Response Of Urinary Bladder Research Articles

Enhanced expression of ncc1 and clc2c in the kidney and urinary bladder accompanies freshwater acclimation in Mozambique tilapia

Euryhaline fishes maintain hydromineral balance in a broad range of environmental salinities via the activities of multiple osmoregulatory organs, namely the gill, gastrointestinal tract, skin, kidney, and urinary bladder. Teleosts residing in freshwater (FW) environments are faced with the diffusive loss of ions and the osmotic gain of water, and, therefore, the kidney and urinary bladder reabsorb Na+ and Cl− to support the production of dilute urine. Nonetheless, the regulated pathways for Na+ and Cl− transport by euryhaline fishes, especially in the urinary bladder, have not been fully resolved. Here, we first investigated the ultrastructure of epithelial cells within the urinary bladder of FW-acclimated Mozambique tilapia (Oreochromis mossambicus) by electron microscopy. We then investigated whether tilapia employ Na+/Cl− cotransporter 1 (Ncc1) and Clc family Cl− channel 2c (Clc2c) for the reabsorption of Na+ and Cl− by the kidney and urinary bladder. We hypothesized that levels of their associated gene transcripts vary inversely with environmental salinity. In whole kidney and urinary bladder homogenates, ncc1 and clc2c mRNA levels were markedly higher in steady-state FW- versus SW (seawater)-acclimated tilapia. Following transfer from SW to FW, ncc1 and clc2c in both the kidney and urinary bladder were elevated within 48 h. A concomitant increase in branchial ncc2, and decreases in Na+/K+/2Cl−cotransporter 1a (nkcc1a) and cystic fibrosis transmembrane regulator 1 (cftr1) levels indicated a transition from Na+ and Cl− secretion to absorption by the gills in parallel with the identified renal and urinary bladder responses to FW transfer. Our findings suggest that Ncc1 and Clc2c contribute to the functional plasticity of the kidney and urinary bladder in tilapia.

Bladder Preservation with Neoadjuvant Chemotherapy Followed by Concurrent Chemoradiation for the Treatment of Muscle-invasive Carcinoma of the Bladder: A Single-Center Experience.

Purpose The purpose of the study was to evaluate the short-term response and acute toxicities in muscle-invasive carcinoma urinary bladder treated with neoadjuvant chemotherapy followed by concurrent chemoradiation. Materials and Methods Thirty patients with muscle-invasive bladder cancer were treated with three cycles of neoadjuvant chemotherapy every 3 weeks. Response assessment was done after 4 weeks with repeat cystoscopy and imaging. Responders were treated with concurrent chemoradiation 60 Gy/30# at 2 Gy/# along with weekly injection cisplatin 35 mg/m 2 . Response assessment was done by new response evaluation criteria in solid tumors (version 1.1). Treatment-related acute toxicities were scored using common terminology criteria for adverse events version 4.0. Results Of the 30 patients, 25 patients responded to neoadjuvant chemotherapy with complete response in 17 patients (56.67%) and partial response in eight patients (26.66%). Five patients (16.66%) showed poor response and were advised radical cystectomy, of which four underwent radical cystectomy and one patient opted for concurrent chemoradiation. Of 26 patients who completed chemoradiation, complete response was seen in 21 patients (80.76%) and partial response was seen in four patients (15.38%). Only one patient developed progression of disease in the form of lung metastasis. All the patients with residual disease were advised to undergo salvage cystectomy. Among the patients receiving chemoradiation, grade 2 cystitis and diarrhea was seen in 10 patients (38.46%) and four patients (15.38%), respectively. Only one patient developed grade 3 diarrhea. Conclusion Bladder preservation treatment is an effective, safe, and convenient option for patients presenting with muscle-invasive carcinoma bladder. Neoadjuvant chemotherapy followed by chemoradiation was well-tolerated with an acceptable rate of complications.

