Experimental Study On The Effects Of Bladder Outlet Obstruction On The Structure And Biomechanical Characteristics Of Bladder Detrusor

According to the urodynamics,the bladder outlet obstruction(BOO)carl be defined asthe resistance elevation of urine outflow at bladder neck and／or proximal urethral,which can be resulted in many causes．BOO is one of the most common pathophysiologieal basis of various clinic lower urinary diseases,which usually induces dysfunction of bladder detrusor smooth muscle cell(DSMC)and consequently some other serious complications．Although relieving obstruction is generally curative,bladder dysfunction persists in somepatients．For instance,about twenty·five percent of patients do not experience completerecovery of bladder function even though various therapeutic options may be offered up tonow according to statistics．Although the diseases resulting in BOO(e．g．benign prostatichyperplasia)can be treated,the abnormal function of detrusor and bladder keptunimproved,even got worse．There is still no therapy focusing on the fun~ional recoveryof bladder after BOO．It is of crucial importance to clarify the exact relationship betweenthe mechanism of bladder dysfuction and the abnormal structure of DSMC．For thesereasons,the three progressively experimental researches undermentioned were performed． Firstly,the relationship between abnormal structure and function of detrusor wasanalyzed after the modification of the obstruction model in rat．Secondl~by theapplication of cyclic mechanical stretch on the cultured DSMC,a brand new BOO modelat cell level was established,which is based on the urodynamic effect of BOO on detrusor．Third,it Was clarified that the phenotypic transformation(remodeling)of DSMC is thestructural basis of dysfunction and abnormal biomechanical characteristics which weredetermined directly at single cell level． The main results and conclusions: 1．The modified method of partial ligation on the proximal urethral of adult rats Wasclarified as a satisfying BOO animal model,vith simple procedure,high survival rate andtypical manifestations of obstruction． 2．The detrusor contractile force to carbachol ofdetrusor instability(DI)group showedsignificant decrease as compared with contr01．Conversely,the contraction ability of detrusor stability group at 2wk and 4wk after BOO resulted in higher and lower force generation as compared with mal-operation group respectively． 3．Observation with light microscope and electron microscope(transmission and scanning),VG dyeing of collagen fibers(CF)and computer-assisted image analysis wereperformed and demonstrated that extracellular matrix such as plenty of collagensaccumulated,which resulted in the elevation of CF／DSMC ratio after BOO． 4．Western blot analysis demonstrated that the protein expression of TGF-β1 indetrusor was progressively elevated through 1 to 4 weeks after BOO．This result suggeststhat TGF-β1 is related to the increase of collagen fibers produced by detrusor,whichdeposites among detrusor cells and affects the coordination of contraction．Furthermore,the time dependant trend of TGF-β1 is suggestive of bladder fibrosis following obstruction． 5．The immunohistochemistry of proliferation cell nuclear antigen(PCNA)in bladderdetrusor and computer-enhanced image analysis displayed increased positive index andreduced gray level value following BOO．The most obvious changes were found 2 weeksafter obstruction．The PCNA alteration might play important role in the proliferation andhyperplasia of detrusor smooth muscle ceils． 6．The culture of bladder detrusor smooth muscle cell from Wistar rat weresuccessfully performed by the method of collagenase digestion．The DSMCs grow inradiation form on 3rd-5th day and 80％surface ofthe culture plate bottom Was cOVered with DSMCs．This results showed that 0.2％collagenase concentration is vital important for the successful culture and is better than tissue clot culture method with higher DSMC purity． 7．Repetitive...