A porcine model of bladder outlet obstruction incorporating radio-telemetered cystometry

Chronic bladder catheterization for precise urine collection in awake mice

Metabolic chambers are routinely used for urine collection in rodents. In mice, due to small urination volume, evaporation in the metabolic chambers (≈50%) distorts diuresis and urinalysis parameters. We have developed a new technique of bladder catheterization enabling long-term accurate and contamination-free urine collection in awake male and female mice for 30 days or longer. Daily diuresis in catheterized mice was twice higher as compared to metabolic cages. The twofold difference in urine recovery was preserved when the circadian variation of diuresis, the effects of furosemide, desmopressin and water load were estimated using the two techniques. Urine osmolarity, urinalysis, and microbiological parameters evidence higher quality of the catheter-collected urine. Using phenol red, we demonstrate utility of our technique for pharmacokinetic studies. 30 days after the surgery the catheters were patent and had minimal impact on the animals' heath. Bladder catheterization is a useful tool for physiological, pharmacological, and toxicological studies.

Pressure-volume analysis of rat's micturition cycles in vivo

AIMS

Though the pressure-volume analysis (PVA), a method based on thermodynamics, is broadly used for assaying cardiac functions, its potential application on the physiology/pathophysiology of the urinary bladder, which processes resemble thermodynamic cycles to the heart, has not been established.

METHODS

Cystometry recording intravesical pressure (IVP) and intravesical volume (IVV) of rhythmic voiding contractions caused by a constant saline infusion (0.04 mL/min) were carried out in forty urethane-anesthetized female Sprague-Dawley rats, and the PVA was established by plotting IVP against IVV.

RESULTS

Pressure-volume points shaped coincident enclosed loops, and loop-associated urodynamic parameters kept stable under a constant infusion rate (0.04 mL/min). Enhancing preload (by elevating infusion rates to 0.08 and 0.12 mL/min) increased the area enclosed by the loop (Apv) and shifted loops to the right and slightly upward. Augmenting afterload (by enhancing resistances using 1/4 and 1/2 urethra clamping) increased Apv and shifted loops markedly to the right and upward. Without affecting Apv, muscarine (0.01 and 0.1 mM)-induced inotropic states shifted loop to the left and upward that was as opposed to the atropine (0.01 and 0.1 mM)-induced anti-inotropic state.

CONCLUSIONS

Not only consistently assayed baseline bladder functions, PVA but also validly measured modified bladder functions due to altered extrinsic environment and intrinsic contractility of the bladder itself. In accompanied by cystometry, PVA could provide a clear concept about the relationship between time, pressure, and volume in the voiding activity.

Augmentation Cystoplasty of Diseased Porcine Bladders with Bi-Layer Silk Fibroin Grafts

IMPACT STATEMENT

The search for an ideal "off-the-shelf" biomaterial for augmentation cystoplasty remains elusive and current scaffold configurations are hampered by mechanical and biocompatibility restrictions. In addition, preclinical evaluations of potential scaffold designs for bladder repair are limited by the lack of tractable large animal models of obstructive bladder disease that can mimic clinical pathology. The results of this study describe a novel, minimally invasive, porcine model of partial bladder outlet obstruction that simulates clinically relevant phenotypes. Utilizing this model, we demonstrate that acellular, bi-layer silk fibroin grafts can support the formation of vascularized, innervated bladder tissues with functional properties.

Benefits and limitations of animal models in partial bladder outlet obstruction for translational research

The functions of the lower urinary tract have been investigated for more than a century. Lower urinary tract symptoms, such as incomplete bladder emptying, weak urine stream, daytime urinary frequency, urgency, urge incontinence and nocturia after partial bladder outlet obstruction, is a frequent cause of benign prostatic hyperplasia in aging men. However, the pathophysiological mechanisms have not been fully elucidated. The use of animal models is absolutely imperative for understanding the pathophysiological processes involved in bladder dysfunction. Surgical induction has been used to study lower urinary tract functions of numerous animal species, such as pig, dog, rabbit, guinea pig, rat and mouse, of both sexes. Several morphological and functional modifications under partial bladder outlet obstruction have not only been observed in the bladder, but also in the central nervous system. Understanding the changes of the lower urinary tract functions induced by partial bladder outlet obstruction would also contribute to appropriate drug development for treating these pathophysiological conditions. In the present review, we discuss techniques for creating partial bladder outlet obstruction, the characteristics of several species, as well as issues of each model, and their translational value.

