Peak Bladder Pressures Research Articles

Urinary dysfunction after spinal cord injury: Comparing outcomes after thoracic spinal transection and contusion in the rat

Spinal cord injury (SCI) above the lumbosacral spinal cord induces loss of voluntary control over micturition. Spinal cord transection (SCT) was the gold standard method to reproduce SCI in rodents, but its translational value is arguable and other experimental SCI methods need to be better investigated, including spinal cord contusion (SCC). At present, it is not fully investigated if urinary impairments arising after transection and contusion are comparable. To explore this, we studied bladder-reflex activity and lower urinary tract (LUT) and spinal cord innervation after SCT and different severities of SCC. Severe-contusion animals presented a longer spinal shock period and the tendency for higher residual volumes, followed by SCT and mild-contusion animals. Urodynamics showed that SCT animals presented higher basal and peak bladder pressures. Immunostaining against growth-associated protein-43 (GAP43) and calcitonin gene-related peptide (CGRP) at the lumbosacral spinal cord demonstrated that afferent sprouting is dependent on the injury model, reflecting the severity of the lesion, with a higher expression in SCT animals. In LUT organs, the expression of GAP43, CGRP cholinergic (vesicular acetylcholine transporter (VAChT)) and noradrenergic (tyrosine hydroxylase (TH)) markers was reduced after SCI in the LUT and lumbosacral cord, but only the lumbosacral expression of VAChT was dependent on the injury model. Overall, our findings demonstrate that changes in LUT innervation and function after contusion and transection are similar but result from distinct neuroplastic processes at the lumbosacral spinal cord. This may impact the development of new therapeutic options for urinary impairment arising after spinal cord insult.

Exosomes isolated from TNF-α-treated bone marrow mesenchymal stem cells ameliorate pelvic floor dysfunction in rats.

Exosomes derived from bone marrow-derived mesenchymal stem cells (BMSCs) can alleviate the symptoms of pelvic floor dysfunction (PFD) in rats. However, the potential therapeutical effects of exosomes derived from BMSCs treated with tumour necrosis factor (TNF)-α on the symptoms of PFD in rats are unknown. Exosomes extracted from BMSCs treated with or without TNF-α were applied to treat PFD rats. Our findings revealed a significant elevation in interleukin (IL)-6 and TNF-α, and matrix metalloproteinase-2 (MMP2) levels in the vaginal wall tissues of patients with pelvic organ prolapse (POP) compared with the control group. Daily administration of exosomes derived from BMSCs, treated either with or without TNF-α (referred to as Exo and TNF-Exo), resulted in increased void volume and bladder void pressure, along with reduced peak bladder pressure and leak point pressure in PFD rats. Notably, TNF-Exo treatment demonstrated superior efficacy in restoring void volume, bladder void pressure and the mentioned parameters compared with Exo treatment. Importantly, TNF-Exo exhibited greater potency than Exo in restoring the levels of multiple proteins (Elastin, Collagen I, Collagen III, IL-6, TNF-α and MMP2) in the anterior vaginal walls of PFD rats. The application of exosomes derived from TNF-α-treated BMSCs holds promise as a novel therapeutic approach for treating PFD.

Colorectal and bladder prokinetic activity of [Lys5, MeLeu9, Nle10]-NKA(4-10) after intranasal or sublingual delivery in dogs.

The feasibility of eliciting defecation and urination after intranasal (IN) or sublingual (SL) delivery of a small peptide NK2 receptor agonist, [Lys5, MeLeu9, Nle10]-NKA(4-10), was examined using prototype formulations in dogs. In anesthetized animals, administration of 100 or 300 µg/kg IN or 2.0-6.7 mg/kg SL increased colorectal peak pressure and area under the curve. Peak bladder pressure was also increased at the same doses, and this was accompanied by highly efficient voiding at normal physiological bladder pressure. The onset of these effects was rapid (≤2.5 min), and the primary contractions lasted ∼25 min, returning to baseline in <60 min. Slight hypotension lasting a few minutes and causing<10% change from baseline was detected after higher doses and was statistically significant after only 100 µg/kg IN. In conscious dogs, there was a dose-related increase in voiding responses and reduction in the latency to urinate and defecate after 300 and 1000 µg/kg IN; emesis was also observed at these doses. SL administration of 6.7 mg/kg induced urination within 10 min, but not defecation or emesis. These findings support the feasibility of developing a convenient dosage form of small peptide NK2 receptor agonists as on-demand defecation or urination therapies.