Effect of distigmine on the contractile response of guinea pig urinary bladder to electrical field stimulation

Distigmine bromide (distigmine) is a reversible carbamate group cholinesterase (ChE) inhibitor. Although mainly used clinically for the treatment of myasthenia gravis, distigmine is also indicated for detrusor underactivity in Japan. According to the pharmacological classification of distigmine, its therapeutic effect against detrusor underactivity appears to be produced by enhanced urinary bladder smooth muscle (UBSM) contractility due to an increased concentration of acetylcholine between parasympathetic nerve endings and UBSM cells. However, ATP as well as acetylcholine is also released from parasympathetic nerve endings that dominate UBSM. The present study was thus carried out to investigate the potentiating effects of distigmine on the two UBSM contractile components in response to parasympathetic nerve stimulation induced by electrical field stimulation (EFS). In isolated guinea pig UBSM tissues, EFS (1–16Hz) produced tetrodotoxin-sensitive, frequency-dependent contractions. The contractile responses to EFS were largely diminished by atropine (10−6M), and the remaining contractile components in the presence of atropine were virtually abolished by α,β-methylene adenosine triphosphate (α,β-mATP) (10−4M). Distigmine (10−6M) significantly potentiated EFS-induced contractile components generated in the presence of α,β-mATP (10−4M), but did not potentiate EFS-induced contractile components generated in the presence of atropine (10−6M). These findings clearly indicate that distigmine strongly potentiates UBSM contraction selectively induced by parasympathetic nerve-derived acetylcholine, suggesting a potential mechanism by which distigmine restores detrusor underactivity.

Sitagliptin exerts anti-apoptotic effect in nephrotoxicity induced by cisplatin in rats.

Sitagliptin is a selective inhibitor of dipeptidylpeptidase-4 enzyme used for the management of diabetes mellitus type II. The anti-inflammatory, antioxidant, and anti-apoptotic properties of sitagliptin were documented. This study was designed to explore the effect of sitagliptin (10mg/kg, orally) on nephrotoxicity induced by cisplatin (7mg/kg, i.p.) in Sprague-Dawley rats. Nephrotoxicity of cisplatin was manifested by elevation in renal somatic index, proteinuria, blood urea nitrogen, creatinine in serum, lactate dehydrogenase, kidney malondialdehyde, NF-κB, Bax, and annexin V. Furthermore, body weight, serum albumin, nitric oxide, creatinine clearance, and the renal antioxidant defense system were significantly decreased by cisplatin. Sitagliptin administration ameliorated cisplatin-induced changes in kidney function, oxidative stress, inflammation, and apoptosis parameters. Improvement in both morphological examination of kidney and the urinary bladder response to acetylcholine supported these results. These findings indicated that sitagliptin, through its anti-inflammatory, anti-apoptotic, and antioxidant effects, can be used as a nephroprotectant against nephrotoxicity induced by cisplatin.

Wild cane toads (Rhinella marina) expel foreign matter from the coelom via the urinary bladder in response to internal injury, endoparasites and disease.

Dissections of >1,200 wild-caught cane toads (Rhinella marina) in tropical Australia confirm a laboratory report that anurans can expel foreign objects from the coelom by incorporating them into the urinary bladder. The foreign objects that we found inside bladders included a diverse array of items (e.g., grass seeds, twigs, insect prey, parasites), many of which may have entered the coelom via rupture of the gut wall. In some cases, the urinary bladder was fused to other organs including liver, fat bodies, ovaries, Bidder’s organs, lungs, mesentery, stomach wall, gall bladder, and the abdominal wall. Acanthocephalan parasites (of a range of developmental stages) were identified from the walls of the urinary bladders of three cane toads. This organ may play a significant role in destroying or excreting metazoan parasites, as well as inanimate objects.

Local Change in Urinary Bladder Contractility Following CNS Dopamine Denervation in the 6-OHDA Rat Model of Parkinson's Disease.

