Validation of a Cholinergic-induced Model of Detrusor Overactivity using a rat isolated whole bladder
IUGA Academy. Cifuentes M. Jun 30, 2018; 213037; 320 Topic: Overactive Bladder
Dra Melissa Cifuentes
Dra Melissa Cifuentes

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320

Validation of a cholinergic-induced model of detrusor overactivity using a rat isolated whole bladder

Cifuentes, M1; Cifuentes, F2; Palacios, J3; Acevedo, R4; Paredes, A2; Lavado, A2; Gutierrez, C2; Vega, JL2

1: Universidad de Valparaíso; 2: Laboratorio de Fisiología Experimental (EPhyL), Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile.; 3: Laboratorio de Bioquímica Aplicada, Facultad de Ciencias de la Salud, Universidad Arturo Prat, Iquique, Chile ; 4: Fundación La Mano Verde, Viña del Mar, Chile

Introduction: The etiology of Detrusor overactivity is related to involuntary detrusor contractions during the filling phase that causes urinary urgency and increased urinary frequency.

Objective: To describe and validate a model of detrusor overactivity in isolated rat whole bladder.

Methods: Sprague-Dawley rat (250 g) were used, after approval of the bioethics committee (CEIC-REV/2013). In some experiments, both ureters were ligated in situ and then the bladder was excised. The proximal end of the urethra was tied around a stainless steel tube. For the vesical administration, a ureter was ligated and another was cannulated with PE-50 tube. The bladder was suspended in a 20 mL organ bath containing oxygenated Krebs Ringer solution at 37°C by constant bubbling with 95% O2 and 5% CO2. The bladder was slowly filled with 0.5 mL of Krebs solution and connected to pressure transducer (TSD120, Biopac Systems, USA) for measurement of intravesical pressure, which reflects contraction of the detrusor. In some protocols, the drugs was exogenously apply into the bath, and the others for the intravesical administration by PE-50 tube. The intravesical pressure was measured using the AcqKnowledge 3.9.1.6 computer program. One-way ANOVA was carried out to detect significant differences, using Software GraphPad Prism 7.00.

Results: Carbachol 1 µM added extravesically caused a sustained and reproducible overactivity of the detrusor in whole bladder. Frequency and pressure of overactivity were 3.9 ± 1.4 bpm and 25 ± 7 mmHg, respectively. Interestingly, carbachol added intravesically does not induce detrusor overactivity. The extravesical addition of oxybutynin 10 nM or trospium chloride 10 nM (muscarinic blockers, M2 y M3)
during the stable phase of carbachol-induced overactivity, significantly reduced vesical pressure and overactivity. The pre-incubation with oxybutynin reduced 60% the vesical pressure before of carbachol stimulation. While, atropine (a non-selective muscarinic antagonist) prevented contractile effect of carbachol. Similar results were obtained in a model of rat bladder rings.

Conclusion: This model that lacks nervous regulation, allows to study parameters such as intravesical pressures and volume, which are involved in the mechanism of detrusor overactivity. This could have relevance in the search of potential new therapies for overactive bladder syndrome.


Disclosure:

Work supported by industry: no.

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