Induced Bladder Contraction Research Articles

Nerve transfer for restoration of lower motor neuron-lesioned bladder and urethra function: establishment of a canine model and interim pilot study results.

Previous patient surveys have shown that patients with spinal cord or cauda equina injuries prioritize recovery of bladder function. The authors sought to determine if nerve transfer after long-term decentralization restores bladder and sphincter function in canines. Twenty-four female canines were included in this study. Transection of sacral roots and hypogastric nerves (S Dec) was performed in 6 animals, and 7 animals underwent this procedure with additional transection of the L7 dorsal roots (L7d+S Dec). Twelve months later, 3 L7d+S Dec animals underwent obturator-to-pelvic nerve and sciatic-to-pudendal nerve transfers (L7d+S Dec+Reinn). Eleven animals served as controls. Squat-and-void behaviors were tracked before and after decentralization, after reinnervation, and following awake bladder-filling procedures. Bladders were cystoscopically injected with Fluoro-Gold 3 weeks before euthanasia. Immediately before euthanasia, transferred nerves were stimulated to evaluate motor function. Dorsal root ganglia were assessed for retrogradely labeled neurons. Transection of only sacral roots failed to reduce squat-and-void postures; L7 dorsal root transection was necessary for significant reduction. Three L7d+S Dec animals showing loss of squat-and-void postures post-decentralization were chosen for reinnervation and recovered these postures 4-6 months after reinnervation. Each showed obturator nerve stimulation-induced bladder contractions and sciatic nerve stimulation-induced anal sphincter contractions immediately prior to euthanasia. One showed sciatic nerve stimulation-induced external urethral sphincter contractions and voluntarily voided twice following nonanesthetized bladder filling. Reinnervation was confirmed by increased labeled cells in L2 and the L4-6 dorsal root ganglia (source of obturator nerve in canines) of L7d+S Dec+Reinn animals, compared with controls. New neuronal pathways created by nerve transfer can restore bladder sensation and motor function in lower motor neuron-lesioned canines even 12 months after decentralization.

Ultracompliant Carbon Nanotube Direct Bladder Device.

The bladder, stomach, intestines, heart, and lungs all move dynamically to achieve their purpose. A long-term implantable device that can attach onto an organ, sense its movement, and deliver current to modify the organ function would be useful in many therapeutic applications. The bladder, for example, can suffer from incomplete contractions that result in urinary retention with patients requiring catheterization. Those affected may benefit from a combination of a strain sensor and electrical stimulator to better control bladder emptying. The materials and design of such a device made from thin layer carbon nanotube (CNT) and Ecoflex 00-50 are described and demonstrate its function with in vivo feline bladders. During bench-top characterization, the resistive and capacitive sensors exhibit stability throughout 5000 stretching cycles under physiology conditions. In vivo measurements with piezoresistive devices show a high correlation between sensor resistance and volume. Stimulation driven from platinum-silicone composite electrodes successfully induce bladder contraction. A method for reliable connection and packaging of medical grade wire to the CNT device is also presented. This work is an important step toward the translation of low-durometer elastomers, stretchable CNT percolation, and platinum-silicone composite, which are ideal for large-strain bioelectric applications to sense or modulate dynamic organ states.

Optogenetic Modulation of Urinary Bladder Contraction for Lower Urinary Tract Dysfunction

As current clinical approaches for lower urinary tract (LUT) dysfunction such as pharmacological and electrical stimulation treatments lack target specificity, thus resulting in suboptimal outcomes with various side effects, a better treatment modality with spatial and temporal target-specificity is necessary. In this study, we delivered optogenetic membrane proteins, such as channelrhodopsin-2 (ChR2) and halorhodopsin (NpHR), to bladder smooth muscle cells (SMCs) of mice using either the Cre-loxp transgenic system or a viral transfection method. The results showed that depolarizing ChR2-SMCs with blue light induced bladder contraction, whereas hyperpolarizing NpHR-SMCs with yellow light suppressed PGE2-induced overactive contraction. We also confirmed that optogenetic contraction of bladder smooth muscles in this study is not neurogenic, but solely myogenic, and that optogenetic light stimulation can modulate the urination in vivo. This study thus demonstrated the utility of optogenetic modulation of smooth muscle as a means to actively control the urinary bladder contraction with spatial and temporal accuracy. These features would increase the efficacy of bladder control in LUT dysfunctions without the side effects of conventional clinical therapies.

