Effect of ischemia-reperfusion on contractile function of rat urinary bladder: possible role of nitric oxide

Effects of Nitric Oxide on Bladder Detrusor Overactivity through the NRF2 and HIF-1α Pathways: A Rat Model Induced by Metabolic Syndrome and Ovarian Hormone Deficiency

Metabolic syndrome (MetS) includes cardiovascular risk factors like obesity, dyslipidemia, hypertension, and glucose intolerance, which increase the risk of overactive bladder (OAB), characterized by urgency, frequency, urge incontinence, and nocturia. Both MetS and ovarian hormone deficiency (OHD) are linked to bladder overactivity. Nitric oxide (NO) is known to reduce inflammation and promote healing but its effect on bladder overactivity in MetS and OHD is unclear. This study aimed to investigate NO's impact on detrusor muscle hyperactivity in rats with MetS and OHD. Female Sprague-Dawley rats were divided into seven groups based on diet and treatments involving L-arginine (NO precursor) and L-NAME (NOS inhibitor). After 12 months on a high-fat, high-sugar diet with or without OVX, a cystometrogram and tracing analysis of voiding behavior were used to identify the symptoms of detrusor hyperactivity. The MetS with or without OHD group had a worse bladder contractile response while L-arginine ameliorated bladder contractile function. In summary, MetS with or without OHD decreased NO production, reduced angiogenesis, and enhanced oxidative stress to cause bladder overactivity, mediated through the NF-kB signaling pathway, whereas L-arginine ameliorated the symptoms of detrusor overactivity and lessened oxidative damage via the NRF2/HIF-1α signaling pathway in MetS with or without OHD-induced OAB.

Effects of electroacupuncture at BL33 on detrusor smooth muscle activity in a rat model of urinary retention

Background

Detrusor smooth muscle (DSM) underactivity may lead to urinary retention (UR). Electroacupuncture (EA) at BL33 may be effective in improving DSM contractions.

Objectives

This study aimed to investigate: (1) the effect of EA at BL33; and (2) the effect of different manipulation methods at BL33 on the modulation of DSM contractions in UR rats.

Methods

30 male Sprague-Dawley rats were anaesthetised with urethane and modelled by urethral outlet obstruction. First, 2 Hz EA at BL33, SP6 and LI4 wasrandomly applied to the UR rats for 5 min to observe the immediate effects (n=10); second, manual acupuncture (MA) (n=10) and 100 Hz EA (n=10) were applied with the same programme. DSM electromyography (EMG) and cystometrogram data were evaluated.

Results

(1) 2 Hz EA at BL33 and SP6 significantly increased DSM discharging frequency (0.80±0.10 Hz, P<0.001, and 0.22±0.14 Hz, P=0.038), shortened micturation intervals (65.67±20.65 s, P=0.008, and 35.62±15.84 s, P=0.042), prolonged the duration of voiding (2.13±0.61 s, P=0.005, and 0.47±0.16 s, P=0.015), and reduced residual pressure (−0.91±0.31 mmHg, P=0.019, and −0.66±0.27 mmHg, P=0.046). EA at LI4 was not associated with any functional effects (P>0.05). Compared with SP6, EA at BL33 had greater positive effects on DSM discharging frequency, duration of discharging, and duration of voiding (all P<0.05). (2) No statistically significant differences were shown between MA, 2 Hz EA and 100 Hz EA interventions when stimulating at BL33, SP6 or LI4.

Conclusions

EA at BL33 improved DSM contractions to a greater degree than EA at SP6 or LI4. There were no differences in effect when stimulating using 2 Hz EA, 100 Hz EA and MA.

Vitamin C Deficiency Reduces Muscarinic Receptor Coronary Artery Vasoconstriction and Plasma Tetrahydrobiopterin Concentration in Guinea Pigs

