The overlooked cause of benign prostatic hyperplasia: prostatic urethral angulation

Benign prostatic hyperplasia (BPH) is one of the most common problems faced by aging men and can be associated with bothersome lower urinary tract symptoms that affect quality of life by interfering with normal daily activities and sleep patterns. Despite the clinical importance of BPH, its pathogenesis is still poorly understood. Previously, our understanding of BPH was centered on bladder outlet obstruction being secondary to benign prostatic enlargement. However, prostate size itself is not correlated with the urine flow rate and symptomatology. The prostatic urethra is a bend tube and the increased prostatic urethral angulation shows a higher bladder neck on cystoscopic examination. Although some urologists suspected that the higher bladder neck might be a causal factor for BPH, the clinical significance of prostatic urethral angulation was previously underestimated. In this study, we propose a new hypothesis that prostatic urethral angulation is a causal factor for BPH. By applying the concept of fluid dynamics to the process of urination in the prostatic urethra, we show that the energy loss in this bending tube (the prostatic urethra) can occur during micturition and it increases proportionally to prostatic urethral angulation; this energy loss results in a decrease of the urine velocity and accordingly, the urine flow rate is inversely associated with prostatic urethral angulation. We also propose that BPH involves prostatic urethral angulation as well as the classical BPH triad of prostatic enlargement, bladder outlet obstruction, and symptomatology. Our hypothesis suggests that prostatic urethral angulation is an overlooked cause of bladder outlet obstruction and is a causal factor of BPH, and provides novel insight into the pathogenesis of BPH. Ultimately, the relationship between prostatic urethral angulation and urine flow rate, and other clinical factors including urodynamic parameters, the symptomatology, the response to treatment, and disease progression, need to be investigated in a clinical setting.     

Development of a rapidly computable descriptor of prostate tissue temperature during transurethral conductive heat therapy for benign prostate hyperplasia

Benign prostate hyperplasia (BPH) is a condition in older men in which the mass of tissue in the prostate gland gradually increases over the course of many years, ultimately leading to urinary outflow obstruction. Current treatment of this condition is to surgically remove the obstructing tissue. One novel alternative therapy being studied is transurethral thermocoagulation of excessive prostatic mass. In this approach, a heat-emitting catheter is placed in the prostatic urethra, and the intraprostatic segment of the catheter is heated to temperatures above 60°C for one hour. Two-dimensional cylindrical-co-ordinate computer simulations of this treatment modality were run to model resultant temperature distributions within the prostate gland and surrounding tissues. The simulations revealed that resultant tissue temperature changes were related directly to the power delivered to the catheter and inversely to the rate of blood perfusion. Further analysis of the temperature profiles produced a rapidly computable predictor of tissue temperature in the radial dimension. Using the predictor, a ‘kill radius’ around the prostatic urethra can be easily computed on-line, during treatment, from clinically available data, catheter, power and catheter temperature. The computed kill radius may serve as a useful predictor of the extent of thermal devitalisation of unwanted obstructing tissue and the long-term success of the treatment in relieving urinary outflow obstruction without surgery.     

男性尿道括约肌失协同的有限元分析

目的 探究内外括约肌失协同对下尿路器官组织应力和尿液流速的影响。方法 基于火棉胶切片对下尿路器官组织进行几何模型重建,并建立含有肌肉主动力的下尿路有限元模型;通过流固耦合仿真,模拟排尿末期内外括约肌均正常收缩、均丧失主动力和单独丧失主动力4种情况下组织应力和尿流速率变化。结果 内外括约肌正常收缩尿道应力变化和临床测得的尿道压力变化趋势相同。与正常收缩情况比较,内括约肌单独丧失主动力,内括约肌和前列腺位置尿道应力分别降低33.6%、13.8%,且此位置尿液流速也降低。外括约肌单独丧失主动力,外括约肌和外尿道位置尿道应力分别降低59.5%、24.03%,而内外括约肌均丧失主动力,内括约肌、前列腺、外括约肌和外尿道位置尿道应力分别降低38.77%、18.6%、63.58%、29.74%,且相对应位置的流速也降低。结论 内外括约肌失协同导致下尿路组织应力和尿液流速的差异性变化。研究结果可为手术治疗因括约肌引起的尿失禁提供理论依据。     