F16357, a novel protease-activated receptor 1 antagonist, improves urodynamic parameters in a rat model of interstitial cystitis.

Background and PurposeThe aims of the present study were to characterize the role of PAR1 in rat bladder under inflammatory conditions and determine whether a selective PAR1 antagonist, F16357, can prevent the pathophysiological symptoms of cyclophosphamide‐induced interstitial cystitis (IC).Experimental ApproachImmunohistochemistry, contractile activity in isolated bladder and urodynamics were determined before and after cyclophosphamide treatment. F16357 was administered intravesically during the acute phase of inflammation, and effects on PAR1 and PAR1‐related bladder contraction evaluated 24 h after cyclophosphamide injection. Urodynamics and associated voided volumes were recorded 7 and 24 h after cyclophosphamide.Key ResultsIn control conditions, PAR1 was present only in some umbrella cells. Cyclophosphamide disrupted the urothelium and expression of PAR1 by all remaining urothelial cells. After F16357 treatment, urothelial damage was absent and PAR1 immunoreactivity similar to control tissues. Thrombin and TFLLR‐NH2 induced bladder contractions. These were increased in inflammatory conditions and antagonized by F16357 in a concentration‐dependent manner. In telemetric experiments, furosemide increased urine production and voiding frequency for 60 min, 7 h after cyclophosphamide injection. Intravesical administration of F16357 blocked these changes with a return to a physiological profile; 24 h after cyclophosphamide, the volume of micturition was still lower with no increase in number of micturitions. F16357 30 μM reduced the number of micturitions and improved bladder capacity, but did not affect diuresis. Under similar experimental conditions, lidocaine 2% induced comparable effects.Conclusions and ImplicationsPAR1 is expressed in rat bladder, overactivated in inflammatory conditions and involved in bladder function and sensation. F16357 could represent an interesting candidate for IC treatment.

315 Alterations of muscarinic induced bladder contractions in a regenerative animal model for neurogenic detrusor underactivity

315 Alterations of muscarinic induced bladder contractions in a regenerative animal model for neurogenic detrusor underactivity

Pudendal but not tibial nerve stimulation inhibits bladder contractions induced by stimulation of pontine micturition center in cats.

This study examined the possibility that pudendal nerve stimulation (PNS) or tibial nerve stimulation (TNS) inhibits the excitatory pathway from the pontine micturition center (PMC) to the urinary bladder. In decerebrate cats under α-chloralose anesthesia, electrical stimulation of the PMC (40 Hz frequency, 0.2-ms pulse width, 10-25 s duration) using a microelectrode induced bladder contractions >20 cmH2O amplitude when the bladder was filled to 60-70% capacity. PNS or TNS (5 Hz, 0.2 ms) at two and four times the threshold (2T and 4T) to induce anal or toe twitch was applied to inhibit the PMC stimulation-induced bladder contractions. Propranolol, a nonselective β-adrenergic receptor antagonist, was administered intravenously (1 mg/kg i.v.) to determine the role of sympathetic pathways in PNS/TNS inhibition. PNS at both 2T and 4T significantly (P < 0.05) reduced the amplitude and area under the curve of the bladder contractions induced by PMC stimulation, while TNS at 4T facilitated the bladder contractions. Propranolol completely eliminated PNS inhibition and TNS facilitation. This study indicates that PNS, but not TNS, inhibits PMC stimulation-induced bladder contractions via a β-adrenergic mechanism that may occur in the detrusor muscle as a result of reflex activity in lumbar sympathetic nerves. Neither PNS nor TNS activated a central inhibitory pathway with synaptic connections to the sacral parasympathetic neurons that innervate the bladder. Understanding the site of action involved in bladder neuromodulation is important for developing new therapies for bladder disorders.

