Effect of bladder outlet obstruction on the morphology, physiology, and pharmacology of the bladder

Effects of Ganoderma Lucidum shell-broken spore on oxidative stress of the rabbit urinary bladder using an in vivo model of ischemia/reperfusion

Oxidative stress plays an important role in specific disease pathophysiology and the aging process. In the history of human kind, many herbs were utilized for disease prevention and anti-aging treatment. However, there are few direct evidences provided by modern laboratory technology. The current study was designed to evaluate Ganoderma Lucidum's (GL) ability to reduce the damage from in vivo ischemia/reperfusion (I/R) using a rabbit model of I/R that has been effectively utilized to prove the effects of drugs and supplements to reduce oxidative stress. Urinary bladder dysfunction secondary to benign prostatic hyperplasia (BPH) is a major affliction of aging men. One of the major etiologies of obstructive bladder dysfunction (OBD) is oxidative stress induced by I/R. Pharmaceutical studies and clinical research have proven that GL is useful in helping to prevent certain types of pathology and also helpful in prolonging human life in part by acting as an antioxidant. Using an in vivo model of I/R, we have investigated the ability of GL to protect bladder function from oxidative damage mediated by I/R. Our studies demonstrated that ischemia followed by reperfusion resulted in a significant decrease in bladder compliance and decreases in the contractile responses to a variety of forms of contractile stimulation. Pretreatment of rabbits with Ganoderma Lucidum prior to subjecting the rabbits to I/R completely inhibited the negative effects of I/R on both the compliance and contractile responses. These results demonstrate that Ganoderma provides excellent protection of bladder function following I/R (oxidative stress).

Benign Prostatic Obstruction Relief in Patients with Lower Urinary Tract Symptoms Suggestive of Benign Prostatic Enlargement Undergoing Endoscopic Surgical Procedures or Therapy with Alpha-Blockers: A Review of Urodynamic Studies

Benign prostatic obstruction (BPO) contributes to the genesis of lower urinary tract symptoms as well as to pathologic remodeling of the lower and upper urinary tract in patients with benign prostate enlargement. Urodynamic studies demonstrate that both medical therapy with alpha-blockers (ABs) and endoscopic surgical procedures provide BPO relief. However, the magnitude of improvement is higher after surgery. Among ABs, silodosin is associated with the highest improvement of bladder outlet obstruction index (BOOI). A complex relationship exists between BOOI improvement and variations of both maximum urinary flow (Q _max) and detrusor pressure. When the reduction of BOOI is small, the improvement of Q _max is clinically irrelevant and the BOOI is mainly influenced by a decrease of detrusor pressure. In contrast, when the magnitude of BOOI reduction is robust, a meaningful improvement of both detrusor pressure and urinary flow is evident. When clustering ABs according to their receptor pharmacologic selectivity and urodynamic efficacy, three subgroups can be identified,with silodosin being the only member of a subgroup characterized by the highest levels of BOOI improvement and α-1A/α-1B receptor affinity ratio.

Hypoxia-increased expression of genes involved in inflammation, dedifferentiation, pro-fibrosis, and extracellular matrix remodeling of human bladder smooth muscle cells

Partial bladder outlet obstruction (pBOO) is characterized by exaggerated stretch, hydrodynamic pressure, and inflammation which cause significant damage and fibrosis to the bladder wall. Several studies have implicated hypoxia in its pathophysiology. However, the isolated progressive effects of hypoxia on bladder cells are not yet defined. Sub-confluent normal human bladder smooth muscle cells (hbSMC) were cultured in 3% O₂ tension for 2, 24, 48, and 72 h. RNA, cellular proteins, and secreted proteins were used for gene expression analysis, immunoblotting, and ELISA, respectively. Transcription of hypoxia-inducible factor (HIF)1α and HIF2α were transiently induced after 2 h of hypoxia (p < 0.05), whereas HIF3 was upregulated after 72 h (p < 0.005). HIF1 and HIF3α proteins were significantly induced after 2 and 72 h, respectively. VEGF mRNA increased significantly after 24 and 72 h (p < 0.005). The inflammatory cytokines, TGFB (protein and mRNA), IL 1β, 1L6, and TNFα (mRNA) demonstrated a time-dependent increased expression. Furthermore, the anti-inflammatory cytokine IL-10 was downregulated after 72 h (p < 0.05). Evidence of smooth muscle cell dedifferentiation included increased αSMA, vimentin, and desmin. Evidence of pro-fibrotic changes included increased CTGF, SMAD 2, and SMAD 3 as well as collagens 1, 2, 3, and 4, fibronectin, aggrecan, and TIMP 1 transcripts (p < 0.05). Total collagen proteins also increased time-dependently (p < 0.05). Together, these results show that exposure of hbSMC to low oxygen tension results in intense hypoxic cascade, including inflammation, de-differentiation, pro-fibrotic changes, and increased extracellular matrix expression. This elucidates mechanisms of hypoxia-driven bladder deterioration in bladder cells, which is important in tailoring in vivo experiments and may ultimately translate into improved clinical outcomes.

Epigallocatechin Gallate Attenuates Partial Bladder Outlet Obstruction-induced Bladder Injury via Suppression of Endoplasmic Reticulum Stress-related Apoptosis-In Vivo Study

OBJECTIVES

To investigate the protective effect of epigallocatechin gallate (EGCG), a green tea extract, on partial bladder outlet obstruction (pBOO)-induced bladder injury in a rat model.

METHODS

The female Sprague-Dawley rats underwent sham or BOO procedures, and were divided into several groups (sham with saline injection, sham with EGCG treatment, BOO with saline injection, and BOO with EGCG treatment). The rats in each group were randomized into 2 groups (48 hours and 30 days after the BOO procedure) for when their bladders were harvested. EGCG (4.5 mg/kg/day) and saline were administered via intraperitoneal injection after the BOO procedure during the study period. Bladder tissue was examined for inflammation, endoplasmic reticulum (ER) stress-related apoptotic markers by Western blot, and histological staining.

RESULTS

BOO induced acute bladder injury (hemorrhage, edema, and neutrophil infiltration) after 48 hours. In addition, cystometry showed a decrease in micturition pressure and intercontractile interval. We also observed increased expressions of cyclooxygenase-2, poly(ADP-ribose) polymerase at 48 hours, as well as ER stress markers such as caspase-12 and CCAAT/-enhancer-binding protein homologous protein (CHOP). Treatment with EGCG significantly improved pBOO-induced histologic changes, bladder dysfunction, and the overexpression of cyclooxygenase-2, CHOP, and caspase-12 at 48 hours. Similarly, EGCG treatment for 30 days effectively recovered compliance and intercontractile interval, submucosal ER stress-related apoptosis (CHOP and caspase-12) at 30 days after pBOO.

CONCLUSIONS

EGCG alleviate pBOO-induced bladder injury and dysfunction via suppression of inflammation and ER stress-related apoptosis.

