Decreased Monoamine Oxidase A Expression and Activity in the Bladders of Rats With Partial Outlet Obstruction

OBJECTIVE

To investigate changes in expression and activity of monoamine oxidase A (MAO-A) in rats with partial bladder outlet obstruction (pBOO). Previous studies suggested that monoamines, such as serotonin (5-hydroxytryptamine [5-HT]) and noradrenaline, are involved in bladder hyperactivity secondary to pBOO. However, little is known about the role of MAO-A, an enzyme oxidizing 5-hydroxytryptamine and noradrenalin, in the pathogenesis.

MATERIALS AND METHODS

Female Sprague Dawley rats were subjected to sham or pBOO operations for 7 days, then their bladders were isolated. MAO-A protein levels in the bladder were examined by Western blotting. MAO-A activity was measured by the commercially available MAO-Glo Assay kit. In addition, MAO-A distribution in the bladder was examined by immunohistochemistry.

RESULTS

Weights of the bladders from rats with pBOO were increased about 3.5-fold, compared with those from sham rats. Significant decreases in MAO-A protein and activity levels were observed in whole bladder of rats with pBOO compared with those of sham rats. By immunohistochemistry, it was firstly demonstrated that MAO-A was predominantly expressed in the detrusor layer of the sham rat bladders. The intensity of staining was decreased after pBOO operation.

CONCLUSION

We demonstrated, for the first time, the distribution of MAO-A in the bladder and the pathologic changes in MAO-A protein and activity levels in rats with pBOO. This marked decrease in MAO-A potentially resulting in increased monoamine levels, especially in the detrusor of rat bladder, might be a key factor explaining the mechanism of bladder overactivity associated with pBOO.

The effect of partial outlet obstruction on calpain and phospholipase-2 activities: analyzed by severity and duration

In an attempt to better understand the two pathways that lead to bladder decompensation following partial obstruction in rabbits one of which is caused by calcium-activated enzymes and the other by oxidative stress, calpain and phospholipase A2 (PLA2) biochemical assays were conducted to see how bladder decompensation is mediated by these two calcium-activated enzymes. Partial outlet obstructions of varying durations (4, 8, and 12 weeks plus controls) were performed on 32 New Zealand white rabbits. The rabbits were also grouped by severity: control, mild, intermediate, and severe. The activities of Calpain and PLA2 on the muscle tissue of the bladders were analyzed. A stronger correlation was seen between activities and severities as opposed to between activities and durations for both PLA2 and calpain. The activity for PLA2 increased dramatically from control to mild and then stayed constant for both intermediate and severe obstructions. Calpain activity increased steadily from control to mild to intermediate to severe. Based on the increase in levels of the calcium-dependent enzymes, it was clearly shown that calcium levels increased in all stages of bladder decompensation most notably with the mild obstructions. Based on previous studies in which nitrotyrosine and dinitrophenol levels did not increase in mildly obstructed rabbits, the calcium overload pathway may predominate in mild decompensation because cells in mildly obstructed bladders are better able to cope with oxidative stress than increased calcium levels.

Effect of doxazosin on expression of eNOS in rat kidney in the presence of partial bladder outlet obstruction

BACKGROUND

The role of nitric oxide in the pathogenesis of renal injury has begun to be appreciated. We therefore designed this study to demonstrate the relationship between endothelial nitric oxide synthase (eNOS) expression and doxazosin in the kidneys of rats with surgically created partial bladder outlet obstruction (BOO), to further understand the role of doxazosin in the prevention of renal parenchymal damage by partial BOO.

MATERIAL AND METHODS

A total of 35 adult female Wistar rats, mean weight 250 g, were randomly allocated to 3 experimental groups: group1, sham-operated (n=10); group 2, partial BOO group (n=14) and group 3, partial BOO group treated with doxazosin (n=11). Partial BOO in rats was surgically induced. Results were assessed by eNOS immunohistochemistry.

RESULTS

eNOS staining in kidneys in group 1 (16.45 ± 1.63) was significantly higher than in group 2 (5.09 ± 0.61) (p<0.05). After 15 days of doxazosin treatment in addition to partial BOO (group 3), eNOS staining in the kidney (11.80 ± 1.63) was significantly higher than in group 2 (5.09 ± 0.61) (p<0.05). In samples taken after 15 days of doxazosin treatment in addition to partial BOO, eNOS staining in kidneys (11.80 ± 1.63) was lower than in the sham-operated group (16.45 ± 1.63), but the difference was not significant (p>0.05).

CONCLUSION

These findings may provide insight into the beneficial and restorative effects of α(1)-adrenoceptor antagonists on eNOS expression in the kidney, when used to treat symptoms of benign prostate hyperplasia and hypertension.