Prostanoid receptors mediating contraction in rat, macaque and human bladder smooth muscle in vitro

Selective prostaglandin EP1 antagonists have been suggested for the treatment of bladder dysfunction. This study assessed the contractile prostanoid receptor subtypes in human and non-human bladder in vitro. Classical tissue bath studies were conducted using bladder strips exposed to prostanoid agonists and antagonists. Prostaglandin E2 (PGE2) contracted rat, macaque and human bladder smooth muscle strips (pEC50 7.91±0.06 (n=7), 6.40±0.13 (n=7), and 6.07±0.11 (n=5), respectively). The EP1 receptor antagonist, PF2907617 (300nM), caused a rightward shift of the PGE2 concentration–response curve in the rat bladder only (pKB 8.40±0.15, n=3). PGE2 responses in rat and macaque bladders, but not human, were antagonised by the EP3 antagonist CJ24979 (1µM). Sulprostone, a mixed EP1/EP3/FP receptor agonist, induced potent contractions of rat bladder muscle (pEC50 7.94±0.31, n=6). The FP receptor agonist, prostaglandin F2α (PGF2α), induced bladder contraction in all species tested, but with a lower potency in rat. The selective FP receptor agonist latanoprost caused potent contractions of macaque and human bladder strips only. SQ29548, a selective TP antagonist, and GW848687X, a mixed EP1/TP antagonist caused rightward shifts of the concentration–response curves to the selective TP agonist, U46619 (pKB estimates 8.53±0.07 and 7.56±0.06, n=3, respectively). Responses to U46619 were absent in rat preparations. These data suggest significant species differences exist in bladder contractile prostanoid receptor subtypes. We conclude that the EP1 subtype does not represent the best approach to the clinical treatment of bladder disorders targeting inhibition of smooth muscle contraction.

Mast Cell Accumulation and Degranulation in Rat Bladder with Partial Outlet Obstruction.

Benign prostatic hyperplasia causes partial bladder outlet obstruction (pBOO), and many patients with pBOO are affected by not only voiding symptoms but also storage symptoms. We previously suggested that enhancement of 5-hydroxytryptamine (5-HT)-induced bladder contraction in the pBOO bladder may be one cause of storage symptoms. However, little is known about the presence of 5-HT in rat bladders. In this study, we hypothesized that mast cells are a source of 5-HT and investigated the distribution of mast cells and 5-HT in the bladders of rats with pBOO. The bladders of female Sprague-Dawley rats were subjected to pBOO and sham operations for 1 week, were isolated, and were fixed for light or electron microscopy. Mast cells and 5-HT in the bladders were detected by toluidine blue staining and immunohistochemical staining, respectively. The mast cells were counted under a light microscope. Degranulated mast cells were observed under an electron microscope and counted under a light microscope. Mast cells were present in the mucosa/submucosa region in sham rat bladders. Their number was increased in the detrusor muscle/subserosa/serosa region, especially the subserosal layer, in pBOO rat bladders. The localization of mast cells almost matched that of 5-HT-positive cells in consecutive sections. Degranulated mast cells were present in sham and pBOO rat bladders, but the proportion of degranulated mast cells was significantly increased in every region in pBOO rat bladders compared with that in sham rat bladders. These results suggest that mast cells contain 5-HT and are more abundant locally in the subserosal layer of pBOO rat bladders. 5-HT released from mast cells could stimulate 5-HT2 receptors on the detrusor muscle, and this may underlie storage symptoms. Asahi Kasei Pharma Corp.

The effect of pentoxifylline on detrusor muscle contractility after partial urethral obstruction in a rat model.

To evaluate the effect of pentoxifylline (PTX), a nonspecific type 4 phosphodiesterase inhibitor, on contractility of obstructed detrusor muscles. Sixty male Sprague-Dawley rats were randomized into three groups each containing 20 animals. The control groups included rats with induced BOO which received the solvent of PTX (drinking water), the sham group included rats with intact bladder outlet which received no treatment, and the treatment group was treated with PTX after induction of BOO. Four weeks after the operation and/or treatment, animals were killed and detrusor muscle of them was evaluated for contractility parameters. Carbachol-induced detrusor muscle tension increased proportionally with concentration of carbachol. The maximum carbachol-inducing muscle tension was significantly higher in the sham group in comparison to the rats with BOO (P < 0.001). In the latter group, PTX treatment caused no significant improvement in the maximum carbachol-induced muscle tension compared to the control group. However, no significant difference was observed among the study groups concerning the pEC50 of carbachol (5.77 ± 0.10, 5.96 ± 0.64, and 5.84 ± 0.17 in the sham, control, and treatment groups, respectively). BOO resulted in a great but statistically non-significant (P = 0.074) decrease in electrically induced bladder contraction in comparison with the sham group. Treatment with PTX reversed this effect significantly (P = 0.023), and the obtained values were almost the same as those of the sham group. PTX improved detrusor muscle contractions in responses to electric stimulation in obstructed bladder. In contrast, no improvement was detected in contractile responses to the carbachol stimulation.

