Bladder Relaxation Research Articles

Neurogenic-derived 6-nitrodopamine is the most potent endogenous modulator of the mouse urinary bladder relaxation

6-Nitrodopamine (6-ND) modulates vas deferens, seminal vesicles, and corpus cavernosum contractility; however, its role on the lower urinary tract organs has not been evaluated. Investigations of isolated urinary bladders from wild-type (WT) mice revealed 6-ND release was comparable to that of dopamine and adrenaline, whereas noradrenaline was hardly detected, as assessed by liquid chromatography coupled to tandem mass spectrometry. In vitro, 6-ND induced concentration-dependent relaxations in carbachol pre-contracted bladders with high potency (pEC50: 8.04 ± 0.86), independently of eNOS/sGC activity. Co-incubation of 6-ND (1–10 μM) antagonizes the contractile effects of acetylcholine (p < 0.05). Experiments using nitric oxide synthase (NOS) knockout mice demonstrated that 6-ND release from isolated urinary bladder was significantly reduced by neuronal NOS (nNOS−/−) deletion and abolished by triple NOSs deletion (n/i/eNOS−/−), while no significant changes were observed in endothelial (eNOS−/−) or inducible (iNOS−/−) knockout mice. Incubation with tetrodotoxin resulted in a significant decrease in 6-ND release in bladders obtained from WT, but not in nNOS−/− mice. The bladders from nNOS−/− and n/i/eNOS−/− mice exhibited significantly higher contractile responses to electric field stimulation (EFS), compared to eNOS−/−, iNOS−/−, or WT bladders. The hyperreactivity observed in triple NOS knockouts was reversed by the incubation with bladder mucosal layer obtained from a donor WT mice, but not with the muscular layer. These findings clearly demonstrate 6-ND is the most potent endogenous relaxing agent of urinary bladder, and inhibition of its release is associated with bladder hyperreactivity.

A Comparative Study of Solifenacin, Mirabegron, and Their Combination as Bladder Relaxants in the Management of Overactive Bladder.

Introduction Overactive bladder (OAB) is a medical state that presents as the urgency of urine and increased frequency of micturition and is diagnosed on the basis of the presence of these symptoms in the absence of other explainable diagnoses. The management of this condition includes conservative management, medical management/pharmacotherapy, and surgical management. The overactive bladder has been treated with smooth muscle relaxants, but there are conflicting results. Hence, this study aimed to assess the result of the two smooth muscle relaxants, mirabegronand solifenacin, and their combination to manage an overactive bladder. Methodology A clinical trial was conducted at Swaroop Rani Nehru Hospital, Motilal Nehru Medical College, Prayagraj, India, over the period from November 2019 to December 2020. Ninety patients with OAB were divided into three groups: G1, G2, and G3. These groups were administered solifenacin, mirabegron, and a combination of mirabegron and solifenacin (S+M), respectively. Follow-ups were conducted at 2, 4, 12, and 18 weeks for evaluation. Data were entered into IBM SPSS Statistics for Windows, Version 23 (Released 2015; IBM Corp., Armonk, New York, United States). Appropriate statistical tests, including the chi-square and ANOVA, were employed in this study. Observation The combination of mirabegron and solifenacin was significantly more effective in terms of response compared to solifenacin alone. There was no significant difference between solifenacin versus mirabegron, or between mirabegron (M) and the combination of mirabegron (M) and solifenacin (S). Side effects were more severe in patients taking high doses of solifenacin. Conclusion The S + M combination has higher efficacy than solifenacin and mirabegronwhen given alone.

Recessive CHRM5 variant as a potential cause of neurogenic bladder.

Neurogenic bladder is caused by disruption of neuronal pathways regulating bladder relaxation and contraction. In severe cases, neurogenic bladder can lead to vesicoureteral reflux, hydroureter, and chronic kidney disease. These complications overlap with manifestations of congenital anomalies of the kidney and urinary tract (CAKUT). To identify novel monogenic causes of neurogenic bladder, we applied exome sequencing (ES) to our cohort of families with CAKUT. By ES, we have identified a homozygous missense variant (p.Gln184Arg) in CHRM5 (cholinergic receptor, muscarinic, 5) in a patient with neurogenic bladder and secondary complications of CAKUT. CHRM5 codes for a seven transmembrane-spanning G-protein-coupled muscarinic acetylcholine receptor. CHRM5 is shown to be expressed in murine and human bladder walls and is reported to cause bladder overactivity in Chrm5 knockout mice. We investigated CHRM5 as a potential novel candidate gene for neurogenic bladder with secondary complications of CAKUT. CHRM5 is similar to the cholinergic bladder neuron receptor CHRNA3, which Mann et al. published as the first monogenic cause of neurogenic bladder. However, functional in vitro studies did not reveal evidence to strengthen the status as a candidate gene. Discovering additional families with CHRM5 variants could help to further assess the genes' candidate status.