Vitamin C (vitC) deficiency is associated with increased cardiovascular disease risk, but its specific interplay with arteriolar function is unclear. This study investigates the effect of vitC deficiency in guinea pigs on plasma biopterin status and the vasomotor responses in coronary arteries exposed to vasoconstrictor/-dilator agents. Dunkin Hartley female guinea pigs (n = 32) were randomized to high (1500 mg/kg diet) or low (0 to 50 mg/kg diet) vitC for 10-12 weeks. At euthanasia, coronary artery segments were dissected and mounted in a wire-myograph. Vasomotor responses to potassium, carbachol, sodium nitroprusside (SNP), U46619, sarafotoxin 6c (S6c) and endothelin-1 (ET-1) were recorded. Plasma vitC and tetrahydrobiopterin were measured by HPLC. Plasma vitC status reflected the diets with deficient animals displaying reduced tetrahydrobiopterin. Vasoconstrictor responses to carbachol were significantly decreased in vitC deficient coronary arteries independent of their general vasoconstrictor/vasodilator capacity (p < 0.001). Moreover, in vitC deficient animals, carbachol-induced vasodilator responses correlated with coronary artery diameter (p < 0.001). Inhibition of cyclooxygenases with indomethacin increased carbachol-induced vasoconstriction, suggesting an augmented carbachol-induced release of vasodilator prostanoids. Atropine abolished carbachol-induced vasomotion, supporting a specific muscarinic receptor effect. Arterial responses to SNP, potassium, S6c, U46619 and ET-1 were unaffected by vitC status. The study shows that vitC deficiency decreases tetrahydrobiopterin concentrations and muscarinic receptor mediated contraction in coronary arteries. This attenuated vasoconstrictor response may be linked to altered production of vasoactive arachidonic acid metabolites and reduced muscarinic receptor expression/signaling.

Purinergic signaling and blood vessels in health and disease

Purinergic signaling plays important roles in control of vascular tone and remodeling. There is dual control of vascular tone by ATP released as a cotransmitter with noradrenaline from perivascular sympathetic nerves to cause vasoconstriction via P2X1 receptors, whereas ATP released from endothelial cells in response to changes in blood flow (producing shear stress) or hypoxia acts on P2X and P2Y receptors on endothelial cells to produce nitric oxide and endothelium-derived hyperpolarizing factor, which dilates vessels. ATP is also released from sensory-motor nerves during antidromic reflex activity to produce relaxation of some blood vessels. In this review, we stress the differences in neural and endothelial factors in purinergic control of different blood vessels. The long-term (trophic) actions of purine and pyrimidine nucleosides and nucleotides in promoting migration and proliferation of both vascular smooth muscle and endothelial cells via P1 and P2Y receptors during angiogenesis and vessel remodeling during restenosis after angioplasty are described. The pathophysiology of blood vessels and therapeutic potential of purinergic agents in diseases, including hypertension, atherosclerosis, ischemia, thrombosis and stroke, diabetes, and migraine, is discussed.

The effects of α-defensin 1 on electrical field stimulation-induced contraction of rat bladders

This study was designed to investigate the effects of α-defensin 1 on electrical field stimulation (EFS)-induced contractions in isolated rat bladder detrusor muscles. We evaluated the effects of α-defensin 1 (50 pM∼5 nM) on EFS-induced contractions in the detrusor smooth muscles from 35 rats (2-30 Hz). Bladder strips were pretreated with α-defensin 1 and then changes of contractions by adenosine 5'-triphosphate (ATP) were observed. Moreover, after pretreatment with α-defensin 1 for 10 min, changes in concentration-response curves to hydrogen peroxide (H2O2) were investigated. Alpha-defensin 1 has increased EFS-induced contractions, significantly, and the contractile response to ATP (1,2,5,10mM) was also increased significantly when strips were pretreated with α-defensin 1. In addition, alpha-defensin 1 increased H2O2-induced contractions. The present study demonstrates that α-defensin 1 increases EFS-induced contractions of rat detrusor muscles via purinergic contraction coupled with the Rho kinase pathway.

Early removal of urinary catheter leads to greater post-void residuals in patients with thoracic epidural

BACKGROUND

A recent study showed that the removal of a bladder catheter is safe in presence of thoracic epidural analgesia (TEA). However, the ability to void satisfactorily can be affected. The aim of this investigation is to determine whether patients with TEA are able to recover the micturition process.

METHODS

On the morning after the surgery patients were randomised into two groups: the early removal group (ERG) (n = 101), with the bladder catheter removed at the same time, and the standard group (SG) (n = 104), where the bladder catheter was kept as long as TEA was functioning (on average 3-5 days after surgery). Following the first micturition, patients underwent regular ultrasound scanning of the bladder until a post-void residual (PVR) less than 200 ml was reached.

