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Open Access Technical advance

Development of an in vitro model to measure bioactivity of botulinum neurotoxin A in rat bladder muscle strips

Janneke IM van Uhm1*, Goedele MA Beckers1, Willem J van der Laarse2, Eric JH Meuleman1, Albert A Geldof13 and Jakko A Nieuwenhuijzen1

Author Affiliations

1 Department of Urology, VU University Medical Center, PO Box 7057, Amsterdam 1007 MB, The Netherlands

2 Department of Physiology, VU University Medical Center, Amsterdam, The Netherlands

3 Department of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands

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BMC Urology 2014, 14:37  doi:10.1186/1471-2490-14-37

Published: 15 May 2014

Abstract

Background

Botulinum toxin A (BoNT-A) is a new treatment modality in various causes of bladder dysfunction; like neurogenic detrusor overactivity and overactive bladder. The best technique of administrating BoNT-A in patients is unknown. A validated in vitro model could be used to investigate newer intravesical administration techniques of BoNT-A. In this study, we describe the development and validation of in vitro model to measure inhibitory effects of BoNT-A on bladder strip contractions.

Methods

Rat bladder strips were mounted in organ baths filled with Krebs’ solution. The strips were stimulated chemically (80 mM potassium chloride, 1 μM carbachol) and electrically (Electrical Field Stimulation (EFS) 100 shocks, 50 V, 20 Hz, every 3 minutes). The viability of the strips was measured by carbachol stimulation at the beginning and at the end of the experiments. The strips were incubated in various concentrations of BoNT-A (0.03, 0.2, 0.3 nM). Controls were incubated in Krebs’ solution only. The inhibition of strip contraction induced by EFS was measured. These measurements were statistically analyzed with a log-logistic model representing diffusion.

Results

All strips remained viable during the experiments. Inhibition of strip contraction was observed after incubation with 0.3 nM BoNT-A. The measurements fitted to a log-logistic model describing diffusion of BoNT-A in the bladder strip. The parameters of the log-logistic model representing diffusion were significant for 0.3 nM BoNT-A. Incubation with 0.2 nM BoNT-A showed insignificant results for 2 out of 3 runs. Incubation with 0.03 nM BoNT-A did not result in significant inhibition of strip contractions.

Conclusions

An in vitro model was developed and validated in which the inhibitory effect of low concentrations of BoNT-A on bladder strip contractions can be measured.

Keywords:
Bladder; Botulinum toxin; Type A; In vitro