Loss of resilience contributes to detrusor underactivity in advanced age.

Volume hyposensitivity resulting from impaired sympathetic detrusor relaxation during bladder filling contributes to detrusor underactivity (DU) associated with aging. Detrusor tension regulation provides an adaptive sensory input of bladder volume to the brainstem and is challenged by physiological stressors superimposed upon biological aging. We recently showed that HCN channels have a stabilizing role in detrusor sympathetic relaxation. While mature mice maintain homeostasis in the face of stressors, old mice are not always capable. In old mice, there is a dichotomous phenotype, in which resilient mice adapt and maintain homeostasis, while non-resilient mice fail to maintain physiologic homeostasis. In this DU model, we used cystometry as a stressor to categorize mice as old-responders (old-R, develop a filling/voiding cycle) or old-non-responders (old-NR, fail to develop a filling/voiding cycle; fluctuating high pressures and continuous leaking), while also assessing functional and molecular differences. Lamotrigine (HCN activator)-induced bladder relaxation is diminished in old-NR mice following HCN-blockade. Relaxation responses to NS 1619 were reduced in old-NR mice, with the effect lost following HCN-blockade. However, RNA-sequencing revealed no differences in HCN gene expression and electrophysiology studies showed similar percentage of detrusor myocytes expressing HCN (Ih) current between old-R and old-NR mice. Our murine model of DU further defines a role for HCN, with failure of adaptive recalibration of HCN participation and intensity of HCN-mediated stabilization, while genomic studies show upregulated myofibroblast and fibrosis pathways and downregulated neurotransmitter-degradation pathways in old-NR mice. Thus, the DU phenotype is multifactorial and represents the accumulation of age-associated loss in homeostatic mechanisms.

International Lower Urinary Tract Function Data Set: A Study in Spinal Cord Injury Population in HRC

Background and aim: The majority of spinal cord injury (SCI) patients will experience bladder dysfunction, referred to as neurogenic bladder, which results in problems related to storage and release of urine. It is critical for primary care providers to work with patients to develop an effective voiding routine to avoid complications of inadequate bladder management. This study reviews the epidemiology data of spinal cord injury patients with the neurogenic bladder in a rehabilitation hospital. Methods: A retrospective survey involved the opportunistic study of 179 patients with SCI who underwent a urodynamic study. The information was collected using International Lower Urinary Tract Function Basic SCI Data Set and analysed using SPSS version 26. Results: There were 179 SCI patients with neurogenic bladder between 1st January 2016 to 31st December 2020. Predominantly was male (n = 121, 68% ) with the mean age of 37. Majority are paraplegia ( n = 121, 68%). The cause of injury is mainly traumatic (n = 102, 57.3%), with the highest number of incomplete injuries (n = 113, 63.5%) compared to incomplete injury. The majority of them have an awareness of the bladder sensation (n = 128, 71.9%). CISC is the main method of bladder emptying technique used by the patients, which comprise 83 patients (46.6%), followed by normal voiding method (n = 63, 35.4%) and other methods that patients have used are straining (n = 3), involuntary reflex (n = 3) and crede (n = 1). CBD is the main method for 16 patients (9%). The majority of these patients have daily leaking (n = 88, 49.4%), requiring a collecting device (n = 80, 44.9%). Only 28 patients (31.8%) with daily leaking has bladder relaxant on board. A total of 77 (43.3%) of the samples has bladder changes within the last year. Conclusion: This descriptive study provides valuable information for clinicians regarding patients’ bladder management. However, the data collection has ideally been done at a timely follow-up interval to better understand the issues.

Health care and rehabilitation services utilization, benefits and satisfaction: a community survey of individuals with spinal cord injury in Thailand.

