Mirabegron is the first β3-adrenoceptor agonist that is clinically effective for overactive bladder.
The effects of mirabegron on primary bladder mechanosensitive single-unit afferent activities (SAAs) and bladder microcontractions were evaluated and compared with the effects of oxybutynin.
Design, setting, and participants
Female Sprague-Dawley rats were anesthetized. The SAAs generated from left L6 dorsal roots were identified by electrical stimulation of the left pelvic nerve and bladder distension. Nerves with conduction velocities (CVs) >2.5 m/s were designated as Aδ-fibers, and nerves with CVs
Outcome measurements and statistical analysis
Two measurements were performed in separate animals. First, after measuring the baselines of SAA during constant filling cystometry, the procedure was repeated with each intravenous administration of mirabegron at three doses—0.1, 0.3, and 1.0
Results and limitations
A total of 74 single-unit afferent fibers were isolated from 55 rats (Aδ-fibers: n
The present study demonstrates that mirabegron can inhibit mechanosensitive bladder afferent activity, especially of Aδ-fibers, which may be related to suppression of bladder microcontractions.
Keywords: β3-Adrenoceptor, Afferent, Sprague-Dawley rats, Urinary bladder.
a Department of Continence Medicine, The University of Tokyo Graduate School of Medicine, Tokyo, Japan
b Department of Urology, The University of Tokyo Graduate School of Medicine, Tokyo, Japan
Corresponding author. Department of Continence Medicine, The University of Tokyo Graduate School of Medicine, 7–3-1, Hongo, Bunkyo-ku, Tokyo, 113–8655, Japan. Tel. +81 3 5800 9792; Fax: +81 3 5800 9792.
© 2012 European Association of Urology, Published by Elsevier B.V.