CHANGE IN BLADDER CONTRACTILITY ASSOCIATED WITH BLADDER OVERACTIVITY IN RATS WITH CEREBRAL INFARCTION

Purpose: To evaluate the contractile properties of overactive bladder from rats in the chronic stage of experimental cerebral infarction. Ma terials and Methods: Cystometry was performed in conscious male S-D ra ts after inducing occlusion of the left middle cerebral artery. Bladde r muscle strips were evaluated for force development in response to fi eld stimulation, acetylcholine and KCl. By measuring the contractile r esponse to field stimulation after adding atropine and alpha,beta-meth ylene-ATP, contributions of cholinergic and purinergic transmission we re determined. Results: Bladder capacity of cerebral-infarcted rats wa s <50% of the capacity of sham-operated rats and significantly less th an that of sham-operated rats even 4 months after surgery. There was n o significant difference in bladder weight between sham-operated rats and cerebral-infarcted rats. No differences in the contractile respons e of detrusor strips to field stimulation and acetylcholine, or in the relative contribution of cholinergic and purinergic transmission to t he contractile response, were observed over time or between strips fro m sham-operated rats and cerebral-infarcted rats. KCl induced signific antly less contraction in strips from 4 month infarcted rats than in s trips from 4 month sham-operated rats, 2 week infarcted rats and 2 mon th infarcted rats. Conclusions: This animal model will be useful for c hronic studies on the mechanism of detrusor hyperactivity (DH).