Update on bladder smooth-muscle physiology

Differentially Expressed mRNA in Streptozotocin-Induced Diabetic Bladder Using RNA Sequencing Analysis

PURPOSE

To detect elements governing the pathogenesis of diabetic cystopathy (DC), mRNA sequencing was carried out for bladder tissues from normal rats and those with induced diabetes mellitus (DM). This research therefore offers possible underlying molecular pathways for the advancement of DC in relation to differential mRNA expression, together with visceral functional and architectural alterations noted in individuals with this condition.

METHODS

An intraperitoneal injection of streptozotocin (STZ) was utilized to provoke DM in male Sprague-Dawley rats. Dysregulation and significant variations between normal rats and those with induced DM were then identified by a fold change of ≥ 1.5 with a false discovery rate P < 0.05. Hierarchical clustering/heat map and Gene Ontology/DAVID reference sources were generated. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and protein-protein interaction analysis were then performed.

RESULTS

The diabetic rodent group exhibited a greater residual urine volume (4.0 ± 0.4 mL) than their control counterparts (0.7 ± 0.2 mL, P < 0.01) at 12 weeks after diagnosis of diabetes. Expression analysis revealed 16 upregulated and 4 downregulated genes in STZDM bladder samples. A notable increase in expression was seen in PTHLH, TNFAIP6, PRC1, MAPK10, LOC686120, CASQ2, ACTG2, PDLIM3, FCHSD1, DBN1, NKD2, PDLIM7, ATF4, RBPMS2, ITGB1 and HSPB8. A notable decrease in expression was seen in SREBLF1, PBGFR1, PBLD1 and CELF1. Major genetic themes associated with mRNA upregulation and downregulation ware identified via Gene Ontology analysis and KEGG pathways. Protein to protein interaction analysis detected PDLIM3, PDLIM7, ITGB1, ACTG2 as core high frequency nodes within the network.

CONCLUSION

Changes in mRNA expression together with biological process and pathways that contribute to the etiologies underlying visceral impairment of the bladder in DM are evident. Our strategy is promising for recognizing mRNAs exclusive to the bladder in DM that might offer useful targets for diagnosis and treatment.

A review of the neural control of micturition in dogs and cats: neuroanatomy, neurophysiology and neuroplasticity

This article discusses the current knowledge on the role of the neurological structures, especially the cerebellum and the hypothalamus, and compares the information with human medicine. Micturition is a complex voluntary and involuntarily mechanism. Its physiological completion strictly depends on the hierarchical organisation of the central nervous system pathways in the peripheral nervous system. Although the role of the peripheral nervous system and subcortical areas, such as brainstem centres, are well established in veterinary medicine, the role of the cerebellum and hypothalamus have been poorly investigated and understood. Lower urinary tract dysfunction is often associated with neurological diseases that cause neurogenic bladder (NB). The neuroplasticity of the nervous system in the developmental changes of the mechanism of micturition during the prenatal and postnatal periods is also analysed.

The influence of altitude hypoxia on uroflowmetry parameters in women

There is scientific evidence to suggest a correlation between hypoxia and the physiology of micturition. During a Himalayan Scientific and Mountaineering Expedition, we performed tests to investigate the functional interactions between altitude hypoxia and uroflowmetry parameters in women. The tests were carried out in seven women (36.3 ± 7.1 yr) from normoxic [1,340 meters above sea level (m a.s.l.)] to hypoxic conditions (up to 5,050 m a.s.l.) and during the return descent. The following measures were determined: uroflowmetry parameters and saturation of peripheral oxygen (SpO2). As expected, SpO2 decreased from 97.7 to 77.8% with increasing altitude. Micturition flow time, flow volume, and voiding time increased with altitude ( P < 0.04 for all), indicating a negative correlation with SpO2. In conclusion, in young adult women, micturition physiological parameters were affected during adaptation to hypoxia; the correlation with SpO2 strongly suggests a role of hypoxia in these changes. These data could help to support the design of new strategies for both prevention and medical treatment. An example of the latter might be hyperbaric oxygen therapy, which in some studies has proved able to reduce the symptoms in patients with hypoxic bladder.

