Inhibition of human detrusor contraction by a urothelium derived factor

PURPOSE: Stimulating muscarinic receptors in pig bladder urothelium causes the release of a diffusable factor that inhibits contractions of the underlying detrusor muscle. We investigated whether the contractions of human detrusor strips elicited by the muscarinic agonist carbachol, electrical field stimulation, KCl or the neurokinin receptor agonist neurokinin A are affected by the urothelium. MATERIALS AND METHODS: Paired intact and urothelium denuded muscle strips were placed in modified gassed Tyrode's solution at 37C. Cumulative concentration-response curves to carbachol or KCl were constructed. In other tissues the strips were stimulated electrically (1 to 40 Hz) with trains of square wave pulses 20 seconds in duration at 5-minute intervals. RESULTS: Cholinergic contractions evoked by electrical field stimulation at 10 and 30 Hz or by carbachol were significantly inhibited in the presence of an intact urothelium. Contractions elicited by KCl and by 10 microM neurokinin A were not modified by the urothelium. The urothelium mediated inhibition of contractions induced by carbachol was not affected by 300 microM L-NG-nitroarginine, 1 microM ODQ (1H-[1,2,4]oxadiazolo[4,3-alpha]quinoxalin-1-one), 1 microM propranolol or 5 microM indomethacin. CONCLUSIONS: Muscarinic agonists stimulate the release of an inhibitory factor from the human urothelium. The factor is distinct from nitric oxide and it persists in the presence beta-adrenoceptor blockade or cyclooxygenase inhibition.     

Chronic ketamine treatment-induced changes in contractility characteristics of the mouse detrusor

Purpose

To understand bladder contractility changes induced by chronic ketamine treatment, noting the prevalence of its abuse worldwide.

Methods

A mouse model of chronic ketamine treatment was used and detrusor strip contractility was measured. Rising and falling phases of contractile responses as well as maximal, average sustained and phasic contractions were measured.

Results

While maximal contractility of ketamine-treated strips was identical to the saline controls, the former displayed slower contraction rates under K⁺-Krebs, carbachol and electrical stimulation. The decay phase of electrically stimulated responses was also slower at most stimulation frequencies in the ketamine-treated strips. Greater sensitivity to varying the strengths of stimuli was observed in the ketamine-treated strips.

Conclusions

Altered contractility characteristics of the bladder after chronic ketamine treatment were revealed, which could potentially be useful in the development of improved treatment regimens.     

The role of the urothelium in mediating bladder responses to isoprenaline

OBJECTIVES: To investigate whether the responses of the pig bladder to isoprenaline (a nonselective beta-adrenoceptor agonist) are influenced by the presence of an intact urothelium and whether any influence might be attributed to the release of nitric oxide (NO), since stimulation of beta-adrenoceptors induces a direct relaxation of detrusor smooth muscle and beta-adrenoceptors are also present on the urothelium. MATERIAL AND METHODS: Paired (in the presence or absence of urothelium) longitudinal strips of pig bladder dome were set up in tissue baths and the developed tension recorded. Relaxation responses to isoprenaline were examined after pre-contraction with carbachol. The inhibitory effects of isoprenaline were examined by comparing responses to carbachol in the absence and presence of isoprenaline. To examine a possible role for NO, similar experiments were performed in the presence of the NO synthase inhibitor N(G)-nitro-L-arginine (L-NNA). RESULTS: In the presence of the urothelium, both the potency (pEC(50)) and the maximum contractile responses to carbachol were depressed. In relaxation experiments, isoprenaline relaxed carbachol pre-contracted tissues by approximately 75%, and the potency and maximum relaxation were similar in the absence and presence of the urothelium. In the inhibition experiments, the presence of isoprenaline caused rightward parallel shifts of the concentration-response curves to carbachol, but isoprenaline did not influence the maximum contractions. In the presence of the urothelium there was a greater shift with 0.1 microm isoprenaline than in denuded tissues. Incubation with L-NNA did not affect the influence of the urothelium on responses to isoprenaline in any experimental group. CONCLUSIONS: The relaxation responses of the bladder to isoprenaline do not appear to involve the urothelium or NO release in vitro. However, contractile responses to carbachol were inhibited in the presence of an intact urothelium, and this might reflect the release of an inhibitory factor other than NO.     