Increased expression of 5-HT(2A) and 5-HT(2B) receptors in detrusor muscle after partial bladder outlet obstruction in rats.

Serotonin (5-hydroxytryptamine; 5-HT)-induced bladder contraction is enhanced after partial bladder outlet obstruction (pBOO) in rats. We investigated time-dependent changes in bladder contraction and expression of 5-HT(2A) and 5-HT(2B) receptor mRNA in bladder tissue to elucidate the mechanism of this enhancement. On day 3 and 7 after pBOO, contractile responses of isolated rat bladder strips to 5-HT were increased compared with that in sham-operated rats; on day 14, the response had decreased to the same level as that in sham rat bladders. In contrast, carbacholinduced contraction was not enhanced by pBOO at any time point. In sham rats, 5-HT(2A) receptor mRNA was expressed in the urothelium, and 5-HT(2B) receptor mRNA was expressed in the detrusor muscle layer. In pBOO rats, both receptor mRNAs were increased in the detrusor muscle and subserosal layers, but not in the urothelium. The increase of 5-HT(2A) receptor mRNA was maintained from day 3 to day 14 after pBOO, and 5-HT(2B) receptor mRNA was increased on day 7 after pBOO. These results suggested that pBOO induced up-regulation of the 5-HT(2A) and 5-HT(2B) receptors in the detrusor muscle and subserosal layers of the bladder, and such up-regulation may be related to the enhanced bladder contractile response to 5-HT.

Functional variability of sacral roots in bladder control.

Sacral roots are involved in sensory, autonomic, and motor innervation of the lower limbs and perineum. Theoretically, it can be assumed that the S-3 root level innervates the bladder; however, clinical practice shows that this distribution can vary. Few researchers have studied this variability. The authors conducted a retrospective study involving 40 patients who underwent surgery requiring an electrophysiological exploration of the sacral roots. They performed stimulations for the monitoring of muscular (3 Hz, 1 V) and bladder responses under cystomanometry (30 Hz, 10 V). Although the S-3 roots were involved in bladder innervation in all cases, they were exclusively involved (i.e., the only nerve roots involved) in only 8 of 40 cases. In the remaining 32 cases, other sacral nerve roots were involved. The most common association was S-3+S-4 (12 cases), followed by S-2+S-3 (6 cases), S-2+S-3+S-4 (5 cases), and S-3+S-4+S-5 (2 cases). Stimulation of S-2 could sometimes induce bladder contraction (15 cases, 40%); however, the amplitude was often low. S-4 nerve roots were involved in 24 of 40 cases (60%) in the bladder motor function, whereas S-5 roots were only involved 7 times (17%). Occasionally, we noticed a horizontal asymmetry in the response, with a predominant response from the right side in 6 of 7 cases, always with a major S-3 response. This is the first study showing a significant horizontal and vertical variability in the functional distribution of sacral roots in bladder innervation. These results show the variability of cauda equina syndromes and their forensic implications. These data should help with the monitoring of sacral roots and the performance of several tasks during surgery, including neurostimulation and neuromodulation.

Bladder Reinnervation Using a Primarily Motor Donor Nerve (Femoral Nerve Branches) is Functionally Superior to Using a Primarily Sensory Donor Nerve (Genitofemoral Nerve)

We determined whether transfer of a primarily motor nerve (femoral) to the anterior vesicle branch of the pelvic nerve would allow for more effective bladder reinnervation than transfer of a primarily sensory nerve (genitofemoral). A total of 41 female mongrel dogs underwent bladder decentralization and then bilateral nerve transfer, or served as sham operated or unoperated controls. Decentralization was achieved by bilateral transection of all sacral roots that induced bladder contraction upon electrical stimulation. Retrograde neuronal labeling dye was injected in the bladder 3 weeks before sacrifice. Increased detrusor pressure after direct stimulation of the transferred nerve, lumbar spinal cord or spinal root was observed in 12 of 17 dogs with genitofemoral nerve transfer and in 9 of 10 with femoral nerve transfer (mean ± SEM 7.6 ± 1.4 and 11.7 ± 3.1 cm H2O, respectively). Mean detrusor pressure after direct electrical stimulation of transferred femoral nerves was statistically significantly greater than after stimulation of transferred genitofemoral nerves. Retrograde labeled neurons from the bladder observed in upper lumbar cord segments after genitofemoral and femoral nerve transfer confirmed bladder reinnervation, as did labeled axons at the nerve transfer site. While transfer of a mixed sensory and motor nerve (genitofemoral) or a primarily motor nerve (femoral) can reinnervate the bladder, using the primarily motor nerve provided greater return of nerve evoked detrusor contraction. This surgical approach may be useful to achieve bladder emptying in patients with lower motor spinal cord injury.