Background: Urinary problems, including urinary frequency, urgency, and nocturia are some of the non-motor symptoms that correlate most with poor quality of life in Parkinson’s disease. However, the mechanism behind these symptoms is poorly understood, in particular regarding peripheral bladder pathophysiology following dopamine degeneration.Objective: In this study, we compared the contractile responsiveness of urinary bladder from the 6-OHDA unilateral rat model of Parkinson’s disease with that of normal untreated animals.Methods: The contractility of the urinary detrusor muscle was evaluated in bladder strip preparations using electrical field stimulation, and muscarinic and purinoceptor stimulations in an vitro organ bath setup.Results: Our data show that the overall contractile response following electrical field stimulation was significantly higher (43% at maximum contraction by 20–40 Hz stimulation) in the 6-OHDA-lesioned rats as compared to control animals. This increase was associated with a significant increase in the cholinergic contractile response, where the muscarinic agonist methacholine produced a 44% (at 10 −4 M concentration) higher response in the 6-OHDA-treated rats as compared to controls with a significant left-shift of the dose response. This indicates an altered sensitivity of the muscarinic receptor system following the specific central 6-OHDA-induced dopamine depletion. In addition a 36% larger contraction of strips from the 6-OHDA animals was also observed with purinoceptor activation using the agonist ATP (5×10 −3 M) during atropine treatment.Conclusions: Our data shows that it is not only the central dopamine control of the micturition reflex that is altered in Parkinson’s disease, but also the local contractile function of the urinary bladder. The current study draws attention to a mechanism of urinary dysfunction in Parkinson’s disease that has previously not been described.

Pannexin 1 channels mediate the release of ATP into the lumen of the rat urinary bladder.

ATP is released through pannexin channels into the lumen of the rat urinary bladder in response to distension or stimulation with bacterial endotoxins. Luminal ATP plays a physiological role in the control of micturition because intravesical perfusion of apyrase or the ecto-ATPase inhibitor ARL67156 altered reflex bladder activity in the anaesthetized rat. The release of ATP from the apical and basolateral surfaces of the urothelium appears to be mediated by separate mechanisms because intravesical administration of the pannexin channel antagonist Brilliant Blue FCF increased bladder capacity, whereas i.v. administration did not. Intravesical instillation of small interfering RNA-containing liposomes decreased pannexin 1 expression in the rat urothelium in vivo and increased bladder capacity. These data indicate a role for pannexin-mediated luminal ATP release in both the physiological and pathophysiological control of micturition and suggest that urothelial pannexin may be a viable target for the treatment of overactive bladder disorders. ATP is released from the bladder epithelium, also termed the urothelium, in response to mechanical or chemical stimuli. Although numerous studies have described the contribution of this release to the development of various bladder disorders, little information exists regarding the mechanisms of release. In the present study, we examined the role of pannexin channels in mechanically-induced ATP release from the urothelium. PCR confirmed the presence of pannexin 1 and 2 mRNA in rat urothelial tissue, whereas immunofluorescence experiments localized pannexin 1 to all three layers of the urothelium. During continuous bladder cystometry in anaesthetized rats, inhibition of pannexin 1 channels using carbenoxolone (CBX) or Brilliant Blue FCF (BB-FCF) (1-100μm, intravesically), or by using intravesical small interfering RNA, increased the interval between voiding contractions. Intravenous administration of BB-FCF (1-100μgkg(-1) ) did not alter bladder activity. CBX or BB-FCF (100μm intravesically) also decreased basal ATP concentrations in the perfusate from non-distended bladders and inhibited increases in ATP concentrations in response to bladder distension (15 and 30cmH2 Opressure). Intravesical perfusion of the ATP diphosphohydrolase apyrase (2Uml(-1) ), or the ATPase inhibitor ARL67156 (10μm) increased or decreased reflex bladder activity, respectively. Intravesical instillation of bacterial lipopolysaccharides (LPS) (Escherichia coli 055:B5, 100μgml(-1) ) increased ATP concentrations in the bladder perfusate, and also increased voiding frequency; these effects were suppressed by BB-FCF. These data indicate that pannexin channels contribute to distension- or LPS-evoked ATP release into the lumen of the bladder and that luminal release can modulate voiding function.

Fourier Transform Analysis of Rabbit Detrusor Autonomous Contractions Reveals Length Dependent Increases in Tone and Slow Wave Development at Long Lengths