Effect of the Chinese traditional prescription Suo Quan Wan on TRPV1 expression in the bladder of rats with bladder outlet obstruction

Background

Suo Quan Wan (SQW) is a Chinese traditional prescription that has been used in clinical treatment of lower urinary tract symptoms for centuries. However, scientific basis of SQW efficacy and mechanism is still needed. This study investigated the effect of SQW on bladder function and transient receptor potential vanilloid 1 (TRPV1) expression in the bladder of rats with bladder outlet obstruction (BOO). The induced changes in bladder function in overactive bladder (OAB) rat model were observed following different periods of outlet obstruction to obtain an appropriate rat model.

Methods

This study was carried out in two parts. In the first part, female Sprague–Dawley rats received sham operations or partial BOO operations. Two, four, and six weeks later, the OAB model groups and control were subjected to urodynamic tests to measure differences in bladder functions. Once the appropriate rat model was obtained, the second part of the experiment was performed. The rat model was recreated and treated with SQW. Urodynamic assessment was conducted, and the bladders of the rats were then removed. Immunofluorescence staining, real-time PCR, and Western blot were performed to localize and quantify the expression of TRPV1 in the bladder.

Results

Results of the first part indicated that at 2 and 4 weeks, the OAB model group exhibited significant differences in urodynamic parameters, including bladder pressure, maximum voiding pressure, and maximum bladder capacity, compared with the sham group. At 4 and 6 weeks, the OAB model group exhibited significant differences in residual volume (RV) and non-voiding contraction frequency. Six-week OAB model group showed much more RV but less voiding efficiency when compared with 6-week sham group or 2—and 4-week OAB model group. Rats that underwent BOO exhibited similarities with the compensated state before four weeks and may have entered decompensated state at six weeks. Studies conducted with 4-week OAB model were appropriate.

In part two of the experiment, unstable bladder in the OAB model group recovered bladder stability after SQW treatment, accompanied by improved bladder hypertrophy, as well as corrected urodynamic parameters. Expression of TRPV1 mRNA and proteins in the bladder was significantly greater in the OAB model group than that in the control group, which subsequently decreased significantly with SQW treatment in BOO-induced rats.

Conclusions

SQW can modulate the expression of TRPV1 in accordance with the recovery of bladder function.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-015-0898-7) contains supplementary material, which is available to authorized users.

Regulation of urinary bladder function by protein kinase C in physiology and pathophysiology

BACKGROUND

Protein kinase C (PKC) is expressed in many tissues and organs including the urinary bladder, however, its role in bladder physiology and pathophysiology is still evolving. The aim of this review was to evaluate available evidence on the involvement of PKC in regulation of detrusor contractility, muscle tone of the bladder wall, spontaneous contractile activity and bladder function under physiological and pathophysiological conditions.

METHODS

This is a non-systematic review of the published literature which summarizes the available animal and human data on the role of PKC signaling in the urinary bladder under different physiological and pathophysiological conditions. A wide PubMed search was performed including the combination of the following keywords: "urinary bladder", "PKC", "detrusor contractility", "bladder smooth muscle", "detrusor relaxation", "peak force", "detrusor underactivity", "partial bladder outlet obstruction", "voltage-gated channels", "bladder nerves", "PKC inhibitors", "PKC activators". Retrieved articles were individually screened for the relevance to the topic of this review with 91 citations being selected and included in the data analysis.

DISCUSSION

Urinary bladder function includes the ability to store urine at low intravesical pressure followed by a subsequent release of bladder contents due to a rapid phasic contraction that is maintained long enough to ensure complete emptying. This review summarizes the current concepts regarding the potential contribution of PKC to contractility, physiological voiding, and related signaling mechanisms involved in the control of both the storage and emptying phases of the micturition cycle, and in dysfunctional voiding. Previous studies linked PKC activation exclusively with an increase in generation of the peak force of smooth muscle contraction, and maximum force generation in the lower urinary tract. More recent data suggests that PKC presents a broader range of effects on urinary bladder function including regulation of storage, emptying, excitability of the detrusor, and bladder innervation. In this review, we evaluated the mechanisms of peripheral and local regulation of PKC signaling in the urinary bladder, and their impact on different phases of the micturition cycle under physiological and pathophysiological conditions.

[Physiopathology of overactive bladder syndrome]

The pathophysiology of OAB is complex, multifactorial and still largely unknown. Several pathophysiological mechanisms have been highlighted that may play a different role in different patient groups. There are now experimental evidences that support both the myogenic and neurogenic hypothesis, but in recent years the "integrative" hypothesis has been gaining more and more acceptance, where a disruption in the multiple interactions between different cell types (neurons, urothelium, interstitial cells, myocytes) and network functions represent a central element of lower urinary tract dysfunctions. Of utmost importance, a disorder in the urothelial sensory function and in the urothelial/suburothelial non-neural cholinergic system, favored by age and comorbidities, appears to be crucial for the development of the OAB. Neuroplastic and detrusor changes in OAB are broadly similar to those observed in bladders exposed to outlet obstruction, neuropathies, inflammation or aging, and may be driven by a common urothelial dysfunction. Several signaling substances and their receptors were found to be involved in central pathways of bidirectional communication between the different cell types in the bladder, and were shown to be modified in several animal models of OAB as well as in human models, indicating new potential therapeutic targets.

Sodium Tanshinone IIA Sulfonate Ameliorates Bladder Fibrosis in a Rat Model of Partial Bladder Outlet Obstruction by Inhibiting the TGF-β/Smad Pathway Activation

Transforming growth factor (TGF)-β1 is known to play a pivotal role in a diverse range of biological systems including modulation of fibrosis in several organs. The precise role of TGF-β/Smad signaling in the progression of bladder fibrosis secondary to partial bladder outlet obstruction (PBOO) is yet to be conclusively. Using a rat PBOO model, we investigated TGF-β1 expression and exaimined whether sodium tanshinone IIA sulfonate (STS) could inhibit TGF-β/Smad signaling pathway activation and ameliorate bladder fibrosis. Forty-eight female Sprague-Dawley rats were randomly divided into three groups: sham operation group (n = 16), PBOO operation without STS treatment group (n = 16) and PBOO operation with STS treatment group (n = 16). Thirty-two rats underwent the operative procedure to create PBOO and subsequently received intraperitoneal injections of STS (10 mg/kg/d; n = 16) or vehicle (n = 16) two days after the surgery. Sham surgery was conducted on 16 rats, which received intraperitoneal vehicle injection two days later. In each of the three groups, an equal number of rats were sacrificed at weeks 4 and 8 after the PBOO or sham operation. The TGF-β/Smad signaling pathway was analyzed using western blotting, immunohistochemical staining and reverse transcriptase polymerase chain reaction (RT-PCR). One-way analysis of variance was conducted to draw statistical inferences. At 4 and 8 weeks, the expression of TGF-β1 and phosphorylated Smad2 and Smad3 in STS-treated PBOO rats was significantly lower than in the PBOO rats not treated with STS. Alpha smooth muscle actin (α-SMA), collagen I and collagen III expression at 4 and 8 weeks post PBOO was lower in STS-treated PBOO rats when compared to that in PBOO rats not treated with STS. Our findings indicate that STS ameliorates bladder fibrosis by inhibiting TGF-β/Smad signaling pathway activation, and may prove to be a potential therapeutic measure for preventing bladder fibrosis secondary to PBOO operation.

