ATHEROSCLEROSIS-INDUCED CHRONIC ISCHEMIA CAUSES BLADDER FIBROSIS AND NON-COMPLIANCE IN THE RABBIT:

Mirodenafil prevents bladder dysfunction induced by chronic bladder ischemia in rats

Purpose:

To investigate the protective effect of mirodenafil on bladder function in a rat model of chronic bladder ischemia (CBI).

Methods:

Twenty-four Sprague-Dawley rats were randomized to three groups: untreated, sham-operated rats (control group); untreated, CBI model rats (CBI group); and CBI rats treated daily with 4 mg/kg mirodenafil (CBI+mirodenafil group). The CBI and CBI+mirodenafil groups underwent endothelial injury to the iliac arteries and were fed a 2% cholesterol diet after injury. Four weeks after surgery, the CBI+mirodenafil group started daily treatment with mirodenafil for four weeks. Eight weeks after surgery, continuous in vivo cystometry and in vivo organ bath studies of detrusor muscle strips were performed.

Results:

in vivo cystometry revealed that the rats in the CBI group had a significantly higher micturition frequency, lower bladder capacity, and lower compliance than the rats in the control and CBI+mirodenafil groups. The detrusor muscle strip study showed that the magnitude of the carbachol-induced contractile response was significantly lower in the CBI group compared to either the control or CBI+mirodenafil group. Addition of daily mirodenafil after induction of CBI decreased the contractile response, compared to untreated CBI rats. CBI induced submucosal fibrosis and degenerative changes in bladder walls, which was reversed by the addition of mirodenafil.

Conclusions:

Daily treatment with mirodenafil showed protective effects against bladder dysfunction resulting from CBI in rats.

Acute alterations in biochemistry, morphology and contractility of rat isolated urinary bladder via increased intra-abdominal pressure

OBJECTIVE

To determine the acute effects of increased intra-abdominal pressure (IAP) on the biochemistry, morphology and contractility of the rat isolated urinary bladder using an experimental laparoscopy model.

METHODS

We divided 24 adult female Sprague-Dawley rats into three groups. The control group (group I) was not subjected to increased IAP. In groups II and III, IAPs of 10 and 20 mm Hg, respectively, were established by carbon dioxide pneumoperitoneum for 60 min. Thirty minutes after desufflation, the rat urinary bladder dome was removed for in vitro pharmacological investigation, measurement of malondialdehyde (MDA) levels and histopathological examination. Statistical comparisons between groups were performed.

RESULTS

Tissue MDA levels in groups II and III were significantly higher than in the control group. In group II, only the lamina propria was significantly damaged. However, the epithelium, lamina propria, and serosa were significantly damaged in group III. Acetylcholine potentiated contractions in both IAP groups. Increased responses to electrical field stimulation in the IAP groups were significant only in group II.

CONCLUSIONS

In this experimental model, 10 and 20 mm Hg of IAP induced by pneumoperitoneum increased MDA levels and caused important changes in the morphology and contractile response of the urinary bladder.

Does ischemia-induced prostate damage during cardiac surgery involving cardiopulmonary bypass cause bladder outlet obstruction?

OBJECTIVE

This study sought to investigate whether ischemia-induced prostate damage during cardiac surgery involving cardiopulmonary bypass causes bladder outlet obstruction.

MATERIALS AND METHODS

The study involved 37 men who underwent elective cardiac surgery involving cardiopulmonary bypass. Prostate-specific antigen (PSA) levels were determined preoperatively (baseline) and on postoperative days 1, 5, and 30. In 4 cases, the PSA level after the operation was unchanged from the preoperative level, so these 4 men were excluded from the study. In the remaining 33 patients, symptoms of bladder outlet obstruction were assessed using the International Prostate Symptom Score. Each subject completed this test preoperatively and 3, 6 and 9 months postoperatively, and the means scores at these time points were compared. The effects of patient age, operative time, CPB time, and aortic clamping time on postoperative increases in PSA levels were investigated.

RESULTS

Thirty-three (89.2%) of the 37 men exhibited increased postoperative PSA levels compared to baseline. The mean PSA level for the 33 cases on day 5 was significantly higher than the baseline mean, but the mean levels on postoperative days 1 and 30 were comparable to baseline. Nine (24.3%) of the 33 men had postoperative PSA levels greater than 4.0 ng/dl (the upper normal limit). There was no significant difference between preoperative and postoperative International Prostate Symptom Scores.

CONCLUSION

The study indicates that men's PSA levels are, indeed, increased after cardiac surgery with cardiopulmonary bypass. However, in 9 months of follow-up, there was no association between this PSA rise and development of BOO, according to International Prostate Symptom Scores.

Ureteral ischemia model: an explanation of ureteral dysfunction after chronic obstruction

BACKGROUND AND PURPOSE

Many models of smooth muscle ischemia have been developed to explain organ insufficiency or failure. Ureteral decompensation may also be described in these terms. We anticipate that ureteral ischemia will result from overdistention brought about by obstruction. A preliminary model to create an ischemic ureter is described herein.

MATERIALS AND METHODS

Six white New Zealand female rabbits were used for this study. All had their left ureters surgically ligated at the level of the urinary bladder. The right ureters served as controls. In the acute-phase group, the ureters were all reexplored 2 weeks postobstruction. Exploration of the other rabbits was delayed for 3 more weeks. A laser Doppler needle (Transonics Inc.) was used to measure tissue perfusion in the rental artery, renal vein, renal parenchyma, renal pelvis, ureteropelvic junction, upper ureter, mid ureter, lower ureter, and lateral wall of the bladder. Baseline and postobstructive measurements of tissue perfusion were collected and compared.

RESULTS

In both the acute and the chronic obstruction groups, there was a demonstrable drop-off in perfusion of the ureteral sidewall. A more notable loss of perfusion was seen in the distal ureter.

CONCLUSION

The increased wall tension in the obstructed ureter results in a significant decrease in smooth muscle perfusion. This ischemia may result in the same functional and histologic changes that occur in other smooth muscle organs. Ultimately, the poor outcomes of some restorative/reconstructive procedures on the ureter may be explained in terms of smooth muscle ischemia.

Ureteral ischemia model: an explanation of ureteral dysfunction after chronic obstruction

BACKGROUND AND PURPOSE

Many models of smooth muscle ischemia have been developed to explain organ insufficiency or failure. Ureteral decompensation may also be described in these terms. We anticipate that ureteral ischemia will result from overdistention brought about by obstruction. A preliminary model of an ischemic ureter is described herein.

MATERIALS AND METHODS

Six female New Zealand rabbits were used for this study. All had their left ureters surgically ligated at the level of the urinary bladder. The right ureters served as controls. In the acute-phase group, the ureters were reexplored 2 weeks after creation of obstruction. The other three rabbits were explored 3 weeks later. A laser Doppler needle was used to measure tissue perfusion with bilateral measurements of the renal artery and vein; renal parenchyma; renal pelvis; ureteropelvic junction; upper, mid, and lower ureter; and the lateral wall of the bladder. Baseline and postobstructive measurements of tissue perfusion were collected.

RESULTS

In both the acute and chronic obstruction groups, there was a demonstrable drop-off in perfusion of the ureteral wall.

CONCLUSION

The increased wall tension in the obstructed ureter results in a significant decrease in smooth muscle perfusion. This ischemia may result in the same functional and histologic changes that occur in other smooth muscle organs deprived of normal blood flow. Ultimately, poor outcomes of some restorative/reconstructive operations on the ureter may be explainable in terms of smooth muscle ischemia.