Electroacupuncture treatment of benign prostatic hyperplasia: A case report

Benign prostatic hyperplasia (BPH) is characterized by symptoms such as frequent urination and difficulty in urination. Currently, treatment is mainly carried out using medications and surgery, but all of these methods can lead to certain adverse effects. In this case, a ninety-year-old male elderly patient came to our acupuncture clinic for treatment of urinary tract occlusion due to BPH. According to the patient's condition, we adopted the eletroacupuncture treatment protocol of Prof. Zhanglian Wang, a famous experienced Chinese medicine doctor. After six weeks of acupuncture treatment, the patient's urinary status improved significantly. This case suggests that acupuncture may be an effective complementary alternative therapy for BPH.     

Changes in the extracellular matrix in periurethral tissue of women with stress urinary incontinence

Changes in structural support of the urethra and bladder neck have been proposed as important factors in the pathogenesis of stress urinary incontinence (SUI). In this context, we undertook an ultrastructural study on the periurethral connective tissue with an emphasis on incontinent women with normotonic and hypotonic urethras. Small specimens of periurethral connective tissue were obtained by dissection during a tension-free vaginal tape-implantation procedure in 34 stress urinary incontinent postmenopausal women with a normotonic urethra and 9 stress urinary incontinent postmenopausal women with a hypotonic urethra. In the samples taken from stress-incontinent women with a normotonic urethra, intact elastic fibers were closely connected with collagen fibers, smooth muscle cells and fibrocytes. In the samples taken from stress-incontinent women with a hypotonic urethra, we detected irregular fragmented distribution of the elastin within the tissue. We assume that these structural changes lead to functional consequences, such as diminished tissue extensibility and loss of stability surrounding the female urethra. These altered connective tissue properties may affect the mechanism of urethral closure under stress (e.g., coughing) and therefore contribute to the occurrence of SUI with a hypotonic urethra.     

The Senescence-Associated Secretory Phenotype Promotes Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is characterized by increased tissue mass in the transition zone of the prostate, which leads to obstruction of urine outflow and considerable morbidity in a majority of older men. Senescent cells accumulate in human tissues, including the prostate, with increasing age. Expression of proinflammatory cytokines is increased in these senescent cells, a manifestation of the senescence-associated secretory phenotype. Multiplex analysis revealed that multiple cytokines are increased in BPH, including GM-CSF, IL-1α, and IL-4, and that these are also increased in senescent prostatic epithelial cells in vitro. Tissue levels of these cytokines were correlated with a marker of senescence (cathepsin D), which was also strongly correlated with prostate weight. IHC analysis revealed the multifocal epithelial expression of cathepsin D and coexpression with IL-1α in BPH tissues. In tissue recombination studies in nude mice with immortalized prostatic epithelial cells expressing IL-1α and prostatic stromal cells, both epithelial and stromal cells exhibited increased growth. Expression of IL-1α in prostatic epithelial cells in a transgenic mouse model resulted in increased prostate size and bladder obstruction. In summary, both correlative and functional evidence support the hypothesis that the senescence-associated secretory phenotype can promote the development of BPH, which is the single most common age-related pathology in older men.Benign prostatic hyperplasia (BPH) is an extremely common disease of older men. By the eighth decade of life, approximately 80% of men have anatomical evidence of BPH, and half of these men exhibit symptoms of this disease.¹ This benign growth of the prostate leads to obstruction of urine outflow and causes considerable morbidity in older men. Complications of BPH, such as acute urinary retention and urinary tract infection, can occasionally lead to death. Up to 30% of men may require treatment for this condition at some time in their lives, and in the United States more than one billion dollars is spent annually on the medical and surgical treatment of this disease.² Thus, BPH is a disease that affects the majority of older men and is of considerable medical importance, but its pathogenesis is still obscure.There are three major zones in the prostate: peripheral, central, and transition. These are not simply anatomical or histological regions, but have different behaviors in the aging prostate. The transition zone (TZ), which is located around the prostatic urethra, gives rise to BPH. Although other factors can play a role in the symptom complex characteristic of BPH, the overgrowth of TZ tissue around the prostatic urethra is clearly of importance in the pathogenesis of this disease. The TZ commonly increases more than 30-fold in size during development of BPH, and both epithelial and stromal elements contribute to this growth.³Cellular senescence is a process that limits proliferation of human cells (and animal cells in general).⁴ The senescence response can be induced by a variety of cellular alterations.⁵ Intrinsic senescence occurs in human cells in response to telomere shortening and/or telomere uncapping as a result of repeated rounds of cell division. Senescence can also be induced by a variety of nontelomeric signals, such as oxidative stress, DNA damage, and inappropriate expression of oncogenes.^5,6 Cellular senescence is subject to complex regulation by p53, p16, and other key proteins.^5,6Senescent cells accumulate in human tissues,⁷ including the prostate,^8,9 with increasing age. These senescent cells have altered function, including increased expression of proinflammatory cytokines, growth factors, and proteases—all of which may alter the function of adjacent cells.^10,11 This phenomenon is known as the senescence-associated secretory phenotype. The senescent cells that accumulate with increasing age may contribute to the aging phenotype and age-related pathologies by secreting factors that act in a paracrine manner on adjacent cells and extracellular matrix. Previous studies from our research group indicated that senescent prostatic epithelial cells express at least two proinflammatory cytokines, IL-1α and IL-8.^9,12–14 With the present study, we extend those initial studies and provide both correlative and functional evidence that the senescence-associated secretory phenotype can promote the development of BPH, which is the single most common age-related pathology of older men.     