Spinal neuronal cannabinoid receptors mediate urodynamic effects of systemic fatty acid amide hydrolase (FAAH) inhibition in rats

AIMS

To test if urodynamic effects from systemic Fatty Acid Amide Hydrolase (FAAH) inhibition involve sacral spinal cannabinoid type 1 (CB1) or type 2 (CB2) receptors.

METHODS

Male rats with or without partial urethral obstruction were used for cystometry or immunohistochemistry. Urodynamic effects of intravenous (IV) 0.3 mg/kg Oleoyl Ethyl Amide (OEtA; FAAH inhibitor), and intrathecal (IT) 5 μg rimonabant (CB1 antagonist) or 5 μg SR144528 (CB2 antagonist) were studied in awake rats.

RESULTS

After administration of rimonabant or SR144528, non-obstructed rats with normal bladder function developed bladder overactivity (BO), which was counteracted by OEtA. OEtA also counteracted BO in obstructed rats. SR144528 did not affect bladder function in obstructed rats but counteracted the urodynamic effects of OEtA. Surprisingly, rimonabant (and AM251, another CB1 antagonist) reduced BO in obstructed rats, whereafter OEtA produced no additional urodynamic effects. CB1 expression increased in the sacral spinal cord of obstructed rats whereas no changes were observed for CB2 or FAAH.

CONCLUSIONS

Urodynamic effects of systemic FAAH inhibition involve activities at spinal neuronal CB1 and CB2 receptors in normal and obstructed rats. Endogenous spinal CB receptor ligands seem to regulate normal micturition and BO. Altered spinal CB receptor functions may be involved in the pathogenesis of obstruction-induced BO. Neurourol. Urodynam. 35:464-470, 2016. © 2015 Wiley Periodicals, Inc.

Cystometric parameters and the activity of signaling proteins in association with the compensation or decompensation of bladder function in an animal experimental model of partial bladder outlet obstruction

We conducted this study to determine whether the degree of detrusor contractility is associated with the compensation or decompensation of bladder function depending on the residual volume (RV) during the first two weeks after the onset of partial bladder outlet obstruction (BOO). Moreover, we also examined whether the degree of the phosphorylation and expression of signaling proteins [AMP-activated kinase (AMPK), extracellular signal‑regulated protein kinases 1 and 2 (ERK1/2) and protein kinase C (PKC)] is associated with the prevalence of compensation or decompensation of bladder function. Twenty-seven female Sprague-Dawley (SD) rats were randomly assigned to either the sham-operated group (n=7) or the group with partial bladder outlet obstruction (BOO) (n=20). We then measured cystometric parameters from three reproducible micturition cycles and averaged the results for a comparison between the two groups. Based on a cut-off value of a mean RV% of 25%, we subdivided our experimental animals into two subgroups: the subgroup with bladder compensation (mean RV%, <25%) and the subgroup with bladder decompensation (mean RV%, >25%). Our results indicated that the degree of detrusor overactivity (DO) was associated with the compensation or decompensation of bladder function depending on the RV during the first two weeks after the onset of BOO in an animal experimental model of partial BOO. Moreover, we also demonstrate that AMPK and ERK1/2 are involved in the compensation or decompensation of bladder function. Furthermore, our results suggest that PKC is not involved in two-phase bladder contraction. Alterations in the activities of signaling proteins, such as AMPK and ERK1/2 may prove to be helpful in the treatment of patients with voiding difficulty.

Spontaneous and evoked contractions are regulated by PKC-mediated signaling in detrusor smooth muscle: involvement of BK channels

Protein kinase C (PKC) and large conductance Ca(2+)-activated potassium channels (BK) are downregulated in the detrusor smooth muscle (DSM) in partial bladder outlet obstruction (PBOO). DSM from these bladders display increased spontaneous activity. This study examines the involvement of PKC in the regulation of spontaneous and evoked DSM contractions and whether pharmacologic inhibition of PKC in normal DSM contributes to increased detrusor excitability. Results indicate the PKC inhibitor bisindolylmaleimide 1 (Bim-1) prevented a decline in the amplitude of spontaneous DSM contractions over time in vitro, and these contractions persist in the presence of tetrodotoxin. Bim-1 also reduced the basal DSM tone, and the ability to maintain force in response to electrical field stimulation, but did not affect maximum contraction. The PKC activator phorbol-12,13-dibutyrate (PDBu) significantly reduced the amplitude and increased the frequency of spontaneous contractions at low concentrations (10 nM), while causing an increase in force at higher concentrations (1 μM). Preincubation of DSM strips with iberiotoxin prevented the inhibition of spontaneous contractions by PDBu. The BK channel openers isopimaric acid and NS1619 reduced the Bim-1-induced enhancement of spontaneous contractions in DSM strips. Our data suggest that PKC has a biphasic activation profile in the DSM and that it may play an important role in maintaining the quiescent state of the normal bladder during storage through the effects on BK channel, while helping to maintain force required for bladder emptying. The data also suggest that PKC dysfunction, as seen in PBOO, contributes to detrusor overactivity.

Partial outlet obstruction in rabbits: duration versus severity

OBJECTIVES

Oxidative stress is a major etiology of obstructed bladder dysfunction. The major goal of the current study was to correlate the level of oxidative stress with both the severity and duration of obstruction.

METHODS

A total of 32 New Zealand White rabbits were divided into four equal groups. Groups 1-3 received partial bladder outlet obstructions by standard methods and survived for 4, 8 or 12 weeks. Group 4 received sham surgery at the end of each time period, isolated strips were taken for contractility studies and the balance of the bladder was frozen as muscle and mucosa for quantification of nitrotyrosine and carbonyl-oxidized proteins derivatized into dinitrophenyl. For each duration, the eight rabbits were divided into three severity groups: mild, intermediate or severe decompensation.

RESULTS

Contractile responses decreased in proportion to both severity and duration. The level of both oxidative products correlated to a much higher degree with the level of severity than the duration. There were significant decreases in the contractile responses in the mild decompensation group, whereas the level of derivatized into dinitrophenyl and nitrotyrosine of the muscle remained at control levels. This was not the case for the 4 weeks obstructed group.

CONCLUSIONS

These findings suggest that the etiology for the mechanism of contractile dysfunction is not an oxidative stress.

Early sequential changes in bladder function after partial bladder outlet obstruction in awake sprague-dawley rats: focus on the decompensated bladder

PURPOSE

We investigated bladder function, with special focus on initial functional changes, by objective report of decompensated bladder according to the percentage of residual urine volume to bladder capacity in awake, obstructed rats.

MATERIALS AND METHODS

Thirty rats were randomly subjected to sham operations (n=10) or partial bladder outlet obstruction (BOO, n=20). Cystometric investigations were performed without anesthesia 1 or 2 weeks after BOO surgery. To reduce the influence of confounding factors in awake cystometry, we used simultaneous recordings of intravesical and intraabdominal pressures. Decompensated bladder was defined as the bladder with more than 20% of residual volume compared with bladder capacity.