Exosomes Derived from miR‐195‐5p Transfected Bone Marrow Mesenchymal Stem Cells Alleviate Pelvic Floor Dysfunction in Rats

AbstractBone marrow‐derived mesenchymal stem cells (BMSCs) can alleviate pelvic floor dysfunction (PFD) in rats. Whether exosomes derived from miR‐195‐5p transfected BMSCs can alleviate PFD is investigated. The rat vaginal distention model is constructed to mimic PFD. miR‐195‐5p is transfected into BMSCs, and exosomes derived from miR‐195‐5p transfected BMSCs are injected into PFD rats via caudal veins. Luciferase reporter assay is performed to confirm the direct interaction between SMAD7 3′‐UTR and miR‐195‐5p mimics. Void volume, bladder void pressure, leak point pressure, and peak bladder pressure are used to evaluate urodynamic function. It is found that miR‐195‐5p directly targets Smad7 and regulates the relative Smad7 expression in rat BMSCs. Exosomes derived from miR‐195‐5p transfected BMSCs can improve urodynamic function than exosomes derived from BMSCs. On the other hand, exosomes derived from miR‐195‐5p transfected BMSCs inhibit the expressions of Smad7 but promote the expressions of elastin in PFD rats with diminished expression of MMP2 and MMP9. This study demonstrates that exosomes derived from miR‐195‐5p genetically engineered BMSCs can target the Tgf‐β/Smad7 pathway to repair connective tissues and restore damaged urodynamic function in PFD rats.

Human primary muscle stem cells regenerate injured urethral sphincter in athymic rats.

BackgroundThe aim of the study was to demonstrate the efficacy of human muscle stem cells (MuSCs) isolated using innovative technology in restoring internal urinary sphincter function in a preclinical animal model.MethodsColonies of pure human MuSCs were obtained from muscle biopsy specimens. Athymic rats were subjected to internal urethral sphincter damage by electrocauterization. Five days after injury, 2 × 105 muscle stem cells or medium as control were injected into the area of sphincter damage (n = 5 in each group). Peak bladder pressure and rise in pressure were chosen as outcome measures. To repeatedly obtain the necessary pressure values, telemetry sensors had been implanted into the rat bladders 10 days prior to injury.ResultsThere was a highly significant improvement in the ability to build up peak pressure as well as a pressure rise in animals that had received muscle stem cells as compared to control (p = 0.007) 3 weeks after the cells had been injected. Only minimal histologic evidence of scarring was observed in treated rats.ConclusionPrimary human muscle stem cells obtained using innovative technology functionally restore internal urethral sphincter function after injury. Translation into use in clinical settings is foreseeable.

Serial transurethral cystometry: A novel method for longitudinal evaluation of reflex lower urinary tract function in adult female rats.

AimsThe aim of the study is to develop a minimally invasive method for longitudinal evaluation of lower urinary tract function that allows for simultaneous measurements of bladder pressure and external urethral sphincter (EUS) electromyographic (EMG) activity.MethodsTo evaluate the reliability of serial transurethral cystometry (STUC), rats (n = 12) underwent three sessions of STUC, one session a week for 3 weeks. During each session, rats were anesthetized with ketamine–xylazine (90 mg/kg and 10 mg/kg), and micturition reflex data were acquired using transurethral cystometry and percutaneous recording of EUS (EMG) activity during continuous infusion of saline into the bladder. The reliability and consistency of the STUC method were assessed using intra‐class correlation (ICC) analysis and repeated measures ANOVA.ResultsICC values calculated from five successive events during the first micturition session indicate good to excellent reliability for measurements of peak bladder pressure, threshold bladder pressure, minimum bladder pressure, volume threshold, duration of EUS bursting, and number of EUS burst events. Across the three recording sessions no significant difference was observed in peak bladder pressure, threshold bladder pressure, minimum bladder pressure, volume threshold, number of EUS burst events, and duration of EUS bursting using repeated measures ANOVA.ConclusionSerial transurethral cystometry under ketamine–xylazine anesthesia with simultaneous percutaneous EUS EMG recording is a novel, reliable, accurate, and minimally invasive method for quantitative assessment of lower urinary tract (LUT) function in adult female rats over extended periods of time.

