Expressions And Significances Of Heat Shock Protein20in Bladders Of Rats With Acute Urinary Retention

Background and Objectives：Acute urinary retention (AUR) is common but severe bladder dysfunction,whichusually leads to severe detrusor underactivity (DU). Many factors can lead to AUR, but thetreatment effectiveness is usually unsatisfactory, and the pathogenesis is still unknown.For normal voiding function, its power must rely on sound muscle cells related tovoiding, and the most important cells are detrusor smooth muscle cells (DSMC). Accordingto the classical sliding filament theory of muscle contraction, smooth muscle contractiondepends on the thickness of myofilament slide relative displacement caused by muscle celllength changes. The process involves including neurotransmitter and receptor, the variousshrinkage related protein and enzyme activation and other events. While the cytoskeletonintegrity is maintained smooth muscle contractile structure foundation, but also a variety ofmechanisms of injury causes contraction of smooth muscle dysfunction common pathway.As a special kind of detrusor of bladder smooth muscle contraction, the regulationmechanism appears to be related to skeletal muscle is more similar, i.e. for the contractileforce and contraction of accuracy is higher, so the stability and precision of the filamentstructure is the guarantee of normal detrusor contraction based. A lot ofcontraction-associated proteins (such as calcium. D, CaD) abnormalities can lead directlyto detrusor actin heterogeneous, and detrusor myocyte hypertrophy. Pathologicalmechanism closely related.Hsp20is a member of the small heat shock protein family, which is described by Katoet al in1994from the skeletal muscle tissue in purification of alpha B crystal protein,Hsp27. Hsp20is expressed in systemic tissues and organs and are mainly distributed in theskeletal muscle, myocardium, vascular smooth muscle, gastrointestinal smooth muscle andbladder detrusor tissue. Research shows that, Hsp20has many biological functions such asregulation of vascular, gastrointestinal, uterine smooth muscle contraction. Sonemany Salinthone et al found that Hsp20could be phosphorylated via PKA signaling pathway, andphosphorylated Hsp20is sufficient to relax smooth muscle, in some cases independent ofchanges in myosin light chain phosphorylation. But the function and mechanism of theHsp20in bladder has not been reported.In this study，we used immunohistochemistry,bladder urodynamic testing,muscleexcitability and contractility of measurement,laser scanning confocal techniques,and soon.Through comparing the bladder detrusor contractility and the expression of Hsp20inAUR rats and normal control rats bladders, preliminarily explore the relationship betweenHsp20with contractile function of uric muscle in rats after acute urinary retention,andprovide a new target point for clinic treatment.Method：Animal model of AUR was established by ligating the external orifice of urethra in rats.Filling cystometry was performed to evaluate the contractile function at0h,1h,6h,12h,24h,3d,5d,7d after AUR. The changes of detrusor excitability and contractilitycompliance were examined by the detrusor strip study in vitro. immunofluorescence andwestern blot were employed to detect and compare the expressions of Hsp20at0h,1h,6h,12h,24h,3d,5d,7d after AUR. preliminarily explore the relationship between Hsp20withcontractile function of uric muscle in rats after acute urinary retention,At last，theseparameters got from both groups were anlyzed with t text.Results：The contractile function of uric muscle was decreased in a time-dependentmanner at1,6,12and24hours after AUR (P <0.05). The maximum detrusor pressure of3d,5d,7dgroup significant rebound over1h,6h,12h and24h group, but was still below the0h groupand control group (P <0.05); The contraction frequency (P<0.05) and amplitude of strips ofdiabetic rat bladder were decreased. Expressions of Hsp20after AUR were a gradualupward trend within24h,and were gradually reduced from24h to7days is graduallyreduced after AUR, but all were significantly higher than control group, the difference wasstatistically significant (P <0.05).Conclusion1. The excitability and contractility of bladder significantly decrease or disappear inAUR bladder of rats, which may be associated with the muscle-derived factors. 2. The upregulation of the expressions of hsp20in the detrusor have a protective effectto detrusor cells after AUR, but it may be one of the factors for the inhibition of detrusormuscle cell contraction after AUR.