Altered response to partial bladder outlet obstruction in mice lacking inducible nitric oxide synthase

INTRODUCTION: Following prolonged partial bladder outlet obstruction (BOO) in the mouse, cholinergic mediated detrusor contractility decreases. Previous work has demonstrated an increase in the inducible form of nitric oxide synthase (iNOS) at the mRNA and protein levels soon after obstruction. Since nitric oxide (NO), the product of the action of iNOS on molecular oxygen and l-arginine, produces vasodilation and decreases platelet aggregation, we believe it is an integral part of the initial detrusor response to obstruction. These experiments evaluated the detrusor response in mice incapable of producing iNOS. MATERIALS AND METHODS: Wild type and knockout mice were partially obstructed for 1, 3, and 5 weeks. Physiologic evaluation consisted of cystometric analyses, and muscle strip studies in response to cholinergic and electrical stimulation. Strips were also relaxed with L-arginine, sodium nitroprusside, and 8-bromoguanosine 3' - 5' cyclic GMP, after precontraction. RESULTS: After 5 weeks of obstruction, both wild type (WT) and knockout (KO) mouse bladders increased significantly in weight. WT bladders obstructed for 5 weeks had the greatest capacity (increase of 42%, p = 0.022), and a decreased contractile response to carbachol (decrease of 32% at 10-5 M, p = 0.018). No differences were noted at 1 and 3 weeks of obstruction. In contrast, KO mice had a significantly larger bladder capacity at 1 week of obstruction compared with WT, and had significantly lower responses to electrical stimulation than WT at the same time (p = 0.03). Additionally, after 5 weeks of obstruction, bladder capacity and contractility returned to baseline levels in KO mice, at a time when WT mice had significantly larger capacity and decreased contractility. CONCLUSIONS: Bladder function following partial BOO in mice incapable of producing iNOS differed significantly from the normal response. Our data suggest that generation of iNOS soon after obstruction is necessary to prevent detrusor dysfunction at that time. Moreover, the enhanced function seen in KO bladders after longer periods of obstruction (5 weeks) in comparison to WT bladders suggests that reactive nitrogen species-induced protein nitrosylation may be involved in the loss of contractile function observed after more prolonged periods of obstruction.     

Inducible nitric oxide synthase promotes pathophysiological consequences of experimental bladder outlet obstruction

PURPOSE: Bladder outlet obstruction leads to histological and functional changes in the bladder over time. We investigated the role of inducible nitric oxide synthase (iNOS) in the progression of pathological changes of the bladder secondary to outlet obstruction in a rat and a mouse model. MATERIALS AND METHODS: To assess expression of iNOS in the bladder, polymerase chain reaction amplification of mRNA was done. Rats were subjected to sham operation or partial bladder outlet obstruction. They were given the iNOS inhibitor aminoguanidine in drinking water or unmodified water. After 2 weeks, awake cystometric evaluation was performed, the bladders were harvested and the degree of fibrosis was assessed. In another series of experiments mice deficient in the iNOS gene (iNOS -/-) were compared to WT mice for cystometric as well as histological changes in the bladder following partial bladder outlet obstruction or sham operation. RESULTS: Partial bladder outlet obstruction induced the expression of iNOS mRNA in the mouse bladder. iNOS -/- mice showed a significantly smaller increase in bladder volume at 3 weeks compared with WT. Pharmacological inhibition of iNOS activity significantly attenuated the increase in bladder size and the number of spontaneous bladder contractions in obstructed rats at 2 weeks. Furthermore, genetic and pharmacological decreases in iNOS led to significantly less fibrosis of the bladder after partial bladder outlet obstruction in mice and rats, respectively. CONCLUSIONS: Pharmacological or genetic decreases in iNOS resulted in amelioration of functional and fibrotic changes in the bladder after partial bladder outlet obstruction, suggesting that NO contributes to the pathophysiology of bladder outlet obstruction.     

