The AUA/SUFU Guideline on the Diagnosis and Treatment of Idiopathic Overactive Bladder.

PURPOSE: The purpose of this guideline is to provide evidence-based guidance to clinicians of all specialties on the evaluation, management, and treatment of idiopathic overactive bladder (OAB). The guideline informs the reader on valid diagnostic processes and provides an approach to selecting treatment options for patients with OAB through the shared decision-making process, which will maximize symptom control and quality of life, while minimizing adverse events and burden of disease. METHODS: An electronic search employing OVID was used to systematically search the MEDLINE and EMBASE databases, as well as the Cochrane Library, for systematic reviews and primary studies evaluating diagnosis and treatment of OAB from January 2013 to November 2023. Criteria for inclusion and exclusion of studies were based on the Key Questions and the populations, interventions, comparators, outcomes, timing, types of studies and settings (PICOTS) of interest. Following the study selection process, 159 studies were included and were used to inform evidence-based recommendation statements. RESULTS: This guideline produced 33 statements that cover the evaluation and diagnosis of the patient with symptoms suggestive of OAB; the treatment options for patients with OAB, including non-invasive therapies, pharmacotherapy, minimally invasive therapies, invasive therapies, and indwelling catheters; and the management of patients with BPH and OAB. CONCLUSION: Once the diagnosis of OAB is made, the clinician and the patient with OAB have a variety of treatment options to choose from and should, through shared decision-making, formulate a personalized treatment approach taking into account evidence-based recommendations as well as patient values and preferences.

Study design of a phase 4, real-world study (COMPOSUR) to evaluate vibegron in patients with overactive bladder.

BACKGROUND: Overactive bladder (OAB) is defined as urinary urgency accompanied by frequency and nocturia, with or without urge urinary incontinence (UUI). Vibegron, a selective ß3-adrenergic receptor agonist approved in the US in December 2020, demonstrated efficacy in reducing symptoms of OAB and was safe and well tolerated in the 12-week EMPOWUR trial and its 40-week, double-blind extension trial. The goal of the COMPOSUR study is to evaluate vibegron in a real-world setting to assess patient treatment satisfaction, tolerability, safety, duration of treatment, and persistence. METHODS: This is a 12-month, prospective, observational, real-world study, with an optional 12-month extension to 24 months, in the US assessing adults ≥ 18 years old starting a new course of vibegron. Patients must be previously diagnosed with OAB with or without UUI, symptomatic for ≥ 3 months before enrollment, and receive prior treatment with an anticholinergic, with mirabegron, or with a combination of an anticholinergic and mirabegron. Enrollment is performed by the investigator following exclusion and inclusion criteria guided by US product labeling, reinforcing a real-world approach. Patients complete the OAB Satisfaction with Treatment Questionnaire (OAB-SAT-q) monthly and the OAB Questionnaire short form (OAB-q-SF) and Work Productivity and Activity Impairment Questionnaire (WPAI:US) at baseline and monthly for 12 months. Patients are followed up via phone call, in-person visits, or telehealth (ie, virtual) visits. The primary endpoint is patient treatment satisfaction as determined by the OAB-SAT-q satisfaction domain score. Secondary endpoints include percent positive responses to individual OAB-SAT-q questions, additional OAB-SAT-q domain scores, and safety. Exploratory endpoints include adherence and persistence. DISCUSSION: OAB leads to a significant decrease in quality of life, as well as impairment of work activities and productivity. Persistence with OAB treatments can be challenging, often due to lack of efficacy and adverse effects. COMPOSUR is the first study to provide long-term, prospective, pragmatic treatment data for vibegron in the US and the resultant effect on quality of life among patients with OAB in a real-world clinical setting. Trial registration ClinicalTrials.gov identifier: NCT05067478; registered: October 5, 2021.

The AUA/SUFU Guideline on Adult Neurogenic Lower Urinary Tract Dysfunction: Treatment and Follow-up.