TRK-380, a Novel Selective Human β3-Adrenoceptor Agonist, Ameliorates Formalin-induced Pollakiuria in Rats and Carbachol-induced Bladder Contraction in Dogs

To investigate the effects of TRK-380, a selective β3-adrenoceptor (β3-AR) agonist, on voiding behavior in rats with pollakiuria and on carbachol (CCh)-induced bladder contraction in dogs. The voiding behavior of female Sprague Dawley rats was recorded continuously with a balance. Rats were intravesically pretreated with 2.5% formalin under isoflurane anesthesia. The next day, the effect of TRK-380 (7.5-30 mg/kg, orally) or tolterodine, an antimuscarinic drug (3.75-15 mg/kg, orally), on the voiding frequency was evaluated. In another experiment, male beagle dogs were anesthetized with pentobarbital, CCh (3 μg/kg, intravenously) was administered tothem, and the effect of TRK-380 (0.1 or 0.3 μg/kg/minute, intravenously infusion) on CCh-induced bladder contraction was evaluated. Rats treated with formalin showed a significant increase in the voiding frequency compared with the sham group, and the increase in it was significantly and dose-dependently suppressed by TRK-380 at doses of ≥15 mg/kg. In contrast, tolterodine did not lead to a significant change in the voiding frequency even at the highest dose. In dogs, CCh-induced bladder contraction was dose-dependently suppressed by TRK-380; the plasma concentration required for 30% suppression of the CCh-induced bladder contraction (30% relaxation) was 4.90 ng/mL. This study indicated that TRK-380 ameliorated pollakiuria, which was resistant to an antimuscarinic drug, and that it also suppressed the bladder contraction induced by cholinergic stimulation in dogs, whose bladder relaxation is known to be predominantly mediated by β3-ARs, as in humans. These data strengthen the therapeutic potential of β3-AR for the treatment of overactive bladder.

290 THE SKELETAL NEUROMUSCULAR JUNCTION NICOTINIC RECEPTOR ANTAGONIST SUCCINYL CHOLINE BLOCKS BLADDER CONTRACTIONS INDUCED BY FUNCTIONAL ELECTRICAL STIMULATION OF A NEW NEURONAL PATHWAY CREATED BY REINNERVATION WITH GENITOFEMORAL TO PELVIC NERVE TRANSFER