Effect of diabetes on the ion pumps of the bladder

OBJECTIVE

To establish whether the activities of Na+/K+-adenosine triphosphatase (ATPase) and Ca2+-ATPases ion pumps in bladder smooth muscle are altered as a consequence of diabetes and, if so, how this might contribute to bladder cystopathy. Urinary bladder dysfunction is a common occurrence in patients with diabetes. Pressure generation requires calcium and cytosolic ATP. Activities of these pumps are responsible for calcium homeostasis.

METHODS

Rat urinary detrusor muscle strips were suspended in organ baths containing Krebs solution for isometric tension recording. Tissue responses to the Na+/K+-ATPase pump inhibitor, ouabain, the plasma membrane Ca2+ ATPase inhibitor, vanadate, and the sarcoplasmic reticulum Ca2+ ATPase inhibitor, cyclopiazonic acid (CPA), were examined from normal and streptozocin-induced diabetic rats for 2, 4, and 12 weeks.

RESULTS

Ouabain, vanadate, and CPA caused concentration-dependent contractions of bladder strips from diabetic and normal rats. The degree of contraction of diabetic bladder muscle was lower than that of controls. This reduction was a function of duration of diabetes. For ouabain, the reduction peaked at 2 weeks, with partial restoration to normal after diabetes induction. For vanadate and CPA, the reduction increased with the duration of diabetes.

CONCLUSION

The ion pumps are important modulators of bladder smooth muscle tone, and in a rat model of streptozotocin-induced diabetes, the activity of these pumps is impaired. Although this is only a single model of diabetes, these findings suggest that a defect in these pumps may be an important component of the development of diabetic bladder cystopathy.

Reversing bladder outlet obstruction attenuates systemic and tissue oxidative stress

What's known on the subject? and What does the study add? Oxidative damage in bladder tissue and systemic oxidative biomarkers were both found to be increased in rabbits with partial bladder outlet obstruction. It is shown that the reversal of partial bladder outlet obstruction will attenuate the systemic oxidative stress.

OBJECTIVE

To investigate whether partial bladder outlet obstruction (PBOO) increases systemic oxidative stress and whether relief of PBOO could attenuate this stress.

MATERIALS AND METHODS

Surgically created PBOO in male New Zealand white rabbits was assessed after 4 weeks in one group of rabbits (n = 4), and was relieved in two additional groups of rabbits (n = 4 each) that were assessed at 4 and 8 weeks after relief of PBOO. Four sham-operated rabbits served as controls. The assessed oxidative stress biomarkers included urinary and plasma 8-hydroxy-2'-deoxyguanosine (8-OHdG) and plasma malondialdehyde (MDA), total anti-oxidant capacity (TAC) and glutathione (GSH). In addition, the copy number of mitochondrial DNA and the 8-OHdG content in bladder tissues from these rabbits were also determined at the beginning and at indicated time points in the experiments.

RESULTS

There were significant increases in both the 8-OHdG levels of urine, plasma and bladder tissue and the plasma MDA after induction of PBOO. There were also significant decreases in the TAC, in GSH levels and in mitochondrial DNA copy number in bladder tissues after PBOO. Most importantly, all of the values returned toward the control levels after the PBOO was reversed at 8 weeks.

CONCLUSION

PBOO increases systemic and oxidative stress and its reversal results in a progressive reduction of both systemic and tissue oxidative stress.

Involvement of hypoxia-triggered endoplasmic reticulum stress in outlet obstruction-induced apoptosis in the urinary bladder