Time dependent bladder apoptosis induced by acute bladder outlet obstruction and subsequent emptying is associated with decreased MnSOD expression and Bcl-2/Bax ratio

Ischemia/reperfusion (I/R) injury-induced oxidative stress plays an important role in the functional impairment of the bladder following acute bladder outlet obstruction (BOO) via induction of apoptosis. The purpose of this study was to investigate the time course of the bladder apoptosis, and apoptosis related molecular changes in the early stage of acute BOO. Twelve-week-old male Sprague Dawley rats were divided into control, acute BOO only (I), and acute BOO plus subsequent emptying (I/R) for 30, 60, 120 min, 3 days and 2 weeks. We examined the extent of bladder apoptosis, expression of Mn-superoxide dismutase (Mn-SOD), Bcl-2, Bax, caspase 3 and poly (ADP-ribose) (PAR) in the bladder. Bladder apoptosis was significantly increased in the I/R group at 30, 60, and 120 min following bladder emptying. BOO plus subsequent emptying for 30, 60, 120 min showed significant decrease in MnSOD and Bcl-2 expression, and significant increase in caspase 3, Bax expression, and amounts of PAR. These results indicate that bladder apoptosis, induced by acute BOO and subsequent emptying, is associated with decreased MnSOD expression, increased PARP activity and imbalance in apoptosis pathways.

Decreased expression of G protein-coupled receptor kinases in the detrusor smooth muscle of human urinary bladder with outlet obstruction

AIM

We examine the expression of mRNA of G protein-coupled receptor kinase (GRK) subtypes and muscarinic acetylcholine receptor (M) subtypes in the detrusor smooth muscle of the human urinary bladder. Furthermore, we confirm the presence and the localization of GRK proteins in the detrusor smooth muscle of the obstructed bladder in comparison with the control bladder.

METHODS

Detrusor smooth muscle tissues of the human urinary bladder were obtained from 12 male patients; 6 patients did not have bladder outlet obstruction, and the other 6 patients had bladder outlet obstruction. Portions of the dome or anterior wall of the urinary bladder were used for the present study. Reverse transcription/polymerase chain reaction for GRK2, M2 and M3 was performed using total RNA extracted from human urinary bladder detrusor. Antibodies to GRK2, GRK3 and GRK4 were used to confirm the presence of the protein product in the human urinary bladder using immunohistochemical staining and the western blotting technique.

RESULTS

All complementary DNA (cDNA) transcribed from three different mRNA (M2, M3 and GRK2) were successfully amplified and size-fractionated. The expression of GRK2 protein was strong in the human bladder detrusor, but was significantly weakened by western blotting in obstructed bladder in comparison with control bladder.

CONCLUSIONS

Failure in desensitization mechanisms of muscarinic acetylcholine receptors might be related to storage symptom elicited by overactivity in obstructed bladder with benign prostatic hyperplasia.

Physiologic role of nitric oxide and nitric oxide synthase in female lower urinary tract

PURPOSE OF REVIEW

In recent years nitric oxide (NO) has gained increasing recognition as an important neurotransmitter and cell signaling molecule with a broad range of functions in the lower urinary tract. This review discusses recently published data related to the physiologic and pathophysiologic roles of NO and nitric oxide synthase (NOS) in the female lower urinary tract.

RECENT FINDINGS

Expression of three isoforms of NOS, namely endothelial NOS, neuronal NOS and inducible NOS, has been identified in various tissues of the lower urinary tract in animals and humans. In addition to its relaxation effects on bladder and urethra, NO also serves as a neurotransmitter in the lower urinary tract. The physiologic roles of NO in overactive bladder, bladder outlet obstruction, diabetic cystopathy, interstitial cystitis, and bladder inflammation have been demonstrated.

SUMMARY

NO plays an important role in the micturition process and in disorders of the lower urinary tract. Improved understanding of the pathophysiologic role of NO/NOS system and of the L-arginine-NO-cGMP pathway may allow us to identify suitable therapeutic targets for lower urinary tract disorders. However, there is a need for further investigation to determine the precise function of NO in human lower urinary tract because most work thus far has been done in animal models.

Dihydrotestosterone and the prostate: the scientific rationale for 5alpha-reductase inhibitors in the treatment of benign prostatic hyperplasia

PURPOSE

We reviewed the physiological and pathogenic role of dihydrotestosterone (DHT), evidence for the beneficial effects of decreasing DHT through 5alpha-reductase inhibition and the effects of altering the androgen balance with these agents.

MATERIALS AND METHODS

A review of the relevant literature was done using published studies identified from the MEDLINE database.

