Assessment of urodynamic bladder behavior on filling with solutions representing physiological extremes of urinary osmolarity

OBJECTIVE: Verify if there is any difference in sensitive and motor bladder response in the presence of solutions with different osmolarities, simulating physiological extremes of urinary osmolarity. MATERIALS AND METHODS: Thirty-three patients (24 men and 9 women) with mean age of 46.4 years (8 to 87 years) took part in this study. They were all subjected to 2 consecutive urodynamic examinations. In each exam, the vesical filling was accomplished by using a hyperosmolar (1000 mOsm/L) or hypo-osmolar (100 mOsm/L) sodium chloride solution in similar speed. The sequence in which each solution was instilled was determined by a double blind draw. The urodynamic results obtained from the infusion of both solutions were compared, regardless the sequence of administration. RESULTS: Fifteen patients (45.4%) showed detrusor hyperactivity, 12 of whom with neurological antecedents. The mean age of those with detrusor hyperactivity was 45.8 years, against 46.9 for those without hyperactivity. The infusion of the hyperosmolar/hypo-osmolar solution generated the following results, when comparing patients without vs. with detrusor hyperactivity: initial sensation of vesical filling (mL): 167.5 / 159.2 vs. 134.9 / 157.3 (p > 0.05); volume of occurrence of the first involuntary bladder contraction (mL): 163.9 / 151.9 (p > 0.05); detrusor micturition pressure (cm H2O): 24.0 / 24.4 vs. 13.8 / 27.5 (p > 0.05). CONCLUSION: The vesical filling with solutions simulating extreme urinary osmolarities, accomplished with similar speed and without previous identification, did not likewise alter the sensitive and motor urodynamic behavior in the current study.Universidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina (EPM) Department of UrologyUNIFESP, EPM, Department of UrologySciEL

The importance of neural factors in the presentation and treatment of prostatic obstruction.

Symptomatic bladder outlet obstruction due to prostatic enlargement is a common problem in urological practice. Hyperactive detrusor function, "detrusor instability", occurs in up to 80% of patients presenting with prostatic obstruction and in most cases it resolves post-operatively when the obstruction has been relieved. This dysfunction is generally regarded as a modern concept but, in 1786, John Hunter recognised the complex nature of prostatic obstruction and reported: “The disease of the bladder arising from obstruction alone, is increased irritability, and its consequences, by which the bladder becomes quick in its action and thick and strong in its coats." Animal models have confirmed the relationship between obstruction and instability. Several hypotheses have been proposed to explain this link and include; (1) post-junctional hypersensitivity possibly related to denervation, (2) altered adrenoceptor function, (3) afferent nerve dysfunction, (4) an imbalance of peptide neuro-transmitters, and (5) a primary or acquired myogenic deficit. The principal motor control of the intraprostatic musculature is mediated by the sympathetic nervous system; however, the mechanism of action and specific localisation of prostatic adrenoceptors and the importance of non-adrenergic neurotransmission in man is poorly understood. A study of patients with symptomatic prostatic obstruction was undertaken to investigate the influence of neural pathways in determining the pathogenesis and clinical presentation of prostatic and detrusor dysfunction. Sixty-two patients were investigated using modern urodynamic techniques and sub-divided into three groups; control, stable obstructed and unstable obstructed. Biopsies of prostate, bladder neck and bladder muscle were taken at the time of surgery, and pharmacological, autoradiographic and histochemical studies performed. The prostate, bladder and bladder neck were found to be innervated by a complex network of noradrenaline-, acetylcholine-, neuropeptide-, and amine-containing nerves. Separate quantitative analyses of these neurons were carried out and corrections applied to compensate for muscle hypertrophy and hyperplasia. The histological findings were complemented wherever possible by biochemical assay of neuro transmitters. There was a significant reduction in the acetylcholinesterase positive innervation of the obstructed bladder compared with control, which was most marked in tissue from patients with detrusor instability. A similar reduction in the non-adrenergic, non-cholinergic sensorimotor neurotransmitters was evident. Biochemical changes within the detrusor included an increase in noradrenaline content and a decrease in the putative sensory neurotransmitter substance P. Detrusor muscle strips from obstructed patients showed increased contraction in response to acetylcholine, suggesting that denervation hypersensitivity might contribute to the pathogenesis of post-obstructive detrusor instability. Normal detrusor muscle relaxed in response to noradrenaline. In contrast, detrusor muscle from unstable obstructed patients contracted; a response most marked in detrusor muscle from patients who had presented in acute retention. In vitro prostatic muscle-strip experiments confirmed that contraction of prostatic muscle is produced by adrenoceptor stimulation. Radioligand binding assays endorsed the results of these experiments by demonstrating a clear excess of α1 receptors over α2 receptors in histologically normal and adenomatous prostate. Auto-radiography showed the precise localization of the two types of adrenoceptor and confirmed the predominance of α1 receptors within prostatic musculature. The complexity and potential importance of the autonomic nervous system in the pathogenesis and symptomatic expression of prostate-mediated bladder outflow obstruction, is demonstrated by this work. Marked changes in the innervation of both the prostate and bladder accompany obstructive benign enlargement of the prostate. The characterisation and localisation of the prostatic adrenoceptor is of considerable relevance since it validates the therapeutic use of selective prostatic α1 blockade in the clinical management of obstructed patients. Preliminary immunohistochemical studies of bladder, bladder neck and prostate are presented, which provide an histological basis for further functional investigative studies

