AMPK Alters Detrusor Contractility During Emptying in Normal Bladder and Hypertrophied Bladder with Partial Bladder Outlet Obstruction via CaMKKß.

AMP-activated protein kinase (AMPK) has been implicated in contractility changes in bladders with partial bladder outlet obstruction (PBOO), but the role of AMPK in the contractile response of normal bladder remains unclear. We investigated the phosphorylation of AMPKα and expression of the involved upstream AMPK kinases (AMPKKs) in a model of bladders with PBOO and sought to determine whether the pharmacological inhibition of these two factors affected detrusor contractility in normal bladders, using female Sprague-Dawley rats. Cystometry and Western blot analysis were performed in rats that were subjected to PBOO induction or a sham operation. Cystometry was performed in normal rats that received selective inhibitors of AMPKα and Ca2+/calmodulin-dependent protein kinase kinase (CaMKKß) (compound C and STO-609, respectively) at doses determined in the experiments. In the PBOO bladders, bladder weight and micturition pressure (MP) were higher and AMPKα phosphorylation (T172) and CaMKKß expression was significantly reduced. Compound C and STO-609 increased MP. The increased contractile response in bladders with PBOO-induced hypertrophy was related to decreased CaMKKß/AMPK signaling activity, and the pharmacological inhibition of this pathway in normal bladders increased detrusor contractility, implying a role of CaMKKß/AMPK signaling in the bladder in the regulation of detrusor contractility.

Nonselective blocking of the sympathetic nervous system decreases detrusor overactivity in spontaneously hypertensive rats.

The involuntary dual control systems of the autonomic nervous system (ANS) in the bladder of awake spontaneously hypertensive rats (SHRs) were investigated through simultaneous registrations of intravesical and intraabdominal pressures to observe detrusor overactivity (DO) objectively as a core symptom of an overactive bladder. SHRs (n = 6) showed the features of overactive bladder syndrome during urodynamic study, especially DO during the filling phase. After injection of the nonselective sympathetic blocking agent labetalol, DO disappeared in 3 of 6 SHRs (50%). DO frequency decreased from 0.98 ± 0.22 min(-1) to 0.28 ± 0.19 min(-1) (p < 0.01), and DO pressure decreased from 3.82 ± 0.57 cm H(2)O to 1.90 ± 0.86 cm H(2)O (p < 0.05). This suggests that the DO originating from the overactive parasympathetic nervous system is attenuated by the nonselective blocking of the sympathetic nervous system. The detailed mechanism behind this result is still not known, but parasympathetic overactivity seems to require overactive sympathetic nervous system activity in a kind of balance between these two systems. These findings are consistent with recent clinical findings suggesting that patients with idiopathic overactive bladder may have ANS dysfunction, particularly a sympathetic dysfunction. The search for newer and better drugs than the current anticholinergic drugs as the mainstay for overactive bladder will be fueled by our research on these sympathetic mechanisms. Further studies of this principle are required.

Persistent detrusor overactivity in rats after relief of partial urethral obstruction.

Detrusor overactivity (DO) persists after prostatectomy in 20% to 25% of patients with benign disease. Assuming that nonvoiding contractions (NVCs) can be used as a surrogate for DO in humans, the rat model of obstruction/deobstruction may allow us to study the pathophysiology of persistent DO after deobstruction. We investigated bladder function, with a special focus on NVCs, in rats by use of a new, modified method of obstruction and deobstruction and compared these results with those obtained by use of the conventional method. Seventy female Sprague-Dawley rats underwent 1) sham operation (n = 10), 2) obstruction by a modified method (Modif-Obs; n = 12), 3) obstruction/deobstruction by the conventional method (Conv-Obs/Deobs; n = 13), or 4) obstruction/deobstruction by the modified method (Modif-Obs/Deobs; n = 35). The Modif-Obs/Deobs animals were divided into subgroups with (DO+) and without (DO-) NVCs. Two weeks after partial urethral obstruction, the animals were deobstructed, and 1 wk later cystometry was performed with recording of intravesical and intra-abdominal pressures. NVCs were shown in all groups: Modif-Obs (80%), Conv-Obs/Deobs (100%), and Modif-Obs/Deobs (40%). In the Modif-Obs/Deobs group, bladder weight and the muscle-to-collagen ratio were higher in DO+ than in DO- rats. The Modif-Obs/Deobs group showed no mortality compared with 25% mortality in the Conv-Obs/Deobs group. The modified method may be more adequate for studying persistent DO after deobstruction, because it resulted in pressure/volume- and DO-related parameters similar to those found in the clinical situation. The persistence of DO after deobstruction may partly be due to irreversible changes in the bladder caused during the period of obstruction.

