The physiological response of the detrusor muscle to experimental bladder outflow obstruction in the pig.

An animal model of bladder outflow obstruction in the pig was used to study the physiological response of the detrusor muscle to obstruction. Bladder muscle strips from obstructed pigs showed a significant increase in sensitivity to acetylcholine and other pharmacological agents compared with controls. In contrast, the response to intramural nerve stimulation was significantly reduced in obstruction, with both cholinergic and non-cholinergic neurotransmission being affected. These findings are consistent with partial denervation of the bladder as a result of obstruction, with the subsequent development of supersensitivity of the detrusor smooth muscle. The occurrence of detrusor instability secondary to bladder outflow obstruction may represent the clinical manifestation of such physiological changes.