Phosphodiesterase-5 Inhibitor Vardenafil Research Articles

The Phosphodiesterase-5 Inhibitor Vardenafil Improves the Activation of BMP Signaling in Response to Hydrogen Peroxide.

The pleiotropic roles of phosphodiesterase-5 inhibitors (PDE5is) in cardiovascular diseases have attracted attention. The effect of vardenafil (a PDE5i) is partly mediated through reduced oxidative stress, but it is unclear whether vardenafil protects against hydrogen peroxide (H2O2)-induced endothelial cell injury, and the molecular mechanisms that are involved remain unknown. We determined the protective role of vardenafil on H2O2-induced endothelial cell injury in cultured human umbilical vein endothelial cells (HUVECs). Vardenafil decreased the number of TUNEL-positive cells, increased the Bcl2/Bax ratio, and ameliorated the numbers of BrdU-positive cells in H2O2-treated HUVECs. The bone morphogenetic protein receptor (BMPR)/p-Smad/MSX2 pathway was enhanced in response to H2O2, and vardenafil treatment could normalize this pathway. To determine whether the BMP pathway is involved, we blocked the BMP pathway using dorsomorphin, which abolished the protective effects of vardenafil. We found that vardenafil improved the H2O2-induced downregulation of BMP-binding endothelial regulator protein (BMPER), which possibly intersects with the BMP pathway in the regulation of endothelial cell injury in response to oxidative stress. We demonstrated for the first time that exogenous H2O2 activates BMPR expression and promotes Smad1/5/8 phosphorylation. Additionally, vardenafil can attenuate H2O2-induced endothelial cell injury in HUVECs. Vardenafil decreases apoptosis through an improved Bcl-2/Bax ratio and increases cell proliferation. Vardenafil protects against endothelial cell injury through ameliorating the intracellular oxidative stress level and BMPER expression. The protective role of vardenafil on H2O2-induced endothelial cell injury is mediated through BMPR/p-Smad/MSX2 in HUVECs.

Combination Therapy of Pulmonary Arterial Hypertension with Vardenafil and Macitentan Assessed in a Human Ex Vivo Model.

Treatment of pulmonary arterial hypertension (PAH) by vasodilator drug monotherapy is often limited in its effectiveness. Combination therapy may help to improve treatment and to reduce drug toxicity. This study assessed the combination of the endothelin receptor antagonist macitentan and the phosphodiesterase-5 inhibitor vardenafil in a human ex vivo model. Study patients did not suffer from PAH. Human pulmonary arteries (PA) and veins (PV) were harvested from resected pulmonary lobes. Contractile forces of blood vessel segments in the presence and absence of the vasodilator drugs macitentan, its main metabolite ACT-132577, and vardenafil were determined isometrically in an organ bath. Macitentan 1E-7M was sufficient to significantly abate endothelin-1-induced vasoconstriction in PA. A concentration of 1E-6M was required for significant effects of macitentan on PV and of ACT-132577 on both vessel types. Combination of 1E-7M macitentan and 1E-6M vardenafil inhibited sequential constriction with endothelin-1 and norepinephrine of PA significantly more than either compound alone. Effects of 3E-7M and 1E-6M macitentan and effects of all doses of ACT-132577 were not further enhanced by 1E-6M vardenafil. These data suggest that vasodilator effects of macitentan and vardenafil combined may surpass monotherapy in vivo if drug doses are adjusted properly. Vasodilation by the longer-acting metabolite ACT-132577 was not further enhanced by vardenafil.

