values in group IV were significantly lower than pretreatment values. A significant decline in sperm motility and morphology was detected in groups III and IV compared to groups I and II. Sperm count was significantly lower in group IV compared to the other groups. Johnsen score was significantly lower in groups III and IV compared to groups I and II and in group IV compared to group III. In addition, histopathological and ultrastructural degenerative changes in rat testes were detected; these changes were dose dependent and increased with increasing the dose of tadalafil.

CONCLUSION

Chronic daily oral administration of tadalafil to male albino rats demonstrates a dose-dependent alteration to testicular histology and semen parameters. The influence of these changes on the actual fertility of these animals remains to be determined.

Tadalafil 5 mg once daily for the treatment of erectile dysfunction during a 6-month observational study (EDATE): impact of patient characteristics and comorbidities

BACKGROUND

To explore the impact of patient-characteristics and relevant comorbidities on treatment continuation rates, effectiveness, and satisfaction in patients with erectile dysfunction (ED) who started or switched to tadalafil 5 mg once daily (TAD-OaD) at baseline.

METHODS

In the EDATE observational study, phosphodiesterase-type-5 (PDE5)-inhibitor pretreated or naïve ED patients who started or switched to TAD-OaD were prospectively followed for 6 months. Time to discontinuation of TAD-OaD was estimated using the Kaplan-Meier product-limit method at Months 2, 4, and 6 in subgroups stratified by age (18 - 65 years and >65 years), PDE5-inhibitor pretreatment, ED-severity (mild, moderate, severe), and presence or absence of relevant comorbidities (BPH, diabetes, CVD, hypertension, dyslipidemia). LSmean change from baseline in International Index of Erectile Function (IIEF) and Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) scores and associated 95 % CIs were assessed using a mixed-model for repeated measures. Visit, ED etiology, and subgroups were included as fixed-effects.

RESULTS

Overall, 778 patients received prescriptions for initiating or switching to TAD-OaD at baseline. At Month 2, >90 % of patients remained on TAD-OaD, except those aged >65 years (86.7 %) and patients with severe ED (89.0 %). More than 80 % of patients in all subgroups, except those aged >65 years (75.0 %), continued TAD-OaD at Month 6. There was a significant LSmean negative effect on IIEF- EF domain-score improvement for BPH (LSmean effect [95 % CI]: -2.77 [-4.98, -0.55], p = 0.014), previous PDE5-inhibitor treatment (-2.13 [-3.33,-0.94], p < 0.001), and mild vs moderate ED (-2.00 [-3.54,-0.46], p = 0.011); the latter possibly linked with a bigger treatment-effect in those with more severe ED at baseline. The LSmean effect on change in IIEF-EF was significantly positive for diabetes (2.28 [0.64,3.92], p = 0.007), most likely because those with diabetes had more severe ED at baseline. For all other parameters, no statistically significant LSmean effects in IIEF-EF changes were observed. No comorbidity or baseline-characteristic except age (18 - 65 years vs >65 years: 11.25 [2.96,19.54], p = 0.008) affected changes in EDITS.

CONCLUSIONS

Under routine clinical conditions, treatment continuation rate or satisfaction does not seem to be significantly affected by the presence of comorbidities in men who choose ED-treatment with TAD-OaD. The magnitude of treatment effectiveness was affected by certain baseline characteristics and comorbid conditions.

TRIAL REGISTRATION

The study (H6D-EW-LVIU) is registered in the German VfA Registry of Non-Interventional Studies (Verband Forschender Arzneimittelhersteller) since 06 December 2011; available at: http://www.vfa.de/de/arzneimittel-forschung/datenbanken-zu-arzneimitteln/nisdb/nis-details/_741 .