Early experimental results of using a novel delivery carrier, hyaluronan-phosphatidylethanolamine (HA-PE), which may allow simple bladder instillation of botulinum toxin A as effectively as direct detrusor muscle injection

Introduction: Botulinum toxin A (BTX-A) is a neurotoxin that inhibits acetylcholine release by cleaving cytosolic synaptosome-associated protein 25 (SNAP-25) and results in bladder relaxation. A BTX-A intravesical injection has been established as an effective option for treating detrusor overactivity. Study design: Sixty female Sprague Dawley rats were equally divided into control and experimental groups. Control Groups 1 to 3 received: BTX-A 10 units + saline instillation; hyaluronan-phosphatidylethanolamine (HA-PE) 0.5 g + saline instillation; and BTX-A 5 Uintra-detrusor injections, respectively. Treatment Groups 4 to 6 received: Alexa ® 594-labeled BTX-A 10 U + HA-PE 0.5 g + saline instillation; BTX-A 5 U + HA-PE 0.2–0.5 g instilled for 60 min; and BTX-A 10 U + HA-PE 0.2–0.5 g instilled for 30 min, respectively. All procedures were performed under isoflurane general anesthesia. The primary outcome of this study was the degree of SNAP-25 staining in control and experimental groups compared to Group 3 (detrusor muscle injection). Urodynamic studies were performed at baseline and at day 14 after 1% acetic acid (AA) instillation, to evaluate the maximum pressure during filling (MP) and inter-contraction intervals (ICI). Group 4 rats were examined for Alexa ® 594 fluorescence to demonstrate physical translocation of BTX-A-HA-PE complex. Standard histology was performed to assess the effect of HA-PE on bladder mucosa and detrusor muscle. Results: Group 3 showed the least SNAP-25 staining (7.3 ± 5.0%) compared with all groups except Group 5A (12.4 ± 12.27%, P = 1.0). Group 6A, which had high HA-PE dose but a shorter instillation time, showed fairly extensive SNAP-25 staining (22.9 ± 10%). Confocal microscopy of Group 4 confirmed the presence of Alexa ® 594 fluorescence across the urothelium. Urodynamic parameters were not significantly different at baseline (P = 1.0). After acetic acid instillation, Group 5A showed minimal change in ICI, which was comparable to ICI in Group 3 rats. Discussion: SNAP-25 staining in Group 5A was comparable to Group 3, suggesting that adequate HA-PE and instillation time allows the efficacy of this carrier mechanism to be comparable to standard intra-detrusor injections. All other groups showed significantly higher SNAP-25 staining compared to Group 3. A dose response effect was demonstrated; higher dose of HA-PE (Group 5A vs Group 5B) and longer instillation time (Group 5 vs Group 6) led to lower SNAP-25 staining. Conclusion: This novel method of BTX-A delivery to the bladder using a carrier (HA-PE) is promising and requires further investigation. Using a larger animal model, identifying an optimal dose of HA-PE and instillation time, and reproducing the current results are further required to validate this carrier