Variations in carbachol- and ATP-induced contractions of the rat detrusor: effects of gender, mucosa and contractile direction

Purpose

Contractile characteristics of the bladder may depend on variables such as gender, mucosa (MU) and direction of the contractions. However, definitive information is not yet available despite earlier studies on the effects of one variable or another. Here, we explored the differences in the rat detrusor attributable to gender, mucosa and contractile direction.

Methods

K⁺, carbachol (CCh) and ATP were used as contractile stimuli on rat detrusor strips with and without MU. Contractility was monitored using a myograph system. Both tonic and phasic contractile activities were analyzed.

Results

MU-independent contractions induced by CCh were more potent in females, an effect specific to the longitudinal direction only. The maximal CCh response was larger also in females when MU was removed, suggesting a stronger MU-independent component in the contraction. The larger area under curves of the females under ATP stimulation showed dependence on MU and contractile direction as well. ATP-induced contractions in the males were affected more by MU in the transverse direction than in the females. Direction- and MU-dependent variability of ATP responses was also observed in the males but not in females.

Conclusions

Findings here added new information to the understanding of bladder contractile physiology, providing insights into the quest for better drugs in managing bladder disorders.     

Do enflurane and isoflurane interfere with the release, action, or stability of endothelium-derived relaxing factors?

Purpose

The volatile anaesthetics enflurane and isoflurane inhibit the endothelium dependent-relaxation in somein vitro preparations. To determine their site of action on the endothelium-derived relaxing factor/nitric oxide (EDRF/NO) pathway, experiments were conducted in a bioassay system.

Method

Continuously perfused cultured bovine aortic endothelial cells (BAEC were the source of EDRF/NO while a phenytephrine-precontracted denuded rabbit aortic ring, directly superfused by the BAEC effluent served to detect EDRF/NO. The effect of basal and bradykinin (Bk)-stimulated EDRF/NO release on vascular tension was measured The effect of 4% enflurane or 2% isoflurane on EDRF/NO-induced relaxation was determined.

Results

Enflurane added to the perfusate either upstream or downstream in relation to BAEC attenuated the relaxation induced by Bk at low concentrations. On the other hand, isoflurane, added either upstream or downstream to BAEC, potentiated the relaxation induced by the basal release of EDRF but attenuated the relaxation induced by the Bk stimulated release of EDRF Neither enflurane nor isoflurane attenuated the relaxation induced by sodium nitroprusside (SNP), an NO donor.

Conclusion

Enflurane decreases the stability of EDRF/NO released after Bk stimulation while isoflurane can have opposite effects depending on whether the relaxation results from basal or Bk-stimulated release of endothelial derived relaxing factor(s). Isoflurane increases the stability or action of the basal relaxing factor, decreases the stability of the Bk-stimulated relaxing factor (which is probably NO).     

Low concentrations of niflumic acid enhance basal spontaneous and carbachol-induced contractions of the detrusor

Purpose

The urinary bladder expresses Ca²⁺-activated Cl^? channels (CACC), but its physiological role in governing contractility remains to be defined. The CACC modulator niflumic acid (NFA) is widely used despite the variable results arisen from different drug concentrations used. This study was designed to examine the effects of NFA at low concentrations on detrusor strip contractility.

Methods

Rat detrusor strips with mucosa-intact (+MU) and mucosa-denuded (?MU) were prepared in transverse (Tr) and longitudinal (Lg) with respect to the bladder orientation. Isometric force measurements were made at baseline (for spontaneous phasic contractile activity) and during drug stimulation (by carbachol, CCh) with and without NFA.

Results

NFA (1 and 10 μmol/L) pretreatment enhanced CCh-induced contractions more in +MU than ?MU strips with no selectivity on contractile direction. For spontaneous phasic contractions, NFA-treated strips in the Tr direction showed increased phasic amplitude, while phasic frequency was unchanged.

Conclusions

The findings suggest low concentrations of NFA having a potentiating effect on detrusor contractions that was sensitive to the MU and contractile direction.     

Synaptic inhibitory effects of edrophonium on sympathetic ganglionic transmission

Purpose

To evaluate the effect of edrophonium on synaptic transmission in the superior cervical ganglion.