PURPOSE: The clinician treating patients with neurogenic lower urinary tract dysfunction (NLUTD) needs to balance a variety of factors when making treatment decisions. In addition to the patient's urologic symptoms and urodynamic findings, other issues that may influence management options of the lower urinary tract include cognition, hand function, type of neurologic disease, mobility, bowel function/management, and social and caregiver support. This Guideline allows the clinician to understand the options available to treat patients, understand the findings that can be seen in NLUTD, and appreciate which options are best for each individual patient. This allows for decisions to be made with the patient, in a shared decision-making manner, such that the patient's quality of life can be optimized with respect to their bladder management. MATERIALS AND METHODS: A comprehensive search for studies assessing patients undergoing evaluation, surveillance, management, or follow-up for NLUTD was conducted from January 2001 through October 2017 and was rerun in February 2021 to capture newer literature. The primary search returned 20,496 unique citations. Following a title and abstract screen, full texts were obtained for 3,036 studies. During full-text review, studies were primarily excluded for not meeting the PICO criteria. One hundred eight-four primary literature studies met the inclusion criteria and were included in the evidence base. RESULTS: This guideline was developed to inform clinicians on the proper evaluation, diagnosis, and risk stratification of adult patients with NLUTD and the non-surgical and surgical treatment options available. Additional statements on urinary tract infection and autonomic dysreflexia were developed to guide the clinician. CONCLUSIONS: NLUTD patients may undergo non-surgical and surgical treatment options depending on their level of risk, symptoms, and urodynamic findings. Appropriate follow-up, primarily based on their risk stratification, must be maintained after treatment.

The AUA/SUFU Guideline on Adult Neurogenic Lower Urinary Tract Dysfunction: Diagnosis and Evaluation.

PURPOSE: The clinician treating patients with neurogenic lower urinary tract dysfunction (NLUTD) needs to balance a variety of factors when making treatment decisions. In addition to the patient's urologic symptoms and urodynamic findings, other issues that may influence management options of the lower urinary tract include cognition, hand function, type of neurologic disease, mobility, bowel function/management, and social and caregiver support. This Guideline allows the clinician to understand the options available to treat patients, understand the findings that can be seen in NLUTD, and appreciate which options are best for each individual patient. This allows for decisions to be made with the patient, in a shared decision-making manner, such that the patient's quality of life can be optimized with respect to their bladder management. MATERIALS AND METHODS: A comprehensive search for studies assessing patients undergoing evaluation, surveillance, management, or follow-up for NLUTD was conducted from January 2001 through October 2017 and was rerun in February 2021 to capture newer literature. The primary search returned 20,496 unique citations. Following a title and abstract screen, full texts were obtained for 3,036 studies. During full-text review, studies were primarily excluded for not meeting the PICO criteria. One hundred eight-four primary literature studies met the inclusion criteria and were included in the evidence base. RESULTS: This guideline was developed to inform clinicians on the proper evaluation, diagnosis, and risk stratification of patients with NLUTD and the non-surgical and surgical treatment options available. Additional statements on urinary tract infection and autonomic dysreflexia were developed to guide the clinician. This Guideline is for adult patients with NLUTD and pediatric NLUTD will not be discussed. CONCLUSIONS: NLUTD patients should be risk-stratified as either low-, moderate-, high-, or unknown-risk. After diagnosis and stratification, patients should be monitored according to their level of risk at regular intervals. Patients who experience new or worsening signs and symptoms should be reevaluated and risk stratification should be repeated.

Six-Month Results of Selective Bladder Denervation in Women with Refractory Overactive Bladder.