Selection of a control rat for conscious spontaneous hypertensive rats in studies of detrusor overactivity on the basis of measurement of intra-abdominal pressures.

AIMS: We investigated which animal model is appropriate as a control for the spontaneous hypertensive rat (SHR) in studies of detrusor overactivity (DO). METHODS: Age-matched SHRs (n = 10), Wistar-Kyoto (WKY) rats (n = 9), Wistar-ST (Wistar) rats (n = 10), and Sprague-Dawley (SD) rats (n = 10) were studied. A balloon-fitted catheter was positioned in the abdominal cavity to record intra-abdominal pressure (IAP). Cystometric pressure- and volume-related parameters and DO-related ones during the filling phase were investigated. Of the intravesical pressure (IVP) rises above 2 cmH(2)O, DO was defined as a rise in IVP without a simultaneous change in IAP and was counted during the filling phase. RESULTS: Compared with SHRs, the WKY rats did not show a significant difference in pressure or volume parameters, but Wistar rats and SD rats showed a significant increase in volume parameters, such as bladder capacity, micturition volume, and micturition interval. Typical DO was seen in SHRs and WKY rats during the filling phase, but not in Wistar and SD rats. Furthermore, the frequency and increased amplitude of the DO were similar in WKY rats and SHRs. CONCLUSION: Although WKY rats are an appropriate control for SHRs in studies of hypertension, they may be inappropriate as controls in studies of DO, because they have inherent DO of similar frequency and amplitude as found in SHRs.

Flow Starting Point and Voiding Mechanisms Measured by Simultaneous Registrations of Intravesical, Intra-abdominal, and Intraurethral Pressures in Awake Rats.

PURPOSE: The aim of this study was to apply a new surgical procedure that allows for the successful monitoring of intraurethral pressure (IUP) changes in the cystometry of awake Sprague-Dawley rats. METHODS: Twenty-six female Sprague-Dawley rats were grouped according to the catheterization method (bladder only; bladder and urethra; or bladder, urethra, and abdomen). Using an arbitrarily determined initial point of the first phase among four rat micturition phases on the simultaneous curves as a reference point, we compared the time differences to the points on an intravesical pressure (IVP) and those on IUP or a detrusor pressure (DP) curve from intra-abdominal pressure (IAP). RESULTS: In awake rat, the start of urethral flow on IUP curve corresponded to the initial point of the second phase, which is same to the results on the anesthetized rat. However, certain results, such as micturition pressure (MP) and intraluminal pressure high-frequency oscillations (IPHFOs), differed between awake and anesthetized rats. Most MP values were checked after the end of urethral flow on the IUP curve, which is due to the peculiar methodology such as transvesical catheterization. Urethral flow was not completely interrupted during the IPHFOs, which suggests the presence of urethral wall tension against the flow during voiding. After removal of the superimposed effects of IAP from IVP, the DP curve clearly showed a peculiar shape, highlighting the possibility of using IAP in place of IUP to detect the flow starting point on the IVP curve. CONCLUSIONS: Awake rat cystometry results have been interpreted based on those in anesthetized rats. However, our awake cystometry data were substantially different in terms of voiding time compared to those of anesthetized rats. This discovery warrants careful interpretation of the voiding parameters in awake rat cystometry.

Mast cell activation and response to tolterodine in the rat urinary bladder in a chronic model of intravesical protamine sulfate and bacterial endotoxin-induced cystitis.