Transurethral versus suprapubic catheterization to test urethral function in rats

Transurethral and suprapubic catheterization have both been used to test urethral function in rats; however, it is unknown whether these methods affect urethral function or if the order of catheterization affects the results. The aim of this cross-over designed experiment was to compare the effects of catheterization methods and order on leak point pressure (LPP) testing. LPP and simultaneous external urethral sphincter electromyography (EUS EMG) were recorded in anesthetized female virgin Sprague-Dawley rats in a cross-over design to test the effects of transurethral and suprapubic catheterization. There was no significant difference in peak bladder pressure during LPP testing whether measured with a transurethral or suprapubic catheter. There was no significant difference in peak bladder pressure between the first and second catheter insertions. However, peak EMG firing rate, as well as peak EMG amplitude and EMG amplitude difference between peak and baseline were significantly higher after the first catheter insertion compared to the second insertion, regardless of the catheter method. Our results suggest that route of catheterization does not alter urethral function, e.g. create a functional partial outlet obstruction. Either catheterization method could be used for LPP and/or EUS EMG testing in rats.

The serotonin (5-hydroxytryptamine) 5-HT7 receptor is up-regulated in Onuf's nucleus in rats with chronic spinal cord injury.

To examine the effect of intrathecal (i.t.) serotonin (5-hydroxytryptamine) 5-HT7 agonist administration on voiding function in the urethane-anesthetised rat, and the change in 5-HT7 receptor (5-HT7 R) expression in the lumbosacral cord Onuf's nucleus after spinal cord injury (SCI). In all, 32 female Sprague-Dawley (SD) rats were equally divided into a spinally intact (SI) group and SCI group (n=16 each). At 8weeks after transection, half of the rats underwent continuous cystometry under urethane anaesthesia, and the 5-HT7 R-selective agonist LP44 was given (i.t.). The remaining rats were used for pseudorabies (PRV) retrograde tracing, immunofluorescence, and Western Blot. LP44 administered i.t. had no effect in the SI rats. In SCI rats, LP44 (1-30μg/kg) induced significant dose-dependent increases in micturition volume, voiding efficiency, number of high-frequency oscillations per micturition; and decreases in residual volume, bladder capacity, peak bladder pressure, threshold pressure and non-voiding contractions. The 5-HT7 R antagonist, SB-269970 (10μg/kg), partially reversed LP44-induced changes. Using PRV retrograde tracing and immunofluorescence, 5-HT7 Rs were found in the L6-S1 spinal cord Onuf's nucleus in both SI and SCI rats, but the expression was significantly greater in the SCI rats. Western blot showed significantly more 5-HT7 Rs in the ventral L6-S1 spinal cord in SCI rats. A 5-HT7 R agonist, given i.t., improved voiding efficiency in urethane-anesthetised SCI rats, and the 5-HT7 R was significantly up-regulated in the lumbosacral cord Onuf's nucleus. If valid for humans, these findings suggest that the 5-HT7 R could be a target for therapeutic interventions.

Acute hypoxia alters reflex micturition behavior in urethane‐anesthetized carotid sinus intact and denervated adult female Sprague‐Dawley rat