PURPOSE: We report 6-month efficacy and safety outcomes of selective bladder denervation in women with refractory overactive bladder. MATERIALS AND METHODS: Women with refractory overactive bladder and urgency urinary incontinence were enrolled in 2 prospective feasibility studies with the same entry criteria. They underwent selective bladder denervation of the subtrigonal region containing afferent sensory nerves. Patients were followed for 6 months and assessed for adverse events, overactive bladder symptoms and health related quality of life measures. RESULTS: In the 35 women with a mean age of 66 years who were enrolled in the study all selective bladder denervation procedures were completed successfully. During 6 months of followup the symptom improvement based on 3-day bladder diaries was 59% for urgency urinary incontinence (p <0.001), 59% for urinary incontinence (p <0.001), 39% for urgency (p <0.001), 9% for urinary frequency (p = 0.01) and 27% for the total urgency and frequency score (p <0.001). Most of this treatment benefit was realized in the first month. The rate of clinical success, defined as a 50% or greater reduction in urgency urinary incontinence, was 70%, treatment benefit was reported in 75% of patients and the dry/cure rate was 27%. Statistically significant improvements during 6 months were identified on the symptom bother and health related quality of life scales on the OAB-q (Overactive Bladder Questionnaire) and on all KHQ (King's Health Questionnaire) domains except general health perception. Device or procedure related adverse events were reported in 6 patients (17%). CONCLUSIONS: Pooled results of 2 prospective feasibility studies suggest that selective bladder denervation is a promising minimally invasive treatment option in women with refractory overactive bladder.

One-year results with selective bladder denervation in women with refractory overactive bladder.

AIMS: To report 1-year results with selective bladder denervation (SBD) of the trigone in women with refractory overactive bladder (OAB). METHODS: In this prospective, international, multicenter case series, women with refractory OAB underwent a single SBD treatment of the bladder subtrigone region using temperature-controlled radiofrequency. Patients were followed for 1 year and evaluated for changes in OAB symptoms and adverse events. RESULTS: Among 35 women, 29 (83%) returned for 1-year follow up. Median symptom reductions based on 3-day bladder diaries were 68% for urgency urinary incontinence ( P < .001), 67% for urinary incontinence ( P < .001), 43% for urgency episodes ( P < .001), 5% for urinary frequency ( P = .19), and 33% for the total urgency and frequency score ( P < .001), with the majority of treatment benefit realized in the first month. Treatment benefit was reported in 72% of patients, the clinical success rate (≥50% reduction in urgency urinary incontinence) was 69%, and the dry rate was 10%. Statistically significant improvements occurred on Symptom Bother and Health-related Quality of Life scales on the Overactive Bladder questionnaire, and on 6 of 9 King's Health Questionnaire domains. Patients with less severe baseline symptoms had similar quality of life improvements as those with more severe baseline symptoms. Device- or procedure-related adverse events were reported in 6 (17%) patients. CONCLUSIONS: A single treatment with selective bladder denervation is durable for 1-year in a significant proportion of women with refractory overactive bladder.

Surgery for urinary incontinence in women: Report from the 6th international consultation on incontinence.

Urinary incontinence is a prevalent condition worldwide and causes a tremendous impact on a woman's quality of life. While conservative and non-surgical therapies are options for treatment, surgery for stress urinary incontinence (SUI) is common. Options include colposuspension, slings (pubovaginal and midurethral), and periurethral bulking. While evidence supports each of these options in the treatment of SUI, each is associated with various rates of success and unique adverse event profiles. Urgency urinary incontinence (UUI) is initially treated with behavioral modification and pharmacologic means, with surgery reserved for those with refractory symptoms or significant complications from medication use. At present, intravesical onabotulinumtoxinA injections, percutaneous tibial nerve stimulation, and sacral neurostimulation are all viable options for refractory UUI/overactive bladder. As with surgical interventions for SUI, each of these is, likewise, associated with unique outcomes and adverse event profiles. Herein, we summarize the findings and conclusions from the 6th International Consultation on Incontinence (ICI) regarding surgical treatment of urinary incontinence in women.

The Use of Tissue Flaps in the Management of Urinary Tract Fistulas.