The aim of the present study was to use an animal model of interstitial cystitis (IC) in order to investigate the histology and function of the bladder, with a particular focus on mast cell degranulation and response to detrusor overactivity (DO) to tolterodine. A total of 18 female Sprague­Dawley rats were used. In 12 rats, lipopolysaccharide (LPS) was intravesically instilled following the induction of IC by protamine sulfate (PS) and six rats were subjected to sham instillations. Following 1 month, cystometry was performed. The effects of tolterodine were tested in half of the animals with IC. All rats in the IC group demonstrated DO during the filling phase and no significant changes in the frequency or pressure compared with that following tolterodine injection were identified. Histological examination revealed a significant increase in the total number of infiltrated mast cells in IC rats compared with that in the sham rats (P<0.05). Degranulated mast cells were evident in 80% of rats with IC; however, they were not apparent in the sham rats. Urinary bladder inflammation, similar to that in human IC in terms of degranulated mast cells and bladder function, was induced in rats. The animal model used in the present study provided insight into the pathophysiological mechanisms underlying the ineffectiveness of anticholinergics in patients with overlapping IC and overactive bladder (OAB).

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 signal­regulated 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.

Transvaginal cystocele repair by purse-string technique reinforced with three simple sutures: surgical technique and results.

PURPOSE: Different techniques for cystocele repair including the conventional anterior colporrhaphy and mesh technique are known. Our goal was to evaluate the anatomical success and safety of our method of transvaginal anterior vaginal wall repair by the purse-string technique reinforced with three simple additional sutures in the repair of cystocele over a 4-year follow-up period. METHODS: This was a retrospective review of 69 consecutive patients (grades 2 to 4) who underwent the above operations between 2001 and 2011, including their success rates as assessed by use of the Baden-Walker halfway classification system. RESULTS: Of the patients, 62 patients (98%) were completely cured of cystocele and 1 patient showed grade 2 cystocele recurrence that required no further treatment. Two patients with grade 4 cystocele were completely cured. There was no vaginal erosion related to the cystocele repair. CONCLUSIONS: Transvaginal anterior colporrhaphy by a purse-string technique reinforced with simple additive sutures appears to be a simple, safe, and easily performed approach in cystocele repair. There is no need for other material for reinforcement, even in high-grade cystocele, which is an advantage of our technique.

Time-related changes in detrusor overactivity in awake rats with spinal cord injury observed by simultaneous registrations of intravesical and intraabdominal pressures.

PURPOSE: To compare the physical characteristics of detrusor overactivity (DO) induced by intravesical infusion of saline in awake, sham rats and rats with chronic spinal cord injury (SCI), by simultaneous registrations of intravesical and intraabdominal pressures. METHODS: Male Sprague-Dawley rats, normal or with a spinal vascular clip at the level of Th9, were investigated cystometrically 1 and 4 weeks after SCI. Intravesical pressure (IVP) and intraabdominal pressure (IAP) were recorded simultaneously to evaluate true DO. During the filling phase, the event of IVP rises, defined as increments that exceeded 2 cmH(2)O from baseline, were determined as DO according to the absence of simultaneous changes in IAP. RESULTS: All SCI rats exhibited DO during the filling phase, which was not shown in sham rats. The frequency and pressure of DO had a tendency to decrease with time. The DO frequency of SCI rats after 4 weeks (0.9±0.2 min(-1)) was decreased compared with that after 1 week (2.1±0.4 min(-1); P<0.05). The DO pressure of SCI rats after 4 weeks (8.4±1.9 cmH(2)O) was decreased compared with that after 1 week (11.6±2.9 cmH(2)O; P>0.05). CONCLUSIONS: Cystometric studies in awake male SCI rats showed some significant changes in bladder function after SCI. All SCI rats exhibited DO during the filling phase, and showed different physical characteristics of DO over the course of time. The neurological basis of these time-related changes remains poorly understood, but may provide important prognostic information about long-term urological management in SCI patients.

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.

Development and changes with age of detrusor overactivity in spontaneous hypertensive rats as observed by simultaneous registrations of intravesical and intraabdominal pressures.

