Bladder Wall Tension Research Articles

Modeling the influence of acute changes in bladder elasticity on pressure and wall tension during filling

Tension-sensitive nerves in the bladder wall are responsible for providing bladder sensation. Bladder wall tension, and therefore nerve output, is a function of bladder pressure, volume, geometry and material properties. The elastic modulus of the bladder is acutely adjustable, and this material property is responsible for adjustable preload tension exhibited in human and rabbit detrusor muscle strips and dynamic elasticity revealed during comparative-fill urodynamics in humans. A finite deformation model of the bladder was previously used to predict filling pressure and wall tension using uniaxial tension test data and the results showed that wall tension can increase significantly during filling with relatively little pressure change. In the present study, published uniaxial rabbit detrusor data were used to quantify regulated changes in the elastic modulus, and the finite deformation model was expanded to illustrate the potential effects of elasticity changes on pressure and wall tension during filling. The model demonstrates a shift between relatively flat pressure-volume filling curves, which is consistent with a recent human urodynamics study, and also predicts that dynamic elasticity would produce significant changes in wall tension during filling. The model results support the conclusion that acute regulation of bladder elasticity could contribute to significant changes in wall tension for a given volume that could lead to urgency, and that a single urodynamic fill may be insufficient to characterize bladder biomechanics. The model illustrates the potential value of quantifying wall tension in addition to pressure during urodynamics.

MP77-05 LOW AMPLITUDE RHYTHMIC CONTRACTIONS INFLUENCE SENSATIONS OF URGENCY IN PATIENTS WITH OVERACTIVE BLADDER SYNDROME

You have accessJournal of UrologyUrodynamics/Lower Urinary Tract Dysfunction/Female Pelvic Medicine: Non-neurogenic Voiding Dysfunction II1 Apr 2016MP77-05 LOW AMPLITUDE RHYTHMIC CONTRACTIONS INFLUENCE SENSATIONS OF URGENCY IN PATIENTS WITH OVERACTIVE BLADDER SYNDROME Andrew Colhoun, Adam Klausner, MaryEllen Dolat, Eugene Bell, Anna Nagle, Paul Ratz, Robert Barbee, and John Speich Andrew ColhounAndrew Colhoun More articles by this author , Adam KlausnerAdam Klausner More articles by this author , MaryEllen DolatMaryEllen Dolat More articles by this author , Eugene BellEugene Bell More articles by this author , Anna NagleAnna Nagle More articles by this author , Paul RatzPaul Ratz More articles by this author , Robert BarbeeRobert Barbee More articles by this author , and John SpeichJohn Speich More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2016.02.1919AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Low amplitude rhythmic contractions (LARC), visualized as phasic intravesical pressure (pves) changes, are commonly seen during urodynamics (UD). A significant rise in pves will increase bladder wall tension and can elicit an increase in sensation. LARC are dampened by the viscoelasticity of the bladder, and not all elevations in bladder wall tension are expected to be sufficient to cause an increase in sensation. This study aims to determine thresholds for pves amplitude elevations that trigger patient-reported changes in sensation during filling. METHODS As part of an IRB-approved urodynamics (UD) protocol, patients with overactive bladder syndrome (OAB), defined as ICIq-OAB question 5a = 3, underwent standard UD testing and simultaneously used a real-time sensation meter to record continuous changes in sensation from 0-100% during filling. Patients were instructed on use of the meter prior to the study. Sensation values were time-linked to pves. Normalized pves was differentiated to identify inflection points, and baseline pves was calculated via polynomial regression (Figure 1). Significant elevation in pves from baseline was defined as = 5% normalized value, while any elevation in patient-reported sensation (values sampled every 10 sec) was considered significant. Significant phasic rises in pves were juxtaposed to sensation changes to determine if pves and sensation events coincided. RESULTS Twelve patients underwent UD with use of the sensation meter – 3 were excluded (transducer error, fill to 30mL, only 10% sensation reached). Average phasic pves and sensation change event frequencies during filling were similar: 2.0±0.2 & 2.1±0.3 cycles/min, respectively (p=0.9). Of sensation changes, 53±8% were within 10 sec of significant pves elevations (average ?pves = 20±3% normalized minimum). CONCLUSIONS The frequency of changes in patient-reported sensation during filling correspond with phasic pves elevations, generated by LARC. Further refinement of sensation thresholds may allow development of non-invasive techniques to better characterize a LARC-mediated subtype of OAB. © 2016FiguresReferencesRelatedDetails Volume 195Issue 4SApril 2016Page: e1017 Advertisement Copyright & Permissions© 2016MetricsAuthor Information Andrew Colhoun More articles by this author Adam Klausner More articles by this author MaryEllen Dolat More articles by this author Eugene Bell More articles by this author Anna Nagle More articles by this author Paul Ratz More articles by this author Robert Barbee More articles by this author John Speich More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Adjustable passive stiffness in mouse bladder: regulated by Rho kinase and elevated following partial bladder outlet obstruction