Cross-sectional study. This study aimed to explore and report on health care and rehabilitation service utilization, rehabilitation service benefits, and levels of satisfaction of individuals with spinal cord injury (SCI) living in communities in Thailand. Four rehabilitation facilities in Thailand, two university hospitals (Maharaj Nakorn Chiang Mai Hospitalin Chiang Mai Provinceand Siriraj Hospital in Bangkok), one large provincial hospital (Ratchaburi Hospital in Ratchaburi Province), and one national rehabilitation institute (Sirindhorn National Medical Rehabilitation Institute in Nonthaburi Province). This study was part of the International Spinal Cord Injury Community Survey (InSCI). Individuals with SCI completed a set of questionnaires, then data related to their health care and rehabilitation services were extracted and analyzed. Of the 320 participants, most were male (71%), and the majority were living with paraplegia (73%). In cases of mild illnesses where hospitalization was not required, 46% went to anearby health service hospital. In cases of serious illnesses where hospitalization was required, 39% went to a higher-level hospital. The majority (80%) were satisfied with their experience with health care services. The three top preferred products and services in descending order were wheelchairs and cushions, increased disability pension, medication and medical equipment including bladder relaxants, urinary catheters and urine bags. Individuals with SCI living in communities in Thailand preferred treatment at a nearby district hospital for mild illnesses with one-third transferring to a higher-level hospital for serious illnesses. The majority were satisfied with the health care services and rehabilitation services.

Pharmacophore-guided Virtual Screening to Identify New β3 -adrenergic Receptor Agonists.

The β3‐adrenergic receptor (β3‐AR) is found in several tissues such as adipose tissue and urinary bladder. It is a therapeutic target because it plays a role in thermogenesis, lipolysis, and bladder relaxation. Two β3‐AR agonists are used clinically: mirabegron 1 and vibegron 2, which are indicated for overactive bladder syndrome. However, these drugs show adverse effects, including increased blood pressure in mirabegron patients. Hence, new β3‐AR agonists are needed as starting points for drug development. Previous pharmacophore modeling studies of the β3‐AR did not involve experimental in vitro validation. Therefore, this study aimed to conduct prospective virtual screening and confirm the biological activity of virtual hits. Ligand‐based pharmacophore modeling was performed since no 3D structure of human β3‐AR is yet available. A dataset consisting of β3‐AR agonists was prepared to build and validate the pharmacophore models. The best model was employed for prospective virtual screening, followed by physicochemical property filtering and a docking evaluation. To confirm the activity of the virtual hits, an in vitro assay was conducted, measuring cAMP levels at the cloned β3‐AR. Out of 35 tested compounds, 4 compounds were active in CHO−K1 cells expressing the human β3‐AR, and 8 compounds were active in CHO−K1 cells expressing the mouse β3‐AR.

Age-related differences in responses to hydrogen sulfide in the bladder of spontaneously hypertensive rats.

To investigate whether a response to hydrogen sulfide donors (GYY4137 and sodium hydrosulfide) and the endogenous hydrogen sulfide system (hydrogen sulfide level and expression of cysteine aminotransferase, cystathionine β-synthase, cystathionine γ-lyase, and 3-mercaptopyruvate sulfurtransferase) in the spontaneously hypertensive rat bladder differ with age, we compared the responses of hydrogen sulfide donors to micturition and bladder relaxation, and the endogenous hydrogen sulfide system in the bladder of 18-week versus 12-week-old spontaneously hypertensive rats. GYY4137 was intravesically administered and cystometry was performed in anesthetized rats. The responses of sodium hydrosulfide were evaluated in carbachol-mediated precontracted bladder strips. Bladder hydrogen sulfide levels and expression levels of each enzyme were investigated using the methylene blue method and Western blotting, respectively. GYY4137 treatment significantly prolonged intercontraction intervals only in 12-week-old rats. Sodium hydrosulfide-induced bladder relaxation was significantly attenuated in the strips of 18-week-old rats compared with that in 12-week-old rats. In the bladder dome, significant increases in hydrogen sulfide levels and in the expression of cystathionine β-synthase, 3-mercaptopyruvate sulfurtransferase, and cysteine aminotransferase were observed in 18-week-old rats compared with 12-week-old rats. However, cystathionine γ-lyase bands were not detected in bladder tissues of either group. Bladder relaxation induced by hydrogen sulfide may be attenuated in spontaneously hypertensive rats in an age-dependent manner.

Receptor GPR91 contributes to voiding function and detrusor relaxation mediated by succinate.

