Objective  To explore the density distribution of interstitial cells of Cajal (ICCs) in the bladder of rats with diabetes mellitus (DM) and its effects on the excitability of the detrusor and the bladder function. Methods  Animal models of DM were made in SD rats by intraperitoneal injection of streptozotocin and identified by fast blood glucose over 16.7 mmol/L. There were 2 groups of rats

DM group (n=20) and age-matched group (n=10). The residual urine volume

the maximum bladder capacity

the maximum bladder pressure and bladder compliance were examined by cystometry and compared between DM group and control group 12 weeks later. The changes of detrusor excitability and contractility compliance were examined by the detrusor strip study in vitro. The ICCs in detrusor tissue pieces were detected by immunofluorescent staining. At last

these parameters got from both groups were analyzed with t test. Results  In diabetic rats

the residual urine volume (P0.01)

the maximum bladder capacity (P0.01) and compliance (P0.01) were increased

however the maximum bladder pressure (P0.05) was decreased compared to that in the controls. The contraction frequency (P0.05) and amplitude of strips of diabetic rat bladder were decreased. There were less ICCs in the bladder detrusor of rats with DM than that in controls (P0.05). Conclusion  ICCs in bladder of rats with DM are significantly decreased

which may play an important role in the changes of the excitability of detrusor and bladder function in DM rats.