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

Objective: Bladder outlet obstruction is a common urological problem that associated
with many cellular changes and remodeling of urinary bladder detrusor smooth
muscle. This study was designed to determine the changes in Rho kinase (ROCK) and
isoprostane levels in urinary bladder homogenate after partial bladder outlet
obstruction (PBOO); and to evaluate the contractile response of isolated rat detrusor
muscle after PBOO. Methods: The present work was carried out on 30 male albino
rats that were divided into 3 groups (10 rats/group): group I: consisted of normal
rats, they were sham operated and considered as control group, group II: consisted of
rats that were undergone PBOO for 14days, group III: consisted of rats that were
undergone PBOO for 28 days. The following parameters were assessed in rats of all
groups: urinary bladder weight, levels of both Rho kinase and isoprostane in the
tissues of urinary bladder as well as the contractile response of detrusor muscle both
spontaneously and in response to acetyl choline. Results: The present study revealed
a significant increase in the weight of urinary bladder in rats of PBOO of group II
and III as compared to sham operated control of group I. There was a significant
increase in the mean value of Rho kinase and isoprostane in the tissue of the urinary
bladder after obstruction. 14 days after obstruction was associated with a significant
increase in the mean value of Rho kinase which was significantly high compared to
group I (sham operated rats) and group III (28days of obstruction), 28 days of
obstruction was associated with decrease in the mean value of Rho kinase compared
to 14 days of obstruction, however, its value was above the control. Regarding the
contractile response, PBOO was associated with increased spontaneous activity of
detrusor muscle and increased tonic response to acetyl choline which was
significantly high after 14 and 28 days of obstruction compared to the control.
Conclusion: The results of the present study demonstrated that Rho kinase and
isoprostane levels were elevated after bladder outlet obstruction and that Rho kinase
could play a crucial role in the regulation of rat urinary bladder smooth muscle
contraction and tone. Therefore, Rho kinase inhibitors may prove to be
therapeutically useful in the treatment of lower urinary tract disorders associated
with changes in the physiology of bladder smooth muscle contractility.