RESULTS

The androgens DHT and testosterone have complementary roles in male physiology. Each is mediated through the intracellular androgen receptor. It has been hypothesized that DHT may provide an amplification mechanism for testosterone, which could be a beneficial adaptation in men with low circulating testosterone. The recognition of the central role of DHT in benign prostatic hyperplasia (BPH) has changed the way the disease is viewed and has led to the introduction of 5alpha-reductase inhibitors, which can prevent and retard the progression of BPH by suppressing DHT synthesis. The 5alpha-reductase inhibitors decrease prostate volume. In doing so they improve symptoms and urinary flow, and decrease the risks of acute urinary retention and the need for BPH related surgery. The predominant drug related adverse events with 5alpha-reductase inhibitors are reproductive events, that is typically decreased libido, impotence and ejaculatory dysfunction. These events occur in a minority of men and tend to decrease with a longer treatment duration.

CONCLUSIONS

DHT appears to have an obligatory role in the development of BPH. The role of 5alpha-reductase inhibitors in the treatment of BPH has been firmly established with an adverse events profile that is suitable for long-term use.

THE EFFECT OF CHRONIC BLADDER OUTLET OBSTRUCTION ON NEURONAL NITRIC OXIDE SYNTHASE EXPRESSION IN THE INTRAMURAL GANGLIA OF THE GUINEA PIG BLADDER

PURPOSE

We examined the effect of chronic partial outlet obstruction on expression of neuronal nitric oxide synthase (nNOS) in the intramural ganglion cells of the guinea pig bladder.

MATERIALS AND METHODS

Partial urethral ligation was done in young male guinea pigs. The animals were sacrificed 2, 4, 6, 8 and 12 weeks after partial outlet obstruction and nNOS immunohistochemistry was done in the intramural neurons of the bladder. This was compared to controls (normal and sham operated). In addition, the mRNA expression of nNOS in bladders of 4-week sham operated and operated animals was also investigated using real-time quantitative reverse transcriptase-polymerase chain reaction.

RESULTS

Two weeks after urethral obstruction a decrease in the number of nNOS positive intramural neurons was detected. This decrease was most drastic at 4 weeks. Cell counting showed a 60.6% decrease in the number of nNOS positive neurons compared to controls. Some neurons appeared to undergo degenerative changes, such as irregular outline, vacuolation and lysis. At 6 weeks the number of nNOS positive neurons increased from the nadir level at 4 weeks and the increase was sustained until 12 weeks, when the number of nNOS positive neurons was almost at the level of controls. Quantitative reverse transcriptase-polymerase chain reaction also showed 42.4% down-regulation of nNOS expression 4 weeks after obstruction comparing with sham operation.

CONCLUSIONS

Partial urethral ligation resulted in an initial decrease in nNOS positive neurons, which have been due to actual neuronal loss and/or enzyme down-regulation. This may be attributable to regional hypoxia as a result of decreased blood flow consequent to high intravesical pressure created by partial ligation. The decrease in nNOS expression followed by a compensatory increase in nNOS positive neurons also suggests an attempt or mechanism to up-regulate nitric oxide bioactivity following increased bladder outlet resistance.

The role of nitric oxide in bladder urothelial injury after bladder outlet obstruction

OBJECTIVE

To investigate the role of nitric oxide (NO) in the pathogenesis of injury to the bladder mucosa after bladder outlet obstruction (BOO).

MATERIALS AND METHODS

The response of bladder mucosa to BOO consists of thickening with fibrous connective tissue; NO is a multipurpose messenger important in blood vessel relaxation, neuronal communication and inflammatory activities of macrophages, and is synthesized by NO synthase (NOS), with three distinct isoforms; inducible (iNOS), endothelial (eNOS) and neuronal (nNOS). Fifteen male guinea pigs had a silk ligature placed around the bladder neck to induce BOO; controls included five sham-operated animals. The animals were killed at 2, 4, 6, 8 and 12 weeks after BOO. NADPH-diaphorase staining was used as a nonspecific method to determine NOS isoform distribution. Single- and double-label immunofluorescence histochemistry for iNOS, eNOS, nNOS and macrophage colony stimulating factor (M-CSF) were used, with laser scanning confocal microscopy to assess the results. The relative amount of iNOS mRNA was evaluated using reverse-transcription-polymerase chain reaction (RT-PCR), and a standard method to determine the degree of apoptosis.

RESULTS

Bladder mucosa had a markedly increased intensity of NADPH-diaphorase staining 2 weeks after BOO. iNOS immunoreactivity was markedly greater in the bladder mucosa 2 weeks after BOO than in controls. The immunolocalization of iNOS and M-CSF was identical in bladder mucosa after BOO. RT-PCR showed stronger iNOS mRNA expression in the obstructed bladder mucosa 2 weeks after BOO than in controls. eNOS and nNOS expression was detected only 8 weeks after BOO, with markedly more immunoreactivity 12 weeks after initiating BOO. Increased eNOS and nNOS immunoreactivity strongly correlated with the induction of apoptosis in the bladder mucosa.

