D. Behr-Roussel

Piboserod (SB 207266), a selective 5-HT4 receptor antagonist, reduces serotonin potentiation of neurally-mediated contractile responses of human detrusor muscle

The aim of this study is to evaluate the potency of piboserod (SB 207266), a selective 5-HT4 receptor antagonist, at inhibiting the 5-HT4-mediated potentiating effect of serotonin (5-HT) on the neurally-mediated contractile responses of human detrusor strips to electrical field stimulations (EFS). Strips of human detrusor muscle were mounted in Krebs-HEPES buffer under a resting tension of 500xa0mg and EFS (20xa0Hz, 1xa0ms duration at 300xa0mA for 5xa0s) was applied continuously at 1xa0min intervals. After stabilization of the EFS-induced contractions, concentration-response curves to 5-HT (0.1xa0nM–100xa0μM) were constructed in the absence or presence of 1 or 100xa0nM of piboserod. The experiments were performed in the presence of methysergide (1xa0μM) and ondansetron (3xa0μM) to block 5HT1/5HT2 and 5-HT3 receptors, respectively. 5-HT potentiated the contractile responses to EFS of human bladder strips in a concentration-dependent manner, with a maximum mean of 60.0±19.9% of the basal EFS-evoked contractions. Piboserod did not modify the basal contractions but concentration-dependently antagonized the ability of 5-HT to enhance bladder strip contractions to EFS. In presence of 1 and 100xa0nM of piboserod, the maximal 5-HT-induced potentiations were reduced to 45.0±7.9 and 38.7±8.7%, respectively. A mean apparent antagonist dissociation constant value (KB) of 0.56±0.09xa0nM was determined. These data show the ability of piboserod to antagonize with high potency the enhancing properties of 5-HT on neurally-mediated contractions of isolated human bladder strips. Therefore, the 5-HT4 receptor might represent an attractive pharmacological target for the treatment of overactive bladder.

268 RHO-KINASE INHIBITION IMPACTS NEUROGENIC DETRUSOR OVERACTIVITY IN CHRONIC SPINALIZED RATS

Effect of Y-27632 on urodynamic parameters in consc ious SCI rats Spinal cord injury (SCI) severely disrupts normal bladder function by inducing neurogenic detrusor overactivity (NDO). First line SCIinduced NDO treatments i.e. antimuscarinics often associated with intermittent catheterization are somewhat limited by a mild to moderate clinical efficacy and a significant incidence of side effects. Thus the development of new effective drugs for the treatment of NDO is of crucial importance. Rho-kinase has a central role in the regulation of detrusor smooth muscle contraction since components of the rhoA/rho-kinase signalling pathway are involved in the Ca2+-sensitization of the smooth muscle 1. Moreover, in vitro and in vivo data from animal models of overactive bladder (OAB) indicate that rho-kinases are involved in pathophysiological mechanisms responsible for OAB 2,3. Thus, we aimed to evaluate the effects of a rho-kin ase inhibitor (Y-27632) on urodynamic parameters in rats with chronic SCI.

COMBINATION OF ALFUZOSIN AND TADALAFIL EXERTS ADDITIVE RELAXANT EFFECT ON HUMAN PROSTATE

**p<0.01; ***p<0.001 **p<0.01; ***p<0.001 log (norepinephrine), M log (norepinephrine), M Comparison of the pD2 or Emax: *p < 0.05, versus vehicle

217 SILDENAFIL AND DOXAZOSIN COMBINATION: RELAXANT EFFECTS IN HUMAN CORPUS CAVERNOSUM

1 Pelvipharm, Domaine CNRS, 1 avenue de la terrasse, Bâtiment 5, F-91190 Gif-sur-Yvette, France – www.pelvipharm.com Sainte Marthe Private Hospital, Urology, Dijon, France, Beau Soleil Private Hospital, Urology, Montpellier, France, Lyon Sud Hospital Pierre Benite, Urology, Lyon, France, Pfizer Global Research and development, Sexual Health, Sandwich, United Kingdom, 6 AP-HP Raymond Poincaré hospital, Department of Neurological rehabilitation, Garches, France giuliano@cyber-sante.org

269 RHO-KINASE INHIBITION RELAXES DETRUSOR FROM NEUROGENIC PATIENTS

Hypothesis / aims of study Rho-kinases have a central role in the regulation of bladder smooth muscle from human and various animal species. In vitro or in vivo data from animal models of overactive bladder (OAB) indicate that rho-kinases could be involved in the pathophysiology of OAB. To date, the role of rho-kinases in patients with neurogenic detrusor overactivity has not yet been explored. We aimed to evaluate the effect of Rho-kinase inhibition on detrusor from neurogenic patients pre-contracted with either carbachol or KCl.

