Urodynamics and bladder muscarinic receptors in rats with cerebral infarction and bladder outlet obstruction.

We characterized muscarinic receptor binding and urodynamic parameters in rats with cerebral infarction and chronic bladder outlet obstruction as models of detrusor overactivity. Bladder weight showed little significant difference between the cerebral-infarcted and sham rats, but the bladder weight was about three times greater in the bladder outlet-obstructed rats. Bladder capacity and voided volume were significantly lower (36.7 and 55.1%, respectively) in the cerebral-infarcted than in the sham rats. Involuntary contractions before micturition were seen in the bladder outlet-obstructed rats but not in sham rats. The bladder outlet-obstructed rats showed significant increases (2.65 and 2.57 times, respectively) in bladder capacity and voided volume, compared with those in sham rats. Bmax values for specific [N-methyl-3H]scopolamine ([3H]NMS) binding in the bladder were significantly (34%) increased in the cerebral-infarcted rats compared with sham rats, whereas Kd was unaffected by infarction. On the other hand, there was little significant change in Kd and Bmax for specific [3H]NMS binding in the bladder-obstructed rats compared with sham rats. In conclusion, the present study shows that cerebral infarction but not bladder outlet obstruction in rats causes up-regulation of bladder muscarinic receptors, and that such regulation of bladder muscarinic receptors may be at least partly associated with the symptoms of detrusor overactivity subsequent to cerebral infarction.