CONCLUSION

There was overexpression of iNOS by activated macrophages in the early stages of BOO. This overexpression did not induce apoptosis in the iNOS-expressing cells of bladder mucosa in the early stages. After long-term BOO bladder mucosa showed strong eNOS and nNOS immunoreactivity, correlating with apoptosis. Thus we suggest that eNOS and nNOS, by triggering cell death, may be important in eliminating hyperplastic urothelial cells, reflecting the plasticity of the bladder response to obstructive stimuli.

Increased expression of neuronal nitric oxide synthase in bladder afferent cells in the lumbosacral dorsal root ganglia after chronic bladder outflow obstruction

Nitric oxide (NO), a neurotransmitter in autonomic reflex pathways, plays a role in functional neuroregulation of the lower urinary tract. Upregulation of the levels of neuronal nitric oxide synthase (nNOS), the enzyme system responsible for NO synthesis, has been documented in the peripheral, spinal and supraspinal segments of the micturition reflex in diseases such as cystitis, bladder/sphincter dyssynergia following spinal cord injury and bladder overactivity after cerebral infarction. These observations suggest that NO might play a role in the development of bladder overactivity. In this study, nNOS-immunoreactivity (IR) was evaluated in bladder afferent and spinal neurons following bladder outflow obstruction (BOO) in male and female rats. Chronic BOO was induced by placing lumen reducing ligatures around the proximal urethra. Six weeks following the obstructive or sham surgery, bladder function was evaluated by awake cystometry. Bladder afferent neurons in L1, L2, L6 and S1 dorsal root ganglia (DRG) were identified by retrograde neuronal labeling with injection of Fast Blue into the bladder smooth muscle. A differential distribution of nNOS-IR was subsequently evaluated in bladder afferent neurons in the DRG and in the associated spinal cord segments. The percentage of bladder afferent neurons expressing nNOS-IR was increased in L6 (1.8-fold in males and 1.9-fold in females) and S1 (2.8-fold in males and 5.3-fold in females) DRG. In contrast, no changes in nNOS-IR in neurons or fiber distribution were observed in any spinal cord segments examined.

The contractile potency of adenosine triphosphate and ecto-adenosine triphosphatase activity in guinea pig detrusor and detrusor from patients with a stable, unstable or obstructed bladder

PURPOSE

We compared the potency of adenosine triphosphate (ATP) and its nonhydrolyzable analogue alpha,beta-methylene ATP for generating contractions in human detrusor smooth muscle from patients with a stable, unstable and obstructed bladders. The different ATP potencies were compared with the ecto-adenosine triphosphatase (ATPase) of these samples.

MATERIALS AND METHODS

Contractile experiments were done in vitro by superfusing samples with purines and dose-response curves were generated. Ecto-ATPase activity was measured from the rate of ATP hydrolysis sensitive to the ecto-ATPase inhibitor ARL 67156 with a luciferin-luciferase assay.

RESULTS

ATP generated contractions with a mean EC50 of 933 microM. in tissue from stable bladders and was significantly more potent in tissue from unstable and obstructed bladders (EC50 141 and 172 microM., respectively). alpha,beta-methylene ATP was more potent in tissue from stable and unstable bladders (mean combined EC50 3 microM.). In guinea pig detrusor the mean EC50 for ATP and alpha,beta-methylene ATP was 138 and 5.5 microM., respectively. Mean total ATPase activity in unstable bladder biopsies plus or minus standard deviation was about 50% of that in stable bladder biopsies (2.54 +/- 1.50 versus 1.37 +/- 0.46 nmol. per second per mg. protein ). The ARL 67156 sensitive fraction was also significantly less in samples from unstable compared with stable bladders (mean 0.94 +/- 0.41 versus 0.36 +/- 0.26 nmol. per second mg. protein ).

CONCLUSIONS

The greater potency of ATP for generating contractions in detrusor from unstable bladders may be due to reduced extracellular hydrolysis, allowing purine greater access to detrusor smooth muscle. This finding may explain atropine resistant purine based contractions in detrusor from unstable bladders.

Physiologic sequelae of partial infravesical obstruction in the mouse: role of inducible nitric oxide synthase

PURPOSE

To develop a mouse model for partial infravesical obstruction, and determine the resultant changes in bladder function, with particular emphasis on the role of inducible nitric oxide synthase (iNOS) in the bladder response.

MATERIALS AND METHODS

Wild type mice were subjected to no intervention, sham operation, and varying durations of partial outlet obstruction (1, 3, and 5 weeks). They then underwent cystometric evaluation, bladder strip stimulation studies using carbachol, and relaxation studies using l-arginine, sodium nitroprusside, and 8-bromoguanosine 3'-5' cyclic guanosine monophosphate. Bladder tissue was subjected to RT-PCR and Western analysis for iNOS. Bladders were also studied histologically using morphometric analysis.