Bladder wall muscle (detrusor) develops low amplitude rhythmic contractions. Low amplitude rhythmic contraction activity is increased in detrusor from patients with overactive bladder. In this in vitro study we used fast Fourier transforms to assess the length dependence of low amplitude rhythmic contraction components. Rabbit detrusor strips were placed in a muscle bath between 2 clips to adjust length and record isometric tension. Tissues stretched from 70% to 130% of a reference muscle length at 10% increments were allowed to develop low amplitude rhythmic contractions at each length for 20 minutes. Low amplitude rhythmic contraction data were analyzed using fast Fourier transforms and represented by a frequency rather than a time spectrum. Based on fast Fourier transform analysis summarized by signal peaks within specific frequency ranges, rabbit low amplitude rhythmic contraction waveforms were divided into 1 tonic and 2 phasic components, defined as A0 + A1F1 + A2F2, where A0 is a length dependent basal tonic component that increases linearly, A1F1 is a slow wave with a length dependent specific amplitude (A1) and a length independent constant frequency (F1) of approximately 11.2 Hz, and A2F2 is a fast wave with a length dependent amplitude (A2) and frequency (F2) of approximately 0.03 Hz. Fast Fourier transform analysis revealed that rabbit low amplitude rhythmic contractions consist of a basal tonic component plus 2 phasic components. The amplitude of all 3 components was length dependent. The frequency of the fast component was not length dependent and the slow component was absent at short muscle lengths, developing only at muscle lengths beyond that producing a maximum active contraction.

Effects of Coenzyme Q10 on Bladder Dysfunction Induced by Chronic Bladder Ischemia in a Rat Model

We investigated the protective effects of coenzyme Q10 on bladder dysfunction in a rat model of atherosclerosis induced chronic bladder ischemia. A total of 24 male Sprague-Dawley® rats at age 16 weeks were divided into 4 groups of 6 each, including group 1--untreated, sham operated rats, group 2--coenzyme Q10 treated, sham operated rats, group 3--untreated rats with chronic bladder ischemia and group 4--coenzyme Q10 treated rats with chronic bladder ischemia. Groups 3 and 4 received an endothelial injury to the iliac arteries and were fed a 2% cholesterol diet for 8 weeks. Groups 2 and 4 were treated with coenzyme Q10 and the others were treated with vehicle for 4 weeks. Eight weeks postoperatively we performed continuous in vivo cystometry, an in vitro detrusor muscle strip study and a malondialdehyde assay. Histological examination of the bladder walls and iliac arteries was also done. In vivo cystometry revealed that coenzyme Q10 administration after the induction of chronic bladder ischemia prolonged micturition frequency and the intercontraction interval, and increased bladder capacity compared to those in untreated rats with chronic bladder ischemia. In the detrusor muscle strip study coenzyme Q10 administration after the induction of chronic bladder ischemia increased contractile responses compared to those in untreated rats with chronic bladder ischemia. Rats with chronic bladder ischemia also showed higher malondialdehyde in bladder tissue and serum than the other groups. Chronic bladder ischemia induced submucosal fibrosis of the bladder walls and a degenerative change in the blood vessel tunical media, as shown on histological examination. Our study suggests that coenzyme Q10 acts as an antioxidant to protect bladder function in this chronic bladder ischemia model.

Donepezil-induced response of Spirulina supplemented rat urinary bladder

At present, very little is known about the effects of donepezil on vascular reactivity. The aim of the present study was to evaluate the responses of rat urinary bladder to donepezil (10-10-3x10-4 M) and the role of Spirulina supplementation in these effects. Animals were divided into the two groups of six animals in each group. The first group received only distilled water daily as vehicle for six weeks and served as the control. The second group received Spirulina 750 mg kg -1 orally, daily for six weeks and served as the spirulina group. Preparations of rat urinary bladder were used from both groups. Donepezil produced concentration dependent relaxation of rat urinary bladder preparations pre-contracted with KCl.The pIC50 value, but not the maximal response of donepezil, was significantly lower (p<0.05) in the Spirulina supplemented group. These results demonstrated for the first time that spirulina treatment can affect urinary bladder activity (Fig. 1, Ref. 20).

Contractile responses of urinary bladder in an experimental model of chronic renal failure

Chronic kidney disease is a public health problem with increasing prevalence caused by diabetes, hypertension and glomerulonephritis. Number of publications investigate the lower urinary tract dysfunction due to CKD is limited. There is a high incidence of bladder dysfunction of different degrees in patients with renal failure. Mechanism of the lower urinary tract dysfunction in these patients is not well known. In this study, we aimed to investigate the effects of CKD on detrusor function in a rat model of CKD. In our study, 20 Wistar Albino rats have been divided into two groups as CKD and control groups. To the experiment group, left partial nephrectomy and right nephrectomy have been applied. CKD confirmation has done with the BUN and creatinin values from the blood of the rats. The bladder strips were prepared from the CKD and control groups and its contractile responses were evaluated in-vitro. There wasn't a considerable difference with the contractile responses caused by carbachol, KCL. There was a considerable increase in the contractile responses caused by ATP, ADP and electrical field stimulation on the behalf of the CKD group. The present study demonstrated that isolated DSM of CKD group showed significantly increased contraction responses to purinergic agonists ADP, ATP and atropine resistant component in electrical field stimulation-induced contractions as compared to those of the control group. Bladder overactivity and reduced bladder volume in CKD patients might be due to the change in purinergic system.