Inhaled nitric oxide therapy for extrapulmonary inflammation

Inhaled nitric oxide (iNO) has been used extensively to treat pulmonary hypertension primarily in newborns. This therapy is a safe and effective therapy to improve the matching between airway ventilation and blood oxygenation. A key conceptual component of iNO therapy is that effects are limited to the pulmonary compartment thereby avoiding unwanted systemic effects. The mechanism underlying this model is that any NO entering the blood stream is rapidly oxidized to nitrate, a relatively inert anion that is excreted. Mediating this oxidation is oxyhemoglobin that becomes oxidized to methemoglobin, accumulation of which is limited by erythrocyte methemoglobin reductase. In this article, we discuss studies that dismiss the notion that once in the blood stream iNO is inactivated and show that a surprising result of iNO therapy is the formation of stable NO-derived products that circulate and can elicit NO-dependent signaling in extra-pulmonary tissues. This pathway has the potential to open up new applications for iNO for treatment of systemic diseases associated with loss of NO signaling.

Epigenetic modulation as a therapeutic approach for pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare but progressive and currently incurable disease, which is characterized by vascular remodeling in association with muscularization of the arterioles, medial thickening and plexiform lesion formation. Despite our advanced understanding of the pathogenesis of PAH and the recent therapeutic advances, PAH still remains a fatal disease. In addition, the susceptibility to PAH has not yet been adequately explained. Much evidence points to the involvement of epigenetic changes in the pathogenesis of a number of human diseases including cancer, peripheral hypertension and asthma. The knowledge gained from the epigenetic study of various human diseases can also be applied to PAH. Thus, the pursuit of novel therapeutic targets via understanding the epigenetic alterations involved in the pathogenesis of PAH, such as DNA methylation, histone modification and microRNA, might be an attractive therapeutic avenue for the development of a novel and more effective treatment. This review provides a general overview of the current advances in epigenetics associated with PAH, and discusses the potential for improved treatment through understanding the role of epigenetics in the development of PAH.

New developments in the pharmacological treatment of hypertension: dead-end or a glimmer at the horizon?

Arterial hypertension is the most prevalent controllable disease world-wide. Yet, we still need to further improve blood pressure control, deal with resistant hypertension, and we hope to reduce risk "beyond blood pressure." The number of candidate molecules aspiring for these aims is constantly declining. The new possible approaches to combat high blood pressure include neprilysin/neutral endopeptidase (NEP) inhibition, particularly when combined with an angiotensin receptor blockade (such as the ARNI, LCZ696), phosphodiesterase 5 (PDE5) inhibition (KD027/Slx-2101), natriuretic agents (PL3994), or a long-lasting vasointestinal peptide (VIP) analogue (PB1046). Other options exploit the protective arm of the renin-angiotensin-aldosterone system by stimulating the angiotensin AT2 receptor (compound 21), the Mas receptor (AVE-0991), or the angiotensin converting enzyme 2. Finally, we review the possibilities how to optimize the use of the available treatment options by using drug combinations or by tailoring therapy to each patient's angiotensin peptide profile.

Angiotensin-converting enzyme inhibition prevents myocardial infarction-induced increase in renal cortical cGMP and cAMP phosphodiesterase activities

We investigated whether myocardial infarction (MI) enhances renal phosphodiesterases (PDE) activities, investigating particularly the relative contribution of PDE1-5 isozymes in total PDE activity involved in both cGMP and cAMP pathways, and whether angiotensin-converting enzyme inhibition (ACEi) decreases such renal PDE hyperactivities. We also investigated whether ACEi might thereby improve atrial natriuretic peptide (ANP) efficiency. We studied renal cortical PDE1-5 isozyme activities in sham (SH)-operated, MI rats and in MI rats treated with perindopril (ACEi) 1 month after coronary artery ligation. Circulating atrial natriuretic peptide (ANP), its second intracellular messenger cyclic guanosine monophosphate (cGMP) and cGMP/ANP ratio were also determined. Cortical cGMP-PDE2 (80.3 vs. 65.1 pmol/min/mg) and cGMP-PDE1 (50.7 vs. 30.1 pmol/min/mg), and cAMP-PDE2 (161 vs. 104.1 pmol/min/mg) and cAMP-PDE4 (307.5 vs. 197.2 pmol/min/mg) activities were higher in MI than in SH rats. Despite increased ANP plasma level, ANP efficiency tended to be decreased in MI compared to SH rats. Perindopril restored PDE activities and tended to improve ANP efficiency in MI rats. One month after coronary ligation, perindopril treatment of MI rats prevents the increase in renal cortical PDE activities. This may contribute to increase renal ANP efficiency in MI rats.