Inverse expression of uroplakins and inducible nitric oxide synthase in the urothelium of patients with bladder outlet obstruction

OBJECTIVE: To assess the expression and distribution of uroplakins, protein subunits of the asymmetric unit membrane (AUM), and inducible nitric-oxide synthase (iNOS) in the urinary bladder urothelium of patients with bladder outlet obstruction (BOO) caused by benign prostatic hyperplasia (BPH). PATIENTS AND METHODS: Urinary bladder urothelium samples from 15 men (mean age 69 years) with BOO secondary to BPH were processed for light and electron immunocytochemistry. Uroplakins and iNOS were detected, and areas of apical surface covered with AUM were compared with those of iNOS-positive urothelial cells. RESULTS: Areas of superficial urothelial cells with no AUM were found in all obstructed bladder samples. The immuno-electron microscopy showed that the uroplakin-positive cells had the characteristic appearance of terminally differentiated umbrella cells, whereas cells from the uroplakin-negative regions were undifferentiated, typically showing microvilli on their apical surface. iNOS was not detected in areas with continuous AUM staining, but was readily detected in the uroplakin-negative areas. There was an inverse correlation between the intensity of uroplakin and iNOS staining. CONCLUSIONS: In patients with BOO associated with BPH, some superficial urothelial cells lacked the AUM, suggesting focal compromise of the blood-urine permeability barrier. In such relatively undifferentiated urothelial zones there was an accompanying increase in the expression of iNOS, which marks perturbed urothelial differentiation and may modulate bladder response to the outlet obstruction.     

Urodynamic evaluation of the human bladder response to an increase in outlet resistance

AIM: We prospectively evaluated the response of the human bladder to a chronic increase in urethral resistance according to the indices of pressure, volume flow rate, total (external) bladder work, and maximum and average detrusor power. METHODS: Six men with incontinence after radical prostatectomy were evaluated urodynamically before and 3-6 months after undergoing a bulbourethral sling procedure. RESULTS: None of the men suffered from significant obstructive or irritative voiding symptoms preoperatively. Urodynamic evaluation showed postoperative increases in both average detrusor pressure and pressure at maximum flow, but there were no significant changes in voided volume, void time, or postvoid residual urine volume. Maximum detrusor power, average detrusor power, and total (external) bladder work were all significantly increased. CONCLUSION: These data confirm that the human bladder possesses a functional reserve, which is elicited by an increase in urethral resistance.     

Severe bladder trabeculation obviates the need for bladder outlet procedures during augmentation cystoplasty in incontinent patients with neurogenic bladder

OBJECTIVE

To evaluate whether the degree of preoperative bladder trabeculation in neurogenic bladder (NB) patients is a marker of significant outlet resistance. If so, severe trabeculation may obviate the need for concomitant bladder outlet procedure (BOP) during augmentation cystoplasty (AC).

PATIENTS AND METHODS

We retrospectively reviewed 48 incontinent patients with NB who had surgery. The patients were divided into two groups: group 1 (23 patients) had AC alone; group 2 (10) had AC with BOP. Children who had a BOP alone (15) were excluded from the study. Success was defined as a dry period of ≥4 h. Preoperative bladder trabeculation was classified as mild or severe. Data collected included continence status, imaging and urodynamic findings.

RESULTS

In group 1 patients before surgery, there was severe bladder trabeculation in 14 (61%), hydronephrosis in 13 (57%) and associated vesico‐ureteric reflux (VUR) in 16 (70%). The mean detrusor leak‐point pressure (DLPP) was 49.7 cmH₂O and the bladder neck was open in nine (39%). Dryness with AC alone was achieved in 91% of group 1 patients. In group 2 patients (10 patients), there was severe bladder trabeculation in five, hydronephrosis in three, and VUR in two. The mean DLPP was 42.8 cmH₂O and the bladder neck was open in eight. After surgery, eight of 10 patients achieved a dry period of 4 h. There was no significant difference between group 1 and 2 patients for age at surgery, gender, ambulatory status, hydronephrosis, degree of trabeculation, detrusor overactivity, DLPP and eventual outcome. The incidence of VUR was higher in group 1 patients (P = 0.009) and more patients in group 2 had an open bladder neck (P = 0.031).