Acute hypoxia is well known to increase respiratory drive by stimulating peripheral chemoreceptors located in the carotid bodies. Ongoing work in our laboratory has been examining the effects acute hypoxia on lower urinary tract (LUT) function in urethane‐anesthetized adult female rats. While these experiments have revealed that exposure to acute hypoxia is capable of modifying LUT function, the contribution of peripheral chemoreceptor‐mediated effects is unknown. Moreover, hypoxia‐induced modulation of LUT behavior is present both during hypoxia and transiently after the hypoxic stimulus is removed, such that hypoxia increases void frequency while the return to normoxia increases the threshold bladder pressure for voiding and prolongs the inter‐contraction interval (ICI). The present study was designed to evaluate whether the changes in LUT function noted are mediated by mechanisms that are dependent on carotid body hypoxia chemoreception. To this end, we conducted a series of experiments using continuous flow bladder cystometry with simultaneous recording of external urethral sphincter (EUS) EMG activity in urethane‐anesthetized spontaneously breathing adult female Sprague‐Dawley rats (n=10). Micturition events were elicited by saline infusion into the bladder via suprapubic catheter with the saline flow rate adjusted to induce a voiding frequency of approximately one void every 4–5 minutes. We also simultaneously recorded tongue, external oblique, and diaphragm muscle EMG activity via bipolar stainless steel EMG electrodes. Each rat was allowed to settle into a stable baseline voiding rhythm which was then recorded for approximately 1‐hr under normoxic conditions, after which an hypoxic challenge (12% O2, 15 min) was performed. In one group of rats, the carotid sinus nerves (CSN) were transected bilaterally prior to beginning the cytometry experiment while in a second group of rats the CSN were left intact. Success of the CSN denervation was confirmed by the absence of an increase in diaphragm EMG burst amplitude and frequency during the hypoxic challenge. Consistent with our prior observations, CSN intact rats responded to hypoxia with an increased voiding frequency, particularly at the onset of hypoxia; however, peak bladder pressure during contraction was variable with no consistent modulation by hypoxia. Upon return to normoxia, the initial voiding event was delayed, and subsequent events displayed increased ICI with elevated bladder pressure threshold. In contrast to CSN intact rats, CSN denervated rats exhibited a marked decrease in peak bladder contraction pressure during hypoxic exposure as well as a smaller increase in bladder pressure threshold after return to normoxia. No notable differences in hypoxia‐induced changes in ICI between CSN intact or transected rats was observed. These results suggest that hypoxia‐mediated carotid body afferent input is not required for producing a modulation of reflex micturition in response to hypoxia, but certain aspects of the hypoxic response may be impacted by carotid body dependent mechanisms.Support or Funding InformationNIH NS096514This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

PD36-01 THE 5-HT7 RECEPTOR IS UP-REGULATED IN ONUF'S NUCLEUC

You have accessJournal of UrologyUrodynamics/Lower Urinary Tract Dysfunction/Female Pelvic Medicine: Neurogenic Voiding Dysfunction II1 Apr 2018PD36-01 THE 5-HT7 RECEPTOR IS UP-REGULATED IN ONUF'S NUCLEUC Jianshu Ni, Baojun Gu, nailong cao, and xiaohu wang Jianshu NiJianshu Ni More articles by this author , Baojun GuBaojun Gu More articles by this author , nailong caonailong cao More articles by this author , and xiaohu wangxiaohu wang More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2018.02.1724AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES It was previously reported that a 5-HT7 agonist, given intravenously, could enhance external urethral sphincter (EUS) activity and improve voiding efficiency after spinal cord injury (SCI). The present study examined the effect of intrathecal 5-HT7 agonist administration on voiding function, and the change of 5-HT7 receptor expression in lumbosacral cord Onuf's nucleus after SCI. METHODS Thirty-two female SD rats were divided into spinally intact (SI) group and SCI group (n=16 each). Eight weeks after transection, half of the rats underwent continuous cystometry under urethane anesthetization, and the 5-HT7 selective agonist LP44 was given intrathecally. Half of the remaining rats were used for pseudorabies (PRV) retrograde tracing, immunofluorescence (IF) and Western Blot. RESULTS Intrathecally administered LP44 had no effect in spinally intact (SI) rats. In SCI rats, LP44 (1-30 ug/kg) induced significant dose-dependent increases in micturition volume, voiding efficiency, number of high-frequency oscillation (HFO) per micturition, and decrease in residual volume, bladder capacity, and peak bladder pressure. The 5-HT7 receptors antagonist, SB-269970 (10 ug/kg), partially reversed LP44-induced changes. By PRV retrograde tracing and IF, 5-HT7 receptors were demonstrated in L6-S1 spinal cord Onuf's nucleus in both SI and SCI rats, but the expression was significantly stronger in SCI rats. Western blot showed a significant increase of 5-HT7 receptors in ventral L6-S1 spinal cord in SCI rats. CONCLUSIONS A 5-HT7 agonist, given intrathecally, improved voiding efficiency in SCI rats, and the 5-HT7 receptor was significantly up-regulated in lumbosacral cord Onuf's nucleus. © 2018FiguresReferencesRelatedDetails Volume 199Issue 4SApril 2018Page: e726 Advertisement Copyright & Permissions© 2018MetricsAuthor Information Jianshu Ni More articles by this author Baojun Gu More articles by this author nailong cao More articles by this author xiaohu wang More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Inducible Loss Of Integrin β1 From Bladder Smooth Muscle Causes Increased Voiding Frequency And Impaired Muscarinic Contractility

