Effects ofl-arginine andl-NAME on chronic partial bladder outlet obstruction in rabbit

The effect of amino acids on the bladder cycle: a concise review

The human bladder maintains a cycle of filling, storing, and micturating throughout an individual's lifespan. The cycle relies on the ability of the bladder to expand without increasing the intravesical pressure, which is only possible with the controlled relaxation of well-complaint muscles and the congruously organized construction of the bladder wall. A competent bladder outlet, which functions in a synchronous fashion with the bladder, is also necessary for this cycle to be completed successfully without deterioration. In this paper, we aimed to review the contemporary physiological findings on bladder physiology and examine the effects of amino acids on clinical conditions affecting the bladder, with special emphasis on the available therapeutic evidence and possible future roles of the amino acids in the treatment of the bladder-related disorders.

Induction of detrusor underactivity by extensive vascular endothelial damages of iliac arteries in a rat model and its pathophysiology in the genetic levels

We tried to establish a reliable detrusor underactivity (DUA) rat model and to investigate pathophysiology of chronic bladder ischemia (CBI) on voiding behavior and bladder function. Adult male rats were divided into five groups. The arterial injury (AI) groups (AI-10, AI-20, AI-30) underwent vascular endothelial damage (VED) of bilateral iliac arteries (with 10, 20, and 30 bilateral repetitions of injury, respectively) and received a 1.25% cholesterol diet. The sham group underwent sham operation and received the same diet. Controls received a regular diet. After 8 weeks, all rats underwent unanesthetized cystometrogram. Bladder tissues were processed for organ bath investigation, immunohistochemistry staining, and genome-wide gene expression analysis. Awake cystometry analysis showed that frequency of voiding contractions and micturition pressure were lower in the AI-30 group than in sham group (p < 0.01). Contractile responses to various stimuli were lower in AI-20 and AI-30 groups (both p < 0.001). In the AI-20 and AI-30 groups, atherosclerotic occlusion in the iliac arteries, tissue inflammation, fibrosis, denervation, and apoptosis of bladder muscle were prominent compared to the sham. Mechanistically, the expression of purinergic receptor P2X-1 was reduced in the AI-30 group, and the genome-wide gene expression analysis revealed that genes related to IL-17 and HIF-1 signaling pathways including INF-γ receptor-1 and C-X-C motif chemokine ligand-2 were upregulated in the CBI-induced DUA rat model. A rat model of progressive VED successfully induced DUA. Abnormal tissue inflammation, fibrosis, denervation, and bladder muscle tissue apoptosis may be involved in CBI-induced DUA pathophysiology.

Effects of nitric oxide inhibitors in mice with bladder outlet obstruction

PURPOSE

To investigate the lower urinary tract changes in mice treated with L-NAME, a non-selective competitive inhibitor of nitric oxide synthase (NOS), or aminoguanidine, a competitive inhibitor of inducible nitric oxide synthase (iNOS), after 5 weeks of partial bladder outlet obstruction (BOO), in order to evaluate the role of constitutive and non-constitutive NOS in the pathogenesis of this experimental condition.

MATERIALS AND METHODS

C57BL6 male mice were partially obstructed and randomly allocated into 6 groups: Sham, Sham + L-NAME, Sham + aminoguanidine, BOO, BOO + L-NAME and BOO + aminoguanidine. After 5 weeks, bladder weight was obtained and cystometry and tissue bath contractile studies were performed.

RESULTS

BOO animals showed increase of non-voiding contractions (NVC) and bladder capacity, and also less contractile response to Carbachol and Electric Field Stimulation. Inhibition of NOS isoforms improved bladder capacity and compliance in BOO animals. L-NAME caused more NVC, prevented bladder weight gain and leaded to augmented contractile responses at muscarinic and electric stimulation. Aminoguanidine diminished NVC, but did not avoid bladder weight gain in BOO animals and did not improve contractile responses.