Targeting Phosphodiesterase-5 by Vardenafil Improves Vascular Graft Function

Ischaemia reperfusion (IR) injury occurs during vascular graft harvesting and implantation during vascular/cardiac surgery. Elevated intracellular cyclic guanosine monophosphate (cGMP) levels contribute to an effective endothelial protection in different pathophysiological conditions. The hypothesis that the phosphodiesterase-5 inhibitor vardenafil would protect vascular grafts against IR injury by upregulating the nitric oxide–cGMP pathway in the vessel wall of the bypass graft was investigated. Lewis rats (n = 6–7/group) were divided into Group 1, control; Group 2, donor rats received intravenous saline; Group 3, received intravenous vardenafil (30 μg/kg) 2 h before explantation. Whereas aortic arches of Group 1 were immediately mounted in an organ bath, aortic segments of Groups 2 and 3 were stored for 2 h in saline and transplanted into the abdominal aorta of the recipient. Two hours after transplantation, the implanted grafts were harvested. Endothelium dependent and independent vasorelaxations were investigated. TUNEL, CD-31, ICAM-1, VCAM-1, α-SMA, nitrotyrosine, dihydroethidium and cGMP immunochemistry were also performed. Compared with the control, the saline group showed significantly attenuated endothelium dependent maximal relaxation (Rmax) 2 h after reperfusion, which was significantly improved by vardenafil supplementation (Rmax control, 91 ± 2%; saline 22 ± 2% vs. vardenafil 39 ± 4%, p < .001). Vardenafil pre-treatment significantly reduced DNA fragmentation (control 9 ± 1%, saline 66 ± 8% vs. vardenafil 13 ± 1%, p < .001), nitro-oxidative stress (control 0.8 ± 0.3, saline 7.6 ± 1.3 vs. vardenafil 3.8 ± 1, p = .036), reactive oxygen species level (vardenafil 36 ± 4, control 34 ± 2 vs. saline 43 ± 2, p = .049), prevented vascular smooth muscle cell damage (control 8.5 ± 0.7, saline 4.3 ± 0.6 vs. vardenafil 6.7 ± 0.6, p = .013), decreased ICAM-1 (control 4.1 ± 0.5, saline 7.0 ± 0.9 vs. vardenafil 4.4 ± 0.6, p = .031), and VCAM-1 score (control 4.4 ± 0.4, saline 7.3 ± 1.0 vs. vardenafil 5.2 ± 0.4, p = .046) and increased cGMP score in the aortic wall (control 11.2 ± 0.8, saline 6.5 ± 0.8 vs. vardenafil 8.9 ± 0.6, p = .016). The marker for endothelial integrity (CD-31) was also higher in the vardenafil group (control 74 ± 4%, saline 22 ± 2% vs. vardenafil 40 ± 3%, p = .008). The results support the view that impairment of intracellular cGMP signalling plays a role in the pathogenesis of the endothelial dysfunction of an arterial graft after bypass surgery, which can effectively be prevented by vardenafil. Its clinical use as preconditioning drug could be a novel approach in vascular/cardiac surgery.

Identification of Mitochondrial Pyruvate Carrier Modulators to Treat Diabetes

Recent work conducted in knockout mouse models or using small molecule modulators of the mitochondrial pyruvate carrier (MPC) have suggested that targeting this protein complex may have efficacy for treating diabetes as insulin sensitizers. To begin to identify other small molecules that interact with the MPC and could potentially be new therapeutic leads, we used a BRET-based MPC reporter assay (reporter sensitive to pyruvate; RESPYR) system that responds to molecules that interact with the pyruvate binding site of the complex. Screening of a 1600 molecule chemical library generated a number of hits for compounds that activated RESPYR activity. Some hits in this unbiased screen confirmed previous reports of MPC interacting drugs, including the insulin-sensitizing thiazolidinediones, pioglitazone and rosiglitazone. Another hit in this screen was Zaprinast, an inhibitor of phosphodiesterase 5 (PDE5). Zaprinast affected RESPYR activity in a dose-dependent manner and at high nM concentrations. Zaprinast also potently inhibited pyruvate-mediated respiration in isolated WT, but not MPC-deficient mitochondria, demonstrating a direct mitochondrial effect and MPC-dependence for this inhibition of pyruvate metabolism. Analyses conducted using other PDE5 inhibitors (Sildenafil, Tadalafil, and Vardenafil) showed no effect on RESPYR activity or mitochondrial respiration. Consistent with the concept that hepatic gluconeogenesis from pyruvate requires mitochondrial pyruvate import, Zaprinast reduced production of glucose from pyruvate in WT, but not MPC-deficient hepatocytes in vitro. Studies are ongoing to determine whether Zaprinast treatment will lower blood glucose in vivo. In conclusion, these data demonstrate the feasibility of screening for novel MPC interacting compounds to identify novel therapeutics for treating diabetes and other metabolic diseases and also suggests that the orphan drug Zaprinast may be a novel antidiabetic agent. Disclosure K.S. McCommis: None. W.T. Hodges: None. Y. Chen: None. K. Chambers: None. B.N. Finck: Board Member; Self; Cirius Therapeutics.