In bladder outlet obstruction (BOO), mechanical stress and ischemia/hypoxia are implicated in structural and functional alterations of the urinary bladder. Because mechanical stress and hypoxia may trigger endoplasmic reticulum (ER) stress, we examined involvement of ER stress in the damage of the bladder caused by BOO. An experimental model of BOO was established in rats by complete ligature of the urethra for 24 h, and bladders were subjected to northern blot analysis and assessment of apoptosis. Isolated urinary bladders and bladder-derived smooth muscle cells (BSMCs) were also exposed to mechanical strain and hypoxia and used for analyses. To examine involvement of ER stress in the damage of the bladder, the effects of a chemical chaperone 4-phenylbutyrate (4-PBA) were evaluated in vitro and in vivo. Outlet obstruction for 24 h induced expression of ER stress markers, GRP78 and CCAAT/enhancer-binding protein-homologous protein (CHOP), in the bladder. It was associated with induction of markers for mechanical stress (cyclooxygenases 2) and hypoxia (vascular endothelial growth factor and glyceraldehyde-3-phosphate dehydrogenase). When isolated bladders and BSMCs were subjected to mechanical strain, induction of GRP78 and CHOP was not observed. In contrast, when BSMCs were exposed to hypoxic stress caused by CoCl2 or thenoyltrifluoroacetone (TTFA), substantial upregulation of GRP78 and CHOP was observed, suggesting involvement of hypoxia in the induction of ER stress. In the bladder subjected to BOO, the number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive cells increased in the epithelial cells and BSMCs. Similarly, treatment with TTFA or CoCl2 induced apoptosis of BSMCs, and 4-PBA significantly attenuated ER stress and apoptosis triggered by these agents. Furthermore, in vivo administration with 4-PBA significantly reduced apoptosis in the bladder subjected to BOO. These results suggested that outlet obstruction caused ER stress via hypoxic stress in the bladder and that hypoxia-triggered ER stress may be involved in the induction of apoptosis in BOO.

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.

Compensatory paracrine mechanisms that define the urothelial response to injury in partial bladder outlet obstruction

Diseases and conditions affecting the lower urinary tract are a leading cause of dysfunctional sexual health, incontinence, infection, and kidney failure. The growth, differentiation, and repair of the bladder's epithelial lining are regulated, in part, by fibroblast growth factor (FGF)-7 and -10 via a paracrine cascade originating in the mesenchyme (lamina propria) and targeting the receptor for FGF-7 and -10 within the transitional epithelium (urothelium). The FGF-7 gene is located at the 15q15-q21.1 locus on chromosome 15 and four exons generate a 3.852-kb mRNA. Five duplicated FGF-7 gene sequences that localized to chromosome 9 were predicted not to generate functional protein products, thus validating the use of FGF-7-null mice as an experimental model. Recombinant FGF-7 and -10 induced proliferation of human urothelial cells in vitro and transitional epithelium of wild-type and FGF-7-null mice in vivo. To determine the extent that induction of urothelial cell proliferation during the bladder response to injury is dependent on FGF-7, an animal model of partial bladder outlet obstruction was developed. Unbiased stereology was used to measure the percentage of proliferating urothelial cells between obstructed groups of wild-type and FGF-7-null mice. The stereological analysis indicated that a statistical significant difference did not exist between the two groups, suggesting that FGF-7 is not essential for urothelial cell proliferation in response to partial outlet obstruction. In contrast, a significant increase in FGF-10 expression was observed in the obstructed FGF-7-null group, indicating that the compensatory pathway that functions in this model results in urothelial repair.

Using gene chips to identify organ-specific, smooth muscle responses to experimental diabetes: potential applications to urological diseases

OBJECTIVE

To identify early diabetes-related alterations in gene expression in bladder and erectile tissue that would provide novel diagnostic and therapeutic treatment targets to prevent, delay or ameliorate the ensuing bladder and erectile dysfunction.

MATERIALS AND METHODS

The RG-U34A rat GeneChip (Affymetrix Inc., Sunnyvale, CA, USA) oligonucleotide microarray (containing approximately 8799 genes) was used to evaluate gene expression in corporal and male bladder tissue excised from rats 1 week after confirmation of a diabetic state, but before demonstrable changes in organ function in vivo. A conservative analytical approach was used to detect alterations in gene expression, and gene ontology (GO) classifications were used to identify biological themes/pathways involved in the aetiology of the organ dysfunction.

RESULTS

In all, 320 and 313 genes were differentially expressed in bladder and corporal tissue, respectively. GO analysis in bladder tissue showed prominent increases in biological pathways involved in cell proliferation, metabolism, actin cytoskeleton and myosin, as well as decreases in cell motility, and regulation of muscle contraction. GO analysis in corpora showed increases in pathways related to ion channel transport and ion channel activity, while there were decreases in collagen I and actin genes.

