Objective: To compare the structures and functions of rabbit bladder after partial bladder outlet obstruction versus without ischemia so as to explore the effects of ischemia on bladder pathogenesis in rabbits with partial bladder outlet obstruction.
Methods: A total of 64 mature male rabbits were divided into 4 groups (n = 16 each). Four of each group underwent operation to establish an ischemic animal model (ischemia group), another 4 underwent operation to establish a partial bladder outlet obstruction animal model (obstruct group), the other 4 underwent operation to establish an ischemic and partial bladder outlet obstruction animal model (combination group) and the remaining 4 underwent a sham operation as control. The rabbits in 4 groups were evaluated at Week 1, 2, 4 and 8 post-operation respectively. The weight of bladder, the thickness of mucosal, submucosa, muscular layer and placenta percreta and the activities of sarco/endoplasmic reticulum Ca(2+) ATPase citrate synthase of cystic smooth muscle were detected respectively. MASSON staining was used to observe the smooth muscle and collagen in stroma of bladder and S-100 staining for observing the neurons in bladder.
Results: In obstruct and combination groups, the weights of bladder at week 1 were (5.10 ± 0.29) g and (4.80 ± 0.37) g respectively. They were both significantly higher than control group [(1.93 ± 0.17) g, all P < 0.05]. The weights of bladder in obstruct and combination groups peaked at Week 4 and they were (18.48 ± 2.03) g and (12.35 ± 0.39) g respectively. The weight of bladder in obstruct group was significantly heavier than combination group in the same terms. And they were both significantly heavier than control and ischemia groups (all P < 0.05). Muscular tissue vicariously thickened during the first 4 weeks, and collagen and stroma increased at Week 4 in obstruct group. Muscular tissue, collagen and stroma all increased initially. But at Week 2 only collagen and stroma increased in combination group. Compare with control group, the other groups all have deletion of neurons, especially in combination group. The activities of sarco/endoplasmic reticulum Ca(2+) ATPase and citrate synthase of cystic smooth muscle of obstruct group peaked at Week 4. In combination group, the activities of sarco/endoplasmic reticulum Ca(2+) ATPase and citrate synthase of cystic smooth muscle were decreased over 2 - 8 weeks. In the same terms, the activities of sarco/endoplasmic reticulum Ca(2+) ATPase and citrate synthase of cystic smooth muscle in control group were significantly higher than those in obstruct and combination groups (all P < 0.05).
Conclusion: Ischemia can reduce the tolerance of bladder and aggravate the impairment of bladder to partial outlet obstruction.