| Background and objective:Benign prostatic hyperplasia(BPH) is a very familiar disease in gerontic males.Unstable bladder is one of the Pathological change caused by BPH, Which may be related to many symptoms such as incontinence,stress and urge etc. Many BPH patiens have been suffering from these symptoms and it is urgent to take efficient measure to control DI in clinic.However,the pathogenesis that BPH led to detrusor instability is still unknown.Recently,more and more studies showed that the mechanism of the detrusor instability caused by urethral obstruction may be related to the ultrastructural changes of detrusor.In this study,we constructed the rat model of urethral obstruction.After sacrificed,bladders of the rats were excised and bladder smooth muscle cells were cultured in vitro and cell anoxia was induced,then observed the change of connexins in the smooth muscle cells by molecularbiology,in order to study the quantitative changes of the gap junction(GJ),and to deduce its functional changes of GJ which mediates intercellular communication(GJIC) in bladder smooth muscle cells,so as to demonstrate one of the mechanisms of the unstale bladder.Materials and methods:60 female rats(Wistar,200-220 g) were used in these studies,they were divided into four groups,30 for the experimental group,10 for the control group, 10 for the cell hypoxia group and 10 for the cell hypoxia control group.The urethral obstruction of the experimental group was produced by partial ligatures of the lower urethral,and the control rats were executed sham-operation with the exception that the suture was never tied around the rod.Percutapubic cystostomy was operated 6 weeks later,followed by a filling cystometry.Then the DI rats were confirmed,and all the bladders of the rats were removed and bladder smooth muscle cells were cultured in vitro.Cell anoxia was induced by replaced the culture media with ischemia buffer and incubated at 37℃in the hypoxic chamber in an atmosphere of 0%O2/5%CO2 for 15-min,30-min and 1-hour.The change of connexins in the smooth muscle cells was observed by RT-PCR and western blot,so as to demonstrate one of the mechanisms of the unstable bladder.Results:1 There were 17 rats turn to be DI in experimental group,13 rats did not turn to be DI, the DI ratio of the experiment group was 56.7%.There was no rat turn to be DI in control group.2 Cell culture:The cultured cells were observed under the inverted microscope.When the cells made contact with the adjacent cells,they become classic spindle-shaped and formed a hill-and-valley appearance.Immunocytochemistry showed that over 95%of the populations were stained positive for SMC-actin.3 RT-PCR showed that Cx40 and Cx43 were expressed in all the cells.Cx40 and Cx43 were marked increase in DI and cell hypoxia groups when compared with their control groups.Moreover,it was showed that after 15min cell hypoxia,the expression of Cx43 were higher than that in the 30min and 1 hour groups.4 Western blot showed that Cx43 was expressed in all the cells and was marked increase in DI and cell hypoxia groups.Again,cells exposed to 15min hypoxia expressed the highest Cx43 protein in the cell hypoxia group.Conclusions:1.Lower urethral obstruction can cause many disfunction of emiction and it is the primary reason for the unstable bladder.2.There are a few gap junction in the normal detrusor,which is one of the requirement of a physiological emiction.While there are extensive gap junction in detrusor instability,that might be the direct reason for the unstable bladder.3.Cell hypoxia can elevate the expressions of connexins.Cell hypoxia induced by bladder outlet obstruction might be the pathogenesis of detrusor instability.
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