Methods

In anaesthetized rats the effect of edrophonium on synaptic transmission was stuthedin vitro by testing whether it blocks the compound action potential recorded from postganglionic fibres evoked by stimulation of preganglionic axons. The superior cervical ganglion was excised and the cervical sympathetic trunk and internal carotid nerve were used for stimulating and recording, respectively. Drugs superfused included edrophonium (0.1–500 μM), neostigmine (0.1–10 μM), and muscarinic M₁ and M₂ antagonists pirenzepine and AFDX-116 (200 nM-10 μM), respectively. To evaluate a presynaptic action, the effect of edrophonium on basal and high-K⁺ (35 mM) evoked release of [³H]ACh from the superior cervical ganglion was stuthed invitro. To evaluate a postsynaptic action, edrophonium’s effect on postganglionic nerve discharge in response to arterial injection of ACh (100 μg) into the superior cervical ganglion was determinedin vivo.

Results

Edrophonium (10–500μM) decreased the compound action potential amplitude (ED₅₀ 163.5 μM). A decrease was not produced by neostigmine, nor was it reversed by pirenzepine or AFDX-116. Edrophonium blocked postganglionic cell firing in response to exogenously administered ACh. Although edrophonium did not affect basal or high-K⁺ evoked ACh release, when the evoked increase was calculated as a multiple of the basal release, it caused approximately a 30% (P < 0.005) reduction.

Conclusions

Edrophonium blocks ganglionic cholinergic transmission postsynaptically and, possibly, presynaptically. The mechanism(s) by which this occurs does not appear to involve inhibition of cholinesterase, or activation of M₁ or M₂ receptor subtypes.     

Change in acetylcholine release from rat bladder with partial outlet obstruction

OBJECTIVE

To investigate changes in acetylcholine release from the bladder of rats with partial bladder outlet obstruction (BOO), as partial BOO leads to hypertrophy and an alteration in the contractions of the detrusor smooth muscle, and acetylcholine plays an important role in urinary bladder contractions but there is little available information on acetylcholine release after BOO.

MATERIAL AND METHODS

Partial BOO was induced in adult female rats by ligating the proximal urethra over a 1 mm angiocatheter; sham‐operated rats served as controls. The rats were killed 2 weeks, 3 and 6 months after induction of BOO. We investigated the contractions induced by carbachol, KCl (80 mm ), ATP and electrical‐field stimulation (EFS, 2.5–40 Hz), and collected the dialysate obtained from a microdialysis probe inserted into the muscle strips during EFS, and measured the amount of acetylcholine in the dialysate fraction by high‐performance liquid chromatography with electro‐chemical detection. S‐100 immunohistochemical staining of the bladder preparations was used for histological examination in BOO and control rats.

RESULTS

The bladder weight gradually increased after BOO. There were no significant changes in KCl‐induced contractions throughout the experimental period in either group. There were no significant changes in carbachol‐induced contractions until 3 months after BOO but there was a significant reduction at 6 months. ATP‐induced contractions were significantly increased 2 weeks and 3 months after BOO. EFS‐induced contractions were gradually reduced after BOO. Acetylcholine release from the bladder strips was not significantly different between the groups until 2 weeks after BOO. However, acetylcholine release in BOO rats was significantly decreased 3–6 months after BOO, being significantly lower than that of the control rats. In the histological study, the number of nerve fibres in the BOO rats was significantly lower than in the control rats.

CONCLUSIONS

We suggest that the prolonged BOO caused a decrease in EFS‐induced acetylcholine release and the number of nerves in the rat urinary bladder, which might contribute to bladder underactivity in BOO.     

Distribution and function of the endocannabinoid system in the rat and human bladder

Introduction and hypothesis

Our aim was to compare expression and distribution of cannabinoid receptors CB1 and CB2, transient receptor potential vanilloid receptor 1 (TRPV1), and modulating enzymes in human and rat bladder. We also evaluated effects of cannabinoid agonists (ACEA, agonist of CB1; GP1A, agonist of CB2) on contractile responses of rat bladder strips.

Methods

Distribution and expression of CB1, CB2 and TRPV1 receptors and enzymes fatty acid amide hydrolase (FAAH) and N-acyl phosphatidylethanolamine-hydrolyzing phospholipase D (NAPE-PLD) was studied using immunohistochemistry and immunoblotting on human and Wistar rat bladders. The effects of cannabinoid agonists on contractile responses of isolated rat bladder strips to electrical-field stimulation (EFS) or carbachol-evoked responses were determined.