Tadalafil Integrates Nitric Oxide-Hydrogen Sulfide Signaling to Inhibit High Glucose-induced Matrix Protein Synthesis in Podocytes

Diabetes-induced kidney cell injury involves an increase in matrix protein expression that is only partly alleviated by current treatment, prompting a search for new modalities. We have previously shown that hydrogen sulfide (H2S) inhibits high glucose-induced protein synthesis in kidney podocytes. We tested whether tadalafil, a phosphodiesterase 5 inhibitor used to treat erectile dysfunction, ameliorates high glucose stimulation of matrix proteins by generating H2S in podocytes. Tadalafil abrogated high glucose stimulation of global protein synthesis and matrix protein laminin γ1. Tadalafil inhibited high glucose-induced activation of mechanistic target of rapamycin complex 1 and laminin γ1 accumulation in an AMP-activated protein kinase (AMPK)-dependent manner. Tadalafil increased AMPK phosphorylation by stimulating calcium-calmodulin kinase kinase β. Tadalafil rapidly increased the expression and activity of the H2S-generating enzyme cystathionine γ-lyase (CSE) by promoting its translation. dl-Propargylglycine, a CSE inhibitor, and siRNA against CSE inhibited tadalafil-induced AMPK phosphorylation and abrogated the tadalafil effect on high glucose stimulation of laminin γ1. In tadalafil-treated podocytes, we examined the interaction between H2S and nitric oxide (NO). N(ω)-Nitro-L-arginine methyl ester and 1H-[1,2,4]-oxadiazolo-[4,3-a]-quinoxalin-1-one, inhibitors of NO synthase (NOS) and soluble guanylyl cyclase, respectively, abolished tadalafil induction of H2S and AMPK phosphorylation. Tadalafil rapidly augmented inducible NOS (iNOS) expression by increasing its mRNA, and siRNA for iNOS and 1400W, an iNOS blocker, inhibited tadalafil stimulation of CSE expression and AMPK phosphorylation. We conclude that tadalafil amelioration of high glucose stimulation of synthesis of proteins including matrix proteins in podocytes requires integration of the NO-H2S-AMPK axis leading to the inhibition of high glucose-induced mechanistic target of rapamycin complex 1 activity and mRNA translation.

Meta-analysis of clinical efficacy of sildenafil, a phosphodiesterase type-5 inhibitor on high altitude hypoxia and its complications

OBJECTIVE

High altitude illness can be life-threatening if left untreated. Acute mountain sickness and high altitude pulmonary hypertension are two syndromes of high altitude illness. Recent clinical studies showed the beneficial effects of phosphodiesterase type 5 (PDE-5) inhibitors on the treatment of pulmonary hypertension. In this report, we performed a meta-analysis to evaluate the clinical efficacy of PDE-5 inhibitors on high altitude hypoxia and its complications.

METHODS

Randomized controlled trials evaluating the efficacy of PDE-5 inhibitor in the setting of high altitude were identified by searching Cochrane Central Register of Controlled Trials (September 2013), PubMed (from 1990 to September 2013), and EMBASE (from 1990 to September 2013). Extracted outcomes from selected studies for meta-analysis included arterial oxygen saturation, pulmonary artery systolic pressure, heart rate, and Lake Louise Consensus AMS symptom score. Weighted mean differences with 95% confidence intervals were presented for the continuous outcomes.