CONCLUSION

Severe bladder trabeculation in incontinent patients with NB might predict an element of intrinsic outlet resistance. In this subset of patients, dryness was achieved by AC alone without further BOP. The degree of bladder trabeculation should be considered in the surgical decision‐making process for incontinent children with NB.     

Serum prostate-specific antigen to predict the presence of bladder outlet obstruction in men with urinary symptoms

OBJECTIVE: To determine whether prostate specific antigen (PSA) level can usefully predict or exclude bladder outlet obstruction (BOO), in men with lower urinary tract symptoms (LUTS). PATIENTS AND METHODS: A cohort of men from 1996 to 1999 who had LUTS caused by BPH was evaluated by serum PSA and pressure-flow urodynamic studies, and a blinded comparison made. The settings were teaching hospitals in London, UK and L'Aquila, Italy. Men (302) were referred by primary-care practitioners with LUTS and a PSA of < 10 ng/mL. Regression analysis was used to predict the extent of BOO, and create likelihood ratios and predictive values for BOO according to the PSA value. RESULTS: PSA was significantly associated with BOO (P < 0.001; r2 0.07), with significant likelihood ratios altering the probability of BOO. If the PSA was > 4 ng/mL, mild or definite BOO was likely (89%), whereas if the PSA was <2 ng/mL, there was about a one-third chance each of no, mild and definite BOO. CONCLUSION: High PSA levels in patients with LUTS are significantly associated with BOO; low PSA levels mean that definite BOO is unlikely.     

Residual fraction as a parameter to predict bladder outlet obstruction in men with lower urinary tract symptoms

Objectives:   To determine whether noninvasive tests including the residual fraction are reliable for the diagnosis of bladder outlet obstruction (BOO).
Methods:   A total of 212 men (median age 68, range 44–89 years) were included in the present study. The median serum prostate-specific antigen level and prostate volume were 1.3 ng/mL (range 0.2 to 9.4) and 37.9 mL (range 11.3 to 148.0), respectively.
Results:   Among the variables analyzed in the multivariate model, the likelihood of BOO varied by the total prostate volume, with a 3.6-fold higher odds for ≥40 mL than for <40 mL (odds ratio [OR], 3.616; 95% confidence interval [CI], 1.217–10.749; P  = 0.021). In the same model, a low maximal flow rate (Qmax) (OR, 2.840; 95% CI, 1.260–6.401; P  = 0.012) and high residual fraction (OR, 7.103; 95% CI, 1.924–26.225; P  = 0.003) were associated with an increased likelihood of BOO. The sensitivity and specificity for predicting BOO using a total prostate volume of 40 mL or greater were 73.7% and 65.2%, respectively. Using a Qmax cut-off of 12 mL/s or less for predicting BOO, the sensitivity and specificity were 77.2% and 54.2%, respectively. Prediction of the BOO by the residual fraction only had a sensitivity and specificity, for a residual fraction of less than 20%, of 75.4% and 67.7%, respectively.
Conclusions:   The presence or absence of BOO might be predicted using non-invasive methods. The residual fraction may help with patient management by better predicting the likely patient classification from pressure-flow studies.     

Activity and expression of nitric oxide synthase in the hypertrophied rat bladder and the effect of nitric oxide on bladder smooth muscle growth