Results

Immunoreactivity for CB1 and TRPV1 receptors and FAAH and NAPE-PLD was present in the bladder of both species. CB1 proteins were of different sizes in rat (57 kDa) and human (40 kDa) bladder. CB2 (45 kDa in both species) immunolocalised to both urothelium and detrusor muscle in human bladder but only to detrusor muscle in rat. FAAH proteins were found at 55 kDa for both species. Rat NAPE-PLD protein (44 kDa) was similar in size to that in human bladder (45 kDa). TRPV1 proteins were found at 104 kDa in both species. ACEA (10^?4?M) attenuated bladder contractions by 35?±?5.4 % (p?<?0.001); GP1a had no effect despite the EC₅₀ values for the carbachol dose–response curves for both agonists being significantly shifted to the right.

Conclusions

The endocannabinoid system is functionally expressed in both species, with CB1 receptors showing both pre- and postsynaptic inhibitory effects on rat bladder contraction, whereas CB2 acts only postsynaptically.     

Mechanisms of Action of the Gasotransmitter Hydrogen Sulfide in Modulating Contractile Activity of Longitudinal Muscle of Rat Ileum

Aim

This study aims to determine mechanisms of action of the gasotransmitter hydrogen sulfide (H₂S) on contractile activity in longitudinal muscle of rat ileum.

Methods

Ileal longitudinal muscle strips were prepared to measure isometric contractions. Effects of sodium hydrosulfide (NaHS), a donor of H₂S, were evaluated on spontaneous contractile activity and after enhanced contractile activity with bethanechol. l-cysteine was evaluated as a potential endogenous donor of H₂S. We evaluated involvement of extrinsic nerves, enteric nervous system, visceral afferent nerves, nitric oxide, and K _ATP ⁺ channel and K _Ca ⁺ channel activity on the action of H₂S using non-adrenergic/non-cholinergic conditions, tetrodotoxin, capsaicin, l-N^G-nitro arginine (l-NNA), glibenclamide, and apamin, respectively, as well as electrical field stimulation.

Result

NaHS dose-dependently and reversibly inhibited spontaneous and bethanechol-stimulated contractile activity (p?<?0.05). l-cysteine had no inhibitory effect. Non-adrenergic/non-cholinergic conditions, tetrodotoxin, capsaicin, l-NNA, glibenclamide, or apamin had no major effect on total contractile activity by NaHS, although both tetrodotoxin and apamin decreased the frequency of bethanechol-enhanced contractile activity (p?<?0.05). We could not demonstrate H₂S release by electrical field stimulation but did show that inhibition of cystathionine ?? synthase, an endogenous source of H₂S, augmented the inhibitory effect of low-frequency electrical field stimulation.

Conclusion

H₂S inhibits contractile activity of ileal longitudinal muscle dose-dependently but not through pathways mediated by the extrinsic or enteric nervous system, visceral afferent nerves, nitric oxide, K _ATP ⁺ channels, or K _Ca ⁺ channels.     

Bedeutung von Phosphodiesteraseisoenzymen in der Kontrolle der humanen Detrusormuskulatur

Objectives

The use of inhibitors of phosphodiesterase (PDE) isoenzymes 1 and 5 to treat overactive bladder has been suggested. To further evaluate the significance of PDE isoenzymes in detrusor smooth muscle relaxation, we investigated the effects of selective PDE inhibitors on the tension induced by carbachol of isolated human detrusor tissue. Using immunohistochemical methods, the expression of PDE1, PDE4, and PDE5 in human detrusor was also investigated.

Material and Methods

The expression of PDE1, PDE4, and PDE5 was evaluated by means of conventional immunohistochemistry (IHC). Using the organ bath technique, the effects of the PDE inhibitors vinpocetine, rolipram, sildenafil, tadalafil, and vardenafil on the tension induced by the muscarinic agonist carbachol (1 µM) were investigated.

Results

The tension induced by carbachol was dose-dependently reversed by the PDE inhibitors; the maximum reversal of tension ranged from 7% (tadalafil) to 34% (vardenafil). IHC revealed that the expression of PDE isoenzymes was limited to the smooth musculature of the detrusor. While there was prominent expression of PDE4 and PDE5, immunoreactions indicating the presence of PDE1 were less abundant.

Conclusion

Despite the fact that inhibitors of PDE1, PDE4, and PDE5 exerted only a weak relaxant response on detrusor strips precontracted by carbachol, our findings indicate that both the cAMP and cGMP pathways might be involved in the relaxation mechanism of human detrusor smooth muscle.     