Detrusor smooth muscle (DSM) contributes to bladder wall tension during filling, and bladder wall deformation affects the signaling system that leads to urgency. The length-passive tension (L-T(p)) relationship in rabbit DSM can adapt with length changes over time and exhibits adjustable passive stiffness (APS) characterized by a L-T(p) curve that is a function of both activation and strain history. Muscle activation with KCl, carbachol (CCh), or prostaglandin E(2) at short muscle lengths can increase APS that is revealed by elevated pseudo-steady-state T(p) at longer lengths compared with prior T(p) measurements at those lengths, and APS generation is inhibited by the Rho Kinase (ROCK) inhibitor H-1152. In the current study, mouse bladder strips exhibited both KCl- and CCh-induced APS. Whole mouse bladders demonstrated APS which was measured as an increase in pressure during passive filling in calcium-free solution following CCh precontraction compared with pressure during filling without precontraction. In addition, CCh-induced APS in whole mouse bladder was inhibited by H-1152, indicating that ROCK activity may regulate bladder compliance during filling. Furthermore, APS in whole mouse bladder was elevated 2 wk after partial bladder outlet obstruction, suggesting that APS may be relevant in diseases affecting bladder mechanics. The presence of APS in mouse bladder will permit future studies of APS regulatory pathways and potential alterations of APS in disease models using knockout transgenetic mice.

Muscarinic acetylcholine receptor subtypes expressed by mouse bladder afferent neurons

Cell bodies of afferent neurons located in lumbosacral dorsal root ganglia (DRG) provide Aδ- and C-fibres to the urinary bladder, reporting bladder wall tension, volume and noxious stimuli. Recent studies suggested an involvement of muscarinic acetylcholine receptors (mAChRs) not only in detrusor contractility but also in modulating afferent function, and this has been linked to the beneficial effects of muscarinic antagonists in the treatment of overactive bladder. Here, we aimed to determine the inventory of mAChR subtypes expressed by bladder afferent neurons in the mouse. Bladder afferent neurons were identified by retrograde neuronal tracing using Fast Blue (FB) or 1, 1′-dioctadecyl-3, 3, 3′, 3′-tetramethylindocarbocyanine perchlorhydrate (DiI) injection into the detrusor muscle. DRG L6-S1 were recognized as the major location of bladder afferent perikarya with an additional smaller peak at L1/L2. Retrogradely labelled bladder afferents located in DRG L4-S2 were subjected to immunohistochemistry or to laser-assisted microdissection with subsequent RT-PCR to study expression of mAChRs subtypes M1R–M5R. Immunolabelling for mAChR subtype M2R, validated on DRG from M2R gene-deficient mice, demonstrated this subtype on 35% of FB-labelled bladder afferents. RT-PCR demonstrated expression of subtypes M2R, M3R and M4R, but not of M1R and M5R, in pooled samples (30 section profiles each) of laser microdissected DiI-labelled bladder afferent cell bodies. In conclusion, bladder afferent neurons express different subtypes of mAChRs (M2R, M3R and M4R). Thus, processing of sensory information from the bladder appears to be under direct cholinergic control.