PURPOSE: We investigated the expression and activity of nitric oxide synthase (NOS) and the localization of cyclic guanosine monophosphate (cGMP) in hypertrophied rat bladder. We also examined whether nitric oxide (NO) has a growth inhibitory effect in bladder smooth muscle cells. MATERIALS AND METHODS: The urethra was partly ligated and the bladder was removed 3 days, 3 or 6 weeks after obstruction. NOS activity was determined as the conversion of L-[14C]citrulline from L-[14C]arginine (Amersham Life Science, Solna, Sweden). Neuronal NOS (nNOS) expression was studied with Western blot analysis and immunohistochemistry. The expression of inducible NOS (iNOS) and cGMP was evaluated by immunohistochemistry. The effect of NO on isolated bladder smooth muscle cell growth was assessed as protein and DNA synthesis by [3H]-leucine and [3H]-thymidine (NEN Life Science Products, Zaventem, Belgium) incorporation, respectively. RESULTS: Ca independent iNOS activity increased after short-term obstruction. Immunohistochemical studies in obstructed bladders demonstrated iNOS expression primarily in urothelial and inflammatory cells. Ca dependent nNOS activity decreased after obstruction, as confirmed by Western blot analysis. The cGMP immunoreactive cells were mainly found within the serosal layer of obstructed bladders. The NO donor DETA-NONOate (Alexis Biochemicals, Lausen, Switzerland) (300 microM.) reduced [3H]-leucine and [ H]-thymidine incorporation by a mean of 29% +/- 2% and 95% +/- 2%, respectively, in cultured bladder smooth muscle cells. CONCLUSIONS: Bladder obstruction caused a small increase in iNOS activity and a decrease in nNOS activity. NO was found to have a growth inhibitory effect in bladder smooth muscle cells, suggesting that changes in NOS activity may influence the progress of bladder hypertrophy.     

Effects of pinacidil on detrusor instability in men with bladder outlet obstruction

In a double-blind, crossover study the effect of the potassium channel opener pinacidil (N'-cyano-N'4-pyridyl-N-1,2,2-trimethylpropylguanidine monohydrate) at 25 mg. per day was evaluated in 10 patients with detrusor instability and bladder outlet obstruction. Nine patients completed the study: in 7 pinacidil was without significant effect on urodynamic variables and in 2 detrusor instability was not found at the end of the pinacidil period. Maximum urinary flow, frequency and nocturia were unchanged during pinacidil treatment, compared to the initial test and the placebo period. There was a significant decrease in standing blood pressure but heart rate was stable throughout the study. No patient experienced distinct symptomatic improvement or side effects during pinacidil treatment. The results suggest that pinacidil at the dosage given is not effective for treatment of unstable detrusor contractions associated with bladder outflow obstruction.     

超声测量逼尿肌厚度在良性前列腺增生诊断中的应用价值

目的 通过对老年良性前列腺增生(BPH)患者逼尿肌厚度与膀胱出口梗阻的相关性研究,探讨超声测量逼尿肌厚度预测老年男性膀胱出口梗阻的价值.方法 130例老年患者行尿动力学检查,以尿动力学检查结果作为膀胱出口梗阻的诊断依据,梗阻标准:Abrams-Griffiths(A-G)指数≥40,LinPURR 梗阻分级≥Ⅱ级.经腹...     

Endoscopic treatment of bladder outlet obstruction in men after pancreas transplantation.

PURPOSE: Diabetic cystopathy comprises a spectrum of voiding dysfunction. The usual clinical manifestations are impaired bladder sensation and detrusor contractility. Diabetic cystopathy is present in as many as 43 to 85% of patients undergoing pancreas transplantation. We evaluated endoscopic management of bladder outlet obstruction for adjuvant treatment of urological complications after pancreas transplantation. MATERIALS AND METHODS: We evaluated 10 men with recurrent urological complications, including bladder leak, urinary tract infection, the dysuria/urethritis syndrome and reflux nephropathy, after pancreas transplantation. Evaluation consisted of peak flow rate, post-void residual and written questionnaires in all cases, and preoperative urodynamics in 2. All patients had signs and symptoms of bladder outlet obstruction at post-transplant presentation and underwent bladder neck incision, direct visual internal urethrotomy, limited transurethral resection of the bladder neck or transurethral resection of the prostate. Hospital costs, including operating room, laboratory, pharmacy, hospital room occupancy, anesthesia and radiology fees, were obtained from the University of Washington. RESULTS: Mean peak flow rate plus or minus standard deviation increased from 10.1+/-3.2 to 21.0+/-5.1 cc per second and post-void residual decreased from 259.2+/-38.6 to 43.6+/-36.8 cc after endoscopic intervention. Of the patients 4 presented early (mean 4.3 months) after transplantation with bladder leak or reflux nephropathy, while late presentation (mean 43 months) was associated with recurrent urinary tract infection, the urethritis/dysuria syndrome and more obstructive symptoms. Complications resolved in all cases after surgery and enteric conversion, which costs 5-fold more than endoscopic intervention, was avoided. CONCLUSIONS: Recurrent urological complications warrant early evaluation for occult bladder dysfunction. Endoscopic procedures to relieve outlet obstruction are beneficial in alleviating recurrent urological complications in men after pancreas transplantation. This cost-effective and low morbidity procedure may obviate the need for enteric conversion in some male transplant recipients.     