Integrins are integral membrane proteins which, in dynamic ways, physically link, the actin cytoskeleton to the extracellular matrix. They exhibit broad functional diversity and are involved in cellular differentiation, adhesion, proliferation and mechanotransduction. Diabetic bladder dysfunction (DBD) is a very common progressive complication of diabetes mellitus resulting in overactivity during the early compensatory phase and ultimately in an atonic bladder which is unable to empty properly. Both genomic and proteomic approaches focused on bladder smooth muscle (BSM) have demonstrated altered expression of cell adhesion proteins and extracellular matrix as well as compromised contractility, as molecular markers of DBD. To begin to understand the role of cell adhesion and mechanosensitive signaling in BSM we created a mouse with tamoxifen (TMX) inducible, smooth muscle‐conditional deletion of β1‐integrin using Cre‐lox (Txβ1‐cKO). Loss of β1‐integrin mRNA and protein following TMX induction by i.p. injection (5 × 2 mg on consecutive days) were confirmed by PCR and Western blotting. Void‐spotting assays on filter paper revealed a progressive increase in number of voids from 2.5/4 h to 8.3/4 h over a period of 60 days following Cre‐induction (n=5 mice/group, P&lt;0.05). Littermate controls injected with vehicle (no TMX) showed no change. The mean volume/void decreased from 264 μl to 158 μl over 60 days in the integrin knockouts. An increase in the number of voids with reduced volume/void is often taken to indicate some form of overactivity. Urodynamic measurements using cystometry under anesthesia, revealed significantly reduced peak bladder pressures during voiding (20 cmH2O vs. 26 cmH2O, P&lt;0.05), reduced intercontraction interval (44 s vs. 249 s, P&lt;0.01), and reduced compliance (17 s/cmH2O vs. 68 s/cmH2O, N.S.) in TMX injected vs. control mice. Thus, in vivo voiding frequency was dramatically increased at the same time as the bladders showed increased resistance to filling and lower expulsive pressures. Urothelium dissected muscle‐strip force measurements by myography revealed a significant loss of contractile force in integrin‐deficient bladders in response to electrical field stimulation (45% and 62% mean reductions at 25 and 60 days post Cre‐induction respectively, for stimulation frequencies of 1 – 50 Hz). Selective inhibition of the muscarinic force component by incubation of strips with 0.5 μM atropine, indicated that muscarinic contractility was severely inhibited in integrin‐deficient BSM (17.2% of force generation was due to muscarinic receptors compared to 50% in controls) while purinergic contractility was largely intact. Masson trichrome staining of paraffin embedded bladder sections revealed a substantial expansion of collagenous connective tissue in BSM and disruption to close packing of smooth muscle bundles. We conclude that β1‐integrin is necessary for BSM structural integrity and for muscarinic signaling during force generation. These findings begin to offer insights into the physiological role of integrin mechanical signaling in BSM and may be relevant to certain bladder pathologies in which integrin expression levels have been shown to be dysregulated.Support or Funding InformationSupport for this work was provided by NIH grants DK‐083299 and DK‐095922.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Serotonergic 5-HT1A receptor agonist (8-OH-DPAT) ameliorates impaired micturition reflexes in a chronic ventral root avulsion model of incomplete cauda equina/conus medullaris injury

Trauma to the thoracolumbar spine commonly results in injuries to the cauda equina and the lumbosacral portion of the spinal cord. Both complete and partial injury syndromes may follow. Here, we tested the hypothesis that serotonergic modulation may improve voiding function after an incomplete cauda equina/conus medullaris injury. For this purpose, we used a unilateral L5–S2 ventral root avulsion (VRA) injury model in the rat to mimic a partial lesion to the cauda equina and conus medullaris. Compared to a sham-operated series, comprehensive urodynamic studies demonstrated a markedly reduced voiding efficiency at 12weeks after the VRA injury. Detailed cystometrogram studies showed injury-induced decreased peak bladder pressures indicative of reduced contractile properties. Concurrent external urethral sphincter (EUS) electromyography demonstrated shortened burst and prolonged silent periods associated with the elimination phase. Next, a 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT), was administered intravenously at 12weeks after the unilateral L5–S2 VRA injury. Both voiding efficiency and maximum intravesical pressure were significantly improved by 8-OH-DPAT (0.3–1.0mg/kg). 8-OH-DPAT also enhanced the amplitude of EUS tonic and bursting activity as well as duration of EUS bursting and silent period during EUS bursting. The results indicate that 8-OH-DPAT improves voiding efficiency and enhances EUS bursting in rats with unilateral VRA injury. We conclude that serotonergic modulation of the 5-HT1A receptor may represent a new strategy to improve lower urinary tract function after incomplete cauda equina/conus medullaris injuries in experimental studies.