Research Findings on Overactive Bladder

Several physiopathologic conditions lead to the manifestation of overactive bladder (OAB). These conditions include ageing, diabetes mellitus, bladder outlet obstruction, spinal cord injury, stroke and brain injury, Parkinson's disease, multiple sclerosis, interstitial cystitis, stress and depression. This review has discussed research findings in human and animal studies conducted on the above conditions. Several structural and functional changes under these conditions have not only been observed in the lower urinary tract, but also in the brain and spinal cord. Significant changes were observed in the following areas: neurotransmitters, prostaglandins, nerve growth factor, Rho-kinase, interstitial cells of Cajal, and ion and transient receptor potential channels. Interestingly, alterations in these areas showed great variation in each of the conditions of the OAB, suggesting that the pathophysiology of the OAB might be different in each condition of the disease. It is anticipated that this review will be helpful for further research on new and specific drug development against OAB.

Telemetric monitoring of bladder function in female Göttingen minipigs

OBJECTIVES

To generate real-time radio-telemetric urodynamic reference data of maximum detrusor pressure (Pdet max ), maximum flow rate (Qmax) and estimated grade of infravesical obstruction, as well as duration of detrusor contraction (DOC), in female Göttingen minipigs and to describe translational aspects of the use of Göttingen minipigs for urological research.

MATERIALS AND METHODS

A telemetric transmitter was implanted into five female Göttingen minipigs, and 24 h measurements in metabolic cages were taken. Through operator-based analysis, synchronized real-time radio-telemetric cystometric data with flowmetric data and video sequences were used to determine voiding detrusor contractions (VCs) and non-voiding detrusor contractions (NVCs). Furthermore, data from telemetric natural-filling cystometry from free-moving and restricted maintenance conditions were compared for potential differences.

RESULTS

The median (range) Pdet max of VCs was 120.6 (21.0-370.0) cmH2 O and, therefore, significantly different from that of NVCs (64.60 [20.4-280.6 cmH2 O] cm H2 O). Intraindividual comparison of minipig data revealed great differences in voiding contractions. The effects of limited movement on VCs were analysed and showed significantly higher Pdet max and lower DOC than in free-moving conditions.

CONCLUSION

The presented data can be used for the development of telecystometric implanted minipig models, to investigate changes of detrusor function such as under- or overactivity, and might serve as model for bladder changes occurring with iatrogenic bladder outlet obstruction (BOO) or different therapeutic options for overactive bladder. Radio-telemetric real-time natural filling and voiding cystometries are feasible, reproducible in non-anaesthetized minipigs with free or limited movement and can give new insights into circadian behaviour and physiological and pathological bladder function.

Urodynamic measurements by radiotelemetry in conscious, freely moving beagle dogs

PURPOSE

Urodynamics have been traditionally recorded in anesthetized or conscious animals implanted with a bladder catheter that is used to artificially fill the bladder while measuring intravesicular bladder pressure. Anesthesia alters the urodynamics and in the conscious state this methodology requires that the dogs be tethered/restrained, which evokes stress and limits the period of continuous urodynamic assessment. A more physiological and chronic method of evaluating pharmacological responses on urodynamics is necessary.

MATERIALS AND METHODS

Adult female beagle dogs were surgically instrumented with radiotelemetry transmitters enabling urodynamic/hemodynamic recordings. Telemetered urodynamics were compared to those measured in anesthetized dogs receiving bladder infusion of saline. The response to diuresis with furosemide (Intervet, Millsboro, Delaware) and the M3 selective antimuscarinic darifenacin (Matrix Laboratories, Hyderabad, India) were evaluated.

RESULTS

Saline infused, anesthetized dogs demonstrated lower peak micturition pressure and higher threshold pressure than conscious, freely moving telemetered dogs. In telemetered dogs a single dose of furosemide increased voiding frequency and average urine volume per void. Darifenacin decreased peak voiding pressure without affecting voiding frequency.

CONCLUSION

Telemetry provides the potential to significantly decrease animal use while enabling the continuous monitoring of urodynamics under more physiological conditions without tethering or artificial filling. In addition, this new model facilitates evaluation of the chronic efficacy of new urological therapies.