前列腺增生腺体的局部解剖观察和临床应用

目的：了解认识前列腺增生腺体的局部解剖结构,改进治疗前列腺增生的手术方式。方法：解剖观察10例耻骨上经膀胱前列腺剜除术的完整标本,在标本上模拟设计尿道外增生腺体摘除的手术方法,在12例实际手术中验证方法。结果：10例标本的尿道起始部与增生腺体前上部分腺体之间存在一隐窝,是两侧增生腺体前面的内侧缘弧线形相交形成的夹角区域,为无增生腺体覆盖的三角形尿道裸区,由这一区域分离尿道与增生腺体,可将增生腺体解剖为外层包绕的薄层组织和两侧增生腺体的主体,并由增生腺体中完整分离出尿道,予以完整保留。实际手术中,12例尿道外全部摘除增生的腺体,完整保留尿道,2例尿道有小的纵行裂口。结论：前列腺存在一个无增生腺体覆盖的尿道裸区,利用这个解剖标志可建立一种新的彻底摘除前列腺增生腺体并保留尿道手术的方法。     

The prostatic urethra as a Venturi effect urine-jet pump to drain prostatic fluid

Several experiments show that prostatic fluid is continuously produced and it is drained from the prostate during urination and ejaculation. The mechanism which causes prostatic fluid to drain from the prostatic acini during urination is currently unclear. Also in current opinion such structures of the prostatic urethra as the urethral crest and the colliculus seminalis have no apparent functional significance. This article describes a mechanism for the draining of the prostatic acini that involves these prostatic urethral structures. It is hypothesized that the prostatic urethra works as a pump using the Venturi effect, in which urine is the carrying or motive liquid during voiding, in order to drain prostatic fluid (the carried liquid) from the acini. The urethral crest and the colliculus seminalis take part in controlling flow rates and liquid pressures for this pump to be effective. The calculated estimation of a pressure drop in the region of the colliculus seminalis during micturition was obtained using morphometric and uroflowmetric data and was used to confirm this hypothesis of prostatic acini drainage. As a consequence of this, a previously unknown function for these intra-prostatic urethral structures is described.     

Stereological evaluation of fibronectin in the periurethral region of the transitional zone from normal human prostates compared with benign prostatic hyperplasia

The aim of this study was to assess the volumetric density (Vv) of the fibronectin in the periurethral region of patients with benign prostatic hyperplasia (BPH) and compare with a control group. Prostatic periurethral tissue samples were obtained from ten patients (age range 65 to 79 years, mean 66) with clinical symptoms of bladder outlet obstruction who had undergone open prostatectomy. The control group samples (periurethral tissue samples from the transitional zone) were collected from prostates obtained during autopsy of accidental death adults of less than 25 years. The volumetric density (Vv) of the fibronectin was determined with stereological methods from 25 random fields per sample using the point-count method with an M-42 grid test system. The quantitative data were analyzed using the Kolmogorov-Smirnov and Mann-Whitney U tests. The Vv in the control and BPH groups was 21.9% ± 1.5% and 29.1 % ± 1.2% in the fibronectin, respectively. BPH tissues presented a significant increase of fibronectin in prostatic periurethral region in the transitional zone that may cause lengthening of the prostatic urethra.     