RESULTS

Compared with that in sham animals, basal pressure was elevated in both BOO groups. Threshold pressure was higher in the 2 week BOO (p<0.01) group. Compliance was decreased in the 1 week BOO group (p<0.01) and increased in the 2 week BOO group (p<0.001). Bladder capacity was not increased in the 1 week BOO group, but was increased in the 2 week BOO group (p<0.01). Decompensation was found in 62.5% of the 1 week BOO group and in 33.3% of the 2 week BOO group.

CONCLUSIONS

From the earlier phase, the bladders exhibited serial changes in pressure and volume parameters, and decompensated bladders defined by the percentage of residual volume to bladder capacity could be seen. During the later phase, there was an increasing tendency of compensated bladders, accompanied by the bladders being enlarged and more compliant.

Overactive bladder in males

The prevalence of overactive bladder (OAB) symptoms is considerable in both men and women and the impact on quality of life (QOL) is equally substantial. Ironically, despite nearly equal prevalence, OAB symptoms in men are infrequently treated, and often with medical therapies aimed at bladder outlet obstruction (BOO). In this review, we examine the pathophysiology of OAB and its evaluation in the context of benign prostatic hypertrophy and concomitant BOO. We then consider the efficacy and safety of individual therapeutic options for lower urinary tract symptoms in men, focusing on the mainstays of medical therapy: α-adrenergic blockers, 5-α reductase inhibitors, and antimuscarinic agents. Finally, we aim to comment on new therapeutic strategies and targets that may one day be available for the treatment of male OAB.

Update on the management of overactive bladder: patient considerations and adherence

Overactive bladder (OAB) is a common condition that causes a profound impact on an individual’s overall health and quality of life. Muscarinic receptor antagonists are the mainstay of oral pharmacotherapy for OAB. Although all of the medications in this class are significantly more effective than placebo, they are also associated with more adverse events that may limit their overall use. Although newer preparations of these medications have sought to improve tolerability and efficacy through alternative routes of delivery and once-daily dosing, improved adherence to treatment and treatment persistence continue to be an ongoing challenge. An improved understanding of the factors involved in persistence of medical OAB therapy is imperative in efforts to optimize therapeutic benefits in this chronic and potentially morbid condition.

Urodynamic interpretation of changing bladder function and voiding pattern after radical prostatectomy: a long-term follow-up

OBJECTIVE

To investigate and compare changes in the bladder function after radical prostatectomy (RP) and to correlate changes in subjective voiding symptoms with the observed changes in function.

PATIENTS AND METHODS

In 72 patients who had RP between 2003 and 2004, we serially evaluated urodynamic studies (UDS) before RP and at 3, 6 and 36 months afterward. The short-form International Continence Society-male symptom questionnaire was also repeated at corresponding periods. Changes in bladder contraction and storage function after RP were compared for changes in subjective symptoms.

RESULTS

On serial UDS, there were reductions in maximum cystometric capacity, maximum detrusor pressure and maximum urethral closure pressure (MUCP) at 3 months, after which all remained relatively unchanged. On the questionnaire, the voiding symptom domain score improved (8.04 to 4.82, P < 0.001) while the storage domain score significantly and progressively worsened, beginning from 3 months (2.25 to 3.78, P= 0.04), resulting in an unchanged overall urinary symptom-related quality of life at 3 years. The incidence of detrusor overactivity increased from 37.5% before RP, to 45.8% at 3 months and 51.4% at 3 years. At 3 years, a recurring postvoid residual urine volume was the cause of the deterioration in the voiding symptom domain score, while a prominent reduction in MUCP resulted in a deterioration in the storage symptom score.

CONCLUSIONS

There is a reduction in bladder capacity, detrusor and sphincteric activity immediately after RP, stabilizing thereafter but remaining significantly reduced at 3 years. Although voiding symptoms improved in most men, the significant deterioration in storage symptoms, which might be attributed to sphincteric incompetence in addition to increased detrusor overactivity, became a source of overall urinary bother in the long term.

Detrusor overactivity is associated with downregulation of large-conductance calcium- and voltage-activated potassium channel protein

Large-conductance voltage- and calcium-activated potassium (BK) channels have been shown to play a role in detrusor overactivity (DO). The goal of this study was to determine whether bladder outlet obstruction-induced DO is associated with downregulation of BK channels and whether BK channels affect myosin light chain 20 (MLC(20)) phosphorylation in detrusor smooth muscle (DSM). Partial bladder outlet obstruction (PBOO) was surgically induced in male New Zealand White rabbits. The rabbit PBOO model shows decreased voided volumes and increased voiding frequency. DSM from PBOO rabbits also show enhanced spontaneous contractions compared with control. Both BK channel alpha- and beta-subunits were significantly decreased in DSM from PBOO rabbits. Immunostaining shows BKbeta mainly expressed in DSM, and its expression is much less in PBOO DSM compared with control DSM. Furthermore, a translational study was performed to see whether the finding discovered in the animal model can be translated to human patients. The urodynamic study demonstrates several overactive DSM contractions during the urine-filling stage in benign prostatic hyperplasia (BPH) patients with DO, while DSM is very quiet in BPH patients without DO. DSM biopsies revealed significantly less BK channel expression at both mRNA and protein levels. The degree of downregulation of the BK beta-subunit was greater than that of the BK alpha-subunit, and the downregulation of BK was only associated with DO, not BPH. Finally, the small interference (si) RNA-mediated downregulation of the BK beta-subunit was employed to study the effect of BK depletion on MLC(20) phosphorylation. siRNA-mediated BK channel reduction was associated with an increased MLC(20) phosphorylation level in cultured DSM cells. In summary, PBOO-induced DO is associated with downregulation of BK channel expression in the rabbit model, and this finding can be translated to human BPH patients with DO. Furthermore, downregulation of the BK channel may contribute to DO by increasing the basal level of MLC(20) phosphorylation.

Effect of Partial Bladder Outlet Obstruction on the Morphology of Elastin in Rabbit Bladder Smooth Muscle

OBJECTIVES

Elastin, in association with collagen, allows the body's organs to stretch and relax. Collagen and elastin, the major components of connective tissue, are present throughout the bladder wall and are intimately related to bladder compliance. The present study was undertaken to evaluate elastin morphologically using immunostaining and electron microscopy in the rabbit model of partial bladder outlet obstruction (PBOO).

METHODS

Four groups of Japanese white rabbits underwent either PBOO by mild ligation of the urethra (2- and 4-week PBOO) or no obstruction (2- and 4-week sham). Histopathological examination was performed by Elastica van Gieson staining, scanning electron microscopy, transmission electron microscopy, and ultra-high voltage electron microscopy. The number of pixels representing elastin fibers in computerized images was analyzed using Adobe Photoshop Version 2.0.

RESULTS

Bladder weight significantly increased after PBOO. Increase in the thickness of the bladder wall was observed after obstruction on histopathological examination. On scanning electron microscopy, elastin was very thick and was found in large configurations. 3-D analysis using electron microscopic tomography revealed that elastic fibers in the bladder had a coil-like appearance in the muscle layer, with each fiber composed of several fibrils. Such structures may be closely related to the physiological function of the bladder.