PURPOSE: Overactive bladder is especially common in the elderly, although it is not regarded as a normal part of aging. Thus, we investigated how aging alters the cystometric and detrusor overactivity (DO) parameters and the density of nerve growth factor (NGF) in awake spontaneous hypertensive rats (SHRs) of different ages. METHODS: Three age groups of 12- (n=5), 17- (n=6), and 21- (n=6) week-old SHRs (Oriental Bio Inc.) were used. A catheter was implanted into the bladder to record the intravesical pressure (IVP), and a balloon-fitted catheter was positioned in the abdominal cavity to record the intraabdominal pressure (IAP). Of the IVP elevations above 2 cm H(2)O, DO was defined as a rise in IVP without a simultaneous change in IAP and was counted during the filling phase. We measured the expression of NGF in the bladders by enzyme-linked immunosorbent assay. RESULTS: Both the body and bladder weights significantly increased with age, but the normalized ratio between those was not changed. As for DO, none of the12-week-old rats showed DO, whereas the other groups did. DO increased significantly with age (P=0.0045 by Mantel-Haenszel trend test), although no significant differences were found in DO frequency or pressure between the 17- and 21-week-old age groups. NGF did not show any significant differences among the three groups. CONCLUSIONS: Our results showed that SHRs begin to shows DO after a certain age, such as 12 weeks of age, and that the occurrence of DO has a close relationship with aging. However, NGF, which is known to be increased in the bladder wall of patients with overactive bladder, did not show any relationship with aging in this study.

Dissimilar effects of tolterodine on detrusor overactivity in awake rats with chemical cystitis and partial bladder outlet obstruction.

PURPOSE: We investigated bladder function, with a special focus on nonvoiding contractions (NVCs), in awake rats with chronic chemical cystitis and bladder outlet obstruction (BOO) by use of simultaneous registrations of intravesical and intraabdominal pressures. In addition, we tested the effects of tolterodine on the NVCs in these models. METHODS: A total of 20 female Sprague-Dawley rats were used in this study. In eight rats, chemical cystitis was induced by intravesical instillation of HCl. Twelve rats were subjected to sham instillations or partial BOO. Four weeks after intravesical instillation or 2 weeks after partial BOO, cystometrograms were obtained by use of simultaneous recording of intravesical and intraabdominal pressure in all unanesthetized, unrestrained rats in metabolic cages. RESULTS: A total of 17 rats survived. In the rats with acute injury by HCl, 50% showed detrusor overactivity (DO), which was not seen in the sham group. The cystitis group had lower DO pressure without a difference in DO frequency compared with the BOO group. After the administration of tolterodine, the cystitis group showed no difference in DO frequency or pressure, whereas the BOO group showed decreased values for both parameters. CONCLUSIONS: Our study showed that toleterodine produced no effect on DO during the filling phase in rats with chronic chemical cystitisbut decreased the frequency and pressure of DO in rats with BOO. Clinically, studies are needed to improve the treatment effect of anticholinergic drugs ininterstitial cystitis patients with overactive bladder.

Urodynamic findings in an awake chemical cystitis rat model observed by simultaneous registrations of intravesical and intraabdominal pressures.

PURPOSE: The aim of this study was to investigate the effect of urinary bladder inflammation on bladder function in a rat chemical cystitis model. We also histologically confirmed the effects of inflammation in the detrusor on chronically inflamed bladder in rats. MATERIALS AND METHODS: A total of 13 female Sprague-Dawley rats were used in this study. In seven rats, intravesical instillation of HCl induced chemical cystitis, and the other rats with intravesical instillation of saline were used as the sham. After 2 weeks, cystometrograms were obtained with additional intraabdominal pressure measurements in all unanesthetized, unrestrained rats in metabolic cages. The rats were killed just after cystometry. The bladders were removed and examined histologically for mast cells and inflammatory changes. RESULTS: The rats with acute injury by HCl showed no differences in pressure parameters, including basal pressure, threshold pressure, and maximum bladder pressure, compared with the sham rats. They showed significantly increased bladder capacity, micturition volume, residual volume, and micturition interval compared with the sham group. They also showed an increased frequency of detrusor overactivity compared with the sham group. The percent of detrusor overactivity was 56.3% among the total intravesical pressure rises above 2 cmH(2)O. The histological findings of the rats with acute injury by HCl were consistent with chemical cystitis. CONCLUSIONS: Overlapping patterns of lower urinary tract symptoms and pelvic pain are common disease characteristics among interstitial cystitis patients. The situation in an animal model of interstitial cystitis is similar, as observed in this study by the histologic and awake cystometric examinations. However, the interstitial cystitis model showed detrusor overactivity during the filling phase without a decrease in bladder capacity and micturition intervals, which differs from the characteristics of overactive bladder patients.

Intravesical PGE2 Administration in Conscious Rats as an Experimental Model of Detrusor Overactivity Observed by Simultaneous Registrations of Intravesical and Intraabdominal Pressures.