RESULTS

All of the patients in the ERG and in the SG started to void and recovered satisfactorily their ability to void, reaching a PVR < 200 ml without requiring a transurethral catheterisation. However, the length of time to reach a PVR < 200 ml in the ERG was significantly longer compared with the SG (345 min ± 169 vs. 207 min ± 122, P < 0.0001).

CONCLUSION

In the presence of TEA, the removal of the bladder catheter on the morning after surgery leads to a transient impairment of the lower urinary tract function with no need for re-catheterisation.

PARP inhibition prevents oxidative injury of bladder induced by acute urinary retention and subsequent emptying

It has been demonstrated that increases in poly(ADP-ribose) polymerase (PARP) activity causes damage to several organs under ischemia/reperfusion (I/R) conditions. The aims of this study were to investigate whether inhibition of PARP could suppress apoptosis in the bladder following acute urinary retention (AUR) and subsequent bladder emptying. Twelve-week-old male Sprague Dawley rats were divided into a control group, saline treated group, and 3-aminobenzamide (3-AB, a specific PARP inhibitor)-treated group. Sixty minutes after the administration of saline and 3-AB, the saline and 3-AB-treated groups had 60 min of over-distension and followed by 2 h of drainage. The degree of bladder apoptosis, levels of malondialdehyde (MDA), ATP and nicotinamide adenine dinucleotide (NAD+); expression of poly(ADP-ribose) (PAR), phosphorylation of protein kinase B (Akt); and levels of Bcl-2, Bax, and caspase 3 activity in the bladder were determined. Molecular and histological analyses showed that bladder apoptosis was associated with increases in the amount of PAR and decreases in ATP and NAD+ levels in the saline treated group. In addition, phosphorylated Akt and Bcl-2/Bax ratio were significantly decreased. The activity of caspase 3 was significantly increased in the saline treated group. Inhibition of PARP significantly increased the levels of ATP and NAD+, phosphorylation of Akt, and Bcl-2/Bax ratio, and significantly reduced the activation of caspase 3. As a result, apoptosis in the bladder was attenuated. These results indicate that PARP activation may be involved in apoptosis in the bladder induced by AUR and subsequent emptying via energy depletion and suppression of Akt activity.

The effect of Nomega-nitro-L-arginine methyl ester and L-arginine on lung injury induced by abdominal aortic occlusion-reperfusion

PURPOSE

The aim of this study was to examine the effects of Nomega-nitro-L-arginine methyl ester (L-NAME) and L-arginine on lung injury after aortic ischemia-reperfusion (IR).

METHODS

Twenty-four Wistar-Albino rats were randomized into four groups (n = 6) as follows: Control (sham laparotomy), Aortic IR (30 min ischemia and 120 min reperfusion), L-Arginine (intraperitoneal 100 mg kg(-1) live weight)+aortic IR, and L: -NAME (intraperitoneal 10 mg kg(-1) live weight)+aortic IR. In the lung specimens, the tissue levels of malondialdehyde (MDA), vascular endothelial growth factor (VEGF), and nitric oxide (NO) were measured and a histological examination was done.

RESULTS

Aortic IR increased MDA, VEGF, and NO. L-Arginine further significantly increased MDA and NO, and decreased VEGF (P < 0.05 vs aortic IR). L-NAME significantly decreased MDA and NO (P < 0.05 vs L-arginine+aortic IR) and increased VEGF (P < 0.05 vs other groups). A histological examination showed the aortic IR to significantly increase (P < 0.05 vs control) while L-arginine also further increased (P > 0.05 vs aortic IR), whereas L-NAME caused a significant decrease in pulmonary leukocyte infiltration (P < 0.05 vs aortic IR).

CONCLUSIONS

Our results indicate that L-arginine aggravates the lung injury induced by aortic IR, while L-NAME attenuates it.

Effects of l-arginine and N(G)-nitro-l-arginine methyl ester treatments on expression of neuronal nitric oxide synthase in the guinea-pig bladder after partial bladder outlet obstruction