Estimation of elastic properties in the urethral flow controlling zone by signal analysis of urodynamic pressure/flow data

When urethral flow is treated as a lossless flow through an elastic tube, the relationship between the detrusor pressure and the urinary flow can be related to the elasticity of the flow-controlling zone of the urethra. A recent analytical method of describing urethral elasticity is implemented on a computer. The function p(Q)=p_mo+L_mQ^m is fitted to the recorded pressure/flow data. p(Q) is the detrusor pressure, Q the flow and p_mo, m and L_m parameters. The elastic properties are then obtained as p(A)=p_mo+K_nAⁿ, where p(A) is the static pressure, A the cross-sectional area of the flow-controlling zone and n and K_n calculated parameters. The urodynamic methods used and the computer implementation of the analytical method are described. In obstructed and unobstructed men without neurological symptoms, the elastic properties could be estimated in 94 per cent of the micturitions. The method makes it possible to describe urethral flow properties with Griffiths' model in a standardised way and compare results obtained by different investigators. It is recommended for quantification of urethral obstruction in research and for assessment of borderline cases of obstruction in clinical practice. deceased     

Dietary supplements for benign prostatic hyperplasia: An overview of systematic reviews

Benign prostatic hyperplasia (BPH) is a common chronic condition in older men. The aim of this overview of systematic reviews (SRs) is to summarise the current evidence on the efficacy and adverse effects of dietary supplements for treating BPH with lower urinary tract symptoms. We searched 5 electronic databases and relevant overviews without limitations on language or publication status. Six SRs of 195 articles were included in this overview. Serenoa repens was reviewed in 3 studies and no specific effect on BPH symptoms and urinary flow measures was observed. However, β-sitosterol, Pygeum africannum and Cernilton were reviewed in one study each, and significant improvement was observed for all three. All the included compounds have mild and infrequent adverse effects. SRs on β-sitosterol, Pygeum africannum and Cernilton have not been updated since 2000, thus an update of reviews on these compounds will be necessary in the future.     

Electrophysiologic characteristics of interoceptive reflex arc

Summary Afferent impulsation in the peripheral end of a pelvic nerve branch and efferent impulsation to the urethra in the central end of the pudendal nerve have been recorded in the course of short experiments on cats. Pressure in the urinary bladder, blood pressure and contractions of the urethra have been simultaneously registered. Slight distention of the urinary bladder to 10–20 mm Hg by inflation of 2–10 cc of air caused insignificant afferent impulsation in the pelvic nerve, increased the frequency and amplitude of efferent impulsation in the pudendal nerve, and a rise of the tonus and contractivity of the urethra. Distention of the urinary bladder to 20–30 mm Hg by inflation of 10–20 cc of air intensified afferent impulsation in the pelvic nerve, lowered efferent impulsation in the pudendal nerve down to complete cessation and relaxation of the urethra. Excitation of intermediate degree led to rhythmic bursts and depression, likewise to altemating contraction and relaxation of the urethra. The same three phases have been noted during natural urination.Submitted by Active Member AMS USSR Drofessor V. N. Chernigovsky     

Tissue elasticity and the dynamics of flow through the urethra in females

A theoretical model of flow through the female urethra is developed, taking account of longitudinal tension in the urethral wall. An elasticity parameter which has the dimension of length appears and is being termed the ‘elastic length’ L of the urethra. This parameter and the spread of the pressure profile produced by the tissue surrounding the urethral wall are important factors in the control of the rate of flow. Because of this, the possibility exists that flow will take place for a bladder pressure below the maximum tissue pressure.     

Chaos and predicting varix hemorrhage

Despite a wide array of mechanisms implicated in esophagogastric varix hemorrhage, predicting the onset of bleeding or even identifying the dominant factor in its causation has proved elusive. In this article we re-examine variceal pathophysiology and hypothesize that bleeding is rooted in turbulent portal system flow, a phenomenon embodied in the 'new' science of chaos and the principles of non-linear, rhythmic fluid dynamics. Analogous to forecasting the weather, predicting turbulent flow hinges on defining the initial physical conditions, and, like the field theory of quantum physics, depends on probabilities and instabilities rather than direct proportional analysis. Based on the complex regional and systemic hemodynamic forces and local physical properties underlying formation and perpetuation of esophagogastric varices, we propose, as with climatologic events, that a relatively minor or remote physiologic adjustment may set into motion a sequence of destabilizing splanchnic blood flow kinetics that ultimately causes a varix to erupt. In other words, the onset of varix bleeding derives from a sudden, erratic switch from disorganized but stable to disruptive turbulent variceal blood flow, and as a 'chaotic' phenomenon, is likely to remain for the foreseeable future highly unpredictable.     