Test-retest variation of pressure flow parameters in men with bladder outlet obstruction

PURPOSE: We assess short-term (5 to 10 minutes) and long-term (24 weeks) test-retest changes of repeated pressure flow examinations. MATERIALS AND METHODS: The pressure flow charts of 84 patients with benign prostatic enlargement and bladder outlet obstruction who had received either androgen suppressive therapy or placebo were reviewed retrospectively. Pressure flow examinations were performed at baseline, and at weeks 24 and 48. Each pressure flow session included 3 sequential voids. RESULTS: Median detrusor opening pressure, maximum detrusor pressure, detrusor pressure at maximum flow rate and minimum voiding pressure decreased statistically significantly from void 1 to 2, ranging from 9.5% to 15.8%. From void 2 to 3 during the same pressure flow session there was a further reduction in obstruction parameters. Median Abrams/Griffiths number was 10.7% lower at void 2 compared to void 1 (p <0.0001) and the urethral resistance algorithm was 3.2% lower (p <0.0001). Long-term test-retest changes from baseline to week 24 and from week 24 to week 48 for the pressure flow parameters studied were negligible. CONCLUSIONS: Changes in pressure flow parameters at short-term test-retesting are considerable and probably of clinical significance. The standard pressure flow nomograms, which are based on single void pressure flow studies, might need modification when applied to repeat void studies.     

Systemic inflammation leads to resistance to atracurium without increasing membrane expression of acetylcholine receptors

BACKGROUND: Systemic inflammation may be associated with resistance to nondepolarizing neuromuscular blocking drugs, the mechanisms of which are, however, uncharacterized. The authors therefore investigated the pharmacodynamics of atracurium and its relation to the expression of nicotinic acetylcholine receptors and alpha1 -acid glycoprotein in a rat model of systemic inflammation. METHODS: To induce a systemic inflammation, male CD rats received 56 mg/kg corynebacterium parvum intravenously. On days 2, 4, 6, 8, 10, 12, 14, or 16 after infection, neuromuscular transmission was measured. The individual effective dose of atracurium was determined, followed by an atracurium infusion at a rate to establish a steady state neuromuscular block of 50%. Total and unbound plasma concentrations of atracurium for 50% paralysis were measured using high-performance liquid chromatography. Acetylcholine receptors were quantitated using 125I-alpha-bungarotoxin. alpha1 -Acid glycoprotein concentrations in the serum were measured using a competitive chemiluminescence immunoassay. RESULTS: The effective dose of atracurium was increased on days 4, 6, and 8. Total atracurium plasma concentrations at 50% neuromuscular paralysis were increased on days 4, 6, 8, and 10, with a peak at day 8 (8.0 +/- 1.3 micro g/ml) compared with control rats (4.23 +/- 0.82 micro g/ml). The alpha1 -acid glycoprotein concentrations were increased between days 2 and 10, with a peak on day 4 (6.52 +/- 1.45 mg/ml), and recovered to control values (0.61 +/- 0.33 mg/ml) on day 12. Unbound plasma concentrations of atracurium to achieve 50% depression, as well as the expression of acetylcholine receptors, did not differ between groups. CONCLUSION: Resistance to atracurium during corynebacterium parvum-induced systemic inflammation is due to increased drug binding to alpha1 -acid glycoprotein and is unrelated to changes in acetylcholine receptor expression.