This study was aimed to examine the effects of pharmacological intervention on partial bladder outlet obstruction (PBOO) on expression of neuronal nitric oxide synthase (nNOS) and nitric oxide (NO) production and NO-related free radical damage using nitrotyrosine as a marker in the guinea-pig bladder. Partial urethral ligation was performed in young male guinea pigs which were then intraperitoneally administered l-arginine, N(G)-nitro-l-arginine methyl ester (l-NAME) or vehicle (saline) for 2 or 4 weeks. At the respective time points, the bladder was removed for nNOS immunohistochemistry, Western blot analysis, nitrotyrosine enzyme-linked immunosorbent assay test and NO colorimetric assay. In l-arginine-treated animals killed at 2 and 4 weeks, the total number of nNOS positive intramural neurons was significantly increased when compared with the corresponding control. Some neurons projected long extending fibers that were closely associated with the blood vessels. Furthermore, at 4 weeks, the nNOS protein content and NO production as reflected by the concentration of nitrite and nitrate were drastically elevated as measured by Western blot analysis and NO colorimetric assay, respectively. In l-NAME-treated group killed at 2 weeks, the number of nNOS positive neurons was markedly reduced when compared with the controls, but the change was not significant at 4 weeks. In the latter, however, the NO production as reflected by the concentration of nitrite and nitrate was markedly reduced; in addition, the nitrotyrosine concentration was significantly lower than the control. The present results support the role of NO in the pathophysiological changes following PBOO. We suggest the potential therapeutic application of l-arginine and l-NAME in PBOO; however, ultimately balancing the bidirectional effects of NO would be essential.

Montelukast reduces ischaemia/reperfusion-induced bladder dysfunction and oxidant damage in the rat

The present study aimed to investigate the possible beneficial effects of the cysteinyl leukotriene-1 receptor antagonist montelukast on contractility and oxidant damage after ischaemia/reperfusion (I/R) of rat urinary bladder. The abdominal aorta of Sprague-Dawley rats was occluded to induce I/R. Montelukast (10 mg kg(-1)) or saline was administered intraperitoneally before I/R. In the sham-operated group, the abdominal aorta was left intact and the animals were treated with montelukast or saline. After decapitation, the bladder was removed and the tissue was either used for functional studies or stored for biochemical assays. In the I/R group, the isometric contractile responses of the bladder strips to carbachol (10(-8)-10(-4) M) were lower than those of the control group and were reversed by treatment with montelukast. Lipid peroxidation and myeloperoxidase activity of the bladder tissues in the I/R group were greater than in the sham-operated group. Montelukast treatment in the I/R group decreased these parameters compared with I/R alone. Similarly, the significant decrease in tissue glutathione level in the I/R group compared with controls was also prevented by montelukast. Treatment with montelukast almost completely reversed the low contractile responses of rat urinary bladder to carbachol and prevented oxidative tissue damage following I/R.

Preventive effects of cyclohexenonic long-chain fatty alcohol on diabetic cystopathy in the rat

In this study, we investigated the preventive effect of n-hexacosanol on diabetes-induced bladder dysfunction in the rat. Diabetes was induced in 8-week-old male Sprague-Dawley rats by administering an injection of streptozotocin (50 mg/kg, i.p.). The rats were randomly divided into 4 groups (age-matched control rats, diabetic rats without treatment with n-hexacosanol, and diabetic rats treated with n-hexacosanol (2 and 8 mg/kg, i.p. every day)) and maintained for 4 weeks. The serum glucose and serum insulin levels were determined, and the functions of bladder were estimated by voiding behavior, cystometric, and functional studies to carbachol and KCl. Furthermore, we examined possible diabetic induced histological changes in these rats. Treatment with n-hexacosanol did not alter diabetic status including body mass, bladder mass, and serum glucose and serum insulin levels, but significantly improved the maximum contraction pressure of the detrusor and residual urine volume in cystometric studies and Emax values to carbachol in functional studies in a dose-dependent manner. Diabetes induced bladder smooth muscle hypertrophy, which tended to be ameliorated by treatment with n-hexacosanol in a dose-dependent manner. Treatment with n-hexacosanol did not alter the diabetic status, but significantly improved diabetic cystopathy in a dose-dependent manner.

Altered Nitric Oxide Synthase, Arginase and Ornithine Decarboxylase Activities, and Polyamine Synthesis in Response to Ischemia of the Rabbit Detrusor

PURPOSE

Little is known about L-arginine catabolism following ischemia in the bladder. We examined the changes in nitric oxide synthase, arginase and ornithine decarboxylase activity, polyamine biosynthesis and the ability to produce nitric oxide following ischemia of the rabbit bladder.

MATERIALS AND METHODS

Bladder ischemia was created by ligation of a unilateral bladder artery. At various time points, that is 1, 4, 8, 24, 48 and 72 hours following ligation, the bladders were excised and harvested for determinations.