P3.9 Muscarinic and nicotinic acetylcholine receptors in mouse bladder afferent neurons and their expression profile in lumbosacral afferents in bladder outlet obstruction

Cell bodies of afferent neurons which innervate urinary bladder are mainly located in the lumbosacral dorsal root ganglia (DRG). They provide Aδ- and C-fibres which report information about bladder wall tension, volume and noxious stimuli. Recently, muscarinic acetylcholine receptor (mAChRs) activation in bladder sensory pathways was reported to alter reflex bladder activity. In addition, activation of nicotinic acetylcholine receptors (nAChRs) in C-fiber bladder afferents can induce detrusor overactivity (DO).

A simple fluid-mechanical model for the prediction of the stress–strain relation of the male urinary bladder

The non-linear, viscoelastic behavior of the male urinary bladder complicates the formulation of suitable stress–strain relations for the quasi-static filling process and the unsteady voiding process. In particular, the voiding process—which, in addition, is affected by contraction of muscles leading to generation of bladder wall tension—makes it difficult to obtain quantitative results. In the present study, a simple model is developed that uses certain urological data from cystometry and uroflowmetry to determine the stress–strain relations of the bladder wall during both filling and voiding.

The relationship between lower urinary tract symptoms and health status: the UREPIK study

To assess the hypothesis that as lower urinary tract symptoms (LUTS) increase in severity, the impact as measured by the BPH impact index (BII) would also increase. The UREPIK survey collected information on this relationship from men and their partners in the Netherlands, Korea, France and the UK. Culturally and linguistically validated versions of three standard questionnaires, the SF-12, the BII and the International Prostate Symptom Score (IPSS) were used to assess the distribution of symptoms and the impact on health status. Stratified random samples of men aged 40-79 years in each community were recruited. Response rates were 72% in Boxmeer, 28% in Auxerre, 60% in Birmingham and 68% in Seoul. Regression analyses were undertaken on total SF-12, BII and IPSS. In all, 4800 index men and 3674 women responded; the BII increased with increasing IPSS. The correlation coefficients were; Boxmeer 0.69, Auxerre 0.56, Birmingham 0.60 and Seoul 0.68. For women, the correlations were slightly lower except in Birmingham, at 0.65 (Boxmeer), 0.44 (Auxerre), 0.71 (Birmingham), 0.57 (Korea). BII scores were higher in women than in men with the same level of IPSS. Adjusting for IPSS there was no association between age and BII. There was an association between IPSS quality-of-life (QoL) score and BII; for men the correlation was 0.62 and for women 0.60. Men and women with the same score on the IPSS QoL reported the same bother. Among those with an IPSS of 20-35 women expressed significantly more bother (P < 0.001). The SF-12 scores decreased as the IPSS and the BII increased in both men and women. Furthermore, the SF-12 mental score decreased with increasing symptoms in the partner. The relationship between the severity of LUTS and BII was similar in all centres. There is a clear association between the BII and the IPSS QoL question in men and women. The BII discriminates between people who are unhappy about their urinary condition compared with those who are pleased. Although designed for use in men with benign prostatic hyperplasia, the index also appears to be a useful among women. The severity of symptoms of LUTS has an adverse effect on the health status of the individual and his/her partner.