CONCLUSION

It can be hypothesized that chronic inhibition of three NOS isoforms in BOO animals leaded to worsening of bladder function, while selective inhibition of iNOS did not improve responses, what suggests that, in BOO animals, alterations are related to constitutive NOS.

Progressive vascular damage may lead to bladder underactivity in rats

PURPOSE

We assessed whether progressive vascular damage causes bladder underactivity in rats.

MATERIALS AND METHODS

Adult male Sprague Dawley® rats were divided into 4 groups. Controls received a regular diet and tap water. The L-NAME group received a 2% cholesterol diet and L-NAME (3 mg/ml) dissolved in drinking water. The arterial injury group underwent balloon endothelial injury of the common iliac arteries and received a 2% cholesterol diet and tap water after injury. The arterial injury/L-NAME group also received L-NAME dissolved in drinking water. At 8 weeks urodynamics were performed, bladder tissue was harvested for pharmacological studies, and the iliac arteries and bladders were histologically examined.

RESULTS

Iliac arteries from the injury and injury/L-NAME groups showed neointimal formation and luminal occlusion but arteries from the L-NAME group did not. In the L-NAME and injury groups bladder capacity and voided volume were less than in controls. Conversely, in the injury/L-NAME group these cystometric parameters were significantly greater than in the other groups. Post-void residual volume in the injury/L-NAME group tended to increase compared with the other groups. Contractile responses of bladder strips to various stimuli in the L-NAME, injury and injury/L-NAME groups were significantly less than in controls and the lowest in the injury/L-NAME group. The injury and injury/L-NAME groups showed a significantly increased percent of collagen compared to controls.

CONCLUSIONS

Pelvic arterial occlusive disease plus vascular endothelial dysfunction may cause progressive vascular damage resulting in bladder dysfunction that develops from bladder hyperactivity to bladder underactivity.

Nitric oxide modulates bladder afferent nerve activity in the in vitro urinary bladder-pelvic nerve preparation from rats with cyclophosphamide induced cystitis

Effects of a nitric oxide (NO) donor (SNAP), NO substrate (l-arginine), and NO synthase inhibitor (l-NAME) on bladder afferent nerve (BAN) activity were studied in an in vitro bladder-pelvic nerve preparation from untreated or cyclophosphamide (CYP) treated rats. Distension of the bladder induced phasic bladder contractions (PBC) that were accompanied by multiunit afferent firing. Intravesical administration of SNAP (2mM) which did not change the amplitude of PBC significantly decreased peak afferent firing from 79 ± 15 spikes/s to 44 ± 8 spikes/s in CYP pretreated but not untreated preparations. In CYP treated preparations SNAP also decreased by 33-55% BAN firing induced by isotonic distension of the bladder at 10-40 cmH(2)O pressures. Electrical stimulation on the surface of the bladder elicited action potentials (AP) in BAN. SNAP significantly increased the voltage threshold by 75% (p<0.05) and decreased by 45% (p<0.05) the area of the AP evoked at submaximal stimulus intensity. Bath application of SNAP (2mM) or l-arginine (50mM) elicited similar inhibitory effects on the distension evoked BAN firing. The effects of l-arginine were blocked by bath application of l-NAME (20mM). l-NAME alone did not alter BAN firing. In preparations from normal rats SNAP or l-arginine did not alter BAN activity. These results suggest that exogenous as well as endogenously generated NO depresses the excitability of sensitized but not normal BAN and that NO may have an antinociceptive function and modulate bladder hyperactivity induced by pathological conditions.

The effect of alpha-blocker treatment on bladder hypoxia inducible factor-1 alpha regulation during lower urinary tract obstruction

AIMS

To determine whether alpha1-blocker treatment, in chronic bladder outlet obstruction (BOO), influences bladder tissue ischemia.

MATERIALS AND METHODS

This prospective study included 60 patients with BOO, of which 40 were under alpha1-blocker medication and 20 without treatment. Patients underwent transurethral resection of the prostate (TURP) or suprapubic prostatectomy (SPP). Ten patients with non-muscle invasive bladder cancer underwent transurethral resection of the bladder tumor and served as the control group. Tissue specimens were immunohistochemically stained for hypoxia inducible factor-1alpha (HIF-1alpha).