128 NITRIC OXIDE/CGMP SIGNALLING MEDIATES AN INHIBITORY ACTION ON SENSORY PATHWAYS OF THE MICTURITION REFLEX IN THE RAT

Hypothesis / aims of study Overactive bladder (OAB) can be associated with an hyperexcitability of bladder afferent fibers. In particular, C-fibers, normally silent, can become hyperexcitable under pathophysiological conditions and therefore could be responsible for inducing bladder hyperactivity. Several studies have suggested that nitric oxide (NO) or its downstream signalling could modulate the micturit ion reflex by reducing the excitability of bladder afferents. We have evaluated the role of the NO/cGMP signalling pathway on the micturition reflex in an acute model of bladder hyperactivity associated with C-fiber excitability in rats induced by acute intravesical capsaicin. Study design, materials and methods Cystometry experiments were performed in isoflurane-anesthetized adult female rats. Sodium nitroprusside (SNP) 0.1mg/kg, a NO donor; 8Br-cGMP 10mg/kg, a cGMP analogue, sildenafil 3 mg/kg and vardenafil 1 mg/kg, two phosphodiesterase 5 inhibitors (IPDE5); N G -nitro-L-arginine methyl ester (L-NAME) 10mg/ml, a NO synthase inhibitor; LY-83583 1mg/kg, a guanylate cyclase inhibitor, were administered 45 min after the beginning of intravesical capsaicin (30μM) instillation. All drugs or vehicle were injected by intravenous route except for L-NAME intravesically administered. Cystometrogram was recorded 1 hour after drug administration. Each group of treatment included 8-12 animals. Urodynamics parameters related to the sensory component of the micturition reflex: intercontraction interval (ICI), micturition pressure threshold (MPT), baseline pressure (BP), and parameters related to the motor component: maximal pressure (MP) and voided volume (VV) were analyzed. Statistical analysis was performed using two-way ANOVA. Results SNP, 8Br-cGMP, and IPDE5 increased ICI by 83, 44, 39 and 43% respectively. In contrast, L-NAME decreased ICI by 16%. SNP, IPDE5 and 8Br-cGMP increased MPT by 35, 40, 25 and 11% respectively. In contrast, L-NAME and LY-83 583 decreased MPT by 55% and 10% respectively. 8Br-cGMP decreased MP by 24% whereas L-NAME and LY-83 583 increased MP by 131% and 29% respectively. SNP, and IPDE5 did not exert any effect on MP. SNP increased VV by 46%. 8Br-cGMP, and IPDE5 also increased this parameter albeit not significantly. In contrast, L-NAME tended to decrease the VV. 8Br-cGMP decreased BP by 22% whereas LY-83 583 increased it by 18%. SNP, IPDE5 and L-NAME did not exert any effect on BP. Interpretation of results Compounds activating NO/cGMP pathway inhibited bladder hyperactivity induced by capsaicin whereas compounds inhibiting NO/cGMP pathway increased it. These results indicate that the NO/cGMP signalling pathway is involved in the regulation of the micturition reflex in a pathophysiological model of bladder hyperactivity with a mechanism of action on both the sensory and the motor components of the micturition reflex. Concluding message The present study could support the potential development of NO/cGMP pathway modulators for the treatment of OAB.

131 COMBINED EFFECT OF A PHOSPHODIESTERASE 5 INHIBITOR, UDENAFIL, WITH AN ANTIMUSCARINIC, OXYBUTYNIN ON HUMAN DETRUSOR RELAXATION

Human bladder samples were obtained from 15 different patients with no known OAB undergoing cystectomy for bladder cancer. Detrusor strips without urothelium were mounted isometrically at a resting tension of 500 mg in a 5 ml organ bath filled with Krebs-HEPES buffer maintained at 37°C and bubbled w ith 95%O2-5%CO2. The strips were connected to force transducers for isometric tension recordings (Pioden Controls Ltd, UK). Following amplification, the tension changes were computerized via MacLabTM/8 using ChartTM 5 software (AD Instruments Ltd).

278 IS RELAXATION OF HUMAN DETRUSOR BY SILDENAFIL RELYING ON PDE 5 INHIBITION

INTRODUCTION AND OBJECTIVES: We evaluate the efficacy and safety of propiverine hydrochloride (antimuscarinics), naftopidil ( 1adrenoceptor antagonists), or both in patients with male lower urinary tract symptoms (LUTS) suggestive of benign prostatic hyperplasia (BPH) and concomitant overactive bladder (OAB). METHODS: Older than fifty years old male who had a total International Prostate Symptom Score (IPSS) of 8 or higher and bladder dairy documenting micturition frequency (more than 8 micturitions per 24 hours) and urgency (more than 1 episode per one day), with or without urgency urinary incontinence and residual post-void residual urine volume (PVR) 50 ml were randomized into 3 groups, group Nnaftopidil (50mg once daily) only, group P-propiverine hydrochloride (20mg once daily) only, and group NPnaftopidil (50mg once daily) plus propiverine hydrochloride (20mg once daily) for a 4-week treatment regimen. Before and after administration, subjective symptoms were assessed using the IPSS and QOL index, and urinary urgency was assessed in four grades by referring to the Urgency Perception Scale. RESULTS: A total of 66 men, including 20 in group N, 23 in group P, and 23 in group NP were treated and 58 (87.9 %) completed the 4 weeks of treatment. IPSS were significantly improved in group N and NP. Urinary frequency was markedly improved in group P and NP. Severity of urgency improved after therapy in all 3 groups, and no significant difference existed in the degree of change among the 3 groups. PVR increased in group P and NP. Significant improvements were noted in each group in urgency episodes. As to adverse event, one patient required catheterization due to acute urinary retention and one patient stopped medication because of complaining of difficulty on voiding in group P. CONCLUSIONS: In patients with male LUTS suggestive of BPH and concomitant OAB, naftopidil monotherapy was the safest, while combination therapy with naftopidil and anticholinergic agent was the most effective. Anticholinergic agent monotherapy was the least effective and safe. As a result, blocker monotherapy should be administered initially to male LUTS suggestive of BPH and concomitant OAB.