Succinate activates the receptor GPR91 identified in the bladder. The present study aims to unravel the mechanisms of bladder relaxation by succinate and how the receptor is involved in structural and functional changes of the bladder. Physiological recordings of bladder function were carried out by cystometry and organ bath from C57BL/6 mice, homozygous GPR91-/- mice,and Sprague-Dawley (SD) rats. GPR91 expression was confirmed by polymerase chain reaction and tissue morphology was examined by light (Masson trichrome) and fluorescence microscopy. Nitric oxide (NO) and ATP secretion were measured. Bladders of GPR91 KO mice had a greater mass to body weight ratio with a thicker bladder wall compared to C57BL/6 mice. They also displayed increased basal and maximal bladder pressures, and decreased intercontraction intervals, bladder capacity, micturition volume, and compliance. During cystometry, bladders of SD rats and C57BL/6 mice instilled with succinate (10 mM) showed signs of relaxation while bladders of GPR91 KO mice were unresponsive. Similarly, in organ bath, succinate relaxed bladder strips preincubated with carbachol, except GPR91 KO ones. Relaxation was stronger in the presence of urothelium and independent of NO synthesis. Bladder strips from all mice groups showed similar responses to KCl, carbachol, and electrical stimulation. In vitro, succinate increased NO secretion in urothelial cell culture of both C57BL6 and GPR91 KO mice while ATP secretion was potently decreased by succinate in C57BL6 culture only. Succinate through GPR91 is essential to bladder structure and contraction. GPR91 relaxes the detrusor partially by decreasing urothelial ATP secretion.

Effect of Nebivolol on the Isolated Rat Bladder Strips Precontracted with Carbachol or Potassium Chloride

Objective: One of the proposed mechanism mediates the vasorelaxant effect of nebivolol is based on its agonistic activity on beta-2 and/or beta-3 adrenergic receptors. These receptors are also involved in the relaxation of urinary bladder. The aim of this study was to explore that the ability of nebivolol to induce relaxation of the isolated rat bladder strip precontracted with cholinergic stimuli using with carbachol or non-cholinergic stimuli using with potassium chloride (KCl). Methods: The isolated bladder strips were mounted in organ bath and contracted by KCl (40 mM) or carbachol(1 µM) before the cumulative addition of nebivolol (0.0001-100 µM). To investigate the role of beta-adrenergic receptors in the nebivolol-induced relaxant response, some bladder strips were incubated with propranolol (1 µM) for 30 min. Statistical significance was tested by Student’s t-test. p&amp;lt;0.05 was considered to be statistically significant. Results: Nebivolol elicited concentration-dependent relaxant response in the bladder strips precontracted with KCl or carbachol. Although the relaxant response to nebivolol in the bladder strips precontracted with carbachol was significantly inhibited by propranolol(p&amp;lt;0.05), the nebivolol-induced relaxation was failed to be inhibited by propranolol in the bladder strips precontracted with KCl. The maximum relaxation in response to nebivolol was found to be significantly higher in the bladder strips precontracted with carbachol compared to that of KCl (p&amp;lt;0.05). Conclusion: The findings of the present study indicate that beta-adrenergic receptors play role in the relaxant response of nebivolol in the isolated rat bladder strip precontracted with carbachol.

Oxytocin Reduces Intravesical Pressure in Anesthetized Female Rats: Action on Oxytocin Receptors of the Urinary Bladder.

Urinary bladder dysfunction affects several people worldwide and shows higher prevalence in women. Micturition is dependent on the Barrington’s nucleus, pontine urine storage center and periaqueductal gray matter, but other brain stem areas are involved in the bladder regulation. Neurons in the medulla oblongata send projections to hypothalamic nuclei as the supraoptic nucleus, which synthetizes oxytocin and in its turn, this peptide is released in the circulation. We investigated the effects of intravenous injection of oxytocin (OT) on the urinary bladder in sham and ovariectomized rats. We also evaluated the topical (in situ) action of OT on intravesical pressure (IP) as well as the existence of oxytocin receptors in the urinary bladder. In sham female Wistar rats, anesthetized with isoflurane, intravenous infusion of OT (10 ng/kg) significantly decreased the IP (–47.5 ± 1.2%) compared to saline (3.4 ± 0.7%). Similar effect in IP was observed in ovariectomized rats after i.v. OT (–41.9 ± 2.9%) compared to saline (0.5 ± 0.6%). Topical administration (in situ) of 0.1 mL of OT (1.0 ng/mL) significantly reduced the IP (22.3.0 ± 0.6%) compared to saline (0.9 ± 0.7%). We also found by qPCR that the gene expression of oxytocin receptor is present in this tissue. Blockade of oxytocin receptors significantly attenuated the reduction in IP evoked by oxytocin i.v. or in situ. Therefore, the findings suggest that (1) intravenous oxytocin decreases IP due to bladder relaxation and (2) OT has local bladder effect, binding directly in receptors located in the bladder.