CONCLUSIONS

The changes in gene expression in these initial experiments are consistent with the pathophysiological characteristics of the bladder and erectile dysfunction seen later in the diabetic disease process. Thus, the observed changes in gene expression might be harbingers or biomarkers of impending organ dysfunction, and could provide useful diagnostic and therapeutic targets for a variety of progressive urological diseases/conditions (i.e. lower urinary tract symptoms related to benign prostatic hyperplasia, erectile dysfunction, etc.).

Structural alterations of the bladder induced by detrusor instability. Experimental study in rabbits

OBJECTIVES

The aim of this study was to evaluate the histopathological and immunohistochemical alterations induced by detrusor instability in the bladder of rabbits submitted to partial bladder outlet obstruction.

MATERIALS AND METHODS

Thirty male Norfolk rabbits were divided into 2 groups, a clinical control and a group with detrusor instability. Urine culture, cystometric study, histopathological and immunohistochemical analysis were performed in all animals prior to surgery (M1) and 4 weeks after-surgery (M2).

RESULTS

Partial obstruction (G2) resulted in a 2.5 fold increment (p < 0.05) in bladder weight when compared to control (G1). Four weeks after surgery, 93% of animals in G2 developed cystitis. Partial obstruction resulted in detrusor instability at M2 and bladder capacity was significantly increased (p < 0.05) from M1 to M2. The incidence of mild to moderate mucosal and adventitious fibrosis at M2 was higher in G2 (p < 0.05) when compared to G1. Inflammatory reaction at M2 was statistically higher (p < 0.05) in G2. There was no difference in muscular hypertrophy between M1 and M2 in G1. However, 67% of G2 bladders showed a moderate to intense muscular hypertrophy at M2. Hyperplasia of the epithelium was also increased in G2 when M1 and M2 were compared (p < 0.05).

CONCLUSION

Detrusor instability induced by partial bladder outlet obstruction caused significant histopathological and immunohistochemical alterations in the bladder of rabbits.

Investigation of early protein changes in the urinary bladder following partial bladder outlet obstruction by proteomic approach

We investigated the pathophysiological mechanism by proteomic approach as a possible tool to detect the marker proteins to develop lower urinary tract symptoms following bladder outlet obstruction (BOO). Rats were randomized into 3 groups; control, sham operation and BOO groups. BOO group was divided into 1, 3, and 5 day-group. Conventional proteomics was performed with high resolution 2-D gel electrophoresis followed by computational image analysis and protein identification using mass spectrometry using rat urinary bladders. A comparison of bladder of BOO group with control bladder showed that three proteins of optineurin, thioredoxin and preprohaptoglobin were over-expressed in the bladder of BOO group. In addition, four proteins, such as peroxiredoxin 2, transgelin, hippocampal cholinergic neurostimulating peptide (HCNP) and beta-galactoside-binding lectin, were under-expressed in the bladder of BOO group. These data supported that downregulation of HCNP might make detrusor muscle be supersensitive to acetylcholine, up-regulation of optineurin means the protection of nerve injury, and down-regulation of transgelin means the decreased contractility of detrusor muscle. Beside these proteins, other proteins are related to oxidative stress or have a nonspecific function in this study. However more information is needed in human bladder tissue for clinical usage.

Effect of the ATP-sensitive potassium channel opener ZM226600 on cystometric parameters in rats with ligature-intact, partial urethral obstruction

The activity of a recent K(ATP) channel opener, the N-(4-Phenylsulfonylphenyl)-3,3,3-trifluoro-2-hydroxy-2-methylpropionamide (ZM226600) was investigated on a female rat model of overactive bladder with outlet obstruction. Both ZM226600 and pinacidil instilled into the bladder (10(-7) M, 30 min) or following systemic administration (10, 100 nmol/kg e.v.) almost completely abolished bladder overactivity and improved residual volume and frequency of micturition. However, pinacidil affected arterial pressure. Oxybutynin instilled into the bladder (10(-7), 10(-6), 10(-5) M, 30 min) decreased detrusor overactivity by about 16%, 25% and 46% respectively, but also blocked micturition reflexes at highest doses tested. Oxybutynin reduced detrusor overactivity by about 50% and 80%, after systemic administration (10, 100 nmol/kg e.v.), but also blocked micturition reflexes at the highest dose tested. In conclusion, ZM226600 is more active than oxybutynin in reducing bladder overactivity, and it is devoid of vascular side effects observed with pinacidil. Its short duration of action (about 1 h) is probably the main problem to solve, in order to consider this compound a valid alternative to antimuscarinics in the therapy of bladder overactivity.