CONCLUSION

Elastin in the bladder assumes the form of a coil during micturition. We examined that the increase in elastin makes it difficult for elastin to stretch linearly resulting in reduced elasticity. This change may be one of the factors involved in the decrease in compliance mediated by PBOO.

Alteration of the PKC-mediated signaling pathway for smooth muscle contraction in obstruction-induced hypertrophy of the urinary bladder

Normal urinary bladder function requires contraction and relaxation of the detrusor smooth muscle (DSM). The DSM undergoes compensatory hypertrophy in response to partial bladder outlet obstruction (PBOO) in both men and animal models. Following bladder hypertrophy, the bladder either retains its normal function (compensated) or becomes dysfunctional (decompensated) with increased voiding frequency and decreased void volume. We analyzed the contractile characteristics of DSM in a rabbit model of PBOO. The protein kinase C (PKC) agonist phorbol 12, 13-dibutyrate (PDBu) elicited similar levels of contraction of DSM strips from normal and compensated bladders. However, PDBu-induced contraction decreased significantly in DSM strips from decompensated bladders. The expression and activity of PKC-alpha were also lowest in decompensated bladders. The PKC-specific inhibitor bisindolylmaleimide-1 (Bis) blocked PDBu-induced contraction and PKC activity in all three groups. Moreover, the phosphorylation of the phosphoprotein inhibitor CPI-17 (a 17-kDa PKC-potentiated inhibitory protein of protein phosphatase-1) was diminished in DSM from the decompensated bladder, which would result in less inhibitory potency of CPI-17 on myosin light chain phosphatase activity and contribute to less contractility. Immunostaining revealed the colocalization of PKC and phosphorylated CPI-17 in the DSM and confirmed the decreases of these signaling proteins in the decompensated bladder. Our results show a differential PKC-mediated DSM contraction with corresponding alterations of PKC expression, activity and the phosphorylation of CPI-17. Our finding suggests a significant correlation between bladder function and PKC pathway. An impaired PKC pathway appears to be correlated with severe bladder dysfunction observed in decompensated bladders.

Complications of mid urethral slings: important outcomes for future clinical trials

PURPOSE

Mid urethral slings are becoming the first line surgical treatment for stress urinary incontinence in women. We reviewed the complications of mid urethral sling placement and their potential pathophysiology.

MATERIALS AND METHODS

We conducted a literature search on MEDLINE from 1995 to 2007 using the key words sling, complications, mid-urethral slings, transvaginal tape, transobturator tape, trials, pathophysiology and complications. The Cochrane database was also searched. The results were summarized according to the type of mid urethral slings reported.

RESULTS

There were 928 MEDLINE citations for sling and complications, 279 for sling and complications and bladder, and 68 for sling and complications and voiding dysfunction. The reported complication rates ranged from 4.3% to 75.1% for retropubic and 10.5% to 31.3% for transobturator mid urethral slings. Complications included bladder perforation, hemorrhage, bowel injury, vaginal extrusion, de novo urgency and urge incontinence, urinary tract infections and voiding dysfunction. Retropubic mid urethral slings led to a higher occurrence of complications such as bladder perforation and hematoma. In addition, the retropubic approach resulted in serious complications such as bowel injury, major vascular injury and death. Groin pain was more common after the transobturator approach. Experimental studies indicated that the potential mechanisms for sling complications may include vaginal dissection, denervation injury and bladder remodeling.

CONCLUSIONS

Mid urethral slings result in bothersome complications which should not be minimized. Awareness of these complications should encourage improvements in patient counseling as well as further investigation of the underlying mechanisms. Decreasing complications should be considered an important outcome for future clinical studies of mid urethral slings.

Treatment-resistant detrusor overactivity--underlying pharmacology and potential mechanisms

Bladder function during filling and micturition is regulated by peripheral and central nervous and hormonal control systems. Micturition occurs in response to afferent signals from the lower urinary tract, and distention of the bladder wall is the primary stimulus. In the animal and human bladder, efferent adrenergic, cholinergic and nonadrenergic, noncholinergic (NANC) neurotransmission has been demonstrated. The most important receptors for activation of contraction are muscarinic (M3) and purinergic receptors (P2X1), however, the contribution of these receptors to contraction may differ between species, and may be changed in bladder dysfunction associated with detrusor overactivity (DO) and/or the overactive bladder (OAB) syndrome, such as outflow obstruction, neurogenic bladders, idiopathic DO and diabetes. The NANC component of the nerve-induced response in such disorders may be responsible for up to 40-50% of the total bladder contraction. Whether this in vitro'atropine-resistance' corresponds to DO/OAB seen in patients not responding to antimuscarinic treatment is not known. Afferent signalling from the urothelium may be involved in both normal bladder function and in DO/OAB, but its role in antimuscarinic-refractory patients remains to be established. Several central nervous system (CNS) transmitters/transmitter systems, including gamma aminobutyric acid (GABA), opioid, serotonin, noradrenaline, dopamine or glutamatergic receptors and mechanisms are known to be involved in micturition control. The contribution of these receptors and mechanisms in DO/OAB resistant to treatment with antimuscarinics is not known, but drugs acting at these sites may offer future treatment possibilities.

A critical review of the pharmacology of the plant extract ofPygeum africanumin the treatment of LUTS

Despite an unremitting increase in the number of patients presenting symptoms of benign prostate hyperplasia (BPH), the viable treatment options remain relatively limited when compared to other disorders of aging. This has spurred an interest in so-called alternative medicines, many of which continue to be used in spite of the more recent emergence of rationally targeted therapies. Nonetheless, in the case of plant extracts, the vast majority of these have not been subjected to the same rigorous pre-clinical pharmacological testing and large-scale clinical trials now required by health authorities. Furthermore, demonstration of their clinical efficacy in BPH has been hindered by trials of limited duration with a high placebo response. Beginning with a preliminary demonstration of in vitro inhibition of growth factor-mediated fibroblast proliferation with Pygeum africanum extract, a detailed series of in vitro and in vivo studies on prostate growth and bladder function were undertaken. These studies, reviewed herein, have permitted the identification of putative molecular targets of Pygeum africanum extract affecting both growth factor-mediated prostate growth as well as specific parameters of bladder function. These results, corroborated in part by short-term clinical efficacy, set the stage for a large-scale clinical trial to investigate the efficacy of Pygeum africanum extract in the treatment of lower urinary tract symptoms.

A preliminary study of JM-27: a serum marker that can specifically identify men with symptomatic benign prostatic hyperplasia

PURPOSE

Benign prostatic hyperplasia is a common disease in men that until recently was considered a single disease with varying symptoms. Our recent analysis has revealed that a molecular marker, JM-27, is able to distinguish at the tissue level between highly symptomatic individuals and those with histological disease. The goal of these studies was to determine if a serum based assay to detect JM-27 could distinguish men with different forms of benign prostatic hyperplasia.

MATERIALS AND METHODS

A serum based enzyme-linked immunosorbent assay was developed using a novel anti-JM-27 monoclonal antibody. The assay was sensitive, detecting JM-27 at the low ng/ml level within the serum. A quantitative measurement of serum JM-27 levels was performed in 68 patients. The patients consisted of 3 groups of 29 patients with asymptomatic benign prostatic hyperplasia (American Urological Association symptom score of 15 or less), 39 with symptomatic benign prostatic hyperplasia (American Urological Association symptom score 16 to 32) and 17 with confirmed prostate cancer. The assay cutoff was determined after a pilot run of samples and applied prospectively.

