Relationship between Rho kinase pathway and the increase of bladder detrusor contraction in rats stimulated by potassium

Abstract

Objective To investigate the relationship between RhoA/Rho kinase pathway and the increase of bladder detrusor contraction in rats stimulated repeatedly by potassium.Methods A total of 20 female SD rats were randomly divided into two groups:experiment group and control group (n =10 each).Intravesical protamine sulfate (10 g/L) and potassium chloride (500 mmol/L) were administered to experiment group once every 3 d for 2 months.Normal saline was used for controls.Urodynamic examinations were conducted subsequently in both groups after 2 months.Bladder detrusor strips isolated from both two groups were first precontracted,then relaxant effects of Y-27632 were observed.Results The bladder intercontraction interval and bladder capacity were significantly reduced [(256 ± 51) s vs.(566 ± 54) s,and (226 ±60) μl vs.(394 ±37) μl,P ＜0.01],and the bladder nonvoiding contractions and pressure threshold were obviously increased [(2.32 ± 0.45) times/min vs.(0.86 ± 0.27) times/min,(9.39 ± 1.2) mm Hg (1 mm Hg=0.133 kPa) vs.(6.03 ±0.81) mm Hg,P＜0.01] in experiment group as compared with control group.As compared with control group,the sensitivity and maximum relaxant effect of Y-27632 were increased significantly in experiment group [(71.5 ± 2.8)％ vs.(45.1 ± 3.1)％,P ＜ 0.01].Conclusion Repeated stimulation of rat bladder tissues by potassium can increase the contraction sensitivity of bladder detrusor,which may be related to the RhoA/Rho kinase pathway.It is deduced that potassium may increase the contractility of bladder detrusor through the RhoA/Rho kinase pathway,leading to the occurrence of interstitial cystitis. Key words: Rho kinase ; Cystitis,interstitial; Bladder detrusor muscle