Urinary tract fistulas represent a complex group of pathologies that present significant management challenges. While most such fistulas ultimately require definitive surgical management, compromised local tissue quality or other factors often render straightforward simple one layered closure challenging with a substantial risk of failure. Interpositional tissue flaps have become a mainstay of treatment in these circumstances, enabling the delivery of healthy tissue from other locations to the site of pathology. Herein, we present an overview of the assessment and management of complex urinary tract fistulas involving the reproductive and gastrointestinal organs, and the decision to utilize flaps. We review the underlying principles of tissue flaps and classify different types of flaps. We conclude with a discussion of the indications, advantages, disadvantages, and harvesting techniques for the most commonly utilized flaps in urinary tract fistula repair.

Study design and outcomes measures: The influence of composite endpoints and other design variables on outcomes in a study of a novel device for stress urinary incontinence.

OBJECTIVES: To perform a post hoc analysis of the outcome data from a phase III study of a novel incontinence therapy for female stress incontinence (SUI) and to understand the pitfalls inherent to performing trials in SUI. METHODS: Results of the SUCCESS Trial, a multicenter, prospective, single-blinded, randomized, sham-controlled study were assessed post hoc for parameters and variables consistent with changes in the symptoms or signs of SUI. Subjects were randomized to either the investigative device (Vesair Balloon) placement or placebo. The efficacy endpoint analysis herein evaluated a composite of both a >50% reduction from baseline on 1-hour provocative pad weight test and a ≥10-point improvement in symptoms on the Incontinence Quality of Life (I-QOL) questionnaire assessed at the three-month study visit. Further analysis was performed utilizing more challenging success criteria for each endpoint and a subset of subjects with more severe baseline symptoms. RESULTS: The three-month composite efficacy endpoint was achieved in 42.1% of treatment group subjects compared with 28.1% of control subjects on an intention-to-treat analysis (P = .046). This difference between groups was not evident when analyzing each component of the composite endpoint separately. These endpoints diverged from endpoints involving improvement in PGI-I score and a 50% reduction of incontinence episode frequency as reported by subjects on a diary. CONCLUSIONS: Individual endpoints may not demonstrate a significant treatment effect as standalone SUI measures but may as components of a composite endpoint. Defining patient selection and outcomes assessments is a critical aspect of study design, experimental flaws, and therapeutic accuracy.

Analysis of Complications of Pelvic Mesh Excision Surgery Using the Clavien-Dindo Classification System.

PURPOSE: We describe and categorize complications using the Clavien-Dindo classification system in patients who underwent vaginal mesh excision surgery. MATERIALS AND METHODS: With institutional review board approval we retrospectively reviewed the records of 277 patients who underwent vaginal mesh extraction between 2007 and 2015 at a single institution. Surgical complications were stratified using the Clavien-Dindo classification system. Complications were perioperative (prior to discharge) or postoperative (within 90 days). Indications for initial mesh placement, mesh revision procedure, time to resolution and medical comorbidities were assessed. RESULTS: Of the 277 patients 47.3% had at least 1 surgical complication, including multiple complications in 7.2%. A total of 155 complications were identified, which were grade II in 49.0% of cases, grade I in 25.8%, grade IIIb in 18.7%, grade IIIa in 5.2% and grade IVa in 1.3%. No grade IVb or V complications were identified. The indication for initial mesh placement did not significantly affect complication frequency. Patients who underwent combined stress urinary incontinence and pelvic organ prolapse mesh revision surgeries had an increased frequency of complications compared to those treated with mesh revision surgery for pelvic organ prolapse or stress urinary incontinence alone (p = 0.045). Most complications occurred postoperatively and resolved by 90 days. Age, body mass index, smoking status and diabetes were not associated with increased complications. CONCLUSIONS: Despite the complexity of mesh revision surgery most complications are minor. Serious complications may develop, emphasizing the need for proper patient counseling and surgical experience when performing these procedures.

