No abstract

Background and purpose: The mechanism(s) of action responsible for the beneficial effects of phosphodiesterase 5 (PDE5) inhibitors including sildenafil on lower urinary tract symptoms suggestive of benign prostate hyperplasia are unclear. In particular, the role of the NO-cGMP signalling pathway in regulating human bladder dome smooth muscle relaxation is questionable. Thus, we assessed the ability of a PDE5 inhibitor, sildenafil, to relax such tissue, and identified the signalling pathways involved in this relaxation. Experimental approach: Human bladder samples were obtained from 20 patients with no overactive bladder undergoing cystectomy for bladder cancer. Detrusor strips were mounted isometrically in Krebs-HEPES solution. Concentration-response curves for sildenafil (10 nM-30 mM) were generated in the presence of various inhibitors on carbachol-induced pre-contraction. Key results: Sildenafil relaxed carbachol-pre-contracted human detrusor strips, starting at 3 mM. This effect was not modified by NO donors, S-nitroso-N-acetylpenicillamine (10 mM) or sodium nitroprusside (300 nM), but was significantly inhibited by inhibition of guanylate cyclase (with ODQ, 10 mM) or adenylyl cyclase (with MDL-12,330A, 10 mM), by the ATP-sensitive potassium channel inhibitor, glibenclamide (10 mM), or inhibition of the large (with iberiotoxin, 30 nM) or small (with apamin, 100 nM) conductance calcium-activated potassium channels. Conclusions and implications:Sildenafil-induced relaxation of human detrusor smooth muscle involved cGMP-, cAMP-and K + channel-dependent signalling pathways, with a minor contribution from NO. The effect of this sildenafil-induced relaxation on the clinical benefit of PDE5 inhibitors on urinary storage symptoms in men deserves further investigation.

suburothelium were mounted isometrically in organ baths filled with Krebs-HEPES (37 ° C; 95% O 2 /5% CO 2 ). Strips were incubated with 10 μ M pinacidil (K ATP opener) followed by 10 μ M glibenclamide (K ATP blocker). In another set of experiments, strips were incubated with 30 μ M NS-1619 (BK Ca opener) followed by 100 n M iberiotoxin (BK Ca blocker) or with 100 n M apamin (SK Ca blocker). RESULTSSCA occurred more frequently with larger amplitude and area under the curve in detrusor strips from NDO patients compared to control patients. The presence of urothelium/suburothelium did not significantly modify SCA in either patient population. Pinacidil markedly inhibited SCA of detrusor strips from control and NDO patients. This effect was reversed by glibenclamide. By contrast, NS-1619 followed by iberiotoxin did not elicit any significant changes in SCA from NDO patients, contrary to control patients. CONCLUSIONSK ATP and SK Ca channels regulate SCA of NDO patients' detrusor strips. By contrast, BK Ca channels are not involved in the regulation of detrusor SCA in NDO patients, whereas they regulate SCA in control patients. These results should be considered in the development of K + channels openers for the treatment of NDO. Moreover, SCA observed in vitro should be regarded as an in vitro modelling of human NDO.

No abstract

Chorioamniotic infection is a leading cause of preterm premature rupture of fetal membranes (amnion and chorion). Bacterial infection induces an inflammatory response characterized by elevated production of proinflammatory cytokines; the latter activate the production of both PGs that stimulate uterine contractions, and matrix metalloproteinases (MMPs) that degrade the extracellular matrix of the chorioamniotic membranes. The inflammatory response is under the control of cAMP content, which is partly regulated by phosphodiesterases (PDE). In this study, we investigated the role of the PDE4 family in the inflammatory process triggered by LPS in a model of amniochorionic explants. We found that PDE4 family is the major cAMP-PDE expressed in human fetal membranes and that PDE4 activity is increased by LPS treatment. Selective inhibition of PDE4 activity affected LPS signaling, because PDE4 inhibitors (rolipram and/or cilomilast) reduced the release of the proinflammatory cytokine TNF-α and increased the release of the anti-inflammatory cytokine IL-10. PDE4 inhibition reduced cyclooxygenase-2 protein expression and PGE2 production and also modulated MMP-9, a key mediator of the membrane rupture process, by inhibiting pro-MMP-9 mRNA expression and pro-MMP-9 activity. These results demonstrate that the PDE4 family participates in the regulation of the inflammatory response associated with fetal membrane rupture during infection. The PDE4 family may be an appropriate pharmacological target for the management of infection-induced preterm delivery.

