Change in bladder contractility associated with bladder overactivity in rats with cerebral infarction

To evaluate the contractile properties of overactive bladder from rats in the chronic stage of experimental cerebral infarction.

Cystometry was performed in conscious male S-D rats after inducing occlusion of the left middle cerebral artery. Bladder muscle strips were evaluated for force development in response to field stimulation, acetylcholine and KCl. By measuring the contractile response to field stimulation after adding atropine and alpha,beta-methylene-ATP, contributions of cholinergic and purinergic transmission were determined.

Bladder capacity of cerebral-infarcted rats was <50% of the capacity of sham-operated rats and significantly less than that of sham-operated rats even 4 months after surgery. There was no significant difference in bladder weight between sham-operated rats and cerebral-infarcted rats. No differences in the contractile response of detrusor strips to field stimulation and acetylcholine, or in the relative contribution of cholinergic and purinergic transmission to the contractile response, were observed over time or between strips from sham-operated rats and cerebral-infarcted rats. KCl induced significantly less contraction in strips from 4 month infarcted rats than in strips from 4 month sham-operated rats, 2 week infarcted rats and 2 month infarcted rats.

This animal model will be useful for chronic studies on the mechanism of detrusor hyperactivity (DH).