RESULTS

Using the determined cutoff, serum levels of JM-27 can distinguish between symptomatic and asymptomatic patient sets. The sensitivity and specificity of the assay are 90% and 77%, respectively. The presence of prostate cancer in these men does not appear to alter the marker levels.

CONCLUSIONS

The present study is believed to represent the first characterization of a serum based marker for severe benign prostatic hyperplasia.

Effect of partial bladder outlet obstruction on nitrotyrosine levels and their correlation with contractile function

AIMS

It has been demonstrated that partial bladder outlet obstruction (PBOO) causes free radical generation that, in turn, results in cellular and subcellular damage. We tested the hypothesis that nitration of proteins is associated with contractile dysfunctions in obstructive bladder disease.

METHODS

Thirty rabbits were subjected to 1-28 days of partial outlet obstruction. Sham operated rabbits served as controls. Western blotting was used to determine the amount of nitrotyrosine level at the protein level. At each time point, isolated strips of bladder body were mounted in individual baths and the contractile response to field stimulation (FS), carbachol, and KCl determined.

RESULTS

Bladder weight increased rapidly during the first 7 days and then increased slowly thereafter. There was a fourfold increase in the amount of nitrotyrosine in the 7 day obstructed groups when compared to sham controls and the levels remain elevated at 14 and 28 days of obstruction. Contractile dysfunction in response to FS (8 and 32 Hz) was noted as early as 1 day after obstruction and increased progressively over the study period. The decrease in response to carbachol and KCl was significant only after 3 days of obstruction and the progressive increase in dysfunction was slower than with FS.

CONCLUSIONS

PBOO is accompanied by an increase in nitrotyrosine, a marker of free radical damage. Simultaneously there was a progressive decrease in contractility of detrusor smooth muscles (DSMs). Nitrotyrosine may be usable as a marker of free radical damage and reperfusion injury.

The detrusor muscle: an innocent victim of bladder outlet obstruction

OBJECTIVES

Benign prostatic hyperplasia (BPH) is considered a frequent cause of bladder outlet obstruction (BOO) and lower urinary tract symptoms (LUTS), although the physiopathologic mechanism through which BPH causes LUTS is not clear. Several morphologic and functional modifications of the bladder detrusor have been described in patients with BPH and could play a direct role in determining symptoms. The opinion is spreading that the enlarged prostates in patients with LUTS is nothing more than a mere bystander. Evidence has accumulated, however, supporting the role of BPH-related BOO as the direct cause determining bladder dysfunction and indirectly causing urinary symptoms. The present review addresses the bladder response to BOO, particularly focusing on the physiopathologic cascade that links obstructive BPH to bladder dysfunction.

METHODS

A literature review of peer-reviewed articles has been performed, including both in vivo and in vitro studies on human tissue and animal model experiments.

RESULTS

Epithelial and smooth muscle cells in the bladder wall are mechanosensitive, and in response to mechanical stretch stress caused by BOO, undergo modifications of gene expression and protein synthesis. This process involves several transduction mechanisms and finally alter the ultrastructure and physiology of cell membranes, cytoskeleton, contractile proteins, mitochondria, extracellular matrix, and neuronal networks.

CONCLUSIONS

BOO is the initiator of a physiopathologic cascade leading to deep changing of bladder structure and function. Before being a direct cause of storing-phase urinary symptoms, the bladder is the first innocent victim of prostatic obstruction.

Rho kinase: a target for treating urinary bladder dysfunction?

Urinary incontinence and other urinary storage symptoms are frequent in the general population but available treatments have limited efficacy and tolerability. Rho kinase (ROCK) has a central role in the regulation of smooth muscle contraction, including that of the urinary bladder. Recent experimental evidence indicates that this role could be deregulated and exacerbated in local and systemic pathological conditions that affect the bladder. In vitro studies with prototypical ROCK inhibitors such as Y27632 and in vivo data from animal models indicate that such drugs have potential as future treatments for bladder dysfunction.

Partial Bladder Outlet Obstruction Induces Urethral Smooth Muscle Hypertrophy and Decreased Force Generation

PURPOSE

PBOO leads to increased urinary frequency, decreased void volume, hypertrophy of the detrusor SM, and alterations in contractile and regulatory proteins. This study was done to determine whether PBOO induced increases in urinary frequency and detrusor SM hypertrophy are associated with an alteration in the contractility and expression of myosin isoforms in urethral SM.

MATERIALS AND METHODS

PBOO was surgically induced in male New Zealand White rabbits, and sham operated rabbits served as controls. After surgery, rabbits were kept 12 days, and prior to sacrifice, urine output and voiding frequency were monitored by keeping the animals in metabolic cages for 24 hours. Animals with increased urinary frequency (mean +/- SEM 43 +/- 12 voids per 24 hours) and sham operated rabbits (6 +/- 3 voids per 24 hours) were used for this study. Morphology of the urethra was studied using light and immunofluorescence microscopy. The expression of myosin isoforms was analyzed at the mRNA and protein levels by RT-PCR and Western blotting.

RESULTS

The urethral wall and SM of PBOO rabbits showed hypertrophy. The force produced by the longitudinal muscle strips of PBOO animals in response to phenylephrine, KCl, or electrical field stimulation was decreased 50%, 37% and 40%, respectively. Immunofluorescence microscopy revealed a decrease in nerve density. RT-PCR and Western blotting showed a decrease in the expression of myosin isoform SM-B with a concomitant increase in SM-A at the mRNA and protein levels.

CONCLUSIONS

Our data show hypertrophy of the urethral wall and SM, and alterations in contraction, innervation, and myosin isoforms in PBOO induced detrusor hypertrophy.

Effect of strip length on the contractile dysfunction of bladder smooth muscle after partial outlet obstruction

OBJECTIVES

Partial outlet obstruction mediates decreased contractile responses and increased collagen synthesis; however, it is not known to what extent the increased collagen contributes to contractile dysfunction.

METHODS

Sixteen WNZ rabbits were divided into three groups: control, 2-week obstructed, and 2-week sham. Each rabbit was anesthetized, and the bladder was excised and cut into equal width strips of 0.5, 1.0, and 2.0-cm lengths. The contractile responses to field stimulation, carbachol, potassium chloride, and adenosine triphosphate were determined. At the end of the experiment, each strip was fixed in formalin and immunostained for collagen.

RESULTS

The contractile responses for the control and sham strips were similar for all strip lengths. In obstructed tissue, the shorter strip lengths generated significantly more tension per cross-sectional area than did the longer strips. The collagen density and distribution were similar for the control and sham bladders. The obstructed bladders had significantly increased collagen deposits between and within the smooth muscle bundles and cells.

CONCLUSIONS

Because the relationship between strip size and contraction were similar for field stimulation, carbachol, and potassium chloride, it is the increased density of connective tissue within and between the muscle bundles and fibers that interferes with contraction (ie, the greater the strip length, the greater the interference and the greater the contractile dysfunction). Therefore, both functional and structural alterations in the obstructed bladder participate in contractile dysfunction.