Optimization of the artificial urinary sphincter: modelling and experimental validation

The artificial urinary sphincter should be long enough to prevent strangulation effects of the urethral tissue and short enough to avoid the improper dissection of the surrounding tissue. To optimize the sphincter length, the empirical three-parameter urethra compression model is proposed based on the mechanical properties of the urethra: wall pressure, tissue response rim force and sphincter periphery length. In vitro studies using explanted animal or human urethras and different artificial sphincters demonstrate its applicability. The pressure of the sphincter to close the urethra is shown to be a linear function of the bladder pressure. The force to close the urethra depends on the sphincter length linearly. Human urethras display the same dependences as the urethras of pig, dog, sheep and calf. Quantitatively, however, sow urethras resemble best the human ones. For the human urethras, the mean wall pressure corresponds to (-12.6 +/- 0.9) cmH2O and (-8.7 +/- 1.1) cmH2O, the rim length to (3.0 +/- 0.3) mm and (5.1 +/- 0.3) mm and the rim force to (60 +/- 20) mN and (100 +/- 20) mN for urethra opening and closing, respectively. Assuming an intravesical pressure of 40 cmH2O, and an external pressure on the urethra of 60 cmH2O, the model leads to the optimized sphincter length of (17.3 +/- 3.8) mm.     

Turbulent blood flow plays an essential localizing role in the development of atherosclerotic lesions in experimentally induced hypercholesterolaemia in rats

Taking into account that atherosclerosis is a focal disease and high levels of plasma cholesterol are closely correlated with its pathogenesis, it is a challenge to explain how equal concentrations of cholesterol bathing the endothelium can produce local, rather than global, effects on arteries. The focal distribution of atherosclerotic lesions has been considered to be dependent, at least in part, on hydrodynamic factors. The present study was carried out to further test the hypothesis that these forces are an important localizing factor in rats feeding a hypercholesterolaemic diet and submitted to infra-diaphragmatic aortic constriction. These animals develop a normotensive prestenotic region with laminar blood flow that serves as control for a normotensive poststenotic region with turbulent blood flow. Our findings clearly demonstrated that the combination of turbulent blood flow and low wall shear stress (WSS) in the presence of hypercholesterolaemia and oxidative stress creates conditions to the formation of focally distributed incipient atherosclerotic lesions observed in the poststenotic segment. In contrast, only diffuse fatty streaks could be observed in the normotensive prestenotic segment with laminar blood flow and normal WSS in the presence of hypercholesterolaemia and oxidative stress. Although haemodynamic forces are not by themselves responsible for the pathogenesis of atherosclerosis, they prime the local vascular wall in which the lesion develop. Further studies are required to establish how haemodynamic forces are detected and transduced into chemical signalling by the cells of the artery wall and then converted into pathophysiologically relevant phenotypic changes.     

Morphological analysis of the urethral muscle of the male pig with relevance to urinary continence and micturition

To investigate whether the pig could be considered a suitable model to study lower urinary tract function and dysfunction, the pelvic urethra of 24 slaughtered male pigs were collected, and the associated muscles were macroscopically, histologically and histochemically analyzed. In cross‐sections of the urethra, a muscular complex composed of an inner layer of smooth muscle and an outer layer of striated muscle that are not separated by fascial planes was observed. A tunica muscularis, composed of differently oriented smooth muscle bundles, is only evident in the proximal part of the pelvic urethra while, in the remaining part, it contributes to form the prostatic fibromuscular stroma. The striated urethral muscle surrounds the pelvic urethra in a horseshoe‐like configuration with a dorsal longitudinal raphe, extending from the bladder neck to the central tendon of perineum. Proximally to the bladder, it is constituted of slow‐twitch and fast‐twitch myofibers of very small diameter, and embedded in an abundant collagen and elastic fiber net. Moving caudally it is gradually encircled and then completely substituted by larger and compact myofibers, principally presenting circular orientation and fast‐twitch histochemical characteristics. So, like in humans, the cranial tract of the muscular system surrounding the pelvic urethra is principally composed of smooth musculature. The striated component cranially may have a role in blocking retrograde ejaculation, while the middle and caudal tracts may facilitate urine and semen flow, and seem especially concerned with the rapid and forceful urethral closure during active continence. Some differences in the morphology and structure between pigs and humans seem due to the different morphology of the ‘secondary’ sexual organs that develop from the urethral wall and to the different effect of gravity on the mechanics of the urinary system in quadruped and bipedal mammals.     