Evaluation of Bipolar Permaloc™ Electrodes for Direct Bladder Stimulation

Purpose: A bladder control system for spinal cord injured (SCI) patients is needed that can be implanted with minimally invasive methods. New Permaloc bipolar electrodes consisting of 6 mm helical, wire, stimulating surfaces separated by 3 mm and a polypropylene securing barb (Synapse Biomedical Inc) were developed for this application. They are implanted on the bladder wall with a 16 gauge needle, a minimally invasive method. Methods: Seven swines were anesthetized, the lower urinary tract exposed and instrumented with pressure transducers. Four Permaloc TM electrodes were implanted following identification of effective bladder wall stimulation sites next to the ureters and dorsal neurovascular bundle. Bladder stimulation to induce high pressures was conducted at 40 Hz, 400 � s pulses, 5 s stimulation periods and a high stimulating current of 40 mA. Results: At the high stimulating current peak bladder pressures were low, ranging from 12±2 to15±3 cm H20, insufficient to induce urination. Urethral sphincter contractions occurred during high bladder pressure. A spinal reflex role for high sphincter pressures during stimulation was shown by similar high pressures recorded during a bladder squeeze test without stimulation. Conclusions: Stimulation with Permaloc TM bipolar electrodes at high currents produced insufficient bladder pressures for urination. Further modifications of the electrode such as greater separation of the bipolar stimulating surfaces or changes in the testing methods such as alternative animal models are needed to induce high bladder pressures without side effects.

The effect of Pueraria mirifica on cytologic and urodynamic findings in ovariectomized rats

To evaluate the effect of Pueraria mirifica on vaginal and urethral cytology, bladder pressure and capacity, residual urine, and leak point pressure in ovariectomized rats. Seventy-two adult, ovariectomized, female Sprague-Dawley rats were placed into one of four groups: control, estradiol, or 100 or 1,000 mg/kg of Pueraria mirifica (PM-100 and PM-1000, respectively). The vaginal and urethral smears were checked after 30 days of ovariectomy at pretreatment and at day 28 of treatment.A single cystometry, defined as the micturition interval, filling pressure, threshold pressure, micturition pressure, and voided volume, was performed. Peak bladder pressure was calculated for each leak point pressure measured at half bladder capacity by slowly and manually increasing abdominal pressure until a leak occurred, at which point external pressure was rapidly released. Leak point pressure was tested three times per rat. After 28 days of treatment, the estradiol, PM-100, and PM-1000 groups had significantly higher numbers of vaginal and urethral superficial cells compared with the control group (P < 0.05). Regarding the urodynamic parameters, the threshold pressure, micturition pressure, and leak point pressure were higher in the estradiol, PM-100, and PM-1000 groups compared with the control group (P < 0.05). The control, PM-100, and PM-1000 groups had the same values for micturition interval, bladder capacity, voided volume, and residual volume (P > 0.05) but lower values compared with the estradiol group (P < 0.05). Pueraria mirifica 100 and 1,000 mg/kg/day showed an estrogen-like effect on the vaginal and urethral epithelium of ovariectomized rats. They did not change bladder capacity and residual urine volume but increased leak point pressure according to urodynamic study.

Effects of vaginal distension on urethral anatomy and function.

