Increased blood flow after catheterization and drainage in the chronically obstructed rabbit urinary bladder

[Functional results after temporary continuous drainage of the hypocontractile bladder. The potential rehabilitation of the detrusor]

BACKGROUND

Impaired bladder emptying is a common problem in older people and a challenging task in treatment. Conservative and medical treatment options have shown beneficial effects on micturition; however, in a substantial number of patients the effectiveness of these therapies is disappointing. In the end the decompensated bladder needs indwelling catheterisation. To study the effects on the detrusor function, we analysed the urodynamic data of 31 patients during long-term bladder drainage retrospectively.

PATIENTS AND METHODS

All 17 female and 14 male patients showed impaired detrusor contractility, enlarged bladder capacity, decreased sensitivity and a high post-void residual urine volume (PVR). After exclusion of an acute pathology, the patients were treated continuously with a suprapubic catheter for an average of 13.1 weeks. By urodynamic measurements before and after the drainage period, we analysed the filling parameters, pressure-flow patterns, PVR and detrusor contractility.

RESULTS

At the end of the drainage period, significant changes in the detrusor function were obvious. Compared with the pre-treatment situation, the bladder volume at first desire to void decreased from 306.92 ml to 281.7 ml and the maximum bladder capacity from 691.8 ml to 496.8 ml, respectively. The compliance of the detrusor muscle diminished in the same period of time from 65.6 ml/cmH2O to 51.8 ml/cmH2O. The PVR dropped by 227.2 ml in average. The maximum flow rate was 9.4 ml/s, and the maximum detrusor pressure increased slightly up to 23.6 cmH2O.

CONCLUSION

The continuous drainage of the bladder results in significant changes in the motoric as well as sensoric detrusor function. The reduced bladder capacity and the decreased PVR might be indications of a regenerating process of the detrusor. The long-term drainage of the bladder shows beneficial and therefore therapeutic effects. It still remains to be investigated on a functional as well as structural basis to what extent age, gender and pathogenesis influences the rehabilitation of the detrusor.

Role of Nitric Oxide in Urinary Bladder Function: Effect of L-Arginine

BACKGROUND

Evidence indicates that decreased blood flow to the bladder plays a major role in obstructive bladder dysfunction in the rabbit model of partial bladder outlet obstruction (PBOO), and that nitric oxide (NO) regulation of blood flow may be important in modulating the degree of obstructive bladder dysfunction. The specific aim of our study is to determine the effect of feeding rabbits a diet high in L-arginine on the response to PBOO.

MATERIALS AND METHODS

Sixteen male NZ White rabbits were separated into 4 groups of 4 each. The rabbits in groups 1 and 3 underwent PBOO. The rabbits in groups 2 and 4 were sham-operated. For 1 week prior to surgery, and 2 weeks postoperatively, each rabbit in groups 1 and 2 was put on a diet containing 7% arginine. Rabbits in groups 3 and 4 were on a normal diet (0.76% arginine).

RESULTS

PBOO resulted in a greater increase in bladder weight in the control group than the arginine group. PBOO resulted in a greater decrease in compliance in the control group than the arginine group. The contractile responses to all agents in the arginine control group were greater than in the control normal diet group. PBOO resulted in a greater decrease in the response to field stimulation in the control group than in the arginine group.

CONCLUSIONS

These studies clearly demonstrate that feeding rabbits a diet high in L-arginine was beneficial for the control rabbits, and reduced the level of dysfunctions following PBOO.

Edaravone protects against ischemia/reperfusion-induced functional and biochemical changes in rat urinary bladder

OBJECTIVES

To investigate the effects of edaravone on ischemia/reperfusion (I/R) injury in the rat bladder. Increasing evidence has shown that I/R are major etiologic factors in the progression of bladder dysfunction induced by partial outlet obstruction, and that part of the damage is due to the generation of free radicals. Edaravone is a newly developed radical scavenging agent that has been used for protection against I/R injury in patients with cerebral infarction.

METHODS

Thirty-five adult male rats were divided into five groups. Groups 1 to 4 underwent 1 hour of ischemia followed by 1 hour of reperfusion. Groups 1 to 3 were treated with edaravone at 1, 3, or 10 mg/kg body weight and group 4 with saline. Group 5 consisted of age-matched control rats. In vivo ischemia was created by clamping the vesical arteries for 1 hour. Reperfusion was accomplished by removing the clips and also lasted for 1 hour. Edaravone or saline was administered into the femoral artery after reperfusion for 30 minutes. After reperfusion, the bladder was excised and separated. The responses to electrical field stimulation, carbachol, and KCl were recorded. Other materials were analyzed for malondialdehyde as a measure of lipid peroxidation.

RESULTS

Edaravone administration resulted in protection of the contractile responses to both field stimulation and carbachol, although the responses to KCl were not affected. I/R resulted in an increase in malondialdehyde, which was reduced to control levels by edaravone.

CONCLUSIONS

These results suggest that edaravone has a potential protective effect against I/R-induced damage in the rat bladder.