Interleukin-1alpha is a paracrine inducer of FGF7, a key epithelial growth factor in benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is an extremely common disease of older men in which there is benign overgrowth of the prostatic transition zone, leading to obstruction of urine outflow. FGF7, a potent growth factor for prostatic epithelial cells, is increased by threefold in BPH and is correlated with increased epithelial proliferation in this condition. Immunohistochemistry of normal and hyperplastic prostate revealed that FGF7-expressing fibroblastic cells were present in higher numbers near the epithelial acini, implying that epithelial cells may express a factor that induces FGF7 expression by stromal cells. Conditioned medium (CM) from primary cultures of prostatic epithelial cells was capable of inducing a two- to sixfold increase in the expression of FGF7 by primary stromal cultures. Blocking experiments with neutralizing anti-interleukin-1alpha (Il-1alpha) antibodies and IL-1Ra, an Il-1alpha receptor antagonist, show that this inducing activity was due to the presence of Il-1alpha in the epithelial CM. Analysis of normal prostatic peripheral zone and BPH tissue by enzyme-linked immunoabsorption assay reveal that Il-1alpha is present at increased levels in hyperplastic prostate and that levels of Il-1alpha correlate strongly with tissue FGF7 concentration in BPH. Therefore Il-1alpha is produced by prostatic epithelial cells and can induce FGF7, a potent epithelial growth factor, which can in turn lead to further epithelial growth and increased Il-1alpha secretion, thus establishing a double paracrine loop that is functionally equivalent to an autocrine growth loop. This double paracrine loop may play a key role in the abnormal proliferation of the transition zone, which is critical to the pathogenesis of BPH.     

Histology of the canine uretha II. Morphometry of the male pelvic urethra

Urinary bladders and pelvic urethrae were collected from six adult and two juvenile male dogs. Within two vesical and six urethral sampling regions, volume densities were estimated for smooth and striated muscle, connective tissue and elastic fibers, stratum cavernosum, luminal epithelium, and prostate. The neck had significantly less smooth muscle and more connective tissue than the body of the bladder. In the prostatic urethra, smooth muscle was associated principally with trabeculae surrounding prostate lobules. Smooth muscle was sparse superficially in the prostatic capsule and practically absent in relation to the mid-prostatic urethra. Thus there was no mechanism for active closure of the middle prostatic urethra, and elastic fiber density was correspondingly high in this region. The smooth muscle sphincter needed to maintain urinary continuence and prevent semen reflux was primarily the vesical neck. Caudal to the body of the prostate, striated muslce comprised more than 50% of the urethral wall. Juvenile and adult postprostatic urethrae were similar except for a decreased quantity of stratum cavernosum in the pups.     

On the peripheral bladder control system of the dog and urodynamics:In vivo characterisation and hybrid computer simulation

A quantitative model of the peripheral bladder control system of the dog is developed. This model is based on the experimental characterisation of the detrusor muscle and the urethra in 25 female dogs. Intravesical pressure, urinary flow and bladder volume were simultaneously recorded during electrical bladder stimulation, and, from these data, a dynamic model of the bladder control system has been deduced. A general equation for predicting urinary flow patterns is developed, and the hybrid computer EAI-690 is used to simulate the evacuation of the bladder. The effect of different parameters of the system on the micturition pattern is investigated in detail. This work may have interesting clinical applications: for example, in the development of adequate techniques for the evacuation of the paraplegic bladder. Also, the experimental procedures elaborated in this study could be applied in the diagnosis of bladder function and urethral obstruction. Indeed, we have been able to characterise the detrusor muscle and the urethra independently using clinically accessible variables.