PD24-05 OXIDATIVE STRESS INDUCES DETRUSOR UNDERACTIVITY AND URETHRAL DYSFUNCTION IN AGING RATS

You have accessJournal of UrologyBladder & Urethra: Anatomy, Physiology & Pharmacology II (PD24)1 Apr 2020PD24-05 OXIDATIVE STRESS INDUCES DETRUSOR UNDERACTIVITY AND URETHRAL DYSFUNCTION IN AGING RATS Asato Ohtsubo*, Takuma Oshiro, Ryu Kimura, Minoru Miyazato, Tomohiro Matsuo, Yasuyoshi Miyata, and Hideki Sakai Asato Ohtsubo*Asato Ohtsubo* More articles by this author , Takuma OshiroTakuma Oshiro More articles by this author , Ryu KimuraRyu Kimura More articles by this author , Minoru MiyazatoMinoru Miyazato More articles by this author , Tomohiro MatsuoTomohiro Matsuo More articles by this author , Yasuyoshi MiyataYasuyoshi Miyata More articles by this author , and Hideki SakaiHideki Sakai More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000881.05AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Age-related symptoms, such as urinary retention and a poor urinary stream have been attributed to detrusor underactivity. Our recent studies showed that by simultaneously recording intravesical pressure and urethral perfusion pressure (UPP), urethral relaxation during bladder contractions was diminished in aged rats. Nevertheless, L-arginine (a substrate of nitric oxide (NO) synthase) could not restore a diminished urethral relaxation. Thus, we hypothesized that age-associated oxidative stress would impair NO/soluble guanylyl cyclase (sGC) system which induces urethral relaxation. This hypothesis was tested by measuring an oxidative stress marker in the bladder and also by simultaneously recording intravesical pressure and UPP using BAY 41-2272 as a novel NO-independent stimulator of sGC. METHODS: Female Sprague Dawley rats (young rats aged 3 months and old rats aged 12–15 months) were used. 1) Oxidative stress marker staining for 8-hydroxy-2’-deoxyguanosine (8-OHdG) and malondialdehyde (MDA) in the bladder was performed in both groups. 2) Urethral activity was evaluated by simultaneously recording the intravesical pressure under isovolumetric conditions and UPP under urethane anesthesia. 3) BAY 41-2272 (1 mg/kg) was administered intravenously in both groups under isovolumetric conditions. RESULTS: 1) Oxidative marker staining revealed that 8-OHdG and MDA levels were higher in aging rats than those in young rats. 2) UPP nadir during urethral relaxation was significantly higher (38%) in aging rats than in young rats (p < 0.05). The mean amplitude of high frequency oscillation (HFO) of the urethral striated muscle was also significantly lower (49%) in aging rats than in normal rats (p < 0.05). 3) BAY 41-2272 increased urethral relaxation in young rats while restoring impaired urethral relaxation in aged rats. CONCLUSIONS: These results indicate that aging induces a dysfunction in urethral relaxation during voiding, as evidenced by a decrease in HFO activity of the urethral striated muscle as well as NO mediated urethral relaxation of the urethral smooth muscle. Because NO-independent stimulator could restore impaired urethral relaxation in the aged bladder, age-associated oxidative stress in the NO/sGC system might be correlated with an age associated impairment in bladder and urethral coordination. This novel study coupled with physiological and morphological changes in the aged bladder would contribute to elucidating the process of aging in bladders. Source of Funding: This work was supported by a Grant-in-Aid for Scientific Research (18K17752, 18K10714 and 18K10749 ). © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e533-e534 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Asato Ohtsubo* More articles by this author Takuma Oshiro More articles by this author Ryu Kimura More articles by this author Minoru Miyazato More articles by this author Tomohiro Matsuo More articles by this author Yasuyoshi Miyata More articles by this author Hideki Sakai More articles by this author Expand All Advertisement PDF downloadLoading ...