Targeting Phosphodiesterase-5 by Vardenafil Improves Vascular Graft Function

Ischaemia reperfusion (IR) injury occurs during vascular graft harvesting and implantation during vascular/cardiac surgery. Elevated intracellular cyclic guanosine monophosphate (cGMP) levels contribute to an effective endothelial protection in different pathophysiological conditions. The hypothesis that the phosphodiesterase-5 inhibitor vardenafil would protect vascular grafts against IR injury by upregulating the nitric oxide-cGMP pathway in the vessel wall of the bypass graft was investigated. Lewis rats (n=6-7/group) were divided into Group 1, control; Group 2, donor rats received intravenous saline; Group 3, received intravenous vardenafil (30μg/kg) 2h before explantation. Whereas aortic arches of Group 1 were immediately mounted in an organ bath, aortic segments of Groups 2 and 3 were stored for 2h in saline and transplanted into the abdominal aorta of the recipient. Two hours after transplantation, the implanted grafts were harvested. Endothelium dependent and independent vasorelaxations were investigated. TUNEL, CD-31, ICAM-1, VCAM-1, α-SMA, nitrotyrosine, dihydroethidium and cGMP immunochemistry were also performed. Compared with the control, the saline group showed significantly attenuated endothelium dependent maximal relaxation (Rmax) 2h after reperfusion, which was significantly improved by vardenafil supplementation (Rmax control, 91±2%; saline 22±2% vs. vardenafil 39±4%, p<.001). Vardenafil pre-treatment significantly reduced DNA fragmentation (control 9±1%, saline 66±8% vs. vardenafil 13±1%, p<.001), nitro-oxidative stress (control 0.8±0.3, saline 7.6±1.3 vs. vardenafil 3.8±1, p=.036), reactive oxygen species level (vardenafil 36±4, control 34±2 vs. saline 43±2, p=.049), prevented vascular smooth muscle cell damage (control 8.5±0.7, saline 4.3±0.6 vs. vardenafil 6.7±0.6, p=.013), decreased ICAM-1 (control 4.1±0.5, saline 7.0±0.9 vs. vardenafil 4.4±0.6, p=.031), and VCAM-1 score (control 4.4±0.4, saline 7.3±1.0 vs. vardenafil 5.2±0.4, p=.046) and increased cGMP score in the aortic wall (control 11.2±0.8, saline 6.5±0.8 vs. vardenafil 8.9±0.6, p=.016). The marker for endothelial integrity (CD-31) was also higher in the vardenafil group (control 74±4%, saline 22±2% vs. vardenafil 40±3%, p=.008). The results support the view that impairment of intracellular cGMP signalling plays a role in the pathogenesis of the endothelial dysfunction of an arterial graft after bypass surgery, which can effectively be prevented by vardenafil. Its clinical use as preconditioning drug could be a novel approach in vascular/cardiac surgery.

CGMP Signaling Increases Antioxidant Gene Expression by Activating Forkhead Box O3A in the Colon Epithelium

Signaling through cGMP has therapeutic potential in the colon, where it has been implicated in the suppression of colitis and colon cancer. In this study, we tested the ability of cGMP and type 2 cGMP-dependent protein kinase (PKG2) to activate forkhead box O (FoxO) in colon cancer cells and in the colon epithelium of mice. We show that activation of PKG2 in colon cancer cells inhibited cell proliferation, inhibited AKT, and activated FoxO. Treatment of colon explants with 8Br-cGMP also activated FoxO target gene expression at both RNA and protein levels, and reduced epithelial reduction-oxidation (redox) stress. FoxO3a was the most prominent isoform in the distal colon epithelium, with prominent luminal staining. FoxO3a levels were reduced in Prkg2-/- animals, and FoxO target genes were unaffected by 8Br-cGMP challenge invitro. Treatment of mice with the phosphodiesterase-5 inhibitor vardenafil (Levitra) mobilized FoxO3a to the nucleus of luminal epithelial cells, which corresponded to increased FoxO target gene expression, reduced redox stress, and increased epithelial barrier integrity. Treatment of human colonic biopsy specimens with 8Br-cGMP also activated catalase and manganese superoxide dismutase expression, indicating that this pathway is conserved in humans. Taken together, these results identify a novel signaling pathway in the colon epithelium, where FoxO tumor suppressors could provide protection from redox stress. Moreover, this pathway is regulated by endogenous cGMP/PKG2 signaling, and can be targeted using phosphodiesterase-5 inhibitors.

Effects of chronic administration of the phosphodiesterase inhibitor Vardenafil on serum levels of adrenal and testicular steroids in men with type 2 diabetes mellitus

