Changes in Urinary Bladder Smooth Muscle Contractility and the Role of Rho Kinase and Isoprostane after Partial Bladder outlet Obstruction in rats

Abstract

Objective: Bladder outlet obstruction is a common urological problem that associatedwith many cellular changes and remodeling of urinary bladder detrusor smoothmuscle. This study was designed to determine the changes in Rho kinase (ROCK) andisoprostane levels in urinary bladder homogenate after partial bladder outletobstruction (PBOO); and to evaluate the contractile response of isolated rat detrusormuscle after PBOO. Methods: The present work was carried out on 30 male albinorats that were divided into 3 groups (10 rats/group): group I: consisted of normalrats, they were sham operated and considered as control group, group II: consisted ofrats that were undergone PBOO for 14days, group III: consisted of rats that wereundergone PBOO for 28 days. The following parameters were assessed in rats of allgroups: urinary bladder weight, levels of both Rho kinase and isoprostane in thetissues of urinary bladder as well as the contractile response of detrusor muscle bothspontaneously and in response to acetyl choline. Results: The present study revealeda significant increase in the weight of urinary bladder in rats of PBOO of group IIand III as compared to sham operated control of group I. There was a significantincrease in the mean value of Rho kinase and isoprostane in the tissue of the urinarybladder after obstruction. 14 days after obstruction was associated with a significantincrease in the mean value of Rho kinase which was significantly high compared togroup I (sham operated rats) and group III (28days of obstruction), 28 days ofobstruction was associated with decrease in the mean value of Rho kinase comparedto 14 days of obstruction, however, its value was above the control. Regarding thecontractile response, PBOO was associated with increased spontaneous activity ofdetrusor muscle and increased tonic response to acetyl choline which wassignificantly high after 14 and 28 days of obstruction compared to the control.Conclusion: The results of the present study demonstrated that Rho kinase andisoprostane levels were elevated after bladder outlet obstruction and that Rho kinasecould play a crucial role in the regulation of rat urinary bladder smooth musclecontraction and tone. Therefore, Rho kinase inhibitors may prove to betherapeutically useful in the treatment of lower urinary tract disorders associatedwith changes in the physiology of bladder smooth muscle contractility.