MP28-10 COMPARISON OF THE HYDROGEN SULFIDE-INDUCED RELAXATION OF THE BLADDER BETWEEN HYPERTENSIVE AND NORMOTENSIVE RATS

You have accessJournal of UrologyBladder & Urethra: Anatomy, Physiology & Pharmacology I (MP28)1 Apr 2020MP28-10 COMPARISON OF THE HYDROGEN SULFIDE-INDUCED RELAXATION OF THE BLADDER BETWEEN HYPERTENSIVE AND NORMOTENSIVE RATS Suo Zou*, Takahiro Shimizu, Shogo Shimizu, Youichirou Higashi, Takaaki Aratake, Masaki Yamamoto, Tomoya Hamada, Yoshiki Nagao, Masashi Honda, and Motoaki Saito Suo Zou*Suo Zou* More articles by this author , Takahiro ShimizuTakahiro Shimizu More articles by this author , Shogo ShimizuShogo Shimizu More articles by this author , Youichirou HigashiYouichirou Higashi More articles by this author , Takaaki AratakeTakaaki Aratake More articles by this author , Masaki YamamotoMasaki Yamamoto More articles by this author , Tomoya HamadaTomoya Hamada More articles by this author , Yoshiki NagaoYoshiki Nagao More articles by this author , Masashi HondaMasashi Honda More articles by this author , and Motoaki SaitoMotoaki Saito More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000867.010AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: We recently reported that hydrogen sulfide (H2S), an endogenous gasotransmitter, is a possible relaxation factor in the rat bladder. Because it has shown that bladder dysfunctions can be developed by chronic hypertension in spontaneously hypertensive rats (SHRs), we compared effects of NaHS and GYY4137 (H2S donors) on the bladder contractility and the micturition reflex, and the endogenous H2S system in the bladder between SHRs and normotensive Wistar rats (Wistars). METHODS: Eighteen-week-old male SHRs and Wistars were used. (1) Under urethane (0.8 g/kg, ip) anesthesia, a catheter was inserted into the bladder to instill reagents (2.4 ml/h) and to measure intravesical pressure. After detecting 4-5 micturition reflexes induced by saline instillation, GYY4137 solution (10-8, 10-7 and 10-6 M) or vehicle was instilled. (2) Bladder dome and trigone (BL-D and BL-T) were prepared from both rats. Effects of NaHS (1×10-8 to 3×10-4 M) were evaluated on carbachol (10-5 M)-induced pre-contracted bladder strips. H2S contents were measured by the methylene blue method. Expression levels of enzymes related to H2S biosynthesis [3-mercaptopyruvate sulfurtransferase (MPST), cysteine aminotransferase (CAT) and cystathionine β-synthase (CBS)] were examined by western blotting. RESULTS: (1) GYY4137 significantly prolonged intercontraction intervals compared to the vehicle-treated group in Wistars, but not in SHRs (Table 1). (2) NaHS-induced relaxation on pre-contracted BL-D and BL-T strips was significantly attenuated in SHRs compared to Wistars (Table 2). The H2S content in the bladder of SHRs was significantly higher than that of Wistars (Fig. C). The expression levels of MPST, but not CAT or CBS, in the SHR bladder were significantly higher than those in the Wistar bladder (Fig. D). CONCLUSIONS: H2S-induced bladder relaxation in SHRs is attenuated, which might be a cause of hypertension-mediated development of bladder dysfunctions. To compensate the less responsiveness, endogenous H2S levels might be increased in the SHR bladder. Therefore, the endogenous H2S system might be a new drug candidate for the treatment of hypertension-mediated bladder dysfunctions. Source of Funding: JSPS KAKENHI (#15K15583), GSK Japan Research Grant 2017 © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e423-e423 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Suo Zou* More articles by this author Takahiro Shimizu More articles by this author Shogo Shimizu More articles by this author Youichirou Higashi More articles by this author Takaaki Aratake More articles by this author Masaki Yamamoto More articles by this author Tomoya Hamada More articles by this author Yoshiki Nagao More articles by this author Masashi Honda More articles by this author Motoaki Saito More articles by this author Expand All Advertisement PDF downloadLoading ...

Urinary Bladder Weight and Function in a Rat Model of Mild Hyperglycemia and Its Treatment With Dapagliflozin.

Hypertrophy and dysfunction of the urinary bladder are consistently observed in animal models of type 1 and less consistently in those of type 2 diabetes. We have tested the effects of mild hyperglycemia (n = 10 per group) in a randomized, blinded study and, in a blinded pilot study, of type 2 diabetes (n = 6 per group) and its treatment with dapagliflozin (1 mg/kg per day) on weight, contraction, and relaxation of the rat bladder. Based on a combination of high-fat diet and a low dose of streptozotocin, animals in the main study reached a mean peak blood glucose level of about 300 mg/dl, which declined to 205 mg/dl at study end. This was associated with a small, if any, increase in bladder weight. In a pooled analysis of all animals of the main and the pilot study, we detected a correlation of moderate strength between blood glucose and bladder weight (r 2 = 0.2013; P = 0.0003 for Pearson correlation coefficient). Neither the main nor the pilot study found evidence for an altered contractility (responses to carbachol or KCl) or relaxation (responses to isoprenaline, fenoterol, CL 316,243, or forskolin). Treatment with dapagliflozin in the absence of hyperglycemia increased diuresis in the main study by 43% relative to control and increased bladder weight by 15% in the pooled groups of both studies (post hoc analysis). We conclude that mild hyperglycemia has no major effects on bladder hypertrophy or function.