RESULTS

Bladders from mice obstructed for 5 weeks were heavier (weight increased by 110%), larger (capacity increased by 73%), and had a higher frequency of abnormal appearing cystometric curves than normal bladders. Tissue bath studies demonstrated decreased contractility in response to cholinergic stimulation at 5 weeks of obstruction (decreased by 55% at maximal stimulation). RT-PCR demonstrated iNOS in approximately 70% of bladders obstructed for 1 and 3 weeks, while the iNOS protein was apparent in 50% of the bladders from the same groups.

CONCLUSIONS

This new animal model of infravesical obstruction is reliable and reproducible. Moreover, the physiologic changes noted are comparable to other models, but an added advantage is the relevance of this model with regard to studying new transgenic or knockout mice. Enhanced expression of iNOS seen early after obstruction may serve to improve oxygenation during obstruction-induced ischemia.

Biochemical evaluation of obstructive bladder dysfunction in men secondary to BPH: a preliminary report

OBJECTIVES

In the rabbit, two of the major cellular alterations that mediate bladder dysfunction secondary to partial outlet obstruction are a decreased ability of the sarcoplasmic reticulum (SR) to store and release Ca2+, and mitochondrial dysfunction. The objective of the current study was to determine whether SR and mitochondrial dysfunctions are associated with symptomatic benign prostatic hyperplasia (BPH) in men.

METHODS

Bladder biopsies were obtained from men with symptomatic BPH and from age-matched men with no urologic dysfunction. Each biopsy was analyzed for the following enzyme activities: malate dehydrogenase and citrate synthase (mitochondrial markers) and the sarcoplasmic reticular enzyme Ca2+ -dependent adenosine triphosphatase (ATPase). These values were compared with the enzyme activities of control rabbit bladder smooth muscle and bladder smooth muscle obtained from rabbits subjected to 2 weeks of partial outlet obstruction.

RESULTS

The enzymatic activities of all three enzymes are significantly lower in human bladder smooth muscle than in rabbit bladder smooth muscle. The maximal activities of all three enzymes are significantly lower in human bladder samples obtained from men with diagnosed obstructive uropathy than in men of equal age with no urologic dysfunction.

CONCLUSIONS

These studies demonstrate that similar to the response of the rabbit to partial outlet obstruction, obstructive dysfunction secondary to BPH is characterized by mitochondrial and SR dysfunction.

Obstruction stimulates COX-2 expression in bladder smooth muscle cells via increased mechanical stretch

Studies were performed to investigate the regulatory mechanism of bladder cyclooxygenase-2 (COX-2) expression after outlet obstruction. In situ hybridization of murine bladder tissues using COX-2-specific riboprobes demonstrated that COX-2 expression was induced predominantly in the bladder smooth muscle cells after outlet obstruction. To study the effect of increased mechanical stretch on COX isoform expression, cultured rat bladder smooth muscle cells were grown on silicone elastomer-bottomed plates coated with collagen type I and were subjected to continuous cycles of stretch/relaxation for variable duration. COX-1 mRNA levels did not change with stretch. COX-2 expression increased in a time-dependent manner after stretch, with maximal mRNA and protein levels occurring after 4 h. PGE2 levels increased more than 40-fold in the culture media after stretch, consistent with increased COX activity, and this was reduced to near completion in the presence of a COX-2 inhibitor, NS-398. Exposure to stretch over a 48-h period induced a 4.7 +/- 0.6-fold increase in tritiated thymidine incorporation rate. This increase in DNA synthesis was markedly suppressed when the cells were stretched in the presence of NS-398. We conclude that in bladder obstruction COX-2 activation occurs predominantly in the smooth muscle cells in response to mechanical stretch. Our findings also suggest that stretch-activated COX-2 expression may participate in bladder smooth muscle cell proliferation and thereby play a role in pathological bladder wall thickening after obstruction.

Effects of outlet obstruction and its reversal on mitochondrial enzyme activity in rabbit urinary bladders

PURPOSE

This study investigated the effects of outlet obstruction and its reversal on mitochondrial enzyme activity in the rabbit urinary bladder.

MATERIALS AND METHODS

We induced mild bladder outlet obstruction in male New Zealand White rabbits. Following two weeks of obstruction, one group of animals (n = 6) was sacrificed, while outlet obstruction was relieved in three additional groups of animals, which were sacrificed one (n = 5), two (n = 5) and four (n = 5) weeks after relieving the obstruction. Seven sham operated rabbits served as controls. We extracted mitochondria from fresh detrusor and assayed activities of key mitochondrial enzymes in the citric acid cycle, citrate synthase and malate dehydrogenase, as well as those in the electron transport chain, succinate cytochrome c reductase, NADH-cytochrome c reductase and cytochrome c oxidase. With high performance liquid chromatography (HPLC) we determined the tissue content of phosphocreatine and the adenine nucleotides (ATP, ADP and AMP), which was used for calculating energy charge. Responses of detrusor strips to 500 microM bethanechol and 120 mM KCl provided the assessment of detrusor contractility.

