Experimental Studies Of The Gap Junction Changes In The Unstable Bladder

Background and objective: Benign prostatic hyperplasia (BPH) is a very common disease in gerontic males. Detrusor instablty (DI)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 patients have been suffering from DI, it is urgent to take efficient measure to control it 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 , then observed the change of Cx43 in the detrusor by molecularbiology and morphology, in order to evaluate the quantitative changes of the gap junction (GJ), and to deduce its functional changes of GJ which mediates intercellular communication(GJIC) in unstable bladder, so as to demonstrate one of the mechanisms of the unstale bladder.Materials and methods: 50 female rats (Wistar , 200-220 g) were used in these studies, they were divided into two groups ,40 for the experimental group and 10 for the control group. The experimental group were producing lower urethral obstruction, and the control rats just execute sham-operationwith 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 the bladder was removed and stored. The normal detrusor was picked-up as control, then observed the change of Cx43 in the detrusor by western blot, HE staining and laser confocal microscopy and immunohistochemistry, directly observe the detrusor turbulence and gap junction increase located in cell membrane in unstable bladder. All data were expressed as means ± SE. Analysis of variance and other appropriate statistical analyses were performed.Results :1 There were 13 rats turn to be DI in the 37 rats of the experimental group(3 rats died ), the DI ratio of the experiment group was 35.1%. There was no rat turn to be DI in control group. The maximum cystometric capacity of the experimental group (1.63 ± 0.20ml ) obviously increased (P<0.01) contrast the control groups(0.28±0.12ml ), and the maximum pressure (55.75 ± 10.54 cmH20 )were obviously higher than the control groups(23.12 + 7.65cmH2O) (P<0.01).2 HE staining and observed under light microscopy: The smooth cell of the control group detrusor presented a shuttle shape, array paralleling and divide evenly. However, the detrusor cell of the DI group differed in size, varied in figure and arranged inordinately, some cell presented crescent-shaped or anomaly, the density of the nucleolus decreased.3 Western blots revealed Cx43 protein expression in both control ( averagegray level 11.701)and DI group( average gray level 31.066) and marked increase of Cx43 protein levels in DI group (PO.01) . 4 Laser confocal microscopy analysis of Cx43 expression in rat bladder: The fascicle of control group detrusor array parallelly and divide evenly, and the Cx43 expressed in very low level or scarcely. The detrusor of DI group differ in size, vary in figure and arrange inordinately. Cx43 expression increase obviously contrasted to the control group (P<0.01) , exhibited in the increase of pixel density(3.45±1.58 to 0.85 + 0.44) and staining size( 19.92 + 8.6 linn2 to 11.46+2.55 v m2) Conclusion: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 is may be one of the mechanisms for the unstable bladder.