Expression of endothelial nitric oxide synthase protein is not necessary for mechanical strain-induced nitric oxide production by cultured osteoblasts

Summary

Regulation of nitric oxide (NO) production is considered essential in mechanical load-related osteogenesis. We examined whether osteoblast endothelial NO synthase (eNOS)-derived NO production was regulated by HSP90. We found that HSP90 is essential for strain-related NO release but appears to be independent of eNOS in cultured osteoblasts.

Introduction

NO is a key regulator of bone mass, and its production by bone cells is regarded as essential in mechanical strain-related osteogenesis. We sought to identify whether bone cell NO production relied upon eNOS, considered to be the predominant NOS isoform in bone, and whether this was regulated by an HSP90-dependent mechanism.

Methods

Using primary rat long bone-derived osteoblasts, the ROS 17/2.8 cell line and primary mouse osteoblasts, derived from wild-type and eNOS-deficient (eNOS^?/?) mice, we examined by immunoblotting the expression of eNOS using a range of well-characterised antibodies and extraction methods, measured NOS activity by monitoring the conversion of radiolabelled l-arginine to citrulline and examined the production of NO by bone cells subjected to mechanical strain application under various conditions.

Results

Our studies have revealed that eNOS protein and activity were both undetectable in osteoblast-like cells, that mechanical strain-induced NO production was retained in bone cells from eNOS-deficient mice, but that this strain-related induction of NO production was, however, dependent upon HSP90.

Conclusions

Together, our studies indicate that HSP90 activity is essential for strain-related NO release by cultured osteoblasts and that this is highly likely to be achieved by an eNOS-independent mechanism.     

Clinical impact of bladder biopsies with TUR-BT according to cytology results in patients with bladder cancer: a case control study

Background

There seems to be no consensus concerning taking bladder biopsies during transurethral resection of bladder tumor (TUR-BT). We investigate the clinical significance of bladder biopsy with TUR-BT and the relationship between urinary cytology and the biopsy results.

Methods

We reviewed a total of 424 patients with non-muscle invasive bladder cancer treated with TUR-BT between 1998 and 2005. Of the total, 293 patients also underwent a bladder biopsy. Biopsies from suspicious-appearing urothelium (N = 59) and those from normal-appearing urothelium (N = 234) were evaluated separately.

Results

Bladder cancer was observed in 23 cases (39.0%) who underwent a biopsy of suspicious-appearing urothelium. Among these 23 cases, 9 cases with visible tumor resection had carcinoma in situ (CIS) only in the biopsies from suspicious-appearing urothelium. Urinary cytology was negative in 3 of the 9 cases. Bladder cancer was observed in 26 cases (11.1%) who underwent a biopsy of normal-appearing urothelium. Of them, 5 cases with visible tumors had CIS only in the multiple biopsies from normal-appearing urothelium. Urinary cytology was positive in all of the 5 cases. No upstaging or upgrading cases were found in these patients by the addition of these two types of biopsy. Furthermore, therapy was not altered in these patients. With or without bladder biopsy was not a significant factor for tumor recurrence in either the univariate or multivariate analysis.

Conclusions

Based on the results, it is concluded the multiple biopsies from normal-appearing urothelium are not necessary in patients with negative cytology results because of the low detection rate and lack of influence on therapeutic decisions. Meanwhile, biopsy of suspicious-appearing urothelium is needed in patients with negative cytology results in order to detect CIS due to staging properties. This result supports a recent EAU guideline.     

Spontaneous contractions of the pig urinary bladder: the effect of ATP-sensitive potassium channels and the role of the mucosa

OBJECTIVE

To investigate the influence of the mucosa on the inhibitory effects of the ATP‐sensitive potassium channel (K_ATP channel) opener, cromakalim, on the spontaneous contractions of pig bladder strips from the bladder dome and trigone. Little is known about the influence of the mucosa on spontaneous contractions and whether the nature of these contractions differs between the bladder dome and trigone.

MATERIALS AND METHODS

Paired longitudinal strips of female pig bladders were isolated from the dome and trigone. The mucosa was removed from one strip per pair and tissues were set up in organ baths. Spontaneous activity was allowed to develop and recorded, and then cumulative concentration–response curves to cromakalim were obtained. The time needed for spontaneous contractions to develop, the frequency and amplitude of spontaneous contractions, and the effect of cromakalim were analysed. The strips of mucosa removed from the dome to produce denuded strips were also analysed by immunofluorescence using antibodies specific for vimentin and α‐smooth muscle actin (α‐SMA).