RESULTS

Contractile response of the detrusor strips to bethanechol stimulation was significantly reduced by outlet obstruction, nevertheless, it recovered gradually toward the control level after the relief of outlet obstruction. Outlet obstruction reduced the detrusor content of phosphocreatine, ATP and energy charge. After relieving the obstruction, however, these recovered gradually, reaching control levels 4 weeks later. The activities of all assayed enzymes were reduced by two weeks of outlet obstruction. Relieving the obstruction restored enzyme activity gradually but at different rates for different enzymes. Activities of the citric acid cycle enzymes citrate synthase and malate dehydrogenase recovered and were similar to control levels four weeks after relief of the obstruction. Of the enzymes in the electron transport chain, NADH cytochrome reductase activity recovered most quickly by one week after relief of the obstruction. The activity of cytochrome c oxidase improved more slowly, but 4 weeks after relieving the obstruction it, also, was restored and was similar to the control level. Succinate cytochrome reductase activity remained lower than the control over the entire four weeks of recovery.

CONCLUSIONS

The close association between mitochondrial enzyme activity, energy metabolism and contractility of the detrusor indicates the important role of mitochondrial enzyme damage in decreasing energy production and impairing contractile function of the urinary bladders following outlet obstruction. Our findings also show that various mitochondrial enzymes exhibit different susceptibilities and reversibilities to pathological stress.

[Pattern of distribution of constitutive isoforms of NO synthase in the normal prostate and obstructive prostatic hyperplasia]

Nitric oxide (NO) is suggested as an important mediator for the regulation of biological processes. In the present study we tried to determine histochemically and immunohistochemically the localization and distribution of the constitutive NO-synthase Isoforms (bNOS and eNOS) of 14 normal non-obstructive and 12 hyperplastic obstructive human prostates. Differentiated nitrinergic innervation was shown for the prostate glands, fibromuscular stroma and blood vessels by NADPH-diaphorase staining and immunohistochemically with specific NOS antibodies. In the specimens with benign prostatic hyperplasia nitrinergic innervation seems to be distinctly reduced. The vascular distribution of NOS provides evidence for segmental differentiation of NO-mediated vascular regulation. The NADPH-diaphorase reaction was not confirmed immunohistochemically by the specific NOS antibody in the glandular epithelium. The distribution of NO synthase shows the importance of nitric oxide in the regulation of smooth muscle tone, blood flow and secretory function in the normal and hyperplastic human prostate.

The role of type IV collagenases in rat bladder development and obstruction

The role of type IV collagenases during rat bladder development and in response to partial bladder outlet obstruction was evaluated. Gelatinase gel zymography was performed on developing rat bladders (gestation d 16 and 19, at birth, 5, 10, 15, 20, 30, and 75 d postnatally), after partial obstruction of the bladder outlet in young adults and after separation of the epithelium from the mesenchyme in young adults. Bladder function was assessed by cystometry in obstructed animals. During development, the 72-kD type-IV collagenase [matrix metalloproteinase (MMP)-2, both latent and activated] was maximally expressed in the fetal period and decreased with age; whereas the 92-kD gelatinase (MMP-9) was not expressed in developing or adult bladders. MMP-2 was localized to the bladder mesenchyme and was undetectable in isolated epithelium. In 46 obstructed rats, there was an 8-fold increase in bladder volume and weight along with smooth muscle hypertrophy (mean smooth muscle cell diameter 7.09 +/- 0.11 microns versus 4.65 +/- 0.05 microns in normal animals, p < 0.001). Obstructed rats had increased quantities of latent and activated MMP-2 and MMP-9 compared with sham-operated and normal controls. These findings suggest that expression and activation of type IV collagenases (MMP-2 and 9) are developmentally regulated and play a role in bladder remodeling during developmental morphogenesis and after partial outlet obstruction.

Effects of tadenan pretreatment on bladder physiology and biochemistry following partial outlet obstruction

PURPOSE

Tadenan is a pharmaceutical agent used in the treatment of BPH. Prior studies demonstrated that pretreatment of rabbits with Tadenan significantly reduced the contractile dysfunction following two weeks of partial outlet obstruction. The specific aim of the present study was to determine the effect of Tadenan pretreatment on the time course of the response to partial outlet obstruction and correlate the effect of Tadenan on the contractile responses to field stimulation, bethanechol, and KCl with both mitochondrial enzyme activity (citrate synthase) and sarcoplasmic reticular function (calcium-ATP'ase activity).