Preoperatively evaluated bladder wall tension as a prognostic parameter for postoperative success after surgery for bladder outlet obstruction

Objectives To evaluate a novel method for the determination of bladder wall tension (BWT) and to correlate these findings with postoperative persistent residual urine, postoperative uroflow, International Prostate Symptom Score, and quality-of-life index in patients with bladder outlet obstruction. Methods In 28 male patients with prostate enlargement or bladder neck sclerosis undergoing surgical treatment, the preoperative BWT was determined after urodynamic investigation and ultrasound determination of bladder weight. The patients were divided into two groups: group 1 (n = 24), postoperative residual urine volume less than 50 mL; and group 2 (n = 4), persistent residual urine volume greater than 50 mL. Five patients in group 1 were unobstructed in accordance with the Abrams-Griffiths nomogram. This group was compared separately with group 2, in which all 4 patients were also classified as unobstructed. Results The preoperative BWT in group 1 was 5.2 ± 4.1 N/cm 2, significantly different from the preoperative BWT in group 2 (0.98 ± 0.3 N/cm 2). The BWT in the 5 unobstructed patients in group 1 (3.4 ± 1.3 N/cm 2) was significantly greater than that in patients in group 2. BWT was the sole parameter that was distinctly different between these 5 patients and the patients in group 2, with a significant influence on postoperative uroflow, International Prostate Symptom Score, and quality-of-life index. Conclusions The results of this pilot study show that the determination of BWT allows further evaluation of the detrusor function. Especially in patients classified as unobstructed according to the Abrams-Griffiths nomogram, preoperative determination of the BWT could become a supplemental and important parameter with predictive value for postoperative success in patients with prostate enlargement or bladder neck sclerosis.

Passive Biaxial Mechanical Properties of the Rat Bladder Wall After Spinal Cord Injury

Changes in the mechanical properties of the bladder wall after spinal cord injury can alter bladder compliance and wall tension, leading to changes in afferent nerve activity and to abnormal reflex mechanisms. To our knowledge we report the first application of biaxial mechanical testing to the normal bladder wall and demonstrate how these properties change after spinal cord injury. Whole bladders were harvested from mature female Sprague-Dawley rats weighing 250 to 300 gm. Test group animals underwent complete spinal cord transection at the T9 to T10 level and normal animals comprised the control group. The bladders were cut open longitudinally, the trigone and apex were removed and the remaining tissue was trimmed to a square of 9 to 13 mm. per side. Mechanical properties of the tissue sample were tested using planar biaxial testing, in which a stress was applied in the circumferential and longitudinal (base-apex) directions, and resulting axial strains were measured. In normal and spinal cord injured rats bladder wall tissue demonstrated isotropic mechanical behavior when equal stress levels were applied in anatomical directions. However, under nonequi-biaxial loading bladder specimens were not truly isotropic but displayed anisotropic-like behavior. Spinal cord injured tissues were consistently more compliant than normal controls. Biaxial mechanical testing can detect differences in normal control and hypertrophied rat bladders 10 and 14 days after spinal cord injury. These changes represent an important component of the bladder response to spinal cord injury.

COMBINED EVALUATION OF DETRUSOR PRESSURE AND BLADDER WALL THICKNESS AS A PARAMETER FOR THE ASSESSMENT OF DETRUSOR FUNCTION: AN EXPERIMENTAL IN VIVO STUDY

We developed a new method for assessing detrusor function, including active detrusor pressure in relation to bladder wall thickness. This parameter should enable the determination of bladder wall tension, defined as detrusor force per cross-sectional area of bladder tissue. In acute studies in 8 male foxhounds sacral anterior roots S2 to S3 were placed into a modified Brindley electrode. The bladder was stimulated at different intravesical volumes with bladder filling in 50 ml. stages up to 700 ml. and intravesical pressure was measured and registered. The volume of bladder tissue was determined following cystectomy. Bladder tissue volume and bladder wall thickness were correlated with intravesical pressure during stimulation, resulting in the determination of detrusor force per cross-sectional area in N./cm.2 bladder tissue. The curve of the intravesical pressure rise during stimulation between 0 and 700 ml. showed a rapid incline with a maximum mean of 70.8 cm. water at 100 ml., followed by a slow decline. The bladder wall tension curve had an approximately symmetrical course with a slow incline, a maximum mean of 10.15 N./cm.2 at 350 ml. and a subsequent slow decline. The different curves of intravesical pressure and bladder wall tension show that these parameters are not identical. Combining detrusor pressure with bladder wall thickness enables further information on detrusor function to be obtained. Therefore, the clinical assessment of bladder wall tension may become a promising supplement to standard diagnostic methods with predictive value in patients with disturbed micturition.