RESULTS

Constitutive nitric oxide synthase, inducible nitric oxide synthase arginase and ornithine decarboxylase activities increased with time, peaking at 48 hours without significant differences between the ligated and nonligated sides in the whole layer. Arginase and ornithine decarboxylase increased mainly in the muscularis following ischemia. Also, putrescine in the muscularis was significantly higher than in the mucosa 48 hours following ischemia. Baseline nitrite/nitrate production in the whole detrusor on the ligated side at 24 hours was significantly lower than that in the normal detrusor. However, nor-hydroxyarginine as an arginase inhibitor and L-arginine increased nitrite/nitrate production in the ischemic detrusor without changing in the normal detrusor. This increasing effect of nor-hydroxyarginine was abolished by nitroarginine methylester as a nitric oxide synthase inhibitor.

CONCLUSIONS

Enzymes related to L-arginine catabolism were involved in the early events of ischemic bladder. Arginase may have 2 independent roles, that is 1) activation of arginase/ornithine decarboxylase/polyamines pathways in the muscle injury and remodeling following ischemia, and 2) endogenous negative regulation of nitric oxide production by limiting the L-arginine substrate for nitric oxide synthase.

General administration of cyclohexenonic long-chain fatty alcohol ameliorates hyperreactivity of STZ-induced diabetic rat aorta

Diabetic neuropathy, a major complication of diabetes mellitus, is associated with the development of vascular dysfunction and autonomic neuropathy. We studied the effects of cyclohexenonic long-chain fatty alcohol (FA) on streptozotocin-diabetic hyperreactivity in the rat aorta smooth muscle. The rats were divided randomly into four groups and were maintained for 4 weeks: age-matched control rats, diabetic rats without treatment with FA, and diabetic rats treated with FA (2 and 8 mg/kg, i.p. everyday). The serum glucose and insulin levels were determined, and the contractile responses of the aorta induced by a thromboxane A2 agonist, U46619 and KCl were investigated. Treatment with FA did not alter rats' diabetic status, i.e., body weight, thickness of the aorta, serum glucose levels, and serum insulin levels, but significantly improved the diabetic-induced hyperreactivity of the rat aorta in a dose-dependent manner. Removal of endothelium did not change contractile force between groups. In histological examinations, thinning of smooth muscle bundle in the wall of aorta was observed in the diabetic rat, which was not significantly improved by treatment with FA. Our data indicate that FA can prevent hyperreactivity in the diabetic aorta.

Effects of cyclohexenonic long-chain fatty alcohol on diabetic rat trachea

In order to investigate the diabetes-associated neuropathy and prevent effects of cyclohexenonic long-chain fatty alcohol, a neurotrophic substance, in trachea, we studied its effect on streptozotocin-diabetic hyper-reactivity in the rat trachea. Diabetes was induced in 8-week-old male Sprague-Dawley rats by administering an intraperitoneal injection of streptozotocin (50 mg/kg). The rats were divided randomly into four groups and were maintained for four weeks: age-matched control rats, diabetic rats without treatment with cyclohexenonic long-chain fatty alcohol, and diabetic rats treated with cyclohexenonic long-chain fatty alcohol (2 and 8 mg/kg, i.p. every day). The serum glucose and insulin levels were determined, and the contractile responses of the trachea induced by carbachol and KCl were investigated. Treatment with cyclohexenonic long-chain fatty alcohol did not alter the rats' diabetic status, i.e., body weight, thickness of the trachea, serum glucose levels, and serum insulin levels, but significantly improved the diabetic-induced hyper-reactivity of the rat trachea in a dose-dependent manner. There was no significant difference in either the carbachol- or KCl-induced contractile forces between groups with or without mucosa in the functional studies. In histological examinations, thinning of cricoid cartilage, thickness of basal membrane, and degeneration, fragmentation of elastic fibers in the submucosal layer, and hypertrophy of smooth muscle bundle in the membranous wall of trachea were observed in the diabetic rat trachea, which were improved by treatment with cyclohexenonic long-chain fatty alcohol. Our data indicate that this drug can prevent hyper-reactivity in the diabetic trachea.