RESULTS

Bladder tissue from obstructed subjects showed high immunoreactivity to HIF-1alpha. The specimens from the control group, showed no or weak, mainly cytoplasmic immunoreactivity to HIF-1alpha. Patients under alpha -blocker treatment did not differ in the number of HIF-1alpha positive cells compared to subjects with no treatment (median number 86.8 [20-150] and 88.6 [0-175], respectively) (p > 0.05). The lowest bladder pressure at which HIF-1alpha was up regulated, was detected at detrusor pressure Qmax (PdetQmax) = 60 cm H2O.

CONCLUSIONS

Treatment with alpha-blockers in obstructed patients considered as non-responders, does not result in HIF-1alpha down regulation, thus bladder continues to be under chronic stress.

Interactions between inducible nitric oxide synthase and cyclooxygenase-2 in response to ischaemia-reperfusion of rabbit bladder

OBJECTIVE

To investigate the interactions between inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in response to ischaemia-reperfusion (I/R) of rabbit bladder.

MATERIALS AND METHODS

Rabbit bladders were exposed to 2 h of ischaemia by bilaterally clamping the major arteries entering the bladder and then a subsequent 36 h of reperfusion (I/R) with or without intraperitoneal administration of a selective iNOS inhibitor n-(3-(amynomethyl)benzyl)acetamidine (1400W) or a selective COX-2 inhibitor NS-398 given 1 h before killing. The bladder tissues were processed for isometric tension experiments, enzymatic NOS activitiy, tissue contents of nitrite/nitrate (NO(X) ), cyclic guanosine monophosphate (cGMP) and COX activity determined by prostaglandin E(2) (PGE(2) ) production.

RESULTS

iNOS and constitutive NOS (cNOS) activities, NO(X) and PGE(2) contents in the bladder tissues at 36 h after reperfusion were significantly higher than those in the sham group with no significant increase in cGMP. Treatment with 1400W abrogated the increases in iNOS activity and NO(X) as well as PGE(2) without changing cNOS activity. In the tension experiments, a NOS substrate, l-arginine, induced detrusor contraction only in the I/R group, which was inhibited by 1400W or NS-398 but not by a selective soluble guanylate cyclase inhibitor 1H-[1,2,4] oxadiazole[4,3-a]quinoxalin-1-one (ODQ). 8-Br-cGMP induced detrusor relaxation in the sham and I/R groups. Also, l-arginine increased NO(X) and PGE(2) in the bladder tissues only in the I/R group, which were inhibited by pretreatment with 1400W. While, l-arginine increased cGMP contents in the I/R group and this increase was suppressed by ODQ but not by 1400W.

CONCLUSION

These results show that NO derived from an up-regulation of iNOS after I/R increases COX-2-derived PG via a cGMP-independent mechanism. NO-mediated activation of COX-2 may be an important mechanism for the modulation of bladder function after I/R injury.

Oxidative stress biomarkers in urine and plasma of rabbits with partial bladder outlet obstruction

What's known on the subject? and What does the study add? It has been known that there is an increase of oxidative damage in the bladder tissues of animals after PBOO. However, no reliable oxidative stress biomarkers in either urine or plasma have been available for the assessment of the severity of PBOO. This study clearly demonstrated that the levels of oxidative stress biomarkers are increased in urine and plasma of the rabbits with PBOO.

OBJECTIVE

To investigate oxidative stress and oxidative damage biomarkers in urine and plasma after partial bladder outlet obstruction (PBOO) in rabbits.

MATERIALS AND METHODS

In all, 16 male New Zealand White rabbits were separated equally into four groups: a control group and PBOO-treated groups for 2, 4 and 8 weeks. The oxidative stress biomarkers assessed included urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) and plasma malondialdehyde (MDA). We also measured the total antioxidant capacity (TAC) in blood plasma. 8-OHdG, MDA and TAC were measured at both the beginning and indicated time points of the experimental design.