Visco-elastic Properties of Isolated Detrusor Smooth Muscle

The generation of force by the contractile apparatus and the modulation of that force by the intra- and extracellular matrix are the initial steps in the production of bladder wall tension. The biomechanical components contributing to the observed rise in bladder wall tension may be studied in isolated detrusor tissue and attempts can be made to isolate these. The problem is to determine whether clinically observed alterations in detrusor function are due to changes in the contractile apparatus or in the surrounding matrix. This review discusses the viscoelastic properties of detrusor muscle, concentrates upon the influence of bladder outflow obstruction on the mechanical properties of the detrusor in an attempt to understand changes in contractile function.

A Computer Model for Describing the Effect of Urethral Afferents on Simulated Lower Urinary Tract Function

A computer model of mechanical properties of the bladder, the urethra and the rhabdosphincter, as well as their neural control is presented in this paper. The model has a rather simple design and processes sensory information from both the bladder wall tension and urethral stretch. It is assumed that afferent signals from the urethra are involved in a sacral excitatory reflex and a supraspinal inhibitory reflex. Pressure and flow signals that resemble experimentally measured normal human behaviour could be simulated with this model. From these simulations the relation between the neural control mechanisms used in the model and the neural control mechanism in vivo cannot be judged entirely because similar behaviour could be simulated with models that are bas ed on different neural control mechanisms. Also behaviour that resembles detrusor overactivity was simulated with our model after an externally induced rise in detrusor pressure was added. Detrusor overactivity, sometimes in combination with urethral relaxation, can occur during a urodynamic investigation. A possible explanation for this detrusor overactivity might be that the micturition reflex is triggered by unknown disturbances and is inhibited immediately after by the same mechanism that normally ceases voiding. The described model provides such a mechanism. Based on these simulations, therefore, it is concluded that urethral afferent signals might be important in lower urinary tract control.

Urine storage mechanisms

The urine storage process depends upon the coordinated control of a storage chamber, the bladder body, and its outlets, the bladder base and urethra. While urine storage disorders are of considerable clinical significance, the mechanisms underlying this process are poorly understood. Many species possess an ability to alter the duration of urine storage in the face of widely varying filling rates. The storage chamber appears largely responsible for this ability to alter capacity and compliance. However, there has been some controversy over the contribution of intrinsic smooth muscle and extrinsic neural systems to the storage process, which is partly related to the various methodologies used in experimental and clinical studies. Thus, the storage phase is greatly influenced by the filling regimes, anaesthesia, non-specific factors and infusates used in these studies. Further, the techniques used to examine and measure urine storage mechanisms often obscure the subtle nature of this process. There is little doubt that, under natural filling conditions, myogenic factors allow the bladder to store increasing volumes at low pressure. More recent studies indicate that, in addition to a quiescent parasympatho-excitatory drive, the extrinsic neural systems contribute to the storage phase with a precisely controlled sympatho-inhibitory drive. However, the sympatho-inhibitory drive does not increase capacity by promoting high compliance. Instead this drive partially reduces the level of bladder wall tension transduced by the bladder wall mechanoreceptors, and thus delays the time at which the micturition tension threshold is reached.