Induction of urothelial cell proliferation by fibroblast growth factor-7 in RAG1-deficient mice

Fibroblast growth factor-7 (FGF-7, keratinocyte growth factor, KGF) is a 163 amino acid glycoprotein synthesized and secreted by mesenchymal cells (e.g. fibroblasts/fibrocytes) in epithelial organs, thereby functioning as a paracrine mediator of epithelial cell proliferation. In the urinary bladder, FGF-7 is transported from the lamina propria across the urothelial basement membrane to where it ultimately binds to splice variants of the FGFR2 receptor present on the basolateral surface of transitional epithelial cells. We administered 100 micrograms/ml (i.p.) recombinant FGF-7 (rFGF-7) to RAG1-deficient mice (n = 3) for 7 days and observed a striking expansion of the urinary bladder urothelium. This expansion was characterized by a layer of stratified urothelium > 20 cells thick and by positive immunostaining for the proliferation marker Ki-67. In contrast, RAG1-deficient mice (n = 3) that received only buffer injection did not exhibit detectable urothelial expansion. rFGF-7 was detected by immunoblot analyses in the serum, but not in the urine, from RAG1-deficient mice that received the recombinant protein. Mice that have a targeted disruption in the gene encoding the V(D)J recombination activation gene RAG1 have small lymphoid organs with no mature B and T lymphocytes, due to the inability of cell progenitors to perform V(D)J recombination. The biological activity of FGF-7 in RAG-1 mice indicates that immuno-dependent mechanisms are not required for the induction of urothelial cell proliferation by this epithelial cell-specific growth factor.

Modulation of insulin-like growth factor-I system of the bladder using a somatostatin analogue in chronic spinalized rats

PURPOSE

We have previously reported the possible role of the insulin-like growth factor-I (IGF-I) system of mitogens in the development of detrusor smooth muscle hyperplasia and hypertrophy after spinal cord injury. We evaluated the in vivo effects of the anti-growth factor somatostatin analogue octreotide on the IGF-I system as well as subsequent changes in bladder smooth muscle hypertrophy and function after spinal cord injury in rats.

MATERIALS AND METHODS

Included in this study were 90 adult female Sprague-Dawley rats weighing 200 to 250 gm. Of the rats 18 served as sham operated controls, while the remaining 72 underwent were spinal cord transection at the level of the T10 vertebra. The spinalized animals were randomly divided into 4 equal groups of 18, of which 1 group served as paraplegic controls. The other 3 groups received octreotide (60 microgram. daily for 4 weeks) delivered via a subcutaneously implanted osmotic pump immediately, 2 and 4 weeks after spinal cord injury. At the end of the experiment (6 to 8 weeks) each group of animals was subdivided into 2 subgroups of 9. In the first group filling cystometrography was done, while in the second subgroup wet bladder weight was estimated and Northern blot analysis was performed.

RESULTS

Mean wet bladder weight plus or minus standard deviation in sham operated and paraplegic controls was 0.11 +/- 0.01 and 0.64 +/- 0.33 gm., respectively (p <0.05). The increase in bladder weight in paraplegic controls was associated with over expression of the IGF-I gene and with marked suppression of IGF binding proteins-3 and 5 compared with sham operated controls. On the other hand, mean wet bladder weight in the animals that received octreotide immediately after spinal cord injury was 0.17 +/- 0.02 gm., which was associated with a dramatic decrease in IGF-I gene expression and increased expression of IGF binding proteins-3 and 5. Mean cystometric bladder capacity in paraplegic controls was 0.48 +/- 0.18 ml. with an associated voiding pressure of 71 +/- 13 cm. water. All paraplegic controls showed detrusor hyperreflexia. In animals that received octreotide immediately after spinal cord injury mean cystometric bladder capacity was 2.49 +/- 1.75 ml. with an associated voiding pressure of 32 +/- 7 cm. water. Detrusor hyperreflexia disappeared in 88.89% of the rats in this group. There were less marked changes in bladder weight (mean 0.24 and 0.29 +/- 0.3 gm.), IGF-I gene expression and its binding proteins and urodynamic parameters when the drug was given 2 and 4 weeks, respectively, after spinal cord injury.