Hydrogen sulfide-induced relaxation of the bladder is attenuated in spontaneously hypertensive rats.

To compare hydrogen sulfide (H2S)-induced relaxation on the bladder between normotensive and spontaneously hypertensive rat (SHR), we evaluated the effects of H2S donors (GYY4137 and NaHS) on the micturition reflex and on the contractility of bladder tissues. We also investigated the content of H2S and the expression levels of enzymes related to H2S biosynthesis [cystathionine β-synthase (CBS), 3-mercaptopyruvate sulfurtransferase (MPST), and cysteine aminotransferase (CAT)] in the bladder. Eighteen-week-old male normotensive Wistar rats and SHRs were used. Under urethane anesthesia, the effects of intravesically instilled GYY4137 (10-8, 10-7 and 10-6 M) on the micturition reflex were evaluated by cystometry. The effects of NaHS (1 × 10-8-3 × 10-4 M) were evaluated on carbachol (10-5 M)-induced pre-contracted bladder strips. Tissue H2S content was measured by the methylene blue method. The expression levels of these enzymes were investigated by Western blot. GYY4137 significantly prolonged intercontraction intervals in Wistar rats, but not in SHRs. NaHS-induced relaxation on pre-contracted bladder strips was significantly attenuated in SHRs compared with Wistar rats. The H2S content in the bladder of SHRs was significantly higher than that of Wistar rats. CBS, MPST and CAT were detected in the bladder of Wistar rats and SHRs. The expression levels of MPST in the SHR bladder were significantly higher than those in the Wistar rat bladder. H2S-induced bladder relaxation in SHRs is impaired, thereby resulting in a compensatory increase of the H2S content in the SHR bladder.

Real-Time Bladder Pressure Estimation for Closed-Loop Control in a Detrusor Overactivity Model.

Overactive bladder (OAB) patients suffer from a frequent urge to urinate, which can lead to a poor quality of life. Current neurostimulation therapy uses open-loop electrical stimulation to alleviate symptoms. Continuous stimulation facilitates habituation of neural pathways and consumes battery power. Sensory feedback-based closed-loop stimulation may offer greater clinical benefit by driving bladder relaxation only when bladder contractions are detected, leading to increased bladder capacity. Effective delivery of such sensory feedback, particularly in real-time, is necessary to accomplish this goal. We implemented a Kalman filter-based model to estimate bladder pressure in real-time using unsorted neural recordings from sacral-level dorsal root ganglia, achieving a 0.88 ± 0.16 correlation coefficient fit across 35 normal and simulated OAB bladder fills in five experiments. We also demonstrated closed-loop neuromodulation using the estimated pressure to trigger pudendal nerve stimulation, which increased bladder capacity by 40% in two trials. An offline analysis indicated that unsorted neural signals had a similar stability over time as compared to sorted single units, which would require a higher computational load. We believe this paper demonstrates the utility of decoding bladder pressure from neural activity for closed-loop control; however, real-time validation during behavioral studies is necessary prior to clinical translation.

Autonomic dysregulation at multiple sites is implicated in age-associated underactive bladder in female mice.

To evaluate the functional and molecular alterations of contractile and relaxant machinery in the bladder and urethra that lead to the underactive bladder (UAB) in old female mice. Female young (3-months) and old (18-months) C57BL/6 mice were used. Urodynamic was assessed in awake and anaesthetized mice. Electrical-field stimulation (EFS) and concentration-response curves to contractile and relaxing agents in isolated bladders and urethras were performed. Messenger RNA (mRNA) expressions of muscarinic, adrenergic, and transient receptor potential vanilloid-4 (TRPV4), and of the enzymes tyrosine hydroxylase and neuronal nitric oxide synthase (nNOS) were determined. Bladder cyclic adenosine monophosphate (cAMP) levels were measured. Cystometry in old mice showed incapacity to produce bladder emptying. On filter paper, old mice showed reduced urinary spots. Compared to the young group, bladder contractions induced by EFS and carbachol were lower in old mice. The β3 -adrenoceptor agonist mirabegron promoted higher bladder relaxation and elevation of cAMP levels in old mice. In old mice urethras, the α1a -adrenoceptor agonist phenylephrine produced higher contractions, but no differences were found for the NO donor sodium nitroprusside-induced relaxations. In old mice, increased mRNA expressions of β3 - and α1a -adrenoceptors in bladder and urethra were found, respectively, whereas the muscarinic M2 and M3 receptors and β2 -adrenoceptors did not change between groups. Reduced mRNA expressions of tyrosine hydroxylase and nNOS were found in old mouse urethras. Additionally, TRPV4 expression was reduced in bladder urothelium from old mice. Age-associated mouse UAB is the result of autonomic dysfunction at multiple levels leading to the less sensitive and overrelaxed bladder, along with urethral hypercontractility.