Smooth muscle membrane organization in the normal and dysfunctional human urinary bladder: a structural analysis

PURPOSE

The decline in contractile properties is a characteristic feature of the dysfunctional bladder as a result of infravesical outlet obstruction. During clinical progression of the disease, smooth muscle cells undergo structural modifications. Since adaptations to constant changes in length require a high degree of structural organization within the sarcolemma, we have investigated the expression of several proteins, which are involved in smooth muscle membrane organization, in specimens derived from normal and dysfunctional organs.

MATERIALS AND METHODS

Specimen from patients with urodynamically normal/equivocal (n = 4), obstructed (n = 2), and acontractile (n = 2) bladders were analyzed relative to their structural features and sarcolemmal protein profile.

RESULTS

Smooth muscle cells within the normal urinary bladder display a distinct sarcolemmal domain structure, characterized by firm actin-attachment sites, alternating with flexible "hinge" regions. In obstructed bladders, foci of cells displaying degenerative sarcolemmal changes alternate with areas of hypertrophic cells in which the membrane appears unaffected. In acontractile organs, the overall membrane structure remains intact, however annexin 6, a protein belonging to a family of Ca2+-dependent, "membrane-organizers," is downregulated.

CONCLUSION

Degenerative changes in smooth muscle cells, which are chronically working against high resistance, are preferentially located within the actin-attachment sites. In acontractile bladders, the downregulation of annexin 6 might have a bearing on the fine-tuning of the plasma membrane during contraction/relaxation cycles.

Changes in detrusor smooth muscle myosin heavy chain mRNA expression following spinal cord injury in the mouse

AIMS

Smooth muscle myosin heavy chain (SMMHC) isoform composition has been shown to be developmentally regulated and to be associated with functional changes in smooth muscle activity. In this study, we sought to determine expression patterns of SMMHC isoforms in a murine model of spinal cord injury (SCI) and to compare these expression patterns to neurologic, cytometric, and morphometric findings.

MATERIALS AND METHODS

Baseline cystometry was performed on adult, female mice followed by either thoracic spinal cord transection (SCI) or sham operation (Sham). At 1, 3, or 6 weeks postoperatively neurologic evaluation and cystometry were performed, bladders were harvested, and expression patterns of SMMHC isoforms (SM1 vs. SM2 and SMA vs. SMB) were assessed by RT-PCR. Morphometrics utilizing computer-assisted color image analysis was also performed on all bladders.

RESULTS

There was a significant increase in bladder weight and capacity 1 week following SCI which normalized over time, however, morphometric analysis did not reveal an alteration in tissue composition amongst the three groups. One week following SCI, SM1 was predominantly expressed over SM2 and began to normalize at 3 weeks. This coincided with the emergence of reflex voiding and detrusor overactivity. SMA was expressed following SCI only, and the number of bladders found to express SMA decreased with increasing duration since SCI.

CONCLUSIONS

Smooth muscle myosin heavy chain mRNA expression patterns appear to be affected by SCI. We believe the induction of SMA may be a factor in altered bladder function following injury.

The uroepithelium: not just a passive barrier

The uroepithelium lines the inner surface of the renal pelvis, the ureters, and the urinary bladder, where it forms a tight barrier that allows for retention of urine, while preventing the unregulated movement of ions, solutes, and toxic metabolites across the epithelial barrier. In the case of the bladder, the permeability barrier must be maintained even as the organ undergoes cyclical changes in pressure as it fills and empties. Beyond furthering our understanding of barrier function, new analysis of the uroepithelium is providing information about how detergent-insoluble membrane/protein domains called plaques are formed at the apical plasma membrane of the surface umbrella cells, how mechanical stimuli such as pressure alter exocytic and endocytic traffic in epithelial cells such as umbrella cells, and how changes in pressure are communicated to the underlying nervous system.

Decreased expression of smooth muscle alpha-actin results in decreased contractile function of the mouse bladder

PURPOSE

Smooth muscle alpha-actin (SMalphaA) is an important actin isoform for functional contractility in the mouse bladder. Alterations in the expression of SMalphaA have been associated with a variety of bladder pathological conditions. Recently, a SMalphaA-null mouse was generated and differences in vascular tone and contractility were observed between wild-type and SMalphaA-null mice suggesting alterations in function of vascular smooth muscle. We used SMalphaA-null mice to explore the hypothesis that SMalphaA is necessary for normal bladder function.

MATERIALS AND METHODS

Reverse transcriptase polymerase chain reaction, Western blotting and immunohistochemical staining were used to confirm the absence of SMalphaA transcript and protein in the bladder of SMalphaA-null mice. In vitro bladder contractility compared between bladder rings harvested from wild-type and SMalphaA-null mice was determined by force measurement following electrical field stimulation (EFS), and exposure to chemical agonists and antagonists including KCl, carbachol, atropine and tetrodotoxin. Resulting force generation profiles for each tissue and agent were analyzed.

RESULTS

There was no detectable SMalphaA transcript and protein expression in the bladder of SMalphaA-null mice. Nine wild-type and 9 SMalphaA-null mice were used in the contractility study. Bladders from SMalphaA-null mice generated significantly less force than wild-type mice in response to EFS after KCl. Similarly, bladders from SMalphaA-null mice generated less force than wild-type mice in response to pretreatment EFS, and EFS after carbachol and atropine, although the difference was not significant. Surprisingly, the bladders in SMalphaA-null mice appeared to function normally and showed no gross or histological abnormalities.

CONCLUSIONS

SMalphaA appears to be necessary for the bladder to be able to generate normal levels of contractile force. No functional deficits were observed in the bladders of these animals but no stress was placed on these bladders. To our knowledge this study represents the first report to demonstrate the importance of expression of SMalphaA in force generation in the bladder.

Urinary bladder contraction and relaxation: physiology and pathophysiology

The detrusor smooth muscle is the main muscle component of the urinary bladder wall. Its ability to contract over a large length interval and to relax determines the bladder function during filling and micturition. These processes are regulated by several external nervous and hormonal control systems, and the detrusor contains multiple receptors and signaling pathways. Functional changes of the detrusor can be found in several clinically important conditions, e.g., lower urinary tract symptoms (LUTS) and bladder outlet obstruction. The aim of this review is to summarize and synthesize basic information and recent advances in the understanding of the properties of the detrusor smooth muscle, its contractile system, cellular signaling, membrane properties, and cellular receptors. Alterations in these systems in pathological conditions of the bladder wall are described, and some areas for future research are suggested.

THE MOLECULAR GENETIC BASIS OF MITOCHONDRIAL MALFUNCTION IN BLADDER TISSUE FOLLOWING OUTLET OBSTRUCTION

PURPOSE

Bladder dysfunction following partial outlet obstruction is a frequent consequence of benign prostatic hyperplasia and an increasingly common problem given the aging of the general population. Recent studies from this and other groups have begun to elucidate the molecular bases for the well described physiological malfunctions that characterize this clinical entity. We summarized and synthesized that information.