Effect of cyclohexenonic long-chain fatty alcohol on rat overactive bladder induced by bladder neck obstruction

We attempted to clarify the preventive effects of cyclohexenonic long-chain fatty alcohol on detrusor overactivity induced by mild bladder neck obstruction. Bladder neck obstruction was created by partial ligation of the urethra. Female Sprague-Dawley rats were divided into three groups: those with bladder neck obstruction treated without long-chain fatty alcohol, those with bladder neck obstruction with long-chain fatty alcohol (8 mg/kg, i.p., every day) and the sham-operated control group (A, B, and C groups, respectively). Six weeks after the induction of bladder neck obstruction, voiding behavior was observed in the metabolic cage, and a cystometrogram was performed in the experimental animals. Furthermore, Hematoxylin and Eosin, Azan-Mallory, and Bodian stainings were performed in these bladders. Bladder weight, voiding behaviors and a cystometry indicated that rats in the A group showed detrusor overactivity, which was improved by treatment with long-chain fatty alcohol. The proportion of connective tissue and the density of bundles of neurofibers in the bladder of the A group was significantly less than that in the other bladders. Mild bladder neck obstruction induces detrusor overactivity, which is improved by treatment with long-chain fatty alcohol.

Expression of HSP 70 and its mRNAS during ischemia-reperfusion in the rat bladder

HSP 70 is an important protein that repairs damaged tissue after injury. In the present study, we investigated the expression of HSP 70 and its mRNAs during ischemia-reperfusion in the rat bladder. Rat abdominal aorta was clamped with a small clip to induce ischemia-reperfusion injury in the bladder dome. Male Wistar rats, 8 weeks old, were divided into six groups: controls, 30-min ischemia, 30-min ischemia and 30-, 60-minute, 1- and 7-day reperfusion, groups A, B, C, D, E, and F, respectively. In functional studies, contractile responses to carbachol were measured in these groups. The expression of HSP 70-1/2 mRNAs was quantified using a real-time PCR method, and that of HSP 70 proteins was measured using ELISA in the bladders. In the functional study, Emax values of carbachol to bladders in the A, B, C, D, E and F groups were 9.3 +/- 1.3, 7.9 +/- 1.7, 4.3 +/- 0.8, 4.2 +/- 0.7, 4.5 +/- 0.6, and 8.1 +/- 1.2 g/mm2, respectively. In the control group, the expression of HSP 70-1/2 mRNA was detected, and the expression of HSP 70-1 mRNAs was significantly higher than that of HSP 70-2 mRNAs in each group. The expression of HSP 70-1 mRNA increased in groups B and C, but decreased in groups D, E, and F. The expression of HSP 70-2 mRNA in group C was significantly higher than that of groups A, D, E, and F. The expression of HSP 70-1/2 mRNAs after 1 day or 1 week of reperfusion was similar to control levels. The expression of HSP 70 proteins was increased shortly after the expression of their mRNAs. The expression of HSP 70 after 1 day or 1 week of reperfusion was almost identical to control levels. Our data indicate that contractile responses of the bladder were decreased by ischemia reperfusion, and that expression of HSP 70 and its mRNAs appeared to increase after a short period of the insult.

Melatonin treatment protects against sepsis-induced functional and biochemical changes in rat ileum and urinary bladder

Sepsis is commonly associated with enhanced generation of reactive oxygen metabolites, which lead to multiple organ dysfunction. The aim of this study was to examine the role of melatonin, a potent antioxidant, in protecting the intestinal and bladder tissues against damage in a rat model of sepsis. Sepsis was induced by cecal ligation and perforation (CLP) in Wistar Albino rats. Sham operated (control) and CLP group received saline or melatonin (10 mg/kg, ip) 30 minutes prior to and 6 hours after the operation. Sixteen hours after the surgery, rats were decapitated and the intestinal and urinary bladder tissues were used for contractility studies, or stored for the measurement of malondialdehyde (MDA) content -an index of lipid peroxidation-, glutathione (GSH) levels -a key antioxidant- and myeloperoxidase (MPO) activity- an index of neutrophil infiltration-. Ileal and bladder MDA levels in the CLP group were significantly increased (p < 0.001) with concomitant decreases in GSH levels (p < 0.01 - p < 0.001) when compared to the control group. Similarly, MPO activity was significantly increased (p < 0.001) in both ileum and bladder tissues. On the other hand, melatonin treatment significantly reversed (p < 0.001) the elevations in MDA and MPO levels, while reduced GSH levels were increased back to the control levels (p < 0.01 - p < 0.001). In the CLP group, the contractility of the ileal and bladder tissues decreased significantly compared with controls. Melatonin treatment of the CLP group restored these responses. In this study, CLP induced dysfunction of the ileal and bladder tissue of rats was reversed by melatonin treatment. Moreover, melatonin, as an antioxidant, abolished the elevation in lipid peroxidation products and myeloperoxidase activity, and reduction in the endogenous antioxidant glutathione and thus protected the tissues against sepsis-induced oxidative damage.