Bladder wall tension and mechanoreceptor discharge

Bladder wall mechanoreceptors are essential elements in micturition and continence reflexes. While they have been described as tension receptors, their response to bladder wall deformation has always been characterised in terms of pressure. The firing patterns of 10 bladder wall mechanoreceptors were determined during bladder distensions at a natural and a much faster rate. In all units firing rate was higher at any given pressure at the slower bladder distension rate. This inverse rate dependence was reduced when firing rate was related to a derived measure of bladder wall tension and abolished when multi-fibre recordings were used. We conclude that it is important to incorporate volume effects in studies of continence control systems.

Role of sympathetic innervation in the feline continence process under natural filling conditions.

1. The effect of the sympathetic innervation on the bladder detrusor muscle was assessed in pentobarbitone-anesthetized cats by measuring the changes in bladder wall tension that occurred during sympathetic ganglion blockade after filling the bladder at a natural rate. 2. At a point 60% of the way through the continence process, systemic sympathetic blockade was produced by intravenous trimethaphan, and selective blockade of postganglionic hypogastric nerve activity was produced by application of trimethaphan to the exposed inferior mesenteric ganglia. The level of blockade was monitored with an in-continuity hypogastric nerve recording. 3. During both systemic and selective ganglion blockade, there was an increase in baseline transmural bladder pressure and a decrease in the amplitude of nonmicturating contractions. 4. Although there was no change in the mean level of transmural bladder pressure during either systemic or selective blockade, there was a significant increase in the mean level of bladder wall mechanoreceptor discharge, suggesting that before the blockade sympathoinhibitory effects were greater than sympathoexcitatory effects. 5. Measurement of bladder wall mechanoreceptor discharge before and during ganglion blockade revealed a net sympathoinhibitory influence on the level of bladder wall tension under natural filling conditions. These results confirm that the detrusor muscle of the feline bladder is under both sympathoinhibitory and sympathoexcitatory influences for a significant portion of the continence process.

Computer simulation of the neural control of bladder and urethra

AbstractA large number of neural reflex loops may be involved in voiding and leak‐free storage of urine. The simplifying hypothesis that only very few reflexes are needed to account for most of the observed behavior has been tested by quantitative simulation of the lower urinary tract and its control system. The mechanical part of the simulation, involving detrusor contraction strength and a carefully defined urethral resistance, is based on previous work. The postulated neural control system involves two mutually inhibitory control regions, leading to a bistable (storage‐voiding) system, and reflexes driven by a single afferent signal with contributions from bladder wall tension and urethral distension. Because the control system is bistable, each of the two afferent contributions has two possible effects, so that four distinct reflexes appear to operate. Simulations, with and without these reflexes, show that this system accounts for many features of normal voiding, stop tests, and catheter voiding. The behavior is not sensitive to arithmetic details of the calculations involved. After triggering by a simulated suprapontine control signal, the voiding detrusor contraction is initially amplified by the afferent signal from the detrusor but it is sustained until the bladder is empty by the urethral afferent. Mechanical urethral obstruction causes slight residual urine. Breakdown of the mutual inhibition of the two control regions leads to detrusor instability, suggesting that this condition may sometimes have a central origin.

Effects of Pinacidil and Cromakalim (BRL 34915) On Bladder Function in Rats with Detrusor Instability