The Validation of a Functional, Isolated Pig Bladder Model for Physiological Experimentation

Characterizing the integrative physiology of the bladder requires whole organ preparations. The purpose of this study was to validate an isolated large animal (pig) bladder preparation, through arterial and intravesical drug administration, intravesical pressure recording, and filming of surface micromotions. Female pig bladders were obtained from the local abattoir and arterially perfused in vitro. Arterial and intravesical pressures were recorded at varying volumes. Bladder viability was assessed histologically and by monitoring inflow and outflow pH. Arterial drug administration employed boluses introduced into the perfusate. Intravesical administration involved slow instillation and a prolonged dwell-time. Surface micromotions were recorded by filming the separation of surface markers concurrently with intravesical pressure measurement. Adequate perfusion to all bladder layers was achieved for up to 8 h; there was no structural deterioration nor alteration in inflow and effluent perfusate pH. Arterial drug administration (carbachol and potassium chloride) showed consistent dose-dependent responses. Localized movements (micromotions) occurred over the bladder surface, with variable correlation with fluctuations of intravesical pressure. The isolated pig bladder is a valid approach to study integrative bladder physiology. It remains viable when perfused in vitro, responds to different routes of drug administration and provides a model to correlate movements of the bladder wall directly to variation of intravesical pressure

Studies on inhibitory modulation of urinary tract motility

Overactive Bladder (OAB) is a symptom syndrome characterized by urgency and frequency, with or without urge incontinence. Research concerning the mechanisms underlying OAB and finding new inhibitory factor(s) is intensive. By using a cascade superfusion system, we confirmed the existence of urothelium- derived inhibitory activity in the guinea pig urinary bladder. The unknown inhibitory activity was transmissible over a significant distance, thus allowing attempts at isolation. The unknown factor(s) was found unlikely to be nitric oxide, an adenosine receptor agonist or cyclo-oxygenase products. During isolation of the unknown transmissible inhibitory factor(s) using HPLC and bioassay technologies, we observed considerable amounts of PGE2 and PGD2 being released from guinea pig urinary bladder urothelium, in the resting state. PGE2 and PGD2 were not only released from the bladder but also exerted modulatory effects regulating the lower urinary tract motility. Organ bath experiments using pharmacological tools in guinea pig urothelium-denuded bladder strips showed that PGE2 increased basal tone and spontaneous contractions. Exogenous PGE2 potentiated contractile responses to EFS, ACh and ATP, while PGD2 caused inhibition of EFS, ACh and ATP induced contractions. The inhibitory effect of PGD2 was exerted via DP1 receptors as judged from agonist and antagonist experiments. PGD2 also had a low affinity excitatory effect via TP receptors. The bladder trigone and urethra have different innervations compared with the bladder dome. Both trigone and proximal urethra are important in continence. The effects of PGE2 and PGD2 were investigated also in these regions in the guinea pig. PGE2 and PGD2 in a dose-dependent manner inhibited trigone contractions induced by EFS and spontaneous contractions of the proximal urethra. Immunohistochemical studies of DP1 and DP2 receptor proteins indicated that DP1 and DP2 receptors were localized in the guinea pig bladder dome, trigone and urethra. Both urothelium/sub-urothelium and smooth muscle cells were immunolabelled with DP1 and DP2 receptor antibodies. Hematopoietic prostaglandin D synthase was abundant in the immediate sub-urothelium. These findings will be of importance in understanding normal function and pathophysiology of the lower urinary tract, hopefully opening up new future treatment modalities