Expression of heat shock protein 70 and its mRNAs during ischemia–reperfusion in the rat prostate

We investigated the expression of heat shock protein (HSP) 70 and its mRNAs during ischemia-reperfusion in the rat prostate. Eight-week-old rats were divided into six groups: a control group, a 30-min ischemia group, and 30-min ischemia+30-min, 60-min, 1-day, and 1-week reperfusion groups (groups A, B, C, D, E, and F, respectively). In vivo real-time blood flow and HSP 70-1 and 70-2 mRNAs and proteins in the prostate were measured using laser Doppler flow meter, real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) methods, respectively. Clamping of the aorta decreased blood flow to 10% of the basal level. The expressions of HSP 70-1/2 mRNAs increased in groups B, C, and D, and decreased in groups E and F. The expression of HSP 70 proteins was increased after a short interval of increase in their mRNAs. Our data indicated that the expressions of HSP 70 proteins and their mRNAs are dramatically changed during ischemia-reperfusion in the rat prostate.

Disruption of bladder epithelium barrier function after spinal cord injury

Neural-epithelial interactions are hypothesized to play an important role in bladder function. We determined whether spinal cord injury (SCI) altered several indicators of urinary bladder epithelium barrier function, including continuity of the surface umbrella cell layer, transepithelial resistance (TER), and urea and water permeability. Within 2 h of SCI, significant changes in uroepithelium were noted, including disruption of the surface umbrella cells and an approximately 50% decrease in TER. By 24 h, TER reached a minimum and was accompanied by significant increases in water and urea permeability. Regeneration of the surface uroepithelium was accomplished by 14 days after SCI and was accompanied by a return to normal TER and urea and water permeabilities. This early disruption of the uroepithelial permeability and accompanying changes in uroepithelial morphology were prevented by pretreatment with hexamethonium (a blocker of ganglion transmission), indicating involvement of sympathetic or parasympathetic input to the urinary bladder. In addition, prior treatment with capsaicin worsened the effect of SCI on uroepithelial permeability, suggesting that capsaicin-sensitive afferents may play a protective role in the process. These results demonstrate that SCI results in a significant disruption of the urinary bladder uroepithelium and that these changes may be mediated in part by an interaction with bladder nerves.

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

Reactive oxygen metabolites play important roles in ischemia/reperfusion (I/R) injury in several systems. The aim of this study was to investigate the role of melatonin against I/R injury of the rat urinary bladder. The abdominal aorta was clamped to induce ischemia for 30 min, then the animals were subjected to 60 min of reperfusion. Melatonin (10 mg/kg, i.p.) or the vehicle (control 1% alcohol i.p.) was administered before I/R. After decapitation, the bladder was removed and the tissue was either used for functional studies or stored for measurement of products of lipid peroxidation (LP), glutathione (GSH) levels and myeloperoxidase activity (MPO). Bladder strips were suspended in oxygenated Tyrode's buffer at 37 degrees C and isometric contractions to carbachol (CCh; 10(-8)-10(-4) m) were recorded. In the I/R group, the contractile responses of the bladder strips were lower than those of the control group (P < 0.01-0.001) and were reversed by treatment with melatonin (P < 0.05-0.001). LP which was higher in I/R group compared with control (27.68 +/- 1.69 and 10.59 +/- 1.27 nmol/g, respectively; P < 0.001) was partially reversed by melatonin (19.01 +/- 1.85 nmol/g; P < 0.01). Similarly, GSH showed a decrease in the I/R group compared with controls (0.27 +/- 0.03 and 0.43 +/- 0.04 micromol/g, respectively; P < 0.05) and melatonin prevented this effect completely (0.45 +/- 0.04 micromol/g; P < 0.05). MPO activity in the I/R group (4.19 +/- 0.08 U/g) was significantly higher than that of the control group (1.41 +/- 0.08 U/g; P < 0.001) and melatonin treatment reduced MPO levels compared with I/R alone (3.16 +/- 0.07; P < 0.001). Melatonin almost completely reversed the low contractile responses of rat urinary bladder strips to CCh and prevented oxidative tissue damage following I/R.