Effect of partial outlet obstruction on nitrotyrosine content and distribution within the rabbit bladder

PURPOSE

Evidence indicates that free radicals are etiological factors in obstructive bladder disease. However, it is not clear which species of reactive oxygen or nitrogen species mediate the damage. The current studies were designed to determine if partial outlet obstruction in rabbits results in the generation of nitrotyrosine (NT).

MATERIALS AND METHODS

Sixteen rabbits were separated into four groups of four. The rabbits in groups 1 and 2 underwent sham operation while rabbits in groups 3 and 4 underwent partial outlet obstruction. The rabbits in groups 1 and 3 were evaluated after 1 week of obstruction and the rabbits in groups 2 and 4 were evaluated after 2 weeks of obstruction. A separate group of four controls were evaluated simultaneously with the sham and obstructed rabbits. Four rabbits from each group were evaluated after 1 and 2 weeks of obstruction. Four control rabbits were also evaluated. Isolated strips were evaluated for contractile responses and NT content of the mucosa and muscle were quantitated by Western blot analysis.

RESULTS

(1) The mucosa contains both 42 and 62 kD proteins exhibiting a strong nitrotyrosine signal; the muscle presents a signal only at 62 kD. (2) The sham operations had no effect on nitrotyrosine distribution or content. (3) The nitrotyrosine of both mucosal proteins and the muscle protein are increased in the 1 week obstructed bladder; whereas, only the 62 kD signal is increased in the two week obstructed bladder mucosa. (4) The contractile response to FS are reduced to a significantly greater degree than the responses to carbachol, KCl, or ATP.

CONCLUSIONS

These studies clearly demonstrated that partial outlet obstruction in rabbits results in significant increases in nitrotyrosine within the bladder and may contribute to the contractile dysfunctions mediated by partial outlet obstruction.

Regional differences in responses of rabbit detrusor to electrical and adrenergic stimulation: influence of outlet obstruction

OBJECTIVE

To examine regional responses of control and obstructed rabbit detrusor strips to electrical and adrenergic stimulation, and determine whether outlet obstruction causes regional variations in blood flow throughout the detrusor, as the detrusor smooth muscle of the bladder body has previously been considered homogeneous in its pharmacological properties.

MATERIALS AND METHODS

Fourteen male rabbits had the bladder outlet surgically obstructed for 2 weeks and were compared with 10 unoperated control rabbits. Blood flow was measured with the bladder empty and at capacity, using fluorescent microspheres. Paired dorsal and ventral strips were harvested from the midline equatorial detrusor and electrically and adrenergically stimulated.

RESULTS

Obstructed rabbits had significantly higher bladder capacities and bladder weights than control rabbits. Dorsal strips from both control and obstructed rabbits contracted in response to noradrenaline, whereas ventral strips relaxed. The addition of prazosin, a nonselective alpha1-adrenergic-receptor blocker, completely blocked the contraction in dorsal strips, but had no effect on responses of ventral strips. There was also a regional difference in response to electrical stimulation, with ventral strips generating significantly more tension than dorsal strips in both control and obstructed rabbits. There were no regional differences in detrusor blood flow. Obstruction resulted in significantly lower responses to all forms of stimulation, and significantly less blood flow throughout the detrusor.

CONCLUSION

There are regional differences in adrenergic receptor function and response to electrical-field stimulation throughout control and obstructed rabbit detrusor, a region that was previously thought to be functionally homogeneous. These differences must be recognized and acknowledged to obtain accurate and reproducible data from in vitro studies of the bladder.

Mechanistic insights into the role of α1-adrenergic receptors in lower urinary tract symptoms

Although alpha(1)AR antagonists have been used for more than two decades to treat lower urinary tract symptoms (LUTS), we have little understanding of the mechanistic basis of their efficacy and their role in the development of LUTS. It is clear that alpha(1)ARs play a critical role in bladder dysfunction and recent data suggest that alpha(1)AR subtype switching may play a key role in this pathophysiology, providing support for use of alpha(1)(d)AR-selective antagonists in treating irritative symptoms. This review seeks to summarize current levels of understanding in this field and discusses new concepts that suggest increased levels of complexity involving cross-talk in multiple receptor systems. Effective therapeutic modalities likely will involve increased subtype selective alpha(1)AR antagonists and other pharmacodynamic factors.