CONCLUSIONS

Modulating the IGF-I system of mitogens in detrusor smooth muscle with consequently decreased bladder hypertrophy and improved urodynamic behavior in spinal cord injured animals using somatostatin analogue could be a possible therapeutic modality in patients with spinal cord injury.

Fibroblast growth factor-10 is a mitogen for urothelial cells

Fibroblast growth factor (FGF)-10 plays an important role in regulating growth, differentiation, and repair of the urothelium. This process occurs through a paracrine cascade originating in the mesenchyme (lamina propria) and targeting the epithelium (urothelium). In situ hybridization analysis demonstrated that (i) fibroblasts of the human lamina propria were the cell type that synthesized FGF-10 RNA and (ii) the FGF-10 gene is located at the 5p12-p13 locus of chromosome 5. Recombinant (r) preparations of human FGF-10 were found to induce proliferation of human urothelial cells in vitro and of transitional epithelium of wild-type and FGF7-null mice in vivo. Mechanistic studies with human cells indicated two modes of FGF-10 action: (i) translocation of rFGF-10 into urothelial cell nuclei and (ii) a signaling cascade that begins with the heparin-dependent phosphorylation of tyrosine residues of surface transmembrane receptors. The normal urothelial phenotype, that of quiescence, is proposed to be typified by negligible levels of FGF-10. During proliferative phases, levels of FGF-10 rise at the urothelial cell surface and/or within urothelial cell nuclei. An understanding of how FGF-10 works in conjunction with these other processes will lead to better management of many diseases of the bladder and urinary tract.

Early molecular changes in bladder hypertrophy due to bladder outlet obstruction

OBJECTIVES

To determine the temporal relationship between the increase in bladder mass and the expression of growth-associated gene products during bladder hypertrophy due to partial bladder outlet obstruction.

METHODS

Adult female rats, subjected to partial bladder outlet obstruction, were killed at defined points, and their bladder weight and total protein were determined and compared with sham-operated and nonoperated controls. Hyperplasia was determined by the expression of proliferating cell nuclear antigen, transcription factors, and cyclins in obstructed rat bladders. Bladder protein was fractionated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and expression of the indicated proteins was determined by Western analysis and immunohistochemistry.

RESULTS

The mean bladder weight in sham-operated rats remained at 127 +/- 17 mg, and the weight in the obstructed animals increased to 239 +/- 56 mg at 12 hours, increasing to 486 +/- 168 mg by 168 hours. The total bladder protein increased 1.8-fold after 12 hours and continued to increase for the duration of obstruction. The expression of proliferating cell nuclear antigen in the obstructed group did not begin until 24 hours of obstruction. The expression of the transcription factors, upstream binding factor, and c-Jun followed a similar pattern. Cyclin E and C expression increased most significantly after 48 hours.

CONCLUSIONS

Bladder growth after 12 hours of partial outlet obstruction represents cellular hypertrophy based on the increases in bladder weight and total protein accumulation. Cellular hyperplasia occurs after 24 hours of obstruction as represented by increases in transcription factors and cell cycle-specific proteins.

The decision to undergo DNA or protein synthesis is determined by the degree of mechanical deformation in human bladder muscle cells

OBJECTIVES

To investigate the effect of varying levels of mechanical deformation (cyclic stretch-relaxation) on protein and DNA synthesis rates in human bladder smooth muscle cells (SMCs). Cells in the bladder wall respond to outlet obstruction by increasing rates of protein synthesis ("hypertrophy") and/or DNA synthesis ("hyperplasia"); however, it is not established how these distinct processes are initiated.

METHODS

Primary cultures of human bladder SMCs were generated and maintained according to published methods. Cells were plated on type I collagen-coated elastomer-bottomed plates and subjected to cyclical stretch-relaxation (0.1 Hz) at 6%, 12%, and 20% elongation using a computer-controlled stretch-inducing device. DNA and protein synthesis rates were determined by uptake of radiolabeled thymidine and leucine, respectively. Nonstretched cells served as controls.