Normal rats as well as rats with bladder hypertrophy secondary to outflow obstruction were investigated cystometrically before and after administration of the potassium channel openers pinacidil or cromakalim one mg./kg. orally.In normal rats cromakalim decreased micturition pressure by 15 ± 6%. A diminished micturition pressure was also seen after pinacidil (by 18 ± 8%) but this did not achieve statistical significance. Further, no clear-cut effects on bladder capacity, residual volume, basal bladder pressure, threshold pressure, bladder compliance or on bladder wall tension were seen in this group of rats neither in the presence of pinacidil nor cromakalim.Rats with bladder hypertrophy exhibited a significant bladder instability during cystometrical investigations. The mean amplitude of the spontaneous bladder contractions exceeded 20cm. H20 prior to micturition. Administration of pinacidil and cromakalim decreased the spontaneous contractions to 26 ± 12% and 22 ± 7%, respectively, of that seen in the absence of the drugs. Furthermore, pinacidil decreased micturition pressure by 61 ± 12%. Also cromakalim decreased micturition pressure (by 27 ± 13%) but this effect did not achieve statistical significance. After both pinacidil and cromakalim these rats tended to develop residual urine. In accordance with the results in normal rats pinacidil and cromakalim showed no effects on bladder capacity, basal bladder pressure, threshold pressure, bladder compliance or on bladder wall tension in rats with bladder hypertrophy.The findings of an almost complete disappearance of spontaneous bladder contractions in rats with bladder instability and a remaining voiding ability after administration of pinacidil or cromakalim suggest that potassium channel openers may be a therapeutic alternative in the treatment of bladder instability associated with outflow obstruction.

Toad bladder compliance and water permeability in response to stretch.

The pressure/volume relationship of toad urinary bladders was measured from 0 to 50 cmH2O. Optimal bladder capacity was derived by extrapolation of the pressure/volume curve to a pressure of 0 cmH2O. The compliance of the bladder wall was calculated from the slope of the pressure/volume curve at intraluminal pressures above 10 cmH2O. Neither vasopressin nor atropine had any effect on bladder wall compliance. Bladders filled with one-fifth strength Ringer fluid and suspended in full-strength Ringer lost weight at 0.02 (at half-optimal capacity), 0.08 (at optimal capacity), and 0.26 mg.min-1.cm-2 (at supra-optimal capacity, 25 cmH2O) in the absence of vasopressin. With 20 mU/ml vasopressin, bladders lost weight at 1.08 (at half-optimal capacity), 1.55 (at optimal capacity), and 1.74 mg.min-1.cm-2 (at supra-optimal capacity, 25 cmH2O). When bladder wall tension was raised from 2,102 to 28,383 dyn/cm, the permeability to [14C]mannitol increased from 8 X 10(-7) to 39 X 10(-7) cm/s. Electron microscopy of bladders fixed at a wall tension of 17,572 dyn/cm showed flattening of the microvilli, rupture of the apical cell membranes of some granular and mitochondria-rich epithelial cells, but no obvious alteration in the tight junctions. This study suggests that stretching the apical plasma membrane to the point at which it ruptures in some cells does not alter the capacity of vasopressin to induce its characteristic increase in permeability to water of this membrane.

Increase in choline acetyltransferase activity in surgically isolated postganglionic parasympathetic neurones of the urinary bladder of adult rats

In the urinary bladder of adult male rats the choline acetyltransferase activity in postganglionic neurones isolated from the central nervous system was shown to increase markedly and rapidly following section of the contralateral postganglionic neurones. The enzyme activity of the operated bladder was 32% of the control 3 days postoperatively, while at the last observation, 25 days postoperatively, it was 86%. As judged from additional studies on totally denervated bladders and on totally decentralized bladders the increase found in the enzyme activity was not due to ingrowth of nerves from outside or to unspecific acetylcholine synthesis neither was it due to increase in bladder wall tension or to increase in tissue mass.

Alpha‐Adrenolytic Treatment in Patients With Autonomous Bladders.

The effect of alpha-adrenolytic treatment (phenoxybenzamine) was studied in 8 patients with lower motor neuron lesions (autonomous bladders). In the cystometrograms, the bladders were more hypotonic and the "autononous waves" appeared at a higher level of filling or were totally extinguished after this pharmacological treatment. With an isotonic volume registration method, a bladder volume increase was recorded after alpha-adrenergic blockage. Using spincterometry or urethral pressure profile studies, a decrease in the urethral resistance was observed after alpha-adrenolytic treatment, resulting in a decrease in residual urine. This decrease in bladder wall tension and in residual urine effected an increased functional bladder capacity in patients with autonomous bladders.