Hypoxia preconditioning attenuates bladder overdistension-induced oxidative injury by up-regulation of Bcl-2 in the rat

We explored whether hypoxic preconditioning minimizes oxidative injury induced by overdistension/emptying in the rat bladder. For hypoxic preconditioning, female Wistar rats were placed in a hypobaric chamber (380 Torr) 15 h day(-1) for 28 days. Overdistension was induced by infusion of two times the threshold volume of saline into the bladder and was maintained for 1 or 2 h, followed by drainage/emptying. During overdistension (ischaemia) and emptying (reperfusion) periods, a bursting increase of reactive oxygen species (ROS) from the bladder was originated from the large numbers of infiltrating leucocytes and scattered resident cells, including urothelial, submucosal, and smooth muscle cells. ROS impaired the voiding function by a reduction of bladder afferent and efferent nerve activity and bethanecol- or ATP-induced detrusor contraction. ROS enhanced pro-apoptotic mechanisms, including increases in the Bax/Bcl-2 ratio, CPP32 expression, and poly(ADP-ribose) polymerase (PARP) fragments with subsequent apoptotic cell formation in the insulted bladders. Hypoxia preconditioning up-regulated Bcl-2 expression in the bladder and significantly reduced the levels of ROS and apoptosis detected in the overdistension/emptying bladders and preserved partial voiding function. Bcl-2 up-regulation by hypoxia preconditioning contributes protection against overdistension/emptying-induced oxidative stress and injury in the bladder.

Reperfusion injury of the rat bladder is worse than ischemia

PURPOSE

Previous studies have demonstrated that in vivo and in vitro ischemia of the bladder results in decreased contractile responses. However, to our knowledge the effect of reperfusion following ischemia of the bladder is not known.

MATERIALS AND METHODS

Adult male rats were subjected to bilateral bladder ischemia and varying periods of reperfusion. In vivo ischemia was created for 4 hours by reversibly clamping the 2 vesical arteries for 4 hours. Reperfusion was produced by removing the clamps and allowing the animals to recover for 1 day, 1 week or 1 month after surgery. Following recovery bladders strips were studied using field stimulation (FS), carbachol and KCl. The maximal contractile response and rate of response generated were recorded digitally and analyzed.

RESULTS

The maximal responses to FS, carbachol and adenosine triphosphate (ATP) were not decreased by 4-hour ischemia alone, whereas the response to KCl was decreased significantly. The contractile responses to FS and KCl were significantly decreased after 1 day and 1 week of reperfusion. Responses after 1 month of reperfusion were increased significantly compared with responses after 1 week of reperfusion. The responses to ATP were not affected by ischemia or reperfusion. The contractile response to KCl was significantly more sensitive to ischemia than the responses to carbachol, ATP or FS, whereas the contractile response to FS was significantly more sensitive to reperfusion than the other forms of stimulation.

CONCLUSIONS

This study demonstrates clearly that injury by reperfusion following ischemia is more detrimental than the effects of ischemia alone and FS contraction is the most sensitive form of stimulation to reperfusion damage. This study also demonstrates the ability of the bladder to recover from ischemic and reperfusion injuries.

Regulation of blood flow and microcirculation resistance in rabbit bladder

PURPOSE

Human and animal studies have shown that filling, contraction and emptying produce cyclical changes in bladder blood flow. The mechanism of these hemodynamic changes remains unclear. We studied the regulation of bladder blood flow in the rabbit model.

MATERIALS AND METHODS

A total of 18 male New Zealand White rabbits were anesthetized. Arterial pressure, intravesical pressure, and dome and base blood flow were measured simultaneously in the empty bladder, at 25 and 50 ml. intravesical volume, and after draining. These measurements were recorded before and then after intravenous administration of atropine, phentolamine, propranolol, L-arginine or N-nitro-L-arginine. Changes in dome and base microcirculation resistance, and blood flow after treatment were compared with those recorded before treatment.

RESULTS

In the empty bladder dome microcirculation resistance was greater than at the base and base blood flow was greater than at the dome. Filling increased dome microcirculation resistance, decreased dome blood flow and increased base blood flow without changing base microcirculation resistance. Emptying produced much greater reactive hyperemia at the dome than at the base. Atropine did not alter microcirculation resistance or blood flow. Phentolamine had no effect on dome or base microcirculation resistance, blood flow in the empty bladder or at 25 ml. intravesical volume but it decreased dome microcirculation resistance at 50 ml. intravesical volume. Propranolol caused dome contraction, increased dome microcirculation resistance and decreased dome blood flow in the empty bladder, and at 25 and 50 ml. intravesical volume. Propranolol increased base blood flow without changing base microcirculation resistance. N-nitro-L-arginine increased dome microcirculation resistance in the empty bladder and at 25 ml. intravesical volume but decreased dome blood flow in the empty bladder alone. N-nitro-L-arginine increased base microcirculation resistance and decreased base blood flow in the empty bladder and at 25 ml. intravesical volume but not at 50 ml. intravesical volume. L-arginine decreased dome and base microcirculation resistance, and increased blood flow in the empty bladder, and at 25 and 50 ml. intravesical volume. Reactive hyperemia decreased after N-nitro-L-arginine and increased after L-arginine.

CONCLUSIONS

Our studies show large variations in bladder dome and base microcirculation resistance and blood flow. Bladder blood flow appears to be largely regulated locally by nitric oxide mediated changes in bladder microcirculation resistance. beta-adrenergic receptors may regulate bladder blood flow indirectly by modulating dome tension and shifting blood flow between the dome and base. Mechanical changes in bladder wall and vasculature shape may also contribute to changes in microcirculation resistance.