MATERIALS AND METHODS

Sixty male New Zealands white rabbit (3 to 5 kg.) were separated into 12 groups of 5 rabbits each. Each rabbit in groups 1-6 received Tadenan orally at 100 mg./kg./day for three weeks; each rabbit in groups 7-12 received vehicle (peanut oil). Each rabbit in groups 2-6 and 8-12 received a partial outlet obstruction as described below. One group of Tadenan treated and one group of vehicle-treated rabbits were euthanized at 1, 3, 5, 7, and 14 days following partial outlet obstruction. The non-obstructed groups were studied after 4 weeks of drug or vehicle treatment. Each bladder was rapidly removed and weighed, and 3 longitudinal strips prepared and mounted in individual baths for contractile studies. The remainder of the bladder was frozen for biochemical analysis. The contractile responses to field stimulation, bethanechol, and KCl were determined; and the enzyme activities of citrate synthase (marker for mitochondrial function) and calcium-ATP'ase (marker for sarcoplasmic reticulum) were determined.

RESULTS

1) Tadenan did not reduce the effect of partial outlet obstruction on bladder mass. 2) Although the contractile responses to forms of stimulation were reduced at 1 day following partial outlet obstruction, Tadenan pretreatment resulted in a significant protective effect on the contractile responses to field stimulation, bethanechol, and KCl at 3, 5, 7, and 14 days of obstruction. 3) The activities of both citrate synthase and calcium ATP'ase were reduced significantly at 1 day following obstruction for both Tadenan treated and vehicle treated groups. The activities of both enzymes returned to near normal levels at 7 and 14 days for the Tadenan groups whereas the activities of both enzymes remained significantly reduced in the vehicle treated groups.

CONCLUSIONS

These results clearly demonstrate that Tadenan pretreatment protected the bladder from both the contractile and metabolic dysfunctions induced by partial outlet obstruction.

Properties of Ca2(+)-Mg2+ ATP-ase in rabbit bladder muscle and mucosa: effect of urinary outlet obstruction

The contractile response of the smooth muscle of the urinary bladder is dependent upon both the entrance of extracellular calcium through receptor-operated calcium channels and the stimulated release of calcium from the sarcoplasmic reticulum. In addition, partial outlet obstruction induces marked alterations in the utilization of intracellular calcium. Although calcium ATP-ase provides the energy for the translocation of intracellular free calcium into storage sites within the sarcoplasmic reticulum, very little is known about the properties of this enzyme in bladder muscle and mucosa. As an initial study, divalent ion specific ATP-ase activity was measured in extracts of rabbit bladder muscle and mucosa from control animals and from rabbits following partial urinary outlet obstruction. In both normal bladder muscle and mucosa, magnesium and calcium ions were equally effective in activating the enzyme. Seven days following partial urinary outlet obstruction, the ATP-ase activity in both bladder muscle and mucosa was significantly depressed by over 70%. The degree of the decreased enzyme activities observed within the muscularis and mucosa would indicate that specific membrane functions supported by divalent-ion-ATP-ase are dysfunctional. This hypothesis is supported by marked alterations in the utilization of intracellular calcium following partial outlet obstruction and the marked dysfunctions in both mucosal permeability and bacterial adherence to mucosa observed following partial outlet obstruction.

Lactate dehydrogenase activity and isoform distribution in the rat pelvic ganglion: effects of diabetes and bladder outlet obstruction

We have previously shown that the intramural motor nerves in the rat bladder can function in anoxic conditions. The present study aims to explore the distribution and activity of lactate dehydrogenase (LDH), the key enzyme for ATP generation in anoxia. The activity and isoform distribution pattern of LDH was studied in pelvic ganglia from male and female rats. A histochemical investigation showed that the LDH activity was intense in the ganglion cells, and weak in the other tissue components (nerve bundles, connective tissue). The male pelvic ganglion weighted 55% more than the female pelvic ganglion, the enzyme activity per unit ganglion weight was 60% higher and the total LDH activity was 155% higher. The isoform distribution was similar, with M4 being dominant isoform, followed by M3H. Infravesical outlet obstruction in the female rat induced a threefold increase in ganglion weight, and the total LDH activity increased twofold. In this hypertrophic female ganglion a decreased relative amount of M4, and an increased amount of MH3, was found. Diabetes in the male rat had no effect on ganglion weight or its contents and isoform distribution of LDH.

Enzymatic digestion of the urethra after pancreatic transplantation: a case report

The most common method of exocrine drainage in pancreatic transplantation is urinary drainage. With the shift from enteric drainage and duct occlusion techniques, there has been a concomitant shift from intraabdominal to urological complications. We present a case in which a simultaneous pancreas-kidney (SPK) transplant recipient developed urethral disruption and associated bladder outlet obstruction 11 months following surgery.