Background. Steroidogenesis is a complex enzymatic process in which cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) play an important role. Phosphodiesterase-5 inhibitors(PDE5i) increase cGMP, improving NO availability.Objective. to investigate whether long-term, chronic treatment with the PDE5i Vardenafil affects adrenal and testicular steroidogenesis in diabetic men, using liquid chromatography-mass spectrometry (LC-MS/MS).Design. A longitudinal, prospective, investigator-started, randomized, placebo-controlled, double-blind, clinical-trial was carried out.Setting and Participants. 54 male patients affected by T2DM diagnosed within the last 5 years were enrolled. 26 and 28 patients were assigned to the verum and placebo-group, respectively.Interventions. The study consisted of an enrolment phase, a treatment phase (24weeks) (Vardenafil/placebo 10mg twice-daily), and a follow-up phase (24weeks).Outcome measurements: progesterone (P), 17-hydroxyprogesterone (17OHP), androstenedione (A), testosterone (T), dehydroepiandrosterone (DHEA), DHEA sulphate (DHEAS), corticosterone, 11-deoxycortisol and cortisol (C), were evaluated using LC-MS/MS.Results. No differences were seen in sex testicular steroids between study and control group. For the adrenal gland, steroids were considered according to the zona in which they are produced. Considering steroids produced in the zona fasciculata, no significant differences were seen in 11-deoxycortisol and C among visits, both in the study and in the control group. For the zona reticularis, DHEA significantly decreased during treatment only in the study group (p=0.007). At post-hoc test DHEA showed higher levels at visit 2 and 8 than in other visits. The DHEAS/DHEAS ratio significantly increased during treatment only in the verum group. Considering the adrenal zona glomerulosa, corticosterone significantly changed among visits both in the study and in the control group (p&lt;0.001). At post-hoc test, in both groups, corticosterone was significantly higher at visit 2 (p=0.028), 8 (p=0.003), and 10 (p=0.044), i.e. in coincidence with the complete clinical and instrumental examination performed only at these visits according to the study protocol.Conclusions. This is the first double-blind, placebo-controlled clinical-trial in which steroidogenesis is extensively investigated by LC-MS/MS in T2DM men chronically treated with Vardenafil for 6 months, and followed-up for 6 months after therapy-withdrawal. Chronically administered Vardenafil reduces DHEA levels and increases DHEAS/DHEA ratio as possible consequences of modulation of steroidogenic enzymes by tissue changes in cGMP and/or cAMP availability. A possibly stress-related increase in corticosterone is suggested for the first time.

Effects of chronic administration of the phosphodiesterase inhibitor vardenafil on serum levels of adrenal and testicular steroids in men with type 2 diabetes mellitus.

To investigate whether long-term, chronic treatment with the phosphodiesterase-5 inhibitor vardenafil affects adrenal and testicular steroidogenesis in diabetic men, using liquid chromatography-tandem mass spectrometry. A longitudinal, prospective, investigator-started, randomized, placebo-controlled, double-blind, clinical-trial was carried out, enrolling 54 male patients affected by type 2 diabetes mellitus diagnosed within the last 5 years. In total, 26 and 28 patients were followed for 1 year and assigned to the study and placebo group, respectively. Progesterone, 17-hydroxyprogesterone, androstenedione, testosterone, dehydroepiandrosterone, dehydroepiandrosterone sulfate, corticosterone, 11-deoxycortisol and cortisol, were evaluated using liquid chromatography-tandem mass spectrometry. No differences were seen in sex testicular steroids between study and control group. As for the adrenal gland, steroids were considered according to the zona in which they are produced. No significant differences were seen in steroid produced in zona fasciculata. For the zona reticularis, dehydroepiandrosterone significantly decreased during treatment only in the study group (p = 0.007), with higher levels at visit 2 and 8 than other visits. The dehydroepiandrosterone sulfate/dehydroepiandrosterone ratio significantly increased during treatment only in the verum group. Considering the adrenal zona glomerulosa, corticosterone significantly changed among visits both in both groups (p < 0.001), with higher levels at visit 2 (p = 0.028), 8 (p = 0.003), and 10 (p = 0.044), i.e., in coincidence with the complete clinical and instrumental examination performed only at these visits according to the study protocol. Chronically administered vardenafil reduces dehydroepiandrosterone levels and increases dehydroepiandrosterone sulfate/dehydroepiandrosterone ratio as possible consequences of modulation of steroidogenic enzymes by tissue changes in cyclic adenosine monophosphate and cyclic guanosine monophosphate availability. A possibly stress-related increase in corticosterone is suggested for the first time.

Antioxidant effects of phosphodiesterase-5 inhibitors

This letter refers to ‘The phosphodiesterase-5 inhibitor vardenafil reduces oxidative stress while reversing pulmonary arterial hypertension’ by Y.-F. Fan et al ., Cardiovascular Research (2013) 99, 395–403. Fan et al .1 have shown convincing results indicating that the phosphodiesterase-5 (PDE5) inhibitor vardenafil reduces oxidative stress and this effect was associated with attenuation of chronic pulmonary hypertension (PH) in rats and in humans. We would like to make the point that the results shown by Fan et al .1 may have underestimated the beneficial effects of …

The phosphodiesterase-5 inhibitor vardenafil reduces oxidative stress while reversing pulmonary arterial hypertension

