Early sequential changes in bladder function after partial bladder outlet obstruction in awake sprague-dawley rats: focus on the decompensated bladder

PURPOSE

We investigated bladder function, with special focus on initial functional changes, by objective report of decompensated bladder according to the percentage of residual urine volume to bladder capacity in awake, obstructed rats.

MATERIALS AND METHODS

Thirty rats were randomly subjected to sham operations (n=10) or partial bladder outlet obstruction (BOO, n=20). Cystometric investigations were performed without anesthesia 1 or 2 weeks after BOO surgery. To reduce the influence of confounding factors in awake cystometry, we used simultaneous recordings of intravesical and intraabdominal pressures. Decompensated bladder was defined as the bladder with more than 20% of residual volume compared with bladder capacity.

RESULTS

Compared with that in sham animals, basal pressure was elevated in both BOO groups. Threshold pressure was higher in the 2 week BOO (p<0.01) group. Compliance was decreased in the 1 week BOO group (p<0.01) and increased in the 2 week BOO group (p<0.001). Bladder capacity was not increased in the 1 week BOO group, but was increased in the 2 week BOO group (p<0.01). Decompensation was found in 62.5% of the 1 week BOO group and in 33.3% of the 2 week BOO group.

CONCLUSIONS

From the earlier phase, the bladders exhibited serial changes in pressure and volume parameters, and decompensated bladders defined by the percentage of residual volume to bladder capacity could be seen. During the later phase, there was an increasing tendency of compensated bladders, accompanied by the bladders being enlarged and more compliant.

Effects of level of consciousness on urodynamic procedure in female cats

Urodynamic evaluation is an invasive and uncomfortable procedure that can cause physical distress and is difficult to perform in uncooperative patients. The aim of this study was to evaluate the effects of consciousness on urodynamic evaluation in an animal model. Repeated cystometry, electromyogram, and measurement of serum cortisol concentrations were performed in female cats under conscious (CON), conscious sedation (CS) and deep anesthesia (DA) conditions. Urodynamic evaluation showed that there were no statistical differences in maximum detrusor pressure or bladder capacity observed among the three conditions. Under the DA condition, but not the CON and CS conditions, bladder contraction was accompanied by an un-relaxed anal sphincter. Residue urine volume significantly increased in the DA condition compared to the CON and CS conditions. The levels of serum cortisol significantly increased after performing urodynamic evaluation under the CON condition, whereas these levels were not significantly increased under the CS and DA conditions. This study showed that conscious sedation has no adverse effects on the urodynamic variables, and that it significantly reduces distress in cats undergoing the examination. These results may provide novel insights for performing urodynamic studies in uncooperative patients.

Changes in Awake Cystometry and Expression of Bladder β-adrenoceptors after Partial Bladder Outlet Obstruction in Male Rats

PURPOSE

To explore possible changes in awake cystometry and expression of beta-adrenoceptors (ARs) as a cause for bladder dysfunction in a male rat model of partial bladder outlet obstruction (pBOO).

MATERIALS AND METHODS

Awake cystometry was performed in rats with pBOO (16) and sham-operated rats (16), 8 weeks after the operation. The expression of mRNA and protein of β-ARs was assessed by real-time PCR and western blot.

RESULTS

The bladders with pBOO (1030mg) were increased compared to those in control rats (230mg). In the cystometric studies, the maximum intravesical pressure significantly increased in the pBOO group compared to control group rats (p=0.001). The time to reach maximal intravesical pressure during micturition in the pBOO group was significantly longer than the sham group (p=0.003). The frequency of non-void contraction in the pBOO group was significantly more than the sham group (p=0.006). The mRNA expressions of β2- and 3-ARs were increased insignificantly in pBOO group compared to sham group. The data of pBOO group expressed as folds of corresponding expression in sham group were 1.28 and 1.46 respectively in β2- and 3-ARs. Compared to the sham groups, the density of 60Kda protein band recognized by β2-AR antibodies and the density of 45Kda protein band recognized by β3-AR antibodies were higher in the bladder from pBOO group rats.

CONCLUSION

PBOO of male rats increase the maximal intravesical pressure and contraction time during micturition and the frequency of non-void contraction as well as weight of bladder. The expression of β2- and 3-ARs subtypes was increased insignificantly compared to sham operated group. This study demonstrates that the changes of cystometric or non-void contraction parameters in pBOO is one of the pathophysiologic processes potentially associated with the alterations of bladder β-ARs.

Intravesical PGE2 Administration in Conscious Rats as an Experimental Model of Detrusor Overactivity Observed by Simultaneous Registrations of Intravesical and Intraabdominal Pressures

PURPOSE

The urodynamic effects of intravesical PGE2 instillation on bladder function and detrusor overactivity (DO) during the filling phase were investigated in rats by measuring intraabdominal and intravesical pressures simultaneously.

MATERIALS AND METHODS

Continuous cystometry was performed inconscious, female and male Sprague- Dawley rats. We investigated pressure-, volume-, and DO-related parameters.

RESULTS

Intravesical instillation of PGE2 increased all pressure-related parameters and decreased volume-related ones, compared to the control cystometric ones. However, among the total number of intravesical pressure rises (IVPRs) above 2 cmH(2)O during the filling phase, only 33% in female rats and 38% in male rats after PGE2 instillation were identified as true DO during the filling phase.

CONCLUSIONS

Our findings suggest that the rat model with intravesical PGE2 is inappropriate for observing the effects of some drugs or mechanisms on DO, because only approximately 30% of IVPRs were confirmed as true DO. However, this model of intravesical PGE2 instillation has some advantages for the observation of changes in pressure and volume parameters rather than in DO-related ones.