RESULTS

There was no significant difference in body weight among rabbits in the four groups. However, there was a significant increase in bladder weight after 2 weeks of PBOO. After 4 and 8 weeks of PBOO, there was an additional significant increase in bladder weight in all three groups. There was no difference in blood creatinine levels among the groups. In the 4- and 8-week PBOO groups, there was a significant increase of 8-OHdG in urine and of MDA in plasma, while there was a significant decrease in TAC in plasma.

CONCLUSION

The results showed that oxidative stress could be detected in the plasma and urine of rabbits after 4 and 8 weeks of PBOO, and not only from bladder tissue as previously reported. Thus, there could be an easy and alternative way to evaluate bladder function by analysis of urine and/or plasma. Additionally, rabbits with chronic PBOO showed an increase in systemic oxidative stress, which could be a novel starting point for examining the link between the lower urinary tract symptoms/benign prostate hyperplasia and metabolic syndrome in future studies.

Comparison of the efficacy of melatonin and 1400W on renal ischemia/reperfusion injury: a role for inhibiting iNOS

INTRODUCTION

We investigated the roles of melatonin (a powerful antioxidant, iNOS inhibitor, and a scavenger of peroxynitrite) and 1400W (a strong and selective inhibitor of inducible nitric oxide) on renal dysfunction and injury induced by ischemia/reperfusion (I/R) of rat kidney, since oxidative and nitrosative injury are believed to be the major causes.

MATERIALS AND METHODS

Thirty-two male Sprague-Dawley rats were divided into four groups of sham-operated, I/R, I/R + Melatonin and I/R + 1400W. Rats were given either melatonin (10 mg/kg) or 1400W (10 mg/kg) in the I/R + Melatonin and I/R + 1400W groups respectively at 6 h prior to ischemia and at the beginning of reperfusion via intraperitoneal route. I/R injury was induced by 60 min of bilateral renal ischemia followed by 6 h of reperfusion. After reperfusion, kidneys and blood were obtained for histopathologic and biochemical evaluation.

RESULTS

Melatonin and 1400W had an ameliorative effect on both oxidative and nitrosative stress in the kidneys against renal I/R injury in rats. In addition, melatonin significantly reduced elevated nitro-oxidative stress product, restored decreased antioxidant enzymes and attenuated histological alterations when compared with 1400W.

CONCLUSIONS

Both Melatonin and 1400W were efficient in ameliorating experimental I/R injury of the kidneys. Moreover, melatonin was more effective than 1400W possibly through inhibiting iNOS as well as scavenging free oxygen radicals and peroxynitrite.

The immediate effect of nitric oxide on the rabbit bladder after ovariectomy

Ovariectomy resulted in decreased blood flow and hypoxia to the bladder mucosa and smooth muscle. Nitric oxide (NO) played an important role in regulating bladder function during bladder ischemia and reperfusion. This study was designed to evaluate the role of NO on bladder function in the first few days after ovariectomy. Female rabbits were separated into three groups, one which received no medication, premedicated with N(omega)-nitro-L-arginine methyl ester (L-NAME) and the third treated with L-arginine. Non-ovariectomized controls and at 1 and 3 days post-ovariectomy, animals from each group were euthanized. Cystometry and in vitro isometric contractile responses were recorded and the oxidative stress markers, nitrotyrosine and protein carbonylation were determined. L-NAME treatment did not significantly alter bladder function after ovariectomy. L-Arginine fed, ovariectomized rabbits had lower intravesical pressure and better contractile responses to all forms of stimulation than the ovariectomized rabbits with or without L-NAME. Furthermore, the ovariectomized ones with or without L-NAME had higher oxidative stress markers than L-arginine fed rabbits. This study clearly demonstrates that feeding rabbits with L-arginine can protect the bladder from oxidative free radical damage following short-term ovariectomy.