Introduction Phosphodiesterase 5 inhibitors (PDE5) such as sildenafil are first-line treatment for erectile dysfunction (ED). Alpha1 (α1)-adrenoceptor antagonists such as doxazosin are indicated for the treatment of patients with lower urinary tract symptoms (LUTS)/benign prostatic hyperplasia (BPH). ED and LUTS/BPH are conditions that are often associated. Accordingly, α1-adrenoceptor antagonists and PDE5 inhibitors will be often prescribed in real life setting together. Aim To evaluate the effects of the combination of sildenafil and doxazosin on human cavernosal and prostatic tissue. Methods Prostatic and erectile tissues were obtained from nine to 12 patients, respectively. Patients underwent cystoprostatectomy for infiltrating bladder cancer or penile surgery for penile implant, congenital curvature or Peyronie’s disease. Main Outcome Measures In organ baths, prostatic and cavernosal strips were submitted to either concentration-response curves (CRC) to phenylephrine (Phe) or norepinephrine (NE), respectively, in presence of vehicle, sildenafil (10−6 M, 10−5 M), doxazosin (10−8 M, 3.10−8 M, or 10−7 M), or a combination of both. Continuous electrical field stimulation (EFS; 32 Hz, 5 ms, 5 seconds, 300 mA) was performed on prostatic strips which were incubated with sildenafil 10−6 M or vehicle before the successive addition of doxazosin (10−7 M, 10−6 M) or vehicle. Cavernosal strips were pre-incubated with doxazosin (10−9 M, 10−8 M) or vehicle, then CRC to sildenafil were constructed on NE (3.10−6 M) precontracted cavernosal strips. Results Combination of sildenafil and doxazosin exerted a greater relaxing effect on CRC to Phe or NE compared with each compound alone in both tissues. Sildenafil significantly enhanced the relaxing effect of doxazosin on EFS-induced contractions in prostatic strips. Doxazosin significantly increased the ability of sildenafil to inhibit NE-induced contractions in cavernosal strips. Conclusions Sildenafil and doxazosin reduced adrenergic tone of prostatic and cavernosal smooth muscle and their combination provided a significant benefit when targeting relaxation of both tissues. These experiments provide support for further clinical evaluation of the sildenafil and doxazosin combination in ED patients with LUTS/BPH.

The anti-inflammatory and utero-relaxant effects of two potent phosphodiesterase 4 (PDE4) inhibitors of the latest generation: cilomilast (one of the most advanced PDE4 inhibitors in clinical development, reportedly more selective for PDE4D) and compound A (which displays 12-fold greater selectivity toward PDE4B and/or PDE4A than toward PDE4D) were evaluated in human uterine smooth muscle. We first established that these compounds exhibit greater efficacy in inhibiting total cAMP-PDE activity in pregnant versus nonpregnant myometrium (E(max) = 78.0% +/- 3.6% and 80.3% +/- 2.2% in pregnant versus 57% +/- 4.7% and 70.5% +/- 5.9% in nonpregnant women for compound A and cilomilast, respectively; P < 0.05 for both compounds), confirming the prominent participation of PDE4 isoforms in cAMP hydrolysis in the near-term pregnant myometrium. Using pregnant myometrial explants, we have shown that both these drugs and also rolipram, the prototype PDE4 inhibitor, produce concentration-dependent inhibition of lipopolysaccharide (LPS) induced tumor necrosis factor alpha (TNFalpha) release with similar potency in each case (pD2 = 8.0 +/- 0.5, 7.9 +/- 0.2, and 7.6 +/- 0.2 for compound A, cilomilast, and rolipram, respectively). The maximum inhibition produced is 65%. Pretreatment with forskolin or 8-bromo-cAMP mimics the PDE4 inhibitor effect. Furthermore, compound A and cilomilast both produce concentration-dependent inhibition of the spontaneous contractions of myometrial strips and are more potent in pregnant than in nonpregnant myometrium (pD2 = 7.3 +/- 0.7 and 8.1 +/- 0.3 in pregnant versus 6.2 +/- 0.9 and 6.6 +/- 0.1 in nonpregnant myometrium for compound A and cilomilast, respectively; P < 0.05 for both compounds). This demonstrates that the PDE4 isoforms involved in the mechanism of contraction are different in the pregnant and nonpregnant myometrium. Our study highlights the importance of developing PDE4 inhibitors for the pharmacological management of infection-induced preterm labor.

No abstract