Responses of acrylamide-treated rat bladders

Acrylamide (ACR) is a chemical used in many industries around the world and more recently was found to be formed naturally in foods cooked at high temperatures. ACR was shown to be a neurotoxicant, reproductive toxicant, and carcinogen in animal species. The aim of the present study is to evaluate the influence of ACR treatment on urinary bladder responses to carbachol (10-9-3x10-4 M) and potassium chloride (KCl; 5-100 mM), each of them causes receptor-dependent and receptor-independent contractions, respectively. We also examined the role of gender in these responses. Rats of both genders were divided into three groups as follows: (1) Control animals (2) ACR-I; ACR-treated (2 mg/kg-d for 90 days) (3) ACR-II; ACR-treated (5 mg/kg-d for 90 days). In rats treated with ACR, the EC50 values of carbachol and KCl, but not the maximal response, to both agents were significantly higher than in control group. Histopathological parameters such as edema, congestion, inflammatory cells, microvascular proliferation, fibrosis, eosinophils, mast cells and epithelial damage were all higher in the ACR-treated group than in the controls. These results demonstrate for the first time that ACR-treatment can induce urinary bladder injury (Tab. 4, Fig. 4, Ref. 30).

The Effects of the c-kit Blocker Glivec on the Contractile Response of Urinary Bladder

To investigate the effects of imatinib (Glivec) on the urinary bladder contraction and excitation induced by neurostimulation, therefore to clarify the relationships between the bladder interstitial cell of Cajal (ICC) and the neural signals. In invivo experiments, pelvic nerves of rats were stimulated by square-wave pulses. The contractile response was recorded before and 40 min after the administration of medications (atropine, Glivec, and ketotifen). In invitro experiments, the bladder contractile response induced by acetylcholine with or without Glivec was evaluated. The space relationship between ICC and neural fibers were observed with double-labeled fluorescence using primary antibodies (anti-c-kit and anti-vesicular acetylcholine transferase) and secondary fluorescent antibodies (Alexa 488 and Alexa 594; Molecular Probes, Eugene, OR). Atropine and Glivec could significantly inhibit the bladder contractile response induced by the electrical stimulation in a dose-dependent manner, while ketotifen did not obviously affect bladder contractile response. In invitro experiments, Glivec did not affect acetylcholine-induced bladder contractile response. The location of ICC in close proximity to cholinergic nerve fibers was confirmed by double-labeled fluorescence. Bladder ICC play an important role as intermediaries in the transmission of cholinergic signals from nerve to smooth muscle cells.

Inhibitory Effect of L-Type Voltage-Dependent Calcium Channel Blocker on Response of Urinary Bladder with Acute Ethanol Intoxication

Purpose: This study was performed to assess the effect of L-type voltage-dependent calcium channel (VDCC) blocker (dilitiazem) on the response of the urinary bladder with ethanol intoxication in in vivo and in vitro studies. Materials and Methods: Sprague-Dawley rats were used for in vivo and in vitro studies. The strips were divided into 5 groups according to pretreatment. Group I-A was treated with ethanol (0.1%), group I-B with ethanol (0.5%), group II with diltiazem treatment (10^–6M), group III-A with pretreatment of diltiazem (10^–6M) with ethanol intoxication (0.1%) and group III-B with pretreatment of diltiazem with ethanol intoxication (0.5%). The carbachol-induced tension was compared before and after each pretreatment. In separate in vivo experiments, the changes of maximal vesical pressure and intercontraction interval after intra-arterial administration of each agent (identical grouping with in vitro study) were monitored. Results: The carbachol-induced contractions in group I-A, group I-B, group II, group III-A and group III-B were significantly decreased after each pretreatment (95 ± 2.73%, 92.6 ± 2.5%, 65.4 ± 2.0%, 52.61 ± 5.16%, 14.9 ± 1.4% of the control). The degree of increment of intercontraction interval and decrement of maximal vesical pressure showed a significant difference in the presence of diltiazem and ethanol intoxication (0.5%) compared with the diltiazem-treated and ethanol-intoxicated groups (0.5%). Conclusions: There is a possibility that ethanol and L-type VDCC blockers have synergistic depressive effect on bladder contractility and that ethanol and L-type VDCC blockers act through a common ionic pathway.