To determine the effect of repeated and prolonged vaginal distension on the leak-point pressure (LPP) and urethral anatomy in the female rat, as prolonged vaginal distension has been clinically correlated with signs of stress urinary incontinence (SUI). Sixty female rats were placed into one of five groups; four groups underwent one of four vaginal distension protocols using a modified 10 F Foley catheter, i.e. prolonged (1 h), brief (0.5 h), intermittent (cycling inflated/deflated for 0.5 h) or sham distension. All animals had a suprapubic bladder catheter implanted 2 days after and were assessed urodynamically 4 days after vaginal distension. The fifth group of rats acted as controls and did not undergo vaginal distension, but did have a suprapubic bladder catheter placed and urodynamics assessed. To measure LPP the rats were anaesthetized with urethane, placed supine and the bladder filled with saline (5 mL/h) while bladder pressure was measured via the bladder catheter. LPPs were measured three times in each animal by manually increasing the abdominal pressure until leakage at the urethral meatus, when the external abdominal pressure was rapidly released. Peak bladder pressure was taken as the LPP and a mean value calculated for each animal. Immediately after measuring LPP the urethra was removed and processed routinely for histology (5 micro m sections, stained with haematoxylin/eosin and trichrome). The means (sem) were compared using a Kruskal-Wallis one-way anova on ranks, followed by a Dunn's test, with P < 0.05 indicating a significant difference. Both LPP and the external increase in abdominal pressure were significantly lower after prolonged distension, at 31.4 (1.7) and 19.8 (1.2) cmH2O, than in the sham group, at 41.1 (3.2) and 32.0 (4.7) cmH2O, respectively. There were no significant differences in LPP or in the increase in abdominal pressure between the brief, intermittent and sham groups. Qualitative histology showed that prolonged distension resulted in extensive disruption and marked thinning of urethral skeletal muscle fibres. Brief and intermittent distension showed mild and focal disruptions, respectively. As observed clinically, prolonged vaginal distension results in a lower LPP, greater anatomical injury and increased severity of SUI. These results suggest that ischaemia is important in the development of SUI after prolonged vaginal distension.

NEUROMODULATION REDUCES C-FOS GENE EXPRESSION IN SPINALIZED RATS: A DOUBLE-BLIND RANDOMIZED STUDY

Neuromodulation of the sacral nerve roots is effective to treat various voiding dysfunctions, but the underlying mechanism of neuromodulation is not known. The objective of this study is to evaluate whether inhibition of afferent c-fiber activity is the underlying mechanism of sacral nerve root neuromodulation. Twenty-nine female Sprague-Dawley rats weighing 220 to 250 gm. were divided into 4 groups: normal control (normal rats without any procedure; n = 5), sham with saline (spinalized rats at T9 with saline bladder instillation; n = 7), sham with acetic acid (spinalized rats at T9 with acetic acid bladder instillation; n = 8) and stimulation group (spinalized rats at T9 with acetic acid bladder instillation plus electrical stimulation; n = 9). A cystometrogram was performed 10 days after spinal cord transection to confirm the development of bladder hyperreflexia. Bilateral electrode wires were implanted into S1 dorsal foramina and electrical stimulation was performed 8 hours a day for three weeks. The rats were perfused with 4% paraformaldehyde and an immunocytochemical method was used to stain fos-protein that was encoded by c-fos gene. A double-blind method was used in counting fos-protein positive neurons. Bladder hyperreflexia developed in all spinalized rats 10 days after spinal cord transection. Peak bladder pressure was found significantly reduced after neuromodulation (30.4 +/- 4.2 cm. water) compared with the same rats before neuromodulation (82.4 +/- 10.2 cm. water; p = 0. 007). The number of fos-protein positive neurons in the L6 spinal cord segment in the neuromodulation group (93.2 +/- 13.3 cells/section) decreased significantly when compared with the sham with acetic acid group (160.6 +/- 25.0 cells/section; p = 0.02). There was no significant difference in c-fos expression between the sham with saline group (90.5 +/- 15.6 cells/section) and the neuromodulation group (p = 0.92). Sacral dorsal root neuromodulation reduces c-fos gene expression and bladder hyperreflexia in spinalized rats, through inhibition of afferent c-fiber activity.

The Use of Iothalamate Meglumine 17.2% as an Effective Testing Medium in Lower Urinary Tract Urodynamic Assessment of Children

Iothalamate meglumine 17.2% was compared to saline as a testing medium in 72 consecutive infants and children undergoing lower urinary tract urodynamic assessment. A total of 97 studies was performed of which 85 were complete. Multiple urodynamic parameters were used to compare test results. Agreement in test results was noted when assessing the change in detrusor pressure in 68 studies (77.6%), leak or peak bladder pressure in 79 (92.9%) and bladder contractions on filling in 81 (95.3%). The difference noted between the 2 testing mediums when comparing these 3 parameters was not statistically significant. The cystometric bladder capacity did vary between iothalamate meglumine 17.2% and saline but no particular trend was identified. The difference in cystometric capacity calculated as a percentage change from the saline baseline was not statistically significant (p = 0.55). Iothalamate meglumine 17.2% can be used as a reliable testing medium for pediatric cystometry.