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.

Microcirculation of the urinary bladder in a rat model of ischemia-reperfusion-induced cystitis

OBJECTIVES

To determine the microcirculatory disturbances in a rat model of ischemia-reperfusion-induced cystitis using intravital fluorescence videomicroscopy.

METHODS

Twenty male Sprague-Dawley rats were used for the experiments. In 10 animals, warm ischemia of the bladder was induced for 60 minutes. After 30 minutes of reperfusion, microvascular macromolecular leakage, leukocyte-endothelial cell interactions, venular red blood cell velocity, functional capillary density, and the arteriolar and venular diameters were determined by intravital videomicroscopy. In addition, the intravesical pressure and macrohemodynamic parameters were assessed during the experiments. Sham-operated animals served as the controls (n = 10).

RESULTS

After ischemia-reperfusion, the numbers of rolling and firmly adherent leukocytes in the postcapillary venules were significantly increased. Venular red blood cell velocity and functional capillary density, as well as the arteriolar and venular diameters, were significantly decreased. The macromolecular leakage had increased in both arterioles and venules.

CONCLUSIONS

After ischemia-reperfusion, inflammatory reactions and microcirculatory failure were observed in the urinary bladder. This study targeted the microcirculatory consequences of cystitis using intravital videomicroscopy. Because the parameters investigated are relevant not only for ischemia-reperfusion of the urinary bladder but also for cystitis caused by other stimuli, this model represents a novel tool in the field of inflammation research in urology.

Preventive effect of long-chain fatty alcohol on ischemia--reperfusion injury in the rat bladder

We attempted in the present study to clarify the preventive effects of cyclohexenonic long-chain fatty alcohol on ischemia-reperfusion injury in the rat bladder. Rat bladders were exposed to 30 min of ischemia and a subsequent 30 min of reperfusion with or without several doses of cyclohexenonic long-chain fatty alcohol (0.5, 2, 8 mg/kg). Muscle-bath studies were performed, and malonaldehyde concentrations were measured in the bladder. Bladder dysfunction and lipid peroxidation caused by ischemia-reperfusion were prevented by cyclohexenonic long-chain fatty alcohol in a dose-dependent manner. Our data indicate that cyclohexenonic long-chain fatty alcohol can prevent the production of free radicals and ischemia-reperfusion injury in the bladder.

The role of endothelin-1 in ischemia-reperfusion induced acute inflammation of the bladder in rats

PURPOSE

Endothelin (ET)-1 is causatively involved in ischemia-reperfusion induced acute inflammatory reactions and microcirculatory disturbances in many organs. We investigated the role of endothelin-1 in the microcirculatory consequences of ischemia-reperfusion of the bladder using intravital fluorescence videomicroscopy.

MATERIALS AND METHODS

Male Sprague-Dawley rats were used in the experiments. The animals were randomly assigned to a sham operated group or to 1 of 2 ischemia-reperfusion groups that underwent 60 minutes of ischemia followed by 30 minutes of bladder reperfusion. In 1 ischemia-reperfusion group the animals were pretreated with BQ 610, a specific ET-A receptor blocker. The bladder was placed on an especially designed stage for intravital fluorescence videomicroscopy measurements. Venular red blood cell velocity, functional capillary density, venular and arteriolar diameter, venular and arteriolar macromolecular leakage, and leukocyte-endothelial cell interactions in postcapillary venules were determined using a computer assisted analyzing system.

RESULTS

Functional capillary density, red blood cell velocity, venular and arteriolar diameter were significantly decreased and macromolecular leakage was significantly enhanced after bladder ischemia-reperfusion. The number of rolling and adherent leukocytes was significantly increased in postcapillary venules. Pretreatment with BQ 610 was effective for attenuating the effects of ischemia-reperfusion induced inflammation but could not completely prevent microcirculatory failure.

CONCLUSIONS

Ischemia-reperfusion induced cystitis leads to significant impairment of the microcirculation and ET-1 is suggested to have an important role in this process. Pretreatment with an ET-A receptor antagonist reduces ischemia-reperfusion related microvascular disturbances in the bladder.