Bladder overactivity in mice after 1 week of outlet obstruction. Mainly afferent dysfunction?
OBJECTIVE
Partial bladder outlet obstruction (BOO) is an established way to create bladder overactivity in animals. However, the micturition pattern achieved can vary considerably. We investigated the correlation between different micturition patterns, post-void residual urine, bladder capacity, bladder weight and in vitro contractility in a conscious mouse model of BOO.


METHODS
Female MNRI mice with moderate (urethral) outlet obstruction were used. After 7 days of BOO cystometry without anesthesia was performed with the animal in a metabolic cage. Results were compared with those in unoperated controls and sham operated animals. In vitro contractility studies were performed.


RESULTS
The majority of obstructed animals had an overactive voiding pattern with increased nonvoiding detrusor activity and without increased bladder weight. The remaining obstructed animals had significantly increased bladder weight and normal micturition volume but increased threshold pressure, bladder capacity and post-void residual urine. Subtle in vitro differences were found among the groups.


CONCLUSIONS
The urodynamic characteristics of BOO mice correlate with bladder weight. However, detrusor overactivity in obstructed mice may develop without an increase in bladder weight and with only subtle changes in smooth muscle function, as investigated in vitro. This observation suggests that major disturbances caused by BOO may lie in the afferent arm of the signaling pathway.
Schröder
Annette
A
Department of Clinical Pharmacology, Lund University Hospital, 221-85 Lund, Sweden. annette.schroeder@klinfarm.lu.se
Uvelius
Bengt
B
Newgreen
Donald
D
Andersson
Karl-Erik
KE
D000818:Animals; D005260:Female; D066298:In Vitro Techniques; D051379:Mice; D008815:Mice, Inbred Strains; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000502:physiology; D009929:Organ Size; D011446:Prospective Studies; D001743:Urinary Bladder / Q000294:innervation / Q000503:physiopathology*; D001748:Urinary Bladder Neck Obstruction / Q000503:physiopathology*; D014563:Urodynamics