PURPOSE: The urodynamic effects of intravesical PGE2 instillation on bladder function and detrusor overactivity (DO) during the filling phase were investigated in rats by measuring intraabdominal and intravesical pressures simultaneously. MATERIALS AND METHODS: Continuous cystometry was performed inconscious, female and male Sprague- Dawley rats. We investigated pressure-, volume-, and DO-related parameters. RESULTS: Intravesical instillation of PGE2 increased all pressure-related parameters and decreased volume-related ones, compared to the control cystometric ones. However, among the total number of intravesical pressure rises (IVPRs) above 2 cmH(2)O during the filling phase, only 33% in female rats and 38% in male rats after PGE2 instillation were identified as true DO during the filling phase. CONCLUSIONS: Our findings suggest that the rat model with intravesical PGE2 is inappropriate for observing the effects of some drugs or mechanisms on DO, because only approximately 30% of IVPRs were confirmed as true DO. However, this model of intravesical PGE2 instillation has some advantages for the observation of changes in pressure and volume parameters rather than in DO-related ones.

Urodynamic Effects of Propiverine on Detrusor Overactivity and Abdominal Straining during Voiding in Awake Rats with Intravesical Prostaglandin E(2) Instillation.

PURPOSE: We investigated the effect of propiverine on cystometric parameters based on intraabdominal pressure (IAP) in awake rats in an overactive bladder (OAB) model induced by intravesical instillation of prostaglandin E(2) (PGE(2)). MATERIALS AND METHODS: Twenty-two female Sprague-Dawley rats were used. Polyethylene catheters were implanted into the bladder to record the intravesical pressure (IVP) and into the femoral artery to administer medication. A balloon-fitted catheter was positioned in the abdominal cavity to record the IAP. Awake cystometries were performed before and after intraarterial administration of propiverine 1 mg/kg (n=6), intravesical administration of 50microM PGE(2) only (n=6), or intravesical PGE(2) plus 1 mg/kg (n=4) or 3 mg/kg (n=6) of intraarterial propiverine. Cystometric pressure and volume parameters and variables related to detrusor overactivity (DO) were investigated. RESULTS: Rats administered intravesical PGE(2) showed increased pressure parameters and decreased volume parameters comparable to the DO model, which was effectively prevented by propiverine (1 or 3 mg/kg). Typical DO shown during the filling phase was decreased by intraarterial propiverine (3 mg/kg) injection. After propiverine (3 mg/kg) injection, IAP was increased at the time of micturition pressure with or without threshold pressure (p<0.05, p<0.01) depending on the dose administered. CONCLUSIONS: Propiverine improved pressure- and volume-related parameters in an OAB model. Furthermore, it also decreased the frequency of DO. However, higher concentrations of propiverine induced straining voiding.

Substantial detrusor overactivity in conscious spontaneously hypertensive rats with hyperactive behaviour.

OBJECTIVE: The spontaneously hypertensive rat (SHR) is a useful model for studying the mechanisms of detrusor overactivity (DO). However, owing to their confounding phenotypic characteristics of hyperactive behaviour, there could be some problems with the interpretation of cystometric data, which is significantly confused by abdominal straining (AS), causing changes in intravesical pressure (IVP). MATERIAL AND METHODS: IVP and intra-abdominal pressure (IAP) were recorded simultaneously to evaluate true DO in conscious healthy male SHRs and Wistar/ST (Wistar) rats. Intravesical pressure rises (IVPRs), defined as increments that exceeded 2 cmH(2)O from baseline, were counted, and those that were caused by AS or DO were determined according to the presence of simultaneous changes in IAP. RESULTS: Compared with Wistar rats, SHRs had a shorter filling phase (p<0.01) and greater frequency of IVPRs (p<0.01). SHRs, but not Wistar rats, showed DO. The substantial DO represented up to 76% of total IVPRs, with the remainder caused by AS. The amplitude (p<0.05) but not the frequency of AS (p>0.05), was higher in SHR than Wistar rats. CONCLUSION: In conscious SHRs, variations in IAP due to hyperactive behaviour may cause misinterpretation of pressure parameters and result in false reports of DO. Thus, simultaneous registration of IAP and IVP is needed for accurate recording of substantial DO in these animals.