Oxidative stress is implicated in the pathology of pulmonary arterial hypertension (PAH). Previously, we demonstrated that vardenafil, a phosphodiesterase-5 inhibitor, has potential as therapy for PAH, although the mechanism remained uncharacterized. Here, we aimed to determine baseline levels of oxidative stress in PAH and investigate whether vardenafil affects oxidative stress levels while improving PAH. Sprague-Dawley rats with monocrotaline-induced PAH were administered oral vardenafil 1 mg kg⁻¹ day⁻¹ for 21 days (n = 12). Treatment-naive patients (n = 15) with PAH were treated with vardenafil 5 mg twice daily for 3 months. Haemodynamic data and plasma levels of nitrate/nitrite and products of oxidative damage were determined in rats and patients. Histopathology, immunohistochemistry, and assessments of oxidative/anti-oxidative enzyme expression were performed in rat lung tissue. Compared with baseline (patients) or untreated controls (rats), vardenafil significantly reduced pulmonary vascular resistance and increased cardiac output (CO). In rats, vardenafil suppressed proliferation and enhanced apoptosis of pulmonary artery smooth muscle cells, attenuating small pulmonary artery remodelling, and right ventricular hypertrophy. Vardenafil significantly reduced levels of oxidative stress biomarkers, such as 8-iso-prostaglandin-F2α and 3-nitrotyrosine, and significantly increased nitric oxide (NO) levels in rats and patients. Furthermore, vardenafil significantly increased endothelial NO synthase expression and superoxide dismutase activity, and down-regulated nicotinamide adenine dinucleotide phosphate oxidase expression in rat lung tissue. Vardenafil reduces oxidative stress in rats and humans while improving PAH, warranting investigation of oxidative stress pathways as targets for PAH therapy.

Pharmacological postconditioning by bolus injection of phosphodiesterase-5 inhibitors vardenafil and sildenafil

Postconditioning enables cardioprotection against ischemia/reperfusion injury either by application of short, repetitive ischemic periods or by pharmacological intervention prior to reperfusion. Pharmacological postconditioning has been described for phosphodiesterase-5 inhibitors when the substances were applied as a permanent infusion. For clinical purposes, application of a bolus is more convenient. In a rat heart in situ model of ischemia reperfusion vardenafil or sildenafil were applied as a bolus prior to reperfusion. Cardioprotective effects were found over a broad dosage range. In accordance with current hypotheses on pharmacological postconditioning signaling, the protective effect was mediated by extracellular signal-regulated kinase and protein kinase C pathway. Interestingly, the extent of protection was independent of the concentration applied for both substances. Full protection comparable to ischemic postconditioning was reached with half-maximal human equivalence dose. In contrast, mean arterial pressure dropped upon bolus application in a dose-dependent manner. Taken together, the current study extends previous findings obtained in a permanent infusion model to bolus application. This is an important step toward clinical application of pharmacological postconditioning with sildenafil and vardenafil, especially because the beneficial effects were proven for concentrations with reduced hemodynamic side effects compared to the dosage applied for erectile dysfunction treatment.

Improvement of exercise capacity in monocrotaline-induced pulmonary hypertension by the phosphodiesterase-5 inhibitor Vardenafil

Vardenafil, a phosphodiesterase-5 inhibitor, is approved for the therapy of erectile dysfunction. However, in contrast to Sildenafil and Tadalafil, little is known about its effects on pulmonary hypertension.Four weeks after monocrotaline-administration rats exhibited a significant increase in right ventricular pressure (RVSP, 94mmHg vs. 25mmHg; p=0.001) right ventricular weight (right ventricle/left ventricle+septum, 59 vs. 23; p=0.001) and pulmonary vascular remodeling (medial wall area 104% vs. 66%; p<0.05) as compared to controls, with a corresponding reduction in exercise capacity (% from baseline value: 67%; p<0.05). Vardenafil treatment resulted in decreased RVSP (56mmHg vs. 95mmHg; p=0.008), right ventricular weight (41 vs. 59; p=0.013), pulmonary vascular remodeling (medial wall area 64% vs. 104%; p<0.05) and a significant better exercise capacity (% from baseline value: 84% vs. 67%; p<0.05) compared to monocrotaline only treated animals.In conclusion, Vardenafil exerts beneficial effects on monocrotaline-induced pulmonary hypertension in rats. Whether it is a treatment option for patients with pulmonary hypertension needs to be elucidated.