RESULTS

In the dome removal of the mucosa delayed the development of spontaneous contractions compared with mucosa‐intact strips, whilst the trigone strips developed spontaneous contractions soon after set up in the organ baths irrespective of the presence or absence of mucosa. In the dome, cromakalim was more potent in suppressing spontaneous contractions when the mucosa was absent; whilst in the trigone the effects of cromakalim were similar in mucosa‐intact and denuded strips. Upon examination of the strips of mucosa by immunofluorescence these strips were shown to contain cells positive for α‐SMA or vimentin and cells positive for both, suggesting the presence of not only urothelium but also suburothelium and some detrusor smooth muscle bundles.

CONCLUSION

In the dome, the urothelium and suburothelium reduce the inhibitory effect of cromakalim on spontaneous contractions, whilst in the trigone these structures appear to have little influence. The mechanism for generating spontaneous contractions in the intact strips seems to be linked to the urothelium and suburothelium in the dome but not in the trigone.     

Effect of urothelium on bladder contractility in diabetic rats

AIM: It is known that physiopathological changes in diabetes affect the function of the bladder. In this study, we aimed to demonstrate the possible effects of diabetes on the urothelium during this physiopathological process. METHODS: Diabetes was induced in rats by tail vein injection of 35 mg/kg streptozotocin. Eight weeks later, intact and denuded bladder strips were prepared from these rats. Electrical field stimulation (EFS; 0.5-32 Hz), carbachol (10(-8)-10(-3) mol/L; cumulative dosage-response curves) and KCl (120 mmol/L) were used for the evaluation of the contractile responses. All responses were expressed as mg tension developed per mg of bladder tissue. Weights of rats and of their bladders, blood glucose levels, and frequency- and concentration-response curves were compared using anova, the paired t-test and the independent t-test. Differences were considered significant at P<0.05. RESULTS: Although no differences related to the weight of bladders of the control and diabetic groups were observed, there were differences in blood glucose levels and body weights between the two groups. Similarly, although there were no differences between the data obtained with EFS and KCl from tissues with intact and denuded strips in the control group, carbachol responses significantly differed between intact and denuded strips in the non-diabetic group. These differences were not observed in the diabetic group. In the control groups, in the presence of additional strips with intact urothelium placed in the medium containing denuded tissue, the differences in contractile responses between the intact control strip and the denuded strip disappeared. CONCLUSIONS: Diabetes possibly changes the interaction between the relaxant factors that are released from urothelium and muscarinic stimulation, but these interactions are not completely understood yet. Consequently, the response of the bladder to contractile stimulants is also affected. Further studies are required to reveal the mechanism by which diabetes influences the urothelium.     

Different bladder defects reconstructed with bladder acellular matrix grafts in a rabbit model

Objective

To evaluate the potential use of the bladder acellular matrix graft (BAMG), two different bladder defects in the rabbit model were reconstructed.

Materials and methods

Two groups of rabbits underwent partial bladder wall cystectomy (group?A, 30?C40%; group?B, 70?C60%) and reconstruction of the defects with an equally sized BAMG. After 4, 12, and 24?weeks, bladder cystographs were performed. Then the rabbits were killed after uneventful postoperative periods, and the grafts were harvested for H&;E staining and immunohistochemical staining.

Results

Two rabbits died on the postoperative days 3 and 6 in group?A due to urinary peritonitis. At 24?weeks, in group?A, the reconstructed bladders reached a mean volume of 94.39±0.54% of the precystectomy bladder capacity. Histologically, complete regeneration of smooth muscle and urothelium tissue was evident. Regenerated SMCs and urothelium stained positive for ??-smooth muscle actin and AE1/AE3. In group?B, the mean bladder volume was 64.5±3.19% of the precystectomy volume. Histologically, group?B was characterized by multilayered urothelium without organized muscle tissue.

Conclusion

The BAMG was an effective scaffold for bladder wall regeneration in the rabbit model. However, the use of BAMG reconstruction in larger bladder defects did not induce the same quality and quantity of bladder regeneration as the reconstruction of smaller bladder defects.     