RESULTS

Mechanical stretch stimulated DNA synthesis in a dose and time-dependent manner with marked upregulation (4.5-fold) in response to 20% elongation. Mechanical deformation also elicited changes in protein synthesis in bladder SMCs. However, in contrast to the DNA synthesis pattern, leucine uptake over time was stimulated at 6% and 12% elongation, and no protein synthesis response was seen at 20% elongation.

CONCLUSIONS

Our findings suggest that stretch, in isolation from other potential mediators such as pressure or hypoxia, can induce either a hyperplastic or hypertrophic response in bladder SMCs and that the cells' response is dependent on the intensity of the stretch stimulus. These observations may be relevant to the process of in vivo tissue remodeling stimulated by bladder distension or contractile dysfunction.

Diagnosis and management of urinary retention

Failure to empty the urinary bladder completely can be attributed to failure of detrusor contractile function, inappropriate outlet resistance, or both. For each of these mechanisms, anatomic, neurogenic, and end-organ (myogenic or idiopathic) abnormalities are possible. The approach to urinary retention involves systematic consideration of neurogenic, obstructive, and functional causes and requires understanding of the neurophysiology and pharmacology of micturation.

Alterations in constituent urinary proteins in response to bladder outlet obstruction in rats

PURPOSE

Benign prostatic hyperplasia, resulting in bladder outflow obstruction, induces well recognized clinical symptoms and morphologic bladder changes. Despite these phenomenon, relatively little is known with regard to the precise molecular events occurring in the bladder as a consequence of obstruction. In an effort to screen for alterations in bladder gene expression induced by obstruction, and/or alterations in uroepithelial integrity, this study compared pre- and post-obstructive constituent urinary proteins in an animal model.

MATERIALS AND METHODS

Outlet obstruction was created using a previously established model system. Experimental animals were surgically obstructed for either 2 or 7 days, at which time the urine was aspirated and the bladders removed and weighed. Urinary proteins were separated using 2-D PAGE. Following comparison of sham versus experimental animals, microsequencing was performed on proteins that were down regulated.

RESULTS

Duplicate experiments confirmed the presence of outflow obstruction. Statistically significant increases (p <0.01) in bladder weights were seen at 2 and 7 days in the obstructed groups as compared with both sham and control groups. 2-D PAGE demonstrated a down regulation of three urinary proteins post-obstruction. Microsequencing identified these proteins as prostatic steroid-binding protein C3 precursor (pI=5.5, MW=15000), glandular kallikrein 9 (S3) precursor (pI=6.2, MW=19000), and glandular kallikrein 8 (P1) precursor (pI=6.2, MW=33000).

CONCLUSIONS

Bladder outflow obstruction alters constituent urinary protein composition in an animal model system. The precise etiology of these alterations remains to be defined.

Cyclooxygenase-2 is expressed in bladder during fetal development and stimulated by outlet obstruction

Studies were undertaken to assess expression of inducible cyclooxygenase (COX)-2 in bladder during fetal development and COX-1 and COX-2 expression after outlet obstruction. Bladder tissue or bladder progenitor tissue was harvested from CD-1 murine embryos at embryonic days 11.5 (E11.5), E14.5, E17.5, E20.5 (newborn), and from adult. Bladder obstruction was created in adult female mice by ligating the urethra, and bladders were harvested after 3-24 h of obstruction. Gene expression was assessed by semiquantitative reverse transcription-polymerase chain reaction and Western blotting. COX-2 was highly expressed at the early stages of bladder development and declined progressively throughout gestation. In adult bladder, both COX-1 and COX-2 were detectable at low levels under basal conditions. An approximately 30-fold increase in COX-2 mRNA was seen after 24 h of obstruction. In contrast, COX-1 did not change with obstruction. COX-2 mRNA levels peaked at 6 h of obstruction. In regional bladder-distention models, COX-2 induction was confined to the area of distention. Bladder outlet obstruction stimulates COX-2 expression dramatically, reactivating a gene that is highly expressed during fetal development.

Basic fibroblast growth factor in the urine of children with voiding pathology

PURPOSE

Basic fibroblast growth factor is a mediator of tissue response to injury. Voiding pathology often results in bladder abnormalities. We prospectively determined whether basic fibroblast growth factor is elevated in the urine of children with bladder dysfunction