Effects of phosphodiesterase-5 inhibitor vardenafil on testicular androgen-binding protein secretion, the maintenance of foci of advanced spermatogenesis and the sperm fertilising capacity in azoospermic men

We evaluated the effects of vardenafil on testicular androgen-binding protein secretion (ABP). Bilaterally obstructed azoospermic (OA)-men (n = 19) (group A) underwent unilateral testicular biopsy. A group of nonobstructed azoospermic (NOA)-men (n = 68) (group B) underwent bilateral testicular biopsy. ABP secretion in vitro by testicular tissue was assessed in each participant of every group. In addition, intracytoplasmic sperm injection (ICSI) cycles were performed in several couples of group A or group B using frozen/thawed spermatozoa from the biopsy material. Ten OA-men (group A1), 14 NOA-men (group B1), and nine different NOA-men (group B2) had been positive for spermatozoa in the biopsy but pregnancies were not achieved in the respective female partners. Men of groups A1, B1 and B2 were treated with vardenafil, vardenafil and L-carnitine respectively. Then, the men of groups A1, B1 and B2 underwent a second testicular (unilateral) biopsy. Within the group A1 and within the group B1, ABP secretion rate was significantly larger after vardenafil treatment than prior to vardenafil treatment. In addition, fertilisation rates in ICSI cycles within groups A1 or B1 were not affected by vardenafil administration. Vardenafil administration in NOA-men increased ABP secretion and did not affect detrimentally the presence of testicular foci of advanced spermatogenesis.

Results of Vardenafil Mediated Power Doppler Ultrasound, Contrast Enhanced Ultrasound and Systematic Random Biopsies to Detect Prostate Cancer

We evaluated the ability of the phosphodiesterase-5 inhibitor vardenafil to increase prostate microcirculation during power Doppler ultrasound. We also evaluated the results of contrast and vardenafil enhanced targeted biopsies compared to those of standard 12-core random biopsies to detect cancer. Between May 2008 and January 2010, 150 consecutive patients with prostate specific antigen more than 4 ng/ml at first diagnosis with negative digital rectal examination and transrectal ultrasound, and no clinical history of prostatitis underwent contrast enhanced power Doppler ultrasound (bolus injection of 2.4 ml SonoVue® contrast agent), followed by vardenafil enhanced power Doppler ultrasound (1 hour after oral administration of vardenafil 20 mg). All patients underwent standard 12-core transrectal ultrasound guided random prostate biopsy plus 1 further sampling from each suspected hypervascular lesion detected by contrast and vardenafil enhanced power Doppler ultrasound. Prostate cancer was detected in 44 patients (29.3%). Contrast and vardenafil enhanced power Doppler ultrasound detected suspicious, contrast enhanced and vardenafil enhanced areas in 112 (74.6%) and 110 patients (73.3%), and was diagnostic for cancer in 32 (28.5%) and 42 (38%), respectively. Analysis of standard technique, and contrast and vardenafil enhanced power Doppler ultrasound findings by biopsy core showed significantly higher detection using vardenafil vs contrast enhanced power Doppler ultrasound and standard technique (41.2% vs 22.7% and 8.1%, p <0.005 and <0.001, respectively). The detection rate of standard plus contrast or vardenafil enhanced power Doppler ultrasound was 10% and 11.7% (p not significant). Vardenafil enhanced power Doppler ultrasound enables excellent visualization of the microvasculature associated with cancer and can improve the detection rate compared to contrast enhanced power Doppler ultrasound and the random technique.

The Relaxation Induced by Uroguanylin and the Expression of Natriuretic Peptide Receptors in Human Corpora Cavernosa

Receptors for natriuretic peptides have been demonstrated as potential targets for the treatment of male erectile dysfunction. This study investigates the relaxant effects of the atrial natriuretic peptide (ANP) and uroguanylin (UGN), and expression of natriuretic peptide receptors on strips of human corpora cavernosa (HCC). Quantitative analysis of natriuretic receptor expression and relaxation of precontracted strips were used to assess the membrane-bound guanylate cyclase-cyclic guanosine monophosphate (cGMP) pathway in HCC strips. HCC was obtained from a cadaver donor at the time of collection of organs for transplantation (14-47 years) and strips were mounted in organ baths for isometric studies. ANP and UGN both induced concentration-dependent relaxation on HCC strips with a maximal response attained at 300 nM, corresponding to 45.4±4.0% and 49±4.8%, respectively. The relaxation is not affected by 30 µM 1H-[1,2,4]oxaolodiazolo[4,3-a]quinoxalin-1-one (ODQ) (a soluble guanylate cyclase inhibitor), but it is significantly blocked by 10 µM isatin, a nonspecific particulate guanylate cyclase (pGC) inhibitor. UGN was unable to potentiate electrical field stimulation (EFS) or acetylcholine-induced relaxations. The potential role of pGC activation and cGMP generation in this effect is reinforced by the potentiation of this effect by phosphodiesterase-5 inhibitor vardenafil (55.0±7.5-UGN vs. 98.6±1.4%-UGN+vardenafil; P<0.05). The relaxant effect was also partially (37.6%) blocked by the combination iberitoxin-apamin but was insensitive to glybenclamide. The expression of guanylate cyclase receptors (GC-A, GC-B, GC-C) and the expression of the natriuretic peptide "clearance" receptor (NPR-C) were confirmed by real-time polymerase chain reaction. The exposure of HCC strips to ANP (1 µM) and UGN (10 µM) significantly increased cGMP, but not cyclic adenosine monophosphate (cAMP) levels. UGN relaxes HCC strips by a guanylate cyclase and K(ca)-channel-dependent mechanism. These findings obtained in HCC reveal that the natriuretic peptide receptors are potential targets for the development of new drugs for the treatment of erectile dysfunction.