You have accessJournal of UrologyBladder and Urethra: Anatomy, Physiology and Pharmacology (I)1 Apr 2013290 THE SKELETAL NEUROMUSCULAR JUNCTION NICOTINIC RECEPTOR ANTAGONIST SUCCINYL CHOLINE BLOCKS BLADDER CONTRACTIONS INDUCED BY FUNCTIONAL ELECTRICAL STIMULATION OF A NEW NEURONAL PATHWAY CREATED BY REINNERVATION WITH GENITOFEMORAL TO PELVIC NERVE TRANSFER Michael Ruggieri, Sandra Gomez, Alan Braverman, Vicky Massicotte, and Mary Barbe Michael RuggieriMichael Ruggieri Philadelphia, PA More articles by this author , Sandra GomezSandra Gomez Philadelphia, PA More articles by this author , Alan BravermanAlan Braverman Philadelphia, PA More articles by this author , Vicky MassicotteVicky Massicotte Philadelphia, PA More articles by this author , and Mary BarbeMary Barbe Philadelphia, PA More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2013.02.1674AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Following bladder denervation by transection of sacral spinal cord roots, genitofemoral nerve (GFN) transfer to vesical branches of pelvic nerve (PN) reinnervates the canine bladder because functional electrical stimulation of the transferred GFN induces bladder contraction. The new pathway reinnervates both intramural bladder ganglia as well as detrusor smooth muscle cells directly which are not normally innervated by parasympathetic spinal cord neurons. This study investigates whether the reinnervated neuronal pathway mediates contraction by the same neurotransmitter and receptor mechanisms as the original pathway. METHODS After bladder, urethral sphincter and anal sphincter denervation in 4 female canines, GFN were transferred bilaterally to PN and implanted with nerve cuff electrodes interfaced with radiofrequency micro-stimulators (RFMS). The effect of GFN stimulation on bladder pressure was determined before and after neuromuscular blockade with succinyl choline (SC) 3-6 months after reinnervation. The effects of SC on bladder contractions induced by intraoperative electrical stimulation of sacral spinal nerve roots was determined in 1 normal control and by stimulation of vesical branches of the pelvic nerve in 3 sham operated controls. RESULTS RFMS functional electrical stimulation of the GFN induced bladder contractions in 7 of 8 transferred nerves causing pressure increases of 11.2±4.1 cm H2O that were completely blocked with succinyl choline. Stimulation of the sacral nerve roots in the normal control induced bladder, urethral sphincter and anal sphincter pressure. The urethral and anal sphincter pressures were completely blocked with succinyl choline but the bladder pressure increases induced by sacral root stimulation in the normal control or pelvic nerve stimulation in the sham operate controls were not affected (13.5±3.3 vs 11.4±3.1 cm H2O). CONCLUSIONS This study demonstrates plasticity in the nicotinic receptors involved in nerve evoked bladder contractions induced by bladder reinnervation. GF to PN transfer results in the emergence of succinyl choline sensitive nicotinic receptors in this pathway that normally mediate cholinergic contractions at the neuromuscular junction of skeletal but not smooth muscle. These new nicotinic receptors may mediate contractions of the reinnervated bladder at the intramural ganglia cells or the newly reinnervated smooth muscle cells. © 2013 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 189Issue 4SApril 2013Page: e118 Advertisement Copyright & Permissions© 2013 by American Urological Association Education and Research, Inc.MetricsAuthor Information Michael Ruggieri Philadelphia, PA More articles by this author Sandra Gomez Philadelphia, PA More articles by this author Alan Braverman Philadelphia, PA More articles by this author Vicky Massicotte Philadelphia, PA More articles by this author Mary Barbe Philadelphia, PA More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Naftopidil inhibits 5-hydroxytryptamine-induced bladder contraction in rats

Naftopidil is an α1D and α1A subtype-selective α1-adrenoceptor antagonist that has been used to treat lower urinary tract symptoms of benign prostatic hyperplasia. In this study, we investigated the effects of naftopidil on 5-hydroxytryptamine (5-HT)-induced rat bladder contraction (10−8–10−4M). Naftopidil (0.3, 1, and 3μM) inhibited 5-HT-induced bladder contraction in a concentration-dependent manner. On the other hand, other α1-adrenoceptor antagonists, tamsulosin, silodosin or prazosin, did not inhibit 5-HT-induced bladder contraction. The 5-HT-induced bladder contraction was inhibited by both ketanserin and 4-(4-fluoronaphthalen-1-yl)-6-propan-2-ylpyrimidin-2-amine (RS127445), serotonin 5-HT2A and 5-HT2B receptor antagonists, respectively. In addition, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) and α-methyl-5-HT, 5-HT2A and 5-HT2 receptor agonists, respectively, induced bladder contraction. The 5-HT-induced bladder contraction was not inhibited by N-[2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl]-N-pyridin-2-yl-cyclohexanecarboxamide (WAY-100635), [1-[2[(methylsulfonyl)amino]ethyl]-4-piperidinyl]methyl-1-methyl-1H-indole-3-carboxylate (GR113808) or (R)-3-[2-[2-(4-methylpiperidin-1-yl)ethyl]pyrrolidine-1-sulphonyl]phenol (SB269970), 5-HT1A, 5-HT4 and 5-HT7 receptor antagonists, respectively. Naftopidil inhibited both the 5-HT2A and 5-HT2 receptor agonists-induced bladder contractions. Naftopidil binds to the human 5-HT2A and 5-HT2B receptors with pKi values of 6.55 and 7.82, respectively. These results suggest that naftopidil inhibits 5-HT-induced bladder contraction via blockade of the 5-HT2A and 5-HT2B receptors in rats. Furthermore, 5-HT-induced bladder contraction was enhanced in bladder strips obtained from bladder outlet obstructed rats, with this contraction inhibited by naftopidil. The beneficial effects of naftopidil on storage symptoms such as urinary frequency and nocturia in patients with benign prostatic hyperplasia may be due, in part, to the blockade of the 5-HT2A and 5-HT2B receptors in the bladder.