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.

Age-dependent vascular endothelial growth factor expression and angiogenic capability of bladder smooth muscle cells: implications for cell-seeded technology in bladder tissue engineering

Cell seeding technology is commonly used in the field of tissue engineering to enhance the performance of bioscaffolds and promote tissue regeneration. The age of cells used for ex vivo seeding to achieve maximal tissue regeneration has not been defined. Since rapid angiogenesis is the most critical step for tissue graft survival and success, we evaluated passage-dependent vascular endothelial growth factor (VEGF) expression in cultured smooth muscle cells (SMCs) obtained from urinary bladder and endothelial cell response to bladder SMCs. Levels of various VEGF isoforms mRNA expression and total VEGF secretion were determined by a semi-quantitative reverse-transcription polymerase chain reaction (RT-PCR) and an enzyme-linked immunosorbent assay (ELISA) analysis, respectively. In vitro endothelial cell migration in Transwell and capillary-like tube formation in Matrigel were used to predict the ability of bladder SMCs to promote angiogenesis. VEGF produced by cultured bladder SMCs increased from passages 4 to 7, and decreased from passages 7 to 12 at both mRNA and protein levels. Endothelial cell migration as well as capillary-like tube formation correlated with levels of VEGF expression by bladder SMCs. Pre-incubation of endothelial cells with a VEGF receptor 1/2 inhibitor, SU5416, significantly reduced the number of capillary-like tubes in SMC-endothelial cell Matrigel co-culture, and confirmed the involvement of VEGF in endothelial cell tube formation. Our results demonstrate that cell passage number is related to levels of VEGF production, which may translate to angiogenesis in engineered tissues.

The TRPV4 Cation Channel Mediates Stretch-evoked Ca2+ Influx and ATP Release in Primary Urothelial Cell Cultures

Transient receptor potential channels have recently been implicated in physiological functions in a urogenital system. In this study, we investigated the role of transient receptor potential vanilloid 4 (TRPV4) channels in a stretch sensing mechanism in mouse primary urothelial cell cultures. The selective TRPV4 agonist, 4alpha-phorbol 12,13-didecanoate (4alpha-PDD) evoked Ca(2+) influx in wild-type (WT) urothelial cells, but not in TRPV4-deficient (TRPV4KO) cells. We established a cell-stretch system to investigate stretch-evoked changes in intracellular Ca(2+) concentration and ATP release. Stretch stimulation evoked intracellular Ca(2+) increases in a stretch speed- and distance-dependent manner in WT and TRPV4KO cells. In TRPV4KO urothelial cells, however, the intracellular Ca(2+) increase in response to stretch stimulation was significantly attenuated compared with that in WT cells. Stretch-evoked Ca(2+) increases in WT urothelium were partially reduced in the presence of ruthenium red, a broad TRP channel blocker, whereas that in TRPV4KO cells did not show such reduction. Potent ATP release occurred following stretch stimulation or 4alpha-PDD administration in WT urothelial cells, which was dramatically suppressed in TRPV4KO cells. Stretch-dependent ATP release was almost completely eliminated in the presence of ruthenium red or in the absence of extracellular Ca(2+). These results suggest that TRPV4 senses distension of the bladder urothelium, which is converted to an ATP signal in the micturition reflex pathway during urine storage.