A Phosphodiesterase-5 Inhibitor Vardenafil Enhances Angiogenesis Through a Protein Kinase G–Dependent Hypoxia-Inducible Factor-1/Vascular Endothelial Growth Factor Pathway

We examined whether phosphodiesterase-5 (PDE5) inhibition can promote ischemia-induced angiogenesis. Unilateral hindlimb ischemia was generated by resecting right femoral artery in wild-type C3H/He mice, treated with either vehicle or a PDE5 inhibitor vardenafil (10 mg/kg per day). Four weeks after surgery, vardenafil significantly enhanced blood flow recovery and augmented capillary collateral formation in ischemic muscle (blood flow ratios of ischemic/nonischemic leg: 0.52+/-0.17 [vehicle] versus 0.92+/-0.09 [vardenafil], P<0.01). Vardenafil upregulated protein expression of vascular endothelial growth factor and hypoxia-inducible factor (HIF)-1 alpha in ischemic muscle and enhanced mobilization of Sca-1/Flk-1-positive endothelial progenitor cells (EPCs) in peripheral blood and bone marrow, contributing to neovascularization. Vardenafil also promoted capillary-like tube formation of human umbilical vein endothelial cells and increased the number of human blood mononuclear cell-derived EPCs in vitro. Furthermore, reporter assays showed that vardenafil and cGMP activated the transactivation activity of HIF-1 under hypoxia. These effects of vardenafil were markedly inhibited by genetic ablation of endothelial nitric oxide synthase, a soluble guanylate cyclase inhibitor, and a protein kinase G inhibitor, respectively. Our results suggest that PDE5 inhibition enhances ischemia-induced angiogenesis with mobilization of EPCs through a protein kinase G-dependent HIF-1/vascular endothelial growth factor pathway. PDE5 inhibition may have a therapeutic potential to treat ischemic cardiovascular diseases.

The phosphodiesterase‐5 inhibitor vardenafil improves cardiovascular dysfunction in experimental diabetes mellitus

Patients with diabetes mellitus exhibit generalized endothelial and cardiac dysfunction with decreased nitric oxide production. Elevated intracellular cyclic guanosine monophosphate (cGMP) levels contribute to an effective cardioprotection in different pathophysiological conditions. In this study, we investigated whether chronic treatment with the phosphodiesterase-5 inhibitor vardenafil could improve diabetic cardiovascular dysfunction by up-regulating the nitric oxide-cGMP pathway in the vessel wall and myocardium. Diabetes was induced in young rats by a single intraperitoneal injection of streptozotocin (60 mg x kg(-1)). In the treatment group, vardenafil (10 mg x kg(-1) x day(-1)) was given orally for 8 weeks. Diabetic control animals received vehicle for the same time. Left ventricular pressure-volume relations were measured by using a microtip Millar pressure-volume conductance catheter, and indexes of contractility, such as the slope of end-systolic pressure-volume relationship (E(max)) and preload recruitable stroke work (PRSW), were calculated. In organ bath experiments for isometric tension with rings of isolated aortae, endothelium-dependent and independent vasorelaxation was investigated by using acetylcholine and sodium nitroprusside. When compared with the non-diabetic controls, diabetic rats showed increased myocardial and vascular transforming growth factor-beta1 expression, impaired left ventricular contractility (impairment of E(max) by 53%, PRSW by 40%; P < 0.05) and vascular dysfunction. Treatment with vardenafil resulted in higher cGMP levels, reduced transforming growth factor-beta1 expression, significantly improved cardiac function (improvement of E(max) by 95%, PRSW by 69%; P < 0.05) and greater vasorelaxation to acetylcholine and sodium nitroprusside in aortae from diabetic animals. Our results demonstrate that impaired vascular cGMP signalling contributes to the development of diabetic vascular and cardiac dysfunction, which can be prevented by chronic phosphodiesterase-5 inhibition.