Tadalafil for the treatment of benign prostatic hyperplasia

ABSTRACTIntroduction: In men, lower urinary tract symptoms (LUTS) are primarily attributed to benign prostatic hyperplasia (BPH). Therapeutic options are targeted to relax prostate smooth muscle and/or reduce prostate enlargement.Areas covered: This article reviews the major preclinical and clinical data on PDE5 inhibitors with a specific focus on tadalafil. It includes details of the role of the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) – PDE5 pathway in the LUT organs (bladder and prostate) in addition to the available data on tadalafil in patients with LUTS secondary to BPH with or without erectile dysfunction (ED).Expert opinion: Preclinical and clinical data have clearly demonstrated that PDE5 inhibitors induce bladder and prostate relaxation, which contributes to the improvement seen in storage symptoms in both animal models of bladder and prostate hypercontractility. Tadalafil is effective both as a monotherapy and add-on therapy in patients with LUTS secondary to BPH. Furthermore, as LUTS-BPH and ED are urological disorders that commonly coexist in aging men, tadalafil is more advantageous than α1-adrenoceptors and should be used as the first option. Tadalafil is a safe and tolerable therapy and unlike α1- adrenoceptors and 5-alpha reductase inhibitors, which can cause sexual dysfunctions, tadalafil improves sexual function.

The aging effects on phenylephrine-induced relaxation of bladder in mice.

Objective:We have demonstrated that phenylephrine (PE) activates the capsaicin-sensitive nerves, and then activates capsaicin-sensitive nerves to release an unknown substance that facilitates the release of norepinephrine (NE) from adrenergic nerves. Subsequently, NE stimulates β-ARs in the detrusor muscle in mice, leading to neurogenic relaxation of the urinary bladder (UB).Materials and Methods:We examined if there existed sensory-motor dysfunction in UB of aging mice. To investigate the change of PE-induced detrusor relaxation in aging male-C57BL/6 mice (12- vs. 24-month-old mice), UB strips from mice were isolated, cut into strips, and mounted in the organ bath.Results:The UB strip contractility responding to various agents was estimated using tissue bath wire myography. Acetylcholine (ACh) and KCl-induced UB strips contraction was not significantly different between 24- and 12-month mice. NE-induced UB strips relaxation was significantly lower in 24-month than 12-month mice. Denuded bladder strips showed similar decreased relaxation response to NE. This NE-induced relaxation was inhibited by silodosin and lidocaine. PE did not induce contraction in UB strips of aging mice. In contrast, PE-induced relaxation was weaker in 24-month than 12-month mice.Conclusion:Our results suggested that the PE-induced relaxation was age related. Aging seemed to lead the sensory-motor dysfunction. More animal and human studies are required to prove this concept and its clinical usefulness in the future.

Modulation of Bladder Wall Micromotions Alters Intravesical Pressure Activity in the Isolated Bladder.

Micromotions are phasic contractions of the bladder wall. During urine storage, such phasic activity has little effect on intravesical pressure, however, changed motile activity may underlie urodynamic observations such as detrusor overactivity. The potential for bladder motility to affect pressure reflects a summation of the overall movements, comprising the initiation, propagation, and dissipation components of micromotions. In this study, the influence of initiation of micromotions was investigated using calcium activated chloride channel blocker niflumic acid, and the effect of propagation using blockers of gap junctions. The overall bladder tone was modulated using isoprenaline. Isolated tissue strips and whole bladder preparations from juvenile rats were used. 18β-glycyrrhetinic acid was used to block gap junctions, reducing the amplitude and frequency of micromotions in in vitro and ex vivo preparations. Niflumic acid reduced the frequency of micromotions but had no effect on the amplitude of pressure fluctuations. Isoprenaline resulted in a reduction in pressure fluctuations and a decrease in pressure baseline. Using visual video data analysis, bladder movement was visible, irrespective of lack of pressure changes, which persisted during bladder relaxation. However, micromotions propagated over shorter distances and the overall bladder tone was reduced. All these results suggest that phasic activity of the bladder can be characterised by a combination of initiation and propagation of movement, and overall bladder tone. At any given moment, intravesical pressure recordings are an integration of these parameters. This synthesis gives insight into the limitations of clinical urodynamics, where intravesical pressure is the key indicator of detrusor activity.