Lactate dehydrogenase activity and isoform distribution in the rat urinary bladder: effects of outlet obstruction and its removal

The rat urinary bladder responded to infravesical obstruction by an increased weight. The weight began to increase after 3 days of obstruction. After 10 days the weight gain had become significant, but increased further with time. At 90 days the bladders weighed 12 times the initial weight. Lactate dehydrogenase (LDH) activity per unit bladder weight increased with the duration of the obstruction. The increase was significant in the 90 day group. The isoform pattern of LDH was determined. For the control group the M3H form was dominant, with M4 second; M4 became the dominant isoform after 3 days of obstruction. The relative amount of M4 had increased by 80% after 90 days. In one group, which was first obstructed for 10 days and then had the obstruction removed for 4 weeks, bladder weight and LDH isoform pattern were normal. We suggest that the changes in isoform pattern in the obstructed bladder reflect a metabolic adaptation to the prolonged voiding time and the increased detrusor pressure, with a consequently compromised oxygen supply, and that the changes are reversible if the outlet conditions are normalized.

Energy turnover and lactate dehydrogenase activity in detrusor smooth muscle from rats with streptozotocin-induced diabetes

Force generation and tissue glucose metabolism were measured in the urinary bladder smooth muscle from rats with streptozotocin-induced diabetes (7-8 wk duration). Bladder wet wt was almost 4-fold higher in the diabetic animals compared with the untreated controls. Morphological analysis showed that the growth was associated with hypertrophy of the smooth muscle component in the bladder wall. Force generation of isolated bladder strip preparations was measured in vitro at different ambient oxygen tensions. Activation of intramural nerves, with electrical field stimulation, induced contractions that were unaffected by reduction of oxygen tension down to PO2 100 mmHg for both control and diabetic muscle strips. At zero PO2 force was reduced by approximately 10-20%, in both groups. High-K+ solution induced 'tonic' contractions that were slightly more inhibited by lowering PO2. At intermediate PO2 (between 100 and 20 mmHg) the diabetic muscle gave slightly higher force. At zero PO2 no significant difference could be detected between strips from control and diabetic animals. Oxygen consumption and lactate production in the preparations were determined at a PO2 of 290 mmHg and related to the volume of smooth muscle. At zero PO2, lactate formation increased 3- to 4-fold. The metabolic tension cost was lower at zero PO2. No differences in basal and contraction related metabolic rates could be detected between the two groups under normoxic and anoxic conditions. The maximal activity of lactate dehydrogenase (LDH) determined in tissue samples was about 2-fold higher in the diabetic bladder muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of partial outlet obstruction on choline acetyltransferase activity in the rat and rabbit

Partial outlet obstruction of the rabbit bladder induces a rapid and significant increase in bladder mass. This increase in mass is associated with a variety of specific contractile dysfunctions, characterized by a marked decrease in the response to field stimulation (acting through the release of neurogenic transmitters). There is histological evidence indicating that the decrease in the contractile response of isolated strips of rabbit urinary bladder to field stimulation is associated with a degeneration of synaptic membranes within the bladder detrusor (neuropathy). In the current experiments, the effect of partial outlet obstruction in rabbit and rat urinary bladders on choline acetyltransferase activity (ChAT) were determined and correlated with both the level of bladder hypertrophy (increase in mass) and the contractile response to field stimulation. The results can be summarized as follows: In the rabbit, partial outlet obstruction induced a rapid 5-fold increase in bladder mass over the 7 day period of study. This increase in mass was associated with a decrease in the contractile response of isolated strips of bladder body and base to field stimulation and a decrease in ChAT activity. Interestingly, the rabbit bladder base showed a significantly higher ChAT activity than the bladder body, although the contractile response to muscarinic stimulation was significantly greater in the bladder body than in the base. In the rat, partial outlet obstruction induced a mild 2-fold increase in bladder mass.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of partial obstruction of the rabbit urinary bladder on malate dehydrogenase and citrate synthase activity

Previous studies have demonstrated that partial outlet obstruction in rabbits induced a significant decrease in oxidative metabolism in urinary bladder smooth muscle. The current experiments were designed to determine whether the decreased oxidative metabolism of obstructed bladder tissue is associated with alterations in the activities of specific mitochondrial enzymes. The activities of two important enzymes in the tricarboxylic acid cycle, malate dehydrogenase and citrate synthase, were measured in samples of bladder body and base from normal bladders and in bladders from rabbits in which partial outlet obstruction had been produced seven days prior to the experiments. The results can be summarized as follows: malate dehydrogenase activity was similar in bladder body and base isolated from control rabbits; and decreased by approximately 40% in both segments of the bladder isolated from obstructed rabbits. In contrast to malate dehydrogenase, citrate synthase activity was significantly higher in the bladder body than in the base of normal rabbits. Outlet obstruction caused about a 50% decrease in activity of this enzyme in the bladder body, but had no significant effect on citrate synthase activity of the bladder base. These findings demonstrate that the deficiency in bladder function following partial outlet obstruction is associated with a marked decrease in the activities of two essential enzymes in oxidative metabolism: malate dehydrogenase and citrate synthase. This decrease in enzyme activity is consistent with the previously observed decrease in oxidative metabolism and would be expected to lead to an inability of the tissue to supply sufficient metabolic energy for proper contractile function.