Effects of pudendal nerve stimulation with different frequency on bladder dysfunction in spinal cord injury dogs

Objective To determine the effects of pudendal ncrve stimulation with different frequency(5 Hz,20 Hz) on bladder dysfunction dogs after spinal cord injury.Methods The study was done in 4 dogs which chronic spinal cord transection at T9-T10 level.All the dogs underwent electrical stimulation of pudendal nerve (5 Hz,20 Hz).Then,bladder capacity,compliance,non-voiding contraction number (NVC) and voiding efficiency before and during stimulation were compared.Results The bladder capacity and the compliance was increased ( 58.9 ± 17.4) ％ and (53.1 ± 4.9 ) ％ ( P ＜ 0.05 ) by pudendal nerve stimulation with low frequency (5 Hz).Detrusor overactivity can be inhibited and the NVC decreased from 1.7 ± 1.3 to 0.9 ± 1.1.Pudendal nerve stimulation with medium frequency ( 20 Hz) can induce bladder contraction and increased voiding efficiency from (5.8 ± 1.0) ％ to ( 16.3 ± 2.6 ) ％ ( P ＜0.05).Conclusions Pudendal nerve stimulation with low frequency can inhibit detrusor overactivity and increase the bladder capacity and compliance in spinal cord injury dogs.Pudendal nerve stimulation with medium frequency can induce bladder contraction and increased voiding efficicncy. Key words: Bladder; Spinal cord injury; Pudendal nerve stimulation; Dogs; Urodynamics

Pharmacological characterisation of the enantiomers of BM-5, a muscarinic partial agonist with opposed enantioselectivity between affinity and efficacy.

The interaction of (R) and (S) enantiomers of the chiral oxotremorine analogue BM-5 with muscarinic acetylcholine receptors was studied in vitro using radioligand binding and isolated tissue preparations. The in vivo effects of (R)-BM-5 were also studied in anaesthetised cat. No receptor or tissue selectivity was found for either enantiomer in radioligand binding studies in cells expressing human muscarinic receptors (M1-M5) or in guinea pig tissues. The affinity of (R)-BM-5 was about 40 times, or 15-60 times higher than that of (S)-BM-5 in recombinant cells or in guinea pig tissues, respectively. Both enantiomers induced contraction of the guinea pig isolated urinary bladder and ileum. (R)-BM-5 was more potent than (S)-BM-5 in bladder (EC50 590 and 3500 nM, respectively) and in ileum (EC50 39 and 2600 nM, respectively). The maximal agonist effect was lower for (R)-BM-5 than for (S)-BM-5 in bladder (2.7% and 6.6%, respectively) and in ileum (32% and 48%, respectively). Contractions were completely inhibited by atropine (1 microM). In vivo, (R)-BM-5 induced bladder contraction and salivation after intravenous administration in the anaesthetised cat (ED50 4.1 and 6.2 microg kg(-1), respectively). In conclusion, (R)- and (S)-BM-5 act as partial muscarinic agonists in the isolated bladder and ileum. (R)-BM-5 was the more potent enantiomer but had a lower maximal agonist effect giving an opposed enantioselectivity for affinity and efficacy. (R)-BM-5 showed agonist activity in vivo, confirming in vitro findings. From affinity and efficacy data it can be concluded that the effects of racemic BM-5 are mediated by the (R)-enantiomer.

Functional Reinnervation of the Canine Bladder after Spinal Root Transection and Immediate Somatic Nerve Transfer