Selective phosphodiesterase-5 inhibition reduces neointimal hyperplasia in rat carotid arteries after surgical endarterectomy

Long-term results of surgical vessel reconstruction are compromised by restenosis caused by neointimal hyperplasia. Recent studies suggest that reduced cyclic guanosine monophosphate signaling is associated with neointima formation. In a rat model of endarterectomy, we investigated the effect of pharmacologic inhibition of cyclic guanosine monophosphate degradation on neointima formation by using the selective phosphodiesterase-5 inhibitor vardenafil. Carotid endarterectomy was performed in male Sprague-Dawley rats by means of incision of the right common carotid artery with removal of intima. Four groups were studied: unoperated control rats (n = 4), sham-operated rats (n = 9), control rats with endarterectomy (n = 9), or endarterectomized rats treated with vardenafil (10 mg/kg/day) postoperatively (n = 9). After 3 weeks, vessel compartment areas were measured by means of conventional microscopy with hematoxylin and eosin staining. Immunohistochemical analysis was performed to confirm neointima formation and the local cyclic guanosine monophosphate content. Plasma levels of cyclic guanosine monophosphate were determined by means of enzyme immunoassay. Student's t test was used for statistical evaluation. Immunohistochemical analysis demonstrated intensive staining for transforming growth factor beta1 and alpha-smooth muscle actin in the control neointima. Vardenafil significantly reduced the stenosis grade (24.64% +/- 7.46% vs 54.12% +/- 10.30% in the control group, P < .05) and expression of transforming growth factor beta1, as well as alpha-smooth muscle actin, in the neointima. The immunohistochemical score for cyclic guanosine monophosphate was higher in the treated neointima (4.80 +/- 0.76 vs 2.84 +/- 0.40 in the control group, P < .05), and increased plasma cyclic guanosine monophosphate levels were found by means of enzyme immunoassay as well (84.65 +/- 12.77 pmol/mL vs 43.50 +/- 3.30 pmol/mL in the control group, P < .05). Treatment with vardenafil can be considered a new possibility to prevent neointimal hyperplasia after endarterectomy.

Increased Cyclic Guanosine Monophosphate Synthesis and Calcium Entry Blockade Account for the Relaxant Activity of the Nitric Oxide–Independent Soluble Guanylyl Cyclase Stimulator BAY 41-2272 in the Rabbit Penile Urethra

To study the direct relaxant activity of 5-cyclopropyl-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]pyrimidin-4-ylamine (BAY 41-2272) in the rabbit penile urethra and to investigate its modulatory effect on nitric oxide (NO)-mediated responses. Urothelium-intact (U+) and denuded (U-) rings were mounted in 10-mL organ baths for isometric force recording. Intracellular cyclic guanosine monophosphate (cGMP) levels were quantified with specific kits. BAY 41-2272 (0.0001 to 10 micromol/L) caused relaxation of urethral rings contracted with phenylephrine (10 micromol/L), with higher potency (P <0.01) in U+ (pEC(50) 7.77 +/- 0.09) compared with U- (pEC(50) 6.84 +/- 0.19) preparations. The NO synthesis inhibitor N(omega)-nitro-L-arginine methyl ester (100 micromol/L) or the soluble guanylate cyclase inhibitor 1H-[1,2,4] oxadiazolo [4,3,-a]quinoxalin-1-one (ODQ) (10 micromol/L) had no effect on BAY 41-2272 responses in U+ or U- rings. The phosphodiesterase-5 inhibitor vardenafil (0.1 micromol/L) potentiated the relaxant effects of BAY 41-2272 in both U+ (10-fold) and U- (sevenfold) tissues. Ca(2+)-induced contractions in K(+) depolarized rings were significantly attenuated by BAY 41-2272 (1 micromol/L) in an ODQ-insensitive manner. BAY 41-2272 (0.03-0.3 micromol/L) increased the amplitude and duration of electrical field stimulation-induced relaxations (1 to 32 Hz), as well as those evoked by the NO donor glyceryl trinitrate (0.0001 to 10 micromol/L). BAY 41-2272 induced ODQ-resistant increases in cGMP levels above baseline (approximately twofold) in both U+ and U- rings. BAY 41-2272 relaxes penile urethra in a synergic fashion with NO. Targeting soluble guanylate cyclase with BAY 41-2272 may represent a new therapy in the management of voiding disturbances associated with impaired NO-cGMP signaling.

Effects of vardenafil, a selective phosphodiesterase-5-inhibitor, on cardiovascular function in a rat model

Background Phosphodiesterase-5-inhibitors are vasoactive drugs used in the treatment of erectile dysfunction and pulmonary hypertension. Their beneficial effects in the pulmonary vasculature are widely described, but it remained unclear, how they influence cardiac performance. In the present study we investigated the effects of the phosphodiesterase5-inhibitor vardenafil on myocardial and vasomotor function in a rat model.