Estrogen modulates permeability and prostaglandin levels in the rabbit urinary bladder

The purpose of this study was to characterize barrier function, hypoxic damage and prostaglandin levels in the urinary bladder in response to estrogen deficiency. Female New Zealand White rabbits were separated into three groups: ovariectomized; sham-operated; and ovariectomized treated with estrogen. Barrier function was compromised in the ovariectomized group compared to that of the sham group and the ovariectomized group treated with estrogen. Urinary bladders of ovariectomized animals showed higher concentrations of hypoxic markers than controls, localized primarily in the urothelium. Levels of 6-keto-PGF 1α and PGF 2α were significantly higher in smooth muscle than the ovariectomized animals and PGE 2 levels were significantly lower in the mucosa of ovariectomized animals. These results suggest that estrogen deficiency induces a loss of barrier function and an increase in hypoxia. The estrogen-dependent decreases of prostaglandin PGE 2 in the urothelium correlate with loss of barrier function, suggesting estrogen regulation of PGE 2 may contribute to maintenance of urothelial function.

Proteomics Analysis Identifies Molecular Targets Related to Diabetes Mellitus-associated Bladder Dysfunction

Protein expression profiles in rat bladder smooth muscle were compared between animal models of streptozotocin-induced diabetes mellitus (STZ-DM) and age-matched controls at 1 week and 2 months after induction of hyperglycemia with STZ treatment. At each time point, protein samples from four STZ-DM and four age-matched control rat bladder tissues were prepared independently and analyzed together across multiple DIGE gels using a pooled internal standard sample to quantify expression changes with statistical confidence. A total of 100 spots were determined to be significantly changing among the four experimental groups. A subsequent mass spectrometry analysis of the 100 spots identified a total of 56 unique proteins. Of the proteins identified by two-dimensional DIGE/MS, 10 exhibited significant changes 1 week after STZ-induced hyperglycemia, whereas the rest showed differential expression after 2 months. A network analysis of these proteins using MetaCore suggested induction of transcriptional factors that are too low to be detected by two-dimensional DIGE and identified an enriched cluster of down-regulated proteins that are involved in cell adhesion, cell shape control, and motility, including vinculin, intermediate filaments, Ppp2r1a, and extracellular matrix proteins. The proteins that were up-regulated include proteins involved in muscle contraction (e.g. Mrlcb and Ly-GDI), in glycolysis (e.g. alpha-enolase and Taldo1), in mRNA processing (e.g. heterogeneous nuclear ribonucleoprotein A2/B1), in inflammatory response (e.g. S100A9, Annexin 1, and apoA-I), and in chromosome segregation and migration (e.g. Tuba1 and Vil2). Our results suggest that the development of diabetes-related complications in this model involves the down-regulation of structural and extracellular matrix proteins in smooth muscle that are essential for normal muscle contraction and relaxation but also induces proteins that are associated with cell proliferation and inflammation that may account for some of the functional deficits known to occur in diabetic complications of bladder.

Immunolocalization of a mammalian aquaporin 3 homolog in water-transporting epithelial cells in several organs of the clawed toad Xenopus laevis

Nucleotide sequences of cDNA were used to construct antibodies against an aquaporin (AQP) expressed in the clawed toad, Xenopus laevis, viz., Xenopus AQP3, a homolog of mammalian AQP3. Xenopus AQP3 was immunolocalized in the basolateral membrane of the principal cells of the ventral skin, the urinary bladder, the collecting duct and late distal tubule of the kidney, the absorptive epithelial cells of the large intestine, and the ciliated epithelial cells of the oviducts. Therefore, we designated this AQP as basolateral Xenopus AQP3 (AQP-x3BL). The intensity of labeling for AQP-x3BL differed between the ventral and dorsal skin, with the basolateral membrane of the principal cells in the ventral skin showing intense labeling, whereas that in the dorsal skin was lightly labeled. AQP-x3BL was also immunolocalized in the basolateral membrane of secretory cells in the small granular and mucous glands of the skin. As AQP-x5, a homolog of mammalian AQP5, is localized in the apical membrane of these same cells, this provides a pathway for fluid secretion by the glands. Although Hyla AQP-h2 is translocated from the cytoplasm to the apical membrane of the Hyla urinary bladder in response to arginine vasotocin (AVT), AQP-h2 immunoreactivity in Xenopus bladder remains in the cytoplasm and barely moves to the apical membrane, regardless of AVT stimulation. AQP-x3 is localized in the basolateral membrane, even though the AVT-stimulated AQP-h2 does not translocate to the apical membrane. These findings provide new insights into AQP function in aquatic anurans.