RESULTS

Five clinical trials that met the selection criteria were identified for the meta-analysis. All of these studies used sildenafil as the PDE-5 inhibitor. A total of 60 subjects received sildenafil, and 72 subjects were given placebo. In accordance with previous report, short-term treatment with sildenafil (1-2 days) significantly reduced pulmonary artery systolic pressure at rest (MD -4.53; 95% CI -6.72, -2.34; p<0.0001). However, treatment with sildenafil (1-2 days) did not improve oxygen saturation after exposure to high altitude (MD 0.07; 95% CI -1.26, 1.41; p=0.91). Moreover, no significant difference was observed in heart rate between sildenafil and placebo-treated group (MD 6.95; 95% CI -3.53, 17.43; p=0.19). AMS score did not improve after treatment at different time points.

CONCLUSION

Short-term treatment with sildenafil can attenuate the altitude-induced high pulmonary systolic arterial pressure, but has no significant beneficial effects on arterial oxygen saturation, heart rate, and acute mountain sickness.

Eight challenges faced by general practitioners caring for patients after an acute coronary syndrome

The general practitioner is essential in the management of the patient who has recently been discharged from hospital following an acute coronary syndrome (ACS), particularly as duration of hospital stay is shorter than in previous decades. GPs caring for patients after an ACS face numerous challenges. Often, the first of these is insufficient or delayed documentation from the discharging hospital, although electronic discharge summaries are alleviating this problem. Post-ACS patients often have comorbidities, and GPs play a key role in managing these. Patients taking dual antiplatelet therapy who need surgery, and post-ACS patients with atrial fibrillation, require particular care from GPs. Patients will often approach their GP for advice on the safety of other drugs, such as smoking cessation medication, and phosphodiesterase type 5 inhibitors for erectile dysfunction. For patients complaining of persistent lethargy after an ACS, GPs must consider several differential diagnoses, including depression, hypotension, hypovolaemia, and side effects of β-blockers. GPs play an important ongoing role in ensuring that target cholesterol levels are reached with statin therapy; this includes ensuring long-term adherence. They may also need to advise patients who want to stop statin therapy, usually due to perceived side effects. Many of these challenges can be met with improved and respectful communication between the hospital, the treating cardiologist and the GP. The patient needs to be closely involved in the decision-making process, particularly when balancing the risks of bleeding versus thrombosis.

Curcumin analogues inhibit phosphodiesterase-5 and dilate rat pulmonary arteries

Objectives

Phosphodiesterase (PDE)-5 inhibitors are useful as vasodilators for the treatment of pulmonary arterial hypertension. We aimed to study curcumin analogues for PDE5 inhibitory activity and vasorelaxation of rat pulmonary arteries.

Methods

Three natural curcuminoids (1–3) and six synthetic analogues (4–9) were tested for PDE5 and PDE6 inhibitory activities using enzymatic radioassay. Their vasorelaxation was measured using freshly isolated segments of rat pulmonary artery and aorta.

Key findings

Curcuminoids (1–3) mildly inhibited PDE5 (half maximal inhibitory concentration (IC50) = 18 µm): the metamethoxyl of curcumin was important for PDE5 inhibition. But hydroxyl rearrangements, removing both methoxyls and one ketomethylene, yielded the potent 7 and 9 (IC50 = 4 µm) (compared with sildenafil, IC50 = 0.03 µm). Only 1, 3 and 4 were PDE5 selective over PDE6. Triazole-carboxylic addition provided water-solubility while preserving potency. All analogues possessed concentration-dependent vasorelaxant activity on pulmonary arteries (40% of maximal effective concentration (EC40) = 29–90 µm, maximum response = 60–90% at 300 µm), while compounds (1–8) were weakly acting in aorta (maximum response &lt;40%). Only demethoxycurcumin (2) and analogues 5, 8, 9 had endothelium-dependent actions. Sildenafil was highly potent (EC40 = 0.04 µm) and highly endothelium dependent in pulmonary artery but weak on intact aorta (EC40 = 1.8 µm). Activity profiles suggest actions through additional cell pathways for promoting vasorelaxation.

Conclusions

Curcumin analogues are potential leads for developing efficacious and selective PDE5 inhibitors and other pathologies of pulmonary hypertension.