Spinal somatosensory evoked potentials after epidural isoproterenol in awake sheep

Purpose

The use of 10–15 μg epinephrine as an epidural test-dose is controversial. Isoproterenol would be a better alternative. However before 5μg isoproterenol can be incorporated in an epidural test-dose, neurotoxicological studies have to be performed. The present study was designed to assess spinal somatosensory evoked potentials (spinal SSEP) before and after epidural isoproteronol.

Methods

Spinal SSEPs were recorded before, 30 min after, and 72 hr after 50 μg isoproterenol were given epidurally (L_3–4) to six chronically instrumented awake sheep. The spinal SSEPs after epidural (L_3–4 administration of 15 ml lidocaine 2% were used to evaluate the model. The SSEPs were generated by transcutaneous stimulation of the sciatic nerve in the thigh. Spinal SSEPs were recorded directly from the spinal cord at vertebra T₁₂ using a monopolar epidural electrode referenced to a subcutaneous needle electrode in the adjacent paraspinal area.

Results

Thirty minutes and 72 hr after epidural injection of 50 μg isoproterenol the latency and the amplitude of the SSEP waves were similar to baseline values. After lidocaine, no SSEPs could be generated in three sheep while in three sheep the latency of wave 2 (W2) was prolonged and the amplitude diminished.

Conclusion

Administration of epidural isoproterenol did not affect spinal SSEPs in this study indicating an absence of neurotoxic side effects.     

Positiv inotroper Effekt von Ivabradin am atrialen Myokard des Menschen

Objectives

The present study tests, whether Ivabradine has an action aside from the sinus node in human atrial tissue.

Methods

Human atrial myocardium was loaded with the fluorescent dye Fura 2 for intracellular calcium measurements. The preparations were electrically stimulated at optimal length while diastolic and systolic intracellular calcium and mechanical force output were simultaneously recorded. Increasing Ivabradine concentrations were tested. Varying stimulation frequencies were applied in order to analyse the force frequency relation under conditions of Ivabradine incubation.

Results

Increasing Ivabadrin concentrations had a direct effect in increasing the amplitude of intracellular calcium transient and on the amplitude of active force generation (p<0.01). There was a reduction of diastolic intracellular calcium and of diastolic resting force with increasing Ivabradine concentrations (p<0.01). Increases of the Ivabradine dose did not further increase the positive inotropic effect.

Conclusion

Ivabradine has a positive inotropic effect aside from the sinus node in atrial myocardium. It is a substance with a direct positive inotropic effect as shown by the present data.     

In Vitro Release of Adenosine Triphosphate from the Urothelium of Human Bladders with Detrusor Overactivity,Both Neurogenic and Idiopathic

Background

There is increased evidence to suggest a role for nonadrenergic–noncholinergic neurotransmission in the pathogenesis of bladder dysfunction.

Objective

In this set of experiments, we have assessed the contribution of the urothelium to purinergic activity by quantifying the amount of adenosine triphosphate (ATP) released from the urothelium of patients with idiopathic detrusor overactivity (IDO) and with neurogenic detrusor overactivity (NDO) and comparing these releases to those of controls.

Design, setting, and participants

Bladder tissue with urodynamically and clinically proven NDO (n = 8) and IDO (n = 8) were included in this study. The carefully dissected urothelium was stimulated by mechanically stretching as well as electrically stimulating and the ATP; thus, release was quantified.

Measurements

We used a Lucy Anthos 1 luminometre (Anthos Labtec Instruments GmBH, Wals, Austria) to perform the assay. The results were analysed using Stingray software (Dazdaq Ltd, Brighton, UK).

Results and limitations

Both mechanical stretch and electric field stimulation (EFS) led to increased ATP release in both sets of tissues with overactivity compared to the controls; this rise was even more significant for the IDO urothelium (2416.7 ± 479.8 pmol/g [p < 0.005]) than for the NDO urothelium (133.1 ± 22.4 pmol/g [p < 0.01]); values for the controls were 77.6 ± 16.2 pmol/g. ATP release following mechanical stretch was more sensitive to tetrodotoxin in bladders with NDO compared to those with IDO as well as to the controls, with ATP levels falling from 233.5 ± 20.7 pmol/g to 107.2 ± 11.6 pmol/g, expressed as percentage of basal levels (p < 0.002). The experiments were performed in vitro, and the female patients were a mix of peri- and postmenopausal states.

Conclusions

These experiments suggested a significant rise in ATP release from the urothelium of bladders with NDO as well as those with IDO in comparison to controls. Most of the ATP released from bladders with NDO is primarily from neuronal sources.