Dimethyl sulfoxide (DMSO) as intravesical therapy for interstitial cystitis/bladder pain syndrome: A review.

AIMS: The purpose of this review is to update the current understanding of dimethyl sulfoxide (DMSO) and its role in the treatment of interstitial cystitis (IC). METHODS: A systematic review was conducted using the PRIMSA checklist to identify published articles involving intravesical DMSO for the treatment of IC. RESULTS: Thirteen cohort studies and three randomized-controlled trials were identified. Response rates relying on subjective measurement scores range from 61 to 95%. No increased efficacy was found with "cocktail" DMSO therapy. Great variation existed in diagnostic criteria, DMSO instillation protocols and response measurements. CONCLUSIONS: The current evidence backing DMSO is a constellation of cohort studies and a single randomized-controlled trial versus placebo. The optimal dose, dwell time, type of IC most likely to respond to DMSO, definitions of success/failure and the number of treatments are not universally agreed upon. Improvements in study design, phenotyping patients based on symptoms, as well as the emergence of reliable biomarkers of the disease may better guide the use of DMSO in the future.

Stress urinary incontinence surgery trends in academic female pelvic medicine and reconstructive surgery urology practice in the setting of the food and drug administration public health notifications.

AIMS: To investigate the possible effects of the Food and Drug Administration (FDA) Public Health Notifications in 2008 and 2011 regarding surgical trends in transvaginal mesh (TVM) placement for stress urinary incontinence (SUI) and related mesh revision surgery in Female Pelvic Medicine & Reconstructive Surgery (FPMRS) practice in tertiary care academic medical centers in the United States. METHODS: Surgical volume for procedures performed primarily by FPMRS surgeons at eight academic institutions across the US was collected using Current Procedural Terminology (CPT) codes for stress urinary incontinence repair and revision surgeries from 2007 to 2013. SAS statistical software was used to assess for trends in the data. RESULTS: There was a decrease in the use of synthetic mesh sling for the treatment of SUI at academic tertiary care centers over the past 7 years; however, this was not statistically significant. While the total number of surgical interventions for SUI remained stable, there was an increase in the utilization of autologous fascia pubovaginal slings (AFPVS). The number of mesh sling revision surgeries, including urethrolysis and removal or revision of slings, increased almost three-fold at these centers. CONCLUSIONS: These observed trends suggest a possible effect of the FDA Public Health Notifications regarding TVM on surgical practice for SUI in academic centers, even though they did not specifically warn against the use of synthetic mesh for this indication. Indications for surgery, complications, and outcomes were not evaluated during this retrospective study. However, such data may provide alternative insights into reasons for the observed trends. Neurourol. Urodynam. 36:1155-1160, 2017. © 2016 Wiley Periodicals, Inc.

Novel regulatory mechanism in human urinary bladder: central role of transient receptor potential melastatin 4 channels in detrusor smooth muscle function.

Transient receptor potential melastatin 4 (TRPM4) channels are Ca(2+)-activated nonselective cation channels that have been recently identified as regulators of detrusor smooth muscle (DSM) function in rodents. However, their expression and function in human DSM remain unexplored. We provide insights into the functional role of TRPM4 channels in human DSM under physiological conditions. We used a multidisciplinary experimental approach, including RT-PCR, Western blotting, immunohistochemistry and immunocytochemistry, patch-clamp electrophysiology, and functional studies of DSM contractility. DSM samples were obtained from patients without preoperative overactive bladder symptoms. RT-PCR detected mRNA transcripts for TRPM4 channels in human DSM whole tissue and freshly isolated single cells. Western blotting and immunohistochemistry with confocal microscopy revealed TRPM4 protein expression in human DSM. Immunocytochemistry further detected TRPM4 protein expression in DSM single cells. Patch-clamp experiments showed that 9-phenanthrol, a selective TRPM4 channel inhibitor, significantly decreased the transient inward cation currents and voltage step-induced whole cell currents in freshly isolated human DSM cells. In current-clamp mode, 9-phenanthrol hyperpolarized the human DSM cell membrane potential. Furthermore, 9-phenanthrol attenuated the spontaneous phasic, carbachol-induced and nerve-evoked contractions in human DSM isolated strips. Significant species-related differences in TRPM4 channel activity between human, rat, and guinea pig DSM were revealed, suggesting a more prominent physiological role for the TRPM4 channel in the regulation of DSM function in humans than in rodents. In conclusion, TRPM4 channels regulate human DSM excitability and contractility and are critical determinants of human urinary bladder function. Thus, TRPM4 channels could represent promising novel targets for the pharmacological or genetic control of overactive bladder.

