Effect of bladder outflow obstruction on the innervation of the rabbit urinary bladder.

The effects of bladder outflow obstruction on the innervation of the bladder were studied using a rabbit animal model. Partial occlusion of the bladder neck was obtained by the placement of a silk ligature at that level; control animals underwent a sham procedure. After a 3-month period, the presence of outflow tract obstruction was confirmed using urodynamic studies. The animals were then killed and pharmacological assessments of the bladder innervation undertaken. Detrusor muscle strip studies provided evidence of damage to the cholinergic innervation of the detrusor. Also, muscle strips from obstructed animals showed reduced inhibitory responses to beta-adrenergic stimulation with isoprenaline. In addition to these muscle strip studies, the bladder content of the neuropeptide substance P was assayed, but no significant change was observed in response to obstruction. This finding suggests that substance P-containing sensory nerves may be spared from the denervating effect of bladder outflow obstruction.