This study was performed to determine whether nerve transfer immediately after spinal root transection would lead to bladder reinnervation in a canine model. In one animal, the left T12 intercostal nerve was mobilized, cut and attached to the severed ends of sacral roots inducing bladder contraction using a graft from the T11 intercostal nerve. On the right side and bilaterally in two other dogs, coccygeal roots innervating tail musculature were cut and attached to the severed bladder sacral roots (coccygeal nerve transfer [CG NT]). In four other dogs, bladder sacral roots were transected in the vertebral column, and the genitofemoral nerve was transferred within the abdomen to the pelvic nerve (genitofemoral nerve transfer [GF NT]). After 14 months for CG NT and 4.5 months for GF NT, electrical stimulation of the pelvic nerve induced bladder pressure and urethral fluid flow on the intercostal nerve transfer side, in each of the five CG NT sites and bilaterally in three of the four GF NT animals. Reinnervation was further shown by retrograde labeling of spinal cord neurons following fluorogold injections into the bladder wall and by histological examination of the root/nerve suture sites. In all CG NT animals, labeled neuronal cell bodies were located in ventral horns in lamina IX of coccygeal cord segments. In the three GF NT animals in which pelvic nerve stimulation induced bladder contraction, abundant labeled cell bodies were observed in lamina IX and lateral zona intermedia of upper lumbar cord. These results clearly demonstrate that bladder reinnervation can be accomplished by immediate nerve transfer of intercostal nerves or coccygeal spinal roots to severed bladder sacral roots, or by transfer of peripheral genitofemoral nerves (L1,2 origin) to pelvic nerves.

Inhibitory and excitatory perigenital-to-bladder spinal reflexes in the cat

This study revealed that in awake chronic spinal cord-injured (SCI) cats reflexes from perigenital skin area to the bladder can be either inhibitory or excitatory. Electrical perigenital stimulation at frequencies between 5 and 7 Hz significantly inhibited large-amplitude rhythmic reflex bladder activity, whereas frequencies between 20 and 40 Hz induced large-amplitude bladder contractions even at low bladder volumes when reflex bladder activity was absent. Both inhibitory and excitatory effects were enhanced as the stimulation intensity increased (5-30 V, 0.2-ms pulse width). During cystometrograms, the inhibitory stimulation (7 Hz) significantly increased the micturition volume threshold 35 +/- 13% above the control volume, while the excitatory stimulation (30 Hz) significantly reduced the threshold 21 +/- 3%. Mechanical perigenital stimulation applied by repeated light stroking of the perigenital skin with a cotton swab only induced an excitatory effect on the bladder. Both electrical and mechanical perigenital stimuli induced large-amplitude (>30 cm H(2)O) bladder contractions that were relatively consistent over a range of bladder volumes (10-90% of the capacity). However, the excitatory electrical stimulation only induced bladder contractions lasting on average 42.2 +/- 3.9 s, but the mechanical stimulation induced bladder contractions that lasted as long as the stimulation continued (2-3 min). Excitatory electrical or mechanical perigenital stimulation also induced poststimulus voiding. The ability to either inhibit or excite the bladder by noninvasive methods could significantly transform the current clinical management of bladder function after SCI.

Smooth muscle caveolae differentially regulate specific agonist induced bladder contractions

Caveolae are cholesterol-rich plasmalemmal microdomains that serve as sites for sequestration of signaling proteins and thus may facilitate, organize, and integrate responses to extracellular stimuli. While previous studies in the bladder have demonstrated alterations in caveolae with particular physiologic or pathologic conditions, little attention has been focused on the functional significance of these organelles. Therefore, the purpose of this study was to investigate the role of caveolae in the modulation of receptor-mediated signal transduction and determine the presence and localization of caveolin proteins in bladder tissue. Contractile responses to physiologic agonists were measured in rat bladder tissue before and after disruption of caveolae achieved by depleting membrane cholesterol with methyl-beta-cyclodextrin. Stimulation with agonists was repeated after caveolae were restored as a result of cholesterol replenishment. RT-PCR, immmunohistochemistry, and Western blotting were used to determine the expression and localization of caveolin mRNA and proteins. Following caveolae disruption, contractile responses to angiotensin II and serotonin were attenuated, whereas responses to bradykinin and phenylephrine were augmented. Cholesterol replenishment restored responses towards baseline. Carbachol and KCl induced contractions were not affected by caveolae disruption. Ultrastructure analysis confirmed loss of caveolae following cholesterol depletion with cyclodextrin and caveolae restoration following cholesterol replacement. Gene and protein expression of caveolin-1, -2, and -3 was detected in bladder tissue. Immunoreactivity for all three caveolins was observed in smooth muscle cells throughout the bladder. The functional effects of cholesterol depletion on specific agonist-induced contractile events and the expression of all three caveolins in bladder smooth muscle support a central role for caveolae in regulation of selective G-protein-coupled receptor signaling pathways in bladder smooth muscle. Thus, caveolae serve to differentially regulate bladder smooth muscle by a stimulus-dependent potentiation or inhibition of bladder contraction.