C-type natriuretic peptide inhibiting vascular calcification might involve decreasing bone morphogenic protein 2 and osteopontin levels

Vascular calcification (VC) is highly associated with increased morbidity and mortality in patients with advanced chronic kidney disease. Paracrine/autocrine factors such as vasoactive peptides are involved in VC development. Here, we investigated the expression of the novel peptide C-type natriuretic peptide (CNP) in the vasculature, tested its ability to prevent VC in vivo and in vitro, and examined the mechanism involved. Rat aortic VC was induced by vitamin D3 plus nicotine (VDN). CNP (500 ng/kg/h) was administered by mini-osmotic pump. Calcification was examined by von Kossa staining; CNP and cyclic guanosine monophosphate (cGMP) contents were detected by radioimmunoassay, and mRNA and protein levels were examined by real-time PCR and Western blot analysis in aortas and calcified vascular smooth muscle cells (VSMCs). VDN-treated rat aortas showed higher CNP content and decreased expression of its receptor natriuretic peptide receptor B, along with increased vascular calcium deposition and alkaline phosphatase (ALP) activity. Low CNP levels were accompanied by increased vascular calcium deposition and ALP activity in VDN-treated rats when compared to vehicle treatment, which was further confirmed in cultured VSMCs. Administration of CNP greatly reduced VC in VDN-treated aortas compared with controls, which was confirmed in calcified VSMCs. The decrease in alpha-actin expression was ameliorated by CNP in vitro. Moreover, protein expression levels of osteopontin (OPN) were significantly up-regulated in calcified aortas, and CNP increased OPN expression in calcified aortas. Furthermore, CNP downregulated OPN and bone morphogenic protein 2 (BMP-2) expression in calcified aortas and VSMCs. Modulation of OPN and BMP-2 expression by CNP and the beneficial effects of CNP on calcified VSMCs were blocked significantly by protein kinase G inhibitor H7. Impaired local endogenous CNP and its receptor system may be associated with increased mineralization in vivo in rat aortas with VC, and administration of CNP inhibits VC development in vivo and in vitro, at least in part, via a cGMP/PKG pathway.

Additional use of a phosphodiesterase 5 inhibitor in patients with pulmonary hypertension secondary to chronic systolic heart failure: a meta-analysis

AIMS

Increased indiscriminate use of pulmonary artery hypertension-targeted drugs has been observed in patients with pulmonary hypertension (PH) secondary to heart failure. We performed a meta-analysis to evaluate the chronic effects of using phosphodiesterase 5 (PDE5) inhibitors to treat patients with PH secondary to chronic systolic heart failure.

METHODS AND RESULTS

PubMed, EMBASE, and the Cochrane Library were searched up to October 2013 for randomized controlled trials (RCTs) assessing PDE5 inhibitor treatments in PH patients secondary to chronic heart failure. Six RCTs involving 206 chronic systolic heart failure patients with PH complications were included. Sildenafil was used in all trials. Sildenafil treatment resulted in fewer hospital admissions compared with the placebo treatment (3.15% vs. 12.20%; risk ratio 0.29; 95% confidence interval 0.11-0.77). Various haemodynamic parameters were improved with additional sildenafil treatment, including reduced mean pulmonary artery pressure [weighted mean difference (WMD) -5.71 mmHg, P<0.05] and pulmonary vascular resistance (WMD -81.5 dynes/cm(-5), P<0.00001), increased LVEF (WMD 3.95%, P<0.01), and unchanged heart rate and blood pressure. The exercise capacity improved (oxygen consumption at peak exercise, WMD 3.20 mL/min(-1)/kg(-1), P<0.00001; ventilation to CO2 production slope, WMD -5.89, P<0.00001), and the clinical symptoms were relieved based on the breathlessness (WMD 7.72, P<0.00001), fatigue (WMD 2.28, P<0.05), and emotional functioning (WMD 5.92, P<0.00001) scores.

CONCLUSIONS

Additional sildenafil treatment is a potential therapeutic method to improve pulmonary exercise capacity and quality of life by ameliorating PH in patients with chronic systolic heart failure.