BK channel regulation by phosphodiesterase type 1: a novel signaling pathway controlling human detrusor smooth muscle function.

Large-conductance Ca(2+)-activated K(+) (BK) channels are critical regulators of detrusor smooth muscle (DSM) function. We aimed to investigate phosphodiesterase type 1 (PDE1) interactions with BK channels in human DSM to determine the mechanism by which PDE1 regulates human urinary bladder physiology. A combined electrophysiological, functional, and pharmacological approach was applied using human DSM specimens obtained from open bladder surgeries. The perforated whole cell patch-clamp technique was used to record transient BK currents (TBKCs) and the cell membrane potential in freshly isolated human DSM cells in combination with the selective PDE1 inhibitor, 8-methoxymethyl-3-isobutyl-1-methylxanthine (8MM-IBMX). Isometric DSM tension recordings were used to measure spontaneous phasic and electrical field stimulation-induced contractions in human DSM isolated strips. Selective pharmacological inhibition of PDE1 with 8MM-IBMX (10 µM) increased TBKC activity in human DSM cells, which was abolished by subsequent inhibition of protein kinase A (PKA) with H-89 (10 µM). The stimulatory effect of 8MM-IBMX on TBKCs was reversed upon activation of muscarinic acetylcholine receptors with carbachol (1 µM). 8MM-IBMX (10 µM) hyperpolarized the DSM cell membrane potential, an effect blocked by PKA inhibition. 8MM-IBMX significantly decreased spontaneous phasic and nerve-evoked contractions of human DSM isolated strips. The results reveal a novel mechanism that pharmacological inhibition of PDE1 attenuates human DSM excitability and contractility by activating BK channels via a PKA-dependent mechanism. The data also suggest interactions between PDE1 and muscarinic signaling pathways in human DSM. Inhibition of PDE1 can be a novel therapeutic approach for the treatment of overactive bladder associated with detrusor overactivity.

Lower urinary tract symptoms in women: epidemiology, diagnosis, and management.

PURPOSE OF REVIEW: The purpose of this review is to summarize and evaluate the most recent literature on the epidemiology, etiology, and treatment of lower urinary tract symptoms (LUTS) in women. RECENT FINDINGS: Several authors have studied characteristics of populations of women with LUTS and addressed care-seeking behavior for these conditions. Multiple investigators also sought greater understanding of the urinary microbiome and its relationship to LUTS in women. Evidence for the treatment of overactive bladder and stress urinary incontinence is being synthesized and innovative treatments are being rigorously studied. SUMMARY: Investigations and high quality research continue to shed light on the epidemiology, diagnosis, and management of LUTS in women.

Functional link between muscarinic receptors and large-conductance Ca2+ -activated K+ channels in freshly isolated human detrusor smooth muscle cells.

