Urinary Bladder Contraction Research Articles

Inhibitory Effects of Mefenamic Acid on Rat Urinary Bladder Contractions In Vitro ( Effects of Mefenamic Acid on Urinary Bladder Contractions )

Objective: In this study, the effect of mefenamic acid, a nonsteroidal anti-inflammatory drug, on the unconstrained contractile movement of the bladder muscle of female Spraque Dawley rats in diestrus was investigated. Since the effect of mefenamic acid on bladder smooth muscle is not known and its use for other conditions may cause possible side effects on the bladder, its effect was investigated for the possibility of using it as an active substance in the treatment of bladder problems. Materials and Methods: In the experimental study, 1.5 cm long smooth muscle strips from seven female Sprague Dawley rats were prepared and suspended in an isolated organ bath system containing Krebs solution under 1.5 g tension. The system was gassed continuously with oxygen/carbon dioxide mixture (95%:5%) and isometric contractions were recorded. At a dose of 300 µM, the contraction/relaxation effects of mefenamic acid concentration on bladder smooth muscle were investigated. The area under the curve (AUC) and amplitude values of bladder contractions were analyzed before and after mefenamic acid administration. With the data obtained from the analysis, the effect of mefenamic acid on bladder contractions was evaluated using paired t-tests in SPSS Statistical Software. Results: The decrease in area and amplitude values was statistically significant (P<0.05). Mefenamic acid had an inhibitory effect on bladder contractions. Conclusion: The present findings demonstrate the relaxant effect of mefenamic acid on the rat bladder and if similar effects are observed in human studies, mefenamic acid may be effective in the treatment of voiding problems such as bladder incontinence.

Benzbromarone inhibition of phasic smooth muscle contractions of mouse urinary bladder

Calcium-activated chloride (ClCa) channels play a key role in generating pacemaker currents responsible for maintaining motility in the phasic smooth muscle of the gastrointestinal tract. These channels may play a similar role in the urinary bladder, resulting in the bladder exhibiting spontaneous phasic contractions. These phasic contractions are known to underlie non-voiding contractions and transient pressure events. The purpose of this study was to determine whether the putative ClCa channel inhibitor benzbromarone has an inhibitory effect on transient pressure events in the isolated perfused mouse urinary bladder. We hypothesized benzbromarone would abolish bladder transient pressure events. Urinary bladders were isolated from male C57Bl6/J mice (7-8 wks old, 23.2-24.5 g body weight) post-euthanasia. Isolated bladders were placed in ice-cold nominally Ca-free dissection solution. Ureters were tied off, the bladder was cannulated through the urethra, and submerged in an organ bath containing physiological saline solution (37 °C, pH 7.4). The bladder was then attached to a syringe pump and inline pressure transducer to infuse at a constant rate of 1.8 mL/hr while recording intraluminal pressure. Urinary bladders were filled until they reached an intravesical pressure of 25 mmHg, which was defined as bladder capacity. Upon reaching bladder capacity, the bladder was emptied through the urethral cannula. Three fills were performed under baseline conditions to establish a consistent pressure-volume relationship. Benzbromarone (10 μM) was applied for 20 minutes. Bladders were subsequently filled to 80 % capacity and transient pressure events allowed to stabilize for at least 5 minutes. Transient pressure events were recorded in the absence and presence of benzbromarone. Transient pressure event frequency, amplitude, and duration were analyzed using a custom MatLab algorithm. Under baseline conditions, transient pressure events occurred at a frequency of 5.2 ± 0.8 events per minute (n = 3). Inhibition of ClCa with benzbromarone decreased transient pressure event frequency to 2.1±1.1 events per minute (n = 3, p = 0.08, paired t-test). Similarly, benzbromarone decreased transient pressure event amplitude from a baseline value of 0.22 ± 0.02 mmHg (n = 3) to 0.06 ± 0.04 mmHg (n = 3, p = 0.17, paired t-test). Transient pressure event duration was unaffected by benzbromarone (baseline duration 5.3 ± 0.3 sec, benzbromarone duration 5.2 ± 2.7 sec, n = 3, p= 0.98, paired t-test). In summary, we found that the putativeClCa channel inhibitor benzbromarone disrupted the rhythmicity and amplitude of transient pressure events, while leaving the duration of these contractile events unaltered. This suggests that ClCa channels play a role in generating the rhythm of phasic smooth muscle contractions in the bladder. The cellualr and molecular basis underlying the involvement of ClCa channels in the urinary bladder remains to be explored. This work was supported by a grant from the National Institute of Diabetes and Digestive and Kidney Diseases (R01DK125543). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Investigations of plausible pharmacodynamics supporting the antispasmodic, bronchodilator, and antidiarrheal activities of Berberis lycium Royle. Via in silico, in vitro, and in vivo studies