MATERIALS AND METHODS

Using modern methods of molecular genetics, including real-time polymerase chain reaction, real-time reverse transcriptase-polymerase chain reaction and others, as well as traditional experimental techniques such as electron microscopy we and others examined the transcriptional profile, morphology, etc of bladder smooth muscle mitochondria in experimental models of outlet obstruction.

RESULTS

Data from many studies have demonstrated that aberrant gene expression in the mitochondrial and mitochondria related nuclear genetic systems underlies the loss of compliance and other attributes of bladder dysfunction following outlet obstruction. Such aberrant transcriptional characteristics engender loss of function in the electron transport and oxidative phosphorylation systems. Morphological studies of mitochondria in the animal model systems support this conclusion.

CONCLUSIONS

In large part the loss of function in bladder smooth muscle following outlet obstruction results from the attenuation of mitochondrial energy production. In this article we reviewed and synthesized all available experimental observations relevant to this problem and we suggest future lines of inquiry that should prove fruitful in developing new strategies to treat the condition.

Smooth muscle hypertrophy following partial bladder outlet obstruction is associated with overexpression of non-muscle caldesmon

Partial bladder outlet obstruction (PBOO) induces remodeling of urinary bladder smooth muscle (detrusor). We demonstrate an increase in bladder wall mass, muscle bundle size, and a threefold increase in the cross-sectional area of detrusor myocytes following PBOO in male New Zealand White rabbits compared to that of controls. Some bladders with detrusor hypertrophy function close to normal (compensated), whereas others were dysfunctional (decompensated), showing high intravesical pressure, large residual urine volume, and voiding difficulty. We analyzed the expression of smooth muscle-specific caldesmon (h-CaD) and non-muscle (l-CaD) by Western blotting, RT-PCR, and real-time PCR. The expression of l-CaD is increased significantly at the mRNA and protein levels in the decompensated bladders compared to that of normal and compensated bladders. The CaD was also co-localized with myosin containing cytoplasmic fibrils in cells dissociated from obstructed bladders and cultured overnight. Our data show that the inability of decompensated bladders to empty, despite detrusor hypertrophy, is associated with an overexpression of l-CaD. The level of l-CaD overexpression might be a useful marker to estimate the degree of detrusor remodeling and contractile dysfunction in PBOO.

Storage and voiding symptoms: pathophysiologic aspects

Lower urinary tract symptoms (LUTS) can be categorized as storage, voiding, and postmicturition symptoms. Although often associated with benign prostatic hyperplasia (BPH), they may also occur in women. This observation, the beneficial effects of alpha-adrenoceptor (AR) antagonists in men with BPH and LUTS, and the frail correlation between LUTS, and prostatic enlargement and/or outflow obstruction have focused interest on the role of extraprostatic alpha-ARs in the pathogenesis of LUTS. It has been suggested that an upregulation of contraction-mediating alpha-ARs and a downregulation of relaxation-mediating beta-ARs can contribute to LUTS generation. However, recent investigations on human bladder tissue could not confirm such a change. Antimuscarinic agents are effective for treatment of the overactive bladder, which is characterized by urge, frequency, urge incontinence, and nocturia (ie, LUTS). This suggests that muscarinic receptors are involved in the pathogenesis of LUTS, and there is recent evidence implicating purinergic receptors. Structural changes in the bladder, such as smooth muscle hypertrophy and connective tissue infiltration, are associated with detrusor overactivity in about 50% to 66% of patients with BPH. However, it is unclear whether this is caused by bladder outlet obstruction because the symptoms may remain in up to 33% of the patients after surgical removal of the obstruction. When outflow obstruction is reversed in rats, there is a subset (20%) that continues to have overactive voiding, despite a reversal of the bladder hypertrophy, suggesting that changes within the central nervous system may be a contributing factor. LUTS can be caused by many, often overlapping, pathophysiologic mechanisms, which may contribute to individual variation in response to treatment.

Oral Kohki Tea and its protective effect against in vitro ischemic damage to the bladder

AIMS

Results of several studies indicate that ischemia/reperfusion (I/R) is an etiological factor in the contractile dysfunctions induced by partial bladder outlet obstruction in animal models. In support of this hypothesis, pretreatment of rabbits with Kohki Tea (Engelhardtia chrysolepis), a Japanese herbal drink very high in antioxidant activity, significantly reduced the contractile dysfunctions induced by partial outlet obstruction. The current study was designed to determine if pretreating rabbits with Kohki Tea could protect the bladder against the contractile damage induced by in vitro ischemia followed by re-oxygenation.

METHODS

Forty-eight New Zealand White rabbits were separated into two groups of 24; Group 1 was pretreated by oral gavage for 3 weeks with Kohki Tea and Group 2 received vehicle (water). Each rabbit was anesthetized with pentobarbital. The urinary bladder was rapidly removed and eight longitudinal muscle strips were cut from the bladder body. Each strip was mounted in a separate 15-ml bath containing Tyrode's solution with glucose (1 mg/ml) and maintained at 37 degrees C. All strips were equilibrated for 30 min with a gas mixture of 95% O2 and 5% CO2. At the end of this period of time, all strips were stimulated with field stimulation (FS) carbachol and KCl. After the last wash, the aeration was changed to hypoxic mixture (nitrogen-CO2) without glucose. At the end of 2 hr, the aeration was changed back to the normal 95% O2 and 5% CO2, and glucose was added to the buffer. After 1 hr of re-oxygenation, a second set of stimulations was performed. In order to represent hyperreflexia, the strips were stimulated at 32-Hz FS at 5-min intervals during the hypoxic period in half of the in vitro experiments.

RESULTS

The results showed that Kohki Tea pretreatment protected the bladder's response to FS from the detrimental effects of repetitive stimulation and the detrimental effects of both in vitro ischemia and repetitive stimulation on the contractile responses to carbachol and KCl.

CONCLUSIONS

These data are consistent with the concept that Kohki Tea acts by protecting the bladder from cellular damage caused by hypoxia and the generation of free radicals.

Alteration in expression of myosin isoforms in detrusor smooth muscle following bladder outlet obstruction

Partial urinary bladder outlet obstruction (PBOO) in men, secondary to benign prostatic hyperplasia, induces detrusor smooth muscle (DSM) hypertrophy. However, despite DSM hypertrophy, some bladders become severely dysfunctional (decompensated). Using a rabbit model of PBOO, we found that although DSM from sham-operated bladders expressed nearly 100% of both the smooth muscle myosin heavy chain isoform SM-B and essential light chain isoform LC17a, DSM from severely dysfunctional bladders expressed as much as 75% SM-A and 40% LC17b (both associated with decreased maximum velocity of shortening). DSM from dysfunctional bladder also exhibited tonic-type contractions, characterized by slow force generation and high force maintenance. Immunofluorescence microscopy showed that decreased SM-B expression in dysfunctional bladders was not due to generation of a new cell population lacking SM-B. Metabolic cage monitoring revealed decreased void volume and increased voiding frequency correlated with overexpression of SM-A and LC17b. Myosin isoform expression and bladder function returned toward normal upon removal of the obstruction, indicating that the levels of expression of these isoforms are markers of the PBOO-induced dysfunctional bladders.