Activation of muscarinic acetylcholine receptors (mAChRs) constitutes the primary mechanism for enhancing excitability and contractility of human detrusor smooth muscle (DSM). Since the large-conductance Ca(2+)-activated K(+) (KCa1.1) channels are key regulators of human DSM function, we investigated whether mAChR activation increases human DSM excitability by inhibiting KCa1.1 channels. We used the mAChR agonist, carbachol, to determine the changes in KCa1.1 channel activity upon mAChR activation in freshly isolated human DSM cells obtained from open bladder surgeries using the perforated whole cell and single KCa1.1 channel patch-clamp recordings. Human DSM cells were collected from 29 patients (23 males and 6 females, average age of 65.9 ± 1.5 years). Carbachol inhibited the amplitude and frequency of KCa1.1 channel-mediated spontaneous transient outward currents and spontaneous transient hyperpolarizations, which are triggered by the release of Ca(2+) from ryanodine receptors. Carbachol also caused membrane potential depolarization, which was not observed in the presence of iberiotoxin, a KCa1.1 channel inhibitor, indicating the critical role of the KCa1.1 channels. The potential direct carbachol effects on KCa1.1 channels were examined under conditions of removing the major cellular Ca(2+) sources for KCa1.1 channel activation with pharmacological inhibitors (thapsigargin, ryanodine, and nifedipine). In the presence of these inhibitors, carbachol did not affect the single KCa1.1 channel open probability and mean KCa1.1 channel conductance (cell-attached configuration) or depolarization-induced whole cell steady-state KCa1.1 currents. The data support the concept that mAChR activation triggers indirect functional KCa1.1 channel inhibition mediated by intracellular Ca(2+), thus increasing the excitability in human DSM cells.

Management of failed stress urinary incontinence surgery.

With the increasing volume of surgery being performed for the treatment of female stress urinary incontinence (SUI), especially with the widespread use of midurethral slings (MUS), recurrent urinary incontinence is becoming an increasingly common condition. Various preoperative and intraoperative factors have been associated with failed SUI surgery. Treatment options for failed SUI surgery include conservative management and/or surgical management, which include pubovaginal sling, MUS, retropubic suspension, periurethral bulking agents, and artificial sphincters. The choice of treatment option will depend on the etiology of the patient's failure, patient comorbidities, and patient preference.

Implications of the FDA statement on transvaginal placement of mesh: the aftermath.

The release of the U.S. Food and Drug Administration (FDA) safety communication on the use of transvaginal mesh (TVM) for pelvic organ prolapse (POP) has resulted in changes in the pelvic reconstruction community. This monograph reviews the implications of the FDA statements over the last 18-24 months. Recent findings show that there have been significant developments in the areas of regulatory mandates, media and medico-legal activity, and statements from surgical societies. In summary, well-publicized communications from the FDA and major medical organizations are defining a change in the use of TVM for POP.

Single-channel biophysical and pharmacological characterizations of native human large-conductance calcium-activated potassium channels in freshly isolated detrusor smooth muscle cells.

Recent studies have demonstrated the importance of large-conductance Ca(2+)-activated K(+) (BK) channels in detrusor smooth muscle (DSM) function in vitro and in vivo. However, in-depth characterization of human native DSM single BK channels has not yet been provided. Here, we conducted single-channel recordings from excised patches from native human DSM cells. Inside-out and outside-out recordings in high K(+) symmetrical solution (containing 140 mM KCl and ~300 nM free Ca(2+)) showed single-channel conductance of 215-220 pS, half-maximum constant for activation of ~+75 to +80 mV, and low probability of opening (P o) at +20 mV that increased ~10-fold at +40 mV and ~60-fold at +60 mV. Using the inside-out configuration at +30 mV, reduction of intracellular [Ca(2+)] from ~300 nM to Ca(2+)-free decreased the P o by ~85 %, whereas elevation to ~800 nM increased P o by ~50-fold. The BK channel activator NS1619 (10 µM) enhanced the P o by ~10-fold at +30 mV; subsequent application of the selective BK channel inhibitor paxilline (500 nM) blocked the activity. Changes in intracellular [Ca(2+)] or the addition of NS1619 did not significantly alter the current amplitude or single-channel conductance. This is the first report to provide biophysical and pharmacological profiles of native human DSM single BK channels highlighting their importance in regulating human DSM excitability.