Ethnopharmacological relevanceBerberis lycium Royle, a member of the Berberidaceae family, is a high-value medicinal plant with a documented history of usage in traditional medicine and has demonstrated significant therapeutic results among local populations throughout the globe. It is used traditionally in many parts of Pakistan to treat diarrhea, abdominal spasms, coughs, and chest problems. Aim of the studyTo investigate the antispasmodic, bronchodilator, and antidiarrheal effects of B. lycium and its possible underlying mechanisms through in silico, in vitro, and in vivo studies. Materials and methodsLC ESI–MS/MS analysis was used to identify bioactive components within the hydromethanolic extract of B. lycium. In silico studies, including network pharmacology and molecular docking, were utilized to investigate the antispasmodic and bronchodilator properties of the extract's bioactive components. In vitro pharmacological studies were conducted using isolated rabbit jejunum, trachea, urinary bladder, and rat ileum preparations. In vivo antidiarrheal activities were conducted in mice, including castor oil-induced diarrhea, intestinal transit, and castor oil-induced enteropooling. ResultsThe LC ESI–MS/MS analysis of the hydromethanolic extract of B. lycium identified 38 bioactive compounds. Network pharmacology study demonstrated that the mechanism of BLR for the treatment of diarrhea might involve IL1B, TLR4, PIK3R1, TNF, PTPRC, IL2, PIK3CD, and ABCB1, whereas, for respiratory ailments, it may involve PIK3CG, TRPV1, STAT3, ICAM1, ACE, PTGER2, PTGS2, TNF, MMP9, NOS2, IL2, CCR5, HRH1, and VDR. Molecular docking research revealed that chlorogenic acid, epigallocatechin, isorhamnetin, quinic acid, gallic acid, camptothecin, formononetin-7-O-glucoside, velutin, caffeic acid, and (S)-luteanine exhibited a higher docking score than dicyclomine with validated proteins of smooth muscle contractions such as CACB2_HUMAN, ACM3_HUMAN, MYLK_HUMAN, and PLCG1_HUMAN. In vitro investigations demonstrated that Blr.Cr, Blr.EtOAc, and Blr.Aq relaxed spontaneously contracting jejunum preparations; carbachol (1 μM)-induced and K+ (80 mM)-induced jejunum, trachea, and urinary bladder contractions in a concentration-dependent manner, similar to dicyclomine. Moreover, Blr.Cr, Blr.EtOAc, and Blr.Aq exhibited a rightward shift in Ca+2 and carbachol cumulative response curves, similar to dicyclomine, demonstrating the coexistence of antimuscarinic and Ca+2 antagonistic mechanisms due to the presence of alkaloids and flavonoids. In vivo antidiarrheal activities showed that the hydromethanolic extract was significantly effective against castor oil-induced diarrhea and castor oil-induced enteropooling, similar to loperamide, and charcoal meal intestinal transit, similar to atropine, in mice at doses of 50, 100, and 200 mg/kg body weight, which supports its traditional use in diarrhea. ConclusionThe dual blocking mechanism of muscarinic receptors and Ca+2 channels behind the smooth muscle relaxing activity reveals the therapeutic relevance of B. lycium in diarrhea, abdominal spasms, coughs, and chest problems.

Investigation of Effects of Metformin on Rats’ Urinary Bladder Contractions Effects of Metformin on Rats’ Bladder Contractions

Objective: The effects of different doses of metformin on the contractility of female Sprague-Dawley rat bladder strips were evaluated. Material and Methods: Rats were decapitated and the bladder strips measuring 2–4 × 6–12 mm prepared from the whole urinary bladder were suspended in isolated tissue organ baths. Tissues in the chambers were rinsed every 30 minutes for 60 minutes and allowed to equilibrate. Afterwards, 10-4 M acetylcholine was added to all isolated tissue baths. After one hour of rinsing, metformin (2 mM) was added and incubated 30 minutes. After 30 minutes, the same dose of acetylcholine was added without rinsing, and immediately after this protocol was performed with 10 mM and 20 mM metformin doses. Results: All of these doses led to increased contractions in a dose-dependent manner. The 2 mM dose did not induce any contraction in area (213.67 ± 33.10 %) compared to control, but there was a significant increase in peak-to-peak amplitude (127.65 ± 4.24 mg, p<0.01). In addition, the peak-to-peak amplitude was significantly increased at the 10 mM and 20 mM doses (163.86 ± 8.57 and 162.58 ± 6.76 mg, p<0.001, respectively) compared to the control and there was a statistically significant difference. In addition, the area value increased significantly compared to control at the 20 mM dose alone (3767.64 ± 733.70 %, p<0.001). Conclusions: Our present data show that the treatment of varied high doses of metformin may lead to the increase of contractions at ex vivo isolated tissue bath. Therefore, this effect can escalate some symptoms of diabetic bladder dysfunction.

Extracorporeal Shock Wave Therapy Protected the Functional and Architectural Integrity of Rodent Urinary Bladder against Ketamine-Induced Damage.

This study tested the hypothesis that extracorporeal-shock-wave (ECSW) protected the functional and anatomical integrity of rat urinary-bladder against ketamine-induced damage. In in vitro study, the rat bladder smooth muscle cells (RBdSMCs) were categorized into G1 (sham-control), G2 (RBdSMCs + menadione), G3 (RBdSMCs + ECSW) and G4 (RBdSMCs + menadione + ECSW). The results showed protein expressions of oxidative-stress/mitochondrial-damaged biomarkers (NOX-1/NOX-2/oxidized protein/cytosolic-cytochrome-C/cyclophilin-D), inflammatory markers (MyD88/TRAF6/p-IKB-α/NF-κB/TNF-α/IL-6/IL-1ß/MMP-9/iNOS), and cell-stress response signalings (ASK1/p-MKK4/p-MKK7/ERK1/2//p-JNK/p-p38/p-53) were significantly increased in G2 than in G1 and G3, and those were significantly reversed in G4 (all p < 0.0001). Adult-male SD rats (n = 24) were equally categorized into group 1 (sham-control), group 2 (ketamine/30 mg/kg/daily i.p. injection for four weeks), group 3 [ketamine/30 mg/kg + ECSW/optimal energy (0.12 mJ/mm2/120 impulses/at 3 h and days 3/7/14/21/28 after ketamine administration)] and group 4 [(ketamine/30 mg/kg + ECSW/higher energy (0.16 mJ/mm2/120 impulses)] and animals were euthanized by day 42. The results showed the urine levels of pro-inflammatory cytokines (TNF-α/IL-6) were lowest in group 1, highest in group 2 and significantly higher in group 3 than in group 4 at days 1/7/14/28 (all p < 0.0001). The duration of urinary bladder contraction was lowest in group 2, highest in group 1 and significantly higher in group 4 than in group 3, whereas the maximal pressure of urinary bladder exhibited an opposite pattern of bladder contraction among the groups (all p < 0.0001). The histopathological findings of fibrosis/inflammation/keratinization and protein expressions of oxidative-stress/mitochondrial-damaged biomarkers (NOX-1/NOX-2/oxidized protein/cytosolic-cytochrome-C/cyclophilin-D), and inflammatory (TLR-2/TLR-4/MyD88/TRAF6/p-IKB-α/NF-κB/TNF-α/IL-1ß/MMP-9/iNOS) and cell-stress response (ASK1/p-MKK4/p-MKK7/ERK1/2//p-JNK/p-p38) signalings and apoptotic/fibrotic biomarkers (cleaved-caspas3/cleaved-PARB/Smad3/TFG-ß) exhibited an identical pattern of urine proinflammatory cytokine among the groups (all p < 0.0001). ECSW effectively attenuated ketamine-induced bladder damage and dysfunction.

Activation of TRPM8 channel inhibits contraction of the isolated human ureter.

The transient receptor potential melastin-8 (TRPM8) channel is a "cooling" receptor expressed in primary sensory neurons and can be activated by compounds like menthol or icilin. TRPM8 is involved in the regulation of urinary bladder sensory function and contraction, but the role of TRPM8 in the ureter, particularly in the human ureter, is poorly understood. The aim of this study is to examine the effects of TRPM8 activation on human ureter contraction. Human ureters were acquired from 20 patients undergoing radical nephrectomy. Contractions of ureter strips were recorded by an isometric transducer in the organ bath. Ureteral TRPM8 expression in the human ureter was examined by immunofluorescence and western blot. The two TRPM8 agonists menthol and icilin both reduced the frequency of spontaneous, electrical field stimulation, or neurokinin A-evoked ureteral contractions in a dose-dependent manner. The inhibitory effects were decreased by 10-fold in mucosa-denuded strips. The inhibitory effects of TRPM8 agonists were mimicked by calcitonin gene-related peptide (CGRP), and were blocked by KRP2579 (a TRPM8 antagonist), tetrodotoxin (a sodium channel blocker), olcegepant (BIBN, a CGRP receptor antagonist), SQ22536 (an adenylate cyclase antagonist), or H89 (a nonspecific cAMP-dependent protein kinase A inhibitor). TRPM8 was coexpressed with CGRP on the nerves located in the suburothelial and intermuscular regions and was not expressed in the urothelium. The TRPM8 channel expressed on sensory nerve terminals of the human ureter is involved in the inhibitory sensory neurotransmission and modulate ureter contraction via the CGRP-adenylyl cyclase-protein kinase A pathway. TRPM8 may be involved in stone-induced changes in ureter contraction or pain.

Possible Involvement of Muscarinic Receptor Blockade in Mirabegron Therapy for Patients with Overactive Bladder.

The selective β 3-adrenoceptor agonist mirabegron, an established alternative to antimuscarinic therapy for patients with overactive bladder, induces additional effects against receptors, transporters, and hepatic enzymes. The present study aimed to elucidate the effects of mirabegron on muscarinic receptors in the rat bladder using radioligand binding and functional assays. Mirabegron (0.1-100 μM) inhibited specific [N-methyl-3H]scopolamine methyl chloride binding in the bladder and other tissues of rats in a concentration-dependent manner. Binding affinity in the bladder was similar to that in the heart and significantly higher than those in the submaxillary gland and brain. Mirabegron induced the concentration-dependent relaxation of carbachol-induced contractions in the rat isolated bladder. Further analyses using a two-site model revealed that the relative quantities of high- and low-affinity components for mirabegron were 44.5% and 55.5%, respectively. Respective pEC50 values were 7.06 and 4.97. Based on the receptor binding affinity and pharmacokinetics of mirabegron, muscarinic receptor occupancy in the human bladder for 24 hours after the administration of a single oral dose of 50 mg mirabegron was 37%-76%. The present results demonstrate for the first time that mirabegron may relax the detrusor smooth muscle not only by β 3-adrenoceptor activation but also muscarinic receptor blockade. SIGNIFICANCE STATEMENT: Mirabegron, the first selective β 3-adrenoceptor agonist, represents an alternative to antimuscarinic agents for management of overactive bladder (OAB). The present study aimed to clarify whether mirabegron directly binds to muscarinic receptors and affects cholinergic agonist-induced contractions in rat urinary bladder and to predict muscarinic receptor occupancy in human bladder after oral administration of mirabegron. The results demonstrated that mirabegron therapy for patients with OAB may be due not only to β 3-adrenoceptor activation but also muscarinic receptor blockade.

Impairment of cholinergic bladder contractility in rat model of type I diabetes complicated by cystitis: Contribution of neurotransmitter-degrading ectoenzymes

Parasympathetic regulation of urinary bladder contractions primarily involves acetylcholine release and activation of detrusor smooth muscle (DSM) muscarinic acetylcholine (mACh) receptors. Co-release of ATP and activation of DSM purinergic P2X1-receptors may participate as well in some species. Both types of neuromuscular transmission (NMT) are impaired in diabetes, however, which factors may contribute to such impairment remains poorly understood. Here by using rats with streptozotocin(STZ)-induced type I diabetes (8th week after induction) we show that contribution of atropine-sensitive m-cholinergic component to the contractions of urothelium-denuded DSM strips evoked by electric field stimulation (EFS) greatly increased when diabetic bladders presented overt signs of accompanying cystitis. Modeling of hemorrhagic cystitis alone in control rats by cyclophosphamide injection only modestly increased m-cholinergic component of EFS-contractions. However, exposure of DSM strips from control animals to acetylcholinesterase (AChE) inhibitor, neostigmine (1–10 μM) largely reproduced alterations in EFS contractions observed in diabetic DSM complicated by cystitis. Ellman's assay revealed statistically significant 31% decrease of AChE activities in diabetic vs. control DSM. Changes in purinergic contractility of diabetic DSM were consistent with altered P2X1-receptor desensitization and re-sensitization. They could be mimicked by pharmacological inhibition of ATP-degrading ecto-ATPases with ARL 67156 (50 μM), pointing to compromised extracellular ATP clearance as underlying reason. We conclude that decreased AChE activities associated with diabetes and likely cystitis provide complementary factor to the described in literature altered expression of mACh receptor subtypes linked to diabetes as well as to cystitis to produce dramatic modification of cholinergic NMT.

Effect of Ferulic Acid on Bladder Over Activity in Diabetic Rat

AbstractBackground: Diabetic bladder dysfunction (DBD) shows a change in the neurotransmission patterns which could be of great importance for drug development.Aim of Study: This study aims to explore whether cholin-ergic or non-adrenergic non-cholinergic (NANC) pathways are altered in their participation in mediating the contraction of diabetic urinary bladder and if ferulic acid could improve DBD.Material and Methods: Rats were divided into three groups (n=12): Streptozotocin induced diabetic group, diabetic with ferulic acid supplemented group, and age matched control group. At the end of 10 weeks, blood samples were collected, and the bladders were removed, weighed, used to measure TBARS reduced glutathione (GSH), and super oxide dismutase (SOD) in bladder homogenate and to record contractility of bladder strips.Results: Diabetic rats received ferulic acid expressed significant reduction in blood glucose, fluid intake, urine output and improvement in bladder wt/body wt. ratio and oxidative stress markers. Ferulic group showed significant improvement in spontaneous contractility and bladder sensi-tivity to different agonist and antagonists when compared to those of diabetic group. The purinergic as well as cholinergic component are significantly decreased in FA treated rats than in diabetic ones which could be explained by its antioxidant activity that ameliorates oxidative stress associated with diabetes. So, in Conclusion: FA could be considered as a beneficial adjuvant in lines of DBD treatment.

The Pharmacological Properties of Artemisia monosperma (Del.)

Plants are rich in secondary metabolites reputed for their pharmacological properties. With demands for bioactive compounds of natural origin, the attention is on commercializing the use of plants for pharmaceutical benefits. Our focus in on defining the biological activities of plants reputed in folk medicine to treat illnesses. We have been focusing on studying Artemisia monosperma to evaluate its potential usage for therapeutic uses. A. monosperma is a desert plant commonly known as an antispasmodic herb. We report that the boiled aqueous extract showed a concentration‐dependent antispasmodic effect of rat smooth muscle of ileum, pulmonary artery and uterus. The effect induced on the tracheal muscle was minimal while the contractile activity of the urinary bladder muscle was not affected. The activity of the cardiac muscle was inhibited upon addition of the aqueous extract which caused a decreased the rat heart rate accompanied by an increased in the contractile activity. This effect was reversible upon removal of the extract. Among compounds identified from A. monosperma, three flavonoids (arcapillin, eupatilin,7‐O‐Methyleriodictyol) showed a concentration‐dependent (10−7M −3×10−4 M) antispasmodic effect on rat smooth muscle of ileum, uterus and pulmonary artery. Only eupatilin and 7‐O‐Methyleriodictyol inhibited the contraction of trachea and urinary bladder. Further evaluation of the physiological effect of eupatilin on cardiac muscle showed that low concentrations (10−6 M and 10−5 M) caused an increase in the magnitude of cardiac muscle contraction accompanied by a decrease in heart rate which was followed by a partial heart blockage. At a concentration of 10−4M, the heart rate was reduced significantly leading to irreversible death of the infused heart. Eupatilin toxicity was determined by the median lethal dose (LD50) over 48hours on albino mice which came up to 31.8mg/kg. These finding indicate the importance of A. monosperma as a source for bioactive compounds of therapeutic significance.Support or Funding InformationSpecial thanks to Central State University and the University of Jordan for the technical support.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Analysis of angiotensin II-Induced rat urinary bladder contractions in the presence of angiotensin II receptors blockers

Objective An application of a specific analysis on recordings obtained from urinary bladder (UB) preparations influenced with Angiotensin II (AngII) and AngII receptor (ATR) blockers was performed. Methods UB preparations were divided as follows: group 1 stimulated with AngII only; group 2:PD123319 (ATR type-2 blocker)+AngII; group 3:Losartan (ATR type-1 blocker)+AngII. The averaged time and force parameters of the contractions were processed by a spline interpolation and graphic images of the different patterns of the contractile activity were obtained. Results The speed of AngII-induced UB contraction, when PD123319 was administered, was significantly higher than those, registered by the application of AngII alone and Losartan + AngII. The presence of Losartan markedly delayed the speed of the overall AngII-induced contraction. Conclusion The study indicates the contribution of both ATR subtypes for the development of AngII-induced UB contraction. Our results showed that probably ATR mediate a reciprocal dynamic response to AngII in the bladder.

Clopidogrel inhibits acetylcholine-induced contractions of urinary bladder in rat

Aim: Clopidogrel as thrombocyte Adenosine Diphosphate (ADP) receptor antagonist is used especially in peripheric artery diseases by lengthening hemorrhage time, disrupting thrombocyte aggregation and decreasing blood viscosity. It shows its antagonist effects through glycoprotein (Gp) IIb/IIIa complex ADP by preventing its activation. Although the usage area and activity is in the vascular system, there are no adequate studies showing the activity of Clopidogrel on smooth muscle contraction-relaxation mechanism. This study was conducted to investigate the effects of Clopidogrel on bladder contraction-relaxation mechanism.Material and Methods: In the present study, the bladder tissues taken from Wistar-Albino (n=7) intact female rats were used. After the decapitation, the longitudinal bladder tissues that were received 1-mm-thick, 8-mm length, and 2-mm-width, were hung in the 5-ml isolated organ bath that had Krebs-Ringer bicarbonate solution by applying 1.5 gr strain. After the bladder contractions were induced with 10 μM dose Acetylcholine (Ach), Clopidogrel was applied as two doses 0.1μM and 10μM in a noncumulative manner. The peak-to-peak (p-p) values and the values below the curve before and after the Clopidogrel application in the contraction induced with Ach were normalized as % change. The statistical analyses of the data were made in the SPSS 22.0 program by applying Paired T-Test. The p

The effects of nitrofurantoin on rat urinary bladder contraction

Nitrofurantoin is a drug used in the antibacterial treatment of urinary tract infections (UTIs) for over 60 years. The aim of our study was to investigate the possible effects of nitrofurantoin, which is commonly used as a urinary tract antiseptic, on bladder contractions in male rats. Bladder tissues obtained from male Sprague-Dawley rats were used in the study (n=24). After decapitation, bladder tissues were suspended in an isolated organ bath of 5 ml containing a Krebs-Ringer bicarbonate solution by applying a tension of 1.5 grams. Nitrofurantoin was administered to three groups at doses of 50, 500 and 1000 μM, respectively. The area, peak-to-peak (p-p) and frequency values of bladder contractions were analyzed before and after administration of nitrofurantoin. The data obtained from the analysis were evaluated using the Paired T-Test in the IBM SPSS Statistics Software. Nitrofurantoin was observed to have an inhibitory effect on bladder contractions at all doses. The decrease in the area and peak-to-peak values was statistically significant at all doses (P

Pharmacological characterization of DA-8010, a novel muscarinic receptor antagonist selective for urinary bladder over salivary gland

Several antimuscarinics have been commonly used for overactive bladder patients, but dry mouth as a major anticholinergic side effect remains a shortcoming to limit long-term use. The aim of this study was to elucidate the pharmacological properties of DA-8010, a novel muscarinic receptor antagonist selective for urinary bladder over salivary gland. DA-8010 exhibited a high binding affinity for human muscarinic M3 receptor with pKi of 8.81 ± 0.05 and great potencies for human M3 receptor and rat bladder preparation. The potency of DA-8010 for bladder smooth muscle cells was 3.6-fold higher than that for salivary gland cells isolated from mice. Intravenous administration of DA-8010 dose-dependently inhibited rhythmic urinary bladder contractions induced by distension in rats, indicating the most potent activity (ID30 = 0.08 mg/kg) among the antimuscarinics tested. Taken together with the inhibitory effects of DA-8010 and other antimuscarinics on carbachol-induced salivary secretion in rats, the in vivo functional selectivity of DA-8010 for urinary bladder over salivary gland was 3.1-fold, 3.2-fold and 5.2-fold greater than those observed for solifenacin, oxybutynin and darifenacin, respectively. Furthermore, oral administration of DA-8010 in mice resulted in more selective and persistent binding for muscarinic receptors in the bladder rather than in the submaxillary gland, in comparison with other antimuscarinics. These findings suggest that DA-8010 is a potent muscarinic M3 receptor antagonist to be highly selective for bladder over salivary gland, which might be a promising agent with greater efficacy and less dry mouth in the treatment of overactive bladder.

The Modulation Of Detrusor Contractility By Agents Influencing Ion Channel Activity

Abstract Background: This study specified the role of several significant ion channels regulating the metabolism of calcium ions in contraction and relaxation of human detrusor muscle in order to identify possible target for future drugs that are capable of treating diseases resulting from impaired detrusor activity, e.g. overactive bladder. Although this disease can be successfully treated with muscarinic receptor antagonists or β3 agonist, many patients may not be suitable for chronic therapy, especially due to the relatively high side effects of the treatment. Material and Methods: The study used the isolated detrusor tissue samples, which were obtained from the macroscopic healthy tissue of urinary bladder from 19 patients undergoing a total prostatectomy because of localized prostate cancer. Each biological sample was prepared into 8 strips. We used oxybutynin and mirabegron as control drugs and several blockers of specific subtypes calcium and potassium ion channels as tested substances. The contractility of bladder was investigated by an organ tissue bath method in vitro and contraction was induced by carbachol. Results: The amplitude of contraction was successfully decreased by positive control drugs and, from tested agents, the comparable effect had the substance capable of influencing IP3 receptors and Orai-STIM channels and combination consisting of drugs possessing an inhibitory effect on IP3 receptors, L- and T-type voltage-gated calcium channels and Orai-STIM channels. Conclusion: The present work represents a new finding about handling Ca2+ in urinary bladder contraction and pointed to a dominant role of IP3 receptor-mediated pathway in the regulation of Ca2+ metabolism, which may represent a future strategy in pharmacotherapy of impaired detrusor activity.

Effect of pregnancy on cooling tone and rhythmic contractions of the rat urinary bladder.

Pregnancy is a physiological alteration that can affect urinary bladder. Cooling of urinary bladder smooth muscle is known as a potent stimulus to micturition due to an increase in muscle tone. The current study investigates the effects of pregnancy on cooling tone and on the rhythmic contractions of the urinary bladder. Twenty-four rats were used in this study as control group (non-pregnant) and pregnant group (18-20-day pregnancy). Isolated rat urinary muscle strips were suspended in organ baths containing Krebs' solution for isometric tension recording. Cooling from 37 to 5°C induced a rapid and reproducible increase in basal tone, proportional to cooling temperature. Cooling also increased the rhythmic activity (amplitude and frequency) at 30 and 25°C, then decreased at 20°C, and abolished at 15-5°C. These responses were more pronounced in pregnant group than in control group. Rhythmic contractions were abolished in calcium-free, EGTA (1mM)-containing Krebs' solution and in the presence of nifedipine, while they were not affected by CPA or TTX in both groups. Our investigation showed that the influx of extracellular calcium is important in inducing the rhythmic contractions. Pregnancy increases cooling-induced contraction in pregnant rat urinary preparations and its rhythmic contractions including amplitude and frequency than non-pregnant rat. Rhythmic contractions are myogenic in nature and highly extracellular calcium dependent. They may play a crucial role in urinary bladder overactivity and incontinence during pregnancy.

Specific inhibition of acetylcholinesterase as an approach to decrease muscarinic side effects during myasthenia gravis treatment

Non-selective inhibitors of cholinesterases (ChEs) are clinically used for treatment of myasthenia gravis (MG). While being generally safe, they cause numerous adverse effects including induction of hyperactivity of urinary bladder and intestines affecting quality of patients life. In this study we have compared two ChEs inhibitors, a newly synthesized compound C547 and clinically used pyridostigmine bromide, by their efficiency to reduce muscle weakness symptoms and ability to activate contractions of urinary bladder in a rat model of autoimmune MG. We found that at dose effectively reducing MG symptoms, C547 did not affect activity of rat urinary bladder. In contrast, at equipotent dose, pyridostigmine caused a significant increase in tonus and force of spontaneous contractions of bladder wall. We also found that this profile of ChEs inhibitors translates into the preparation of human urinary bladder. The difference in action observed for C547 and pyridostigmine we attribute to a high level of pharmacological selectivity of C547 in inhibiting acetylcholinesterase as compared to butyrylcholinesterase. These results raise reasonable hope that selective acetylcholinesterase inhibitors should show efficacy in treating MG in human patients with a significant reduction in adverse effects related to hyperactivation of smooth muscles.

Assessment of the effects of antidepressants on contractile function of guinea pig urinary bladder and urethra

Background: We aimed to find antidepressants that possessed a minimal incidence of drug-induced urinary disorders by investigating 18 clinically available antidepressants in Japan for potential inhibitory/augmentative effects on acetylcholine/adenosine triphosphate (ACh/ATP)-induced urinary bladder (UB) contractions and noradrenaline (NA)-induced urethral contractions.

Effects of chlorogenic acid on carbachol-induced contraction of mouse urinary bladder

Chlorogenic acid (CGA) is a polyphenol found in coffee and medicinal herbs such as Lonicera japonica. In this study, the effect of CGA-induced relaxation on carbachol (CCh)-induced contraction of mouse urinary bladder was investigated. CGA (30–300 μg/ml) inhibited CCh- or U46619-induced contraction in a concentration-dependent manner. SQ22536 (adenylyl cyclase inhibitor) recovered CGA-induced relaxation of CCh-induced contraction; however, ODQ (guanylyl cyclase inhibitor) did not have the same effect. In addition, 3-isobutyl-1-methylxanthine (IBMX) enhanced CGA-induced relaxation; however, forskolin or sodium nitroprusside did not have the same effect. Moreover, Ro 20–1724, a selective phosphodiesterase (PDE) 4 inhibitor, enhanced CGA-induced relaxation, but vardenafil, a selective PDE5 inhibitor, did not have the same effect. In the presence of CCh, CGA increased cyclic adenosine monophosphate (cAMP) level, whereas SQ22536 inhibited the increase of cAMP levels. Moreover, higher cAMP levels were obtained with CGA plus IBMX treatment than the total cAMP levels obtained with separate CGA and IBMX treatments. In conclusion, these results suggest that CGA inhibited CCh-induced contraction of mouse urinary bladder by partly increasing cAMP levels via adenylyl cyclase activation.

Inhibitory Effects of Urothelium-related Factors.

The urothelium of the bladder has long been recognized as a protective barrier between detrusor and urine. In recent years, it has become more evident that the urothelium plays a role as an active source of mediators. The urothelium can release neurotransmitters and modulators such as acetylcholine, ATP, nitric oxide, prostaglandins and neuropeptides. They exert both excitatory and inhibitory effects in modulating urinary tract motility. In addition, several studies have reported the existence of an urothelium-derived unknown inhibitory factor in the urinary bladder. By the use of a new serial cascade superfusion bioassay on guinea pig ureter, recent studies confirm that the guinea pig bladder urothelium releases a substance with inhibitory bioactivity, which was resistant to treatment with nitric oxide synthase inhibitor and cyclooxygenase inhibitor and to adenosine A1/A2 receptor blockade. Lately, a marked and quickly inactivated novel release of PGD2 from the bladder urothelium was discovered, together with localization of prostaglandin D synthase therein. PGD2 was found to have an inhibitory influence on nerve-induced contractions in guinea pig urinary bladder and on spontaneous contractions in the out-flow region. An altered release of excitatory and inhibitory factors is likely to play an important part in bladder motility disturbances, of which the prostanoids are a notable group. Due to the fact that the bladder is relaxed 99% of the time, not only excitatory mechanisms in the bladder are necessary to study, but also inhibitory mechanisms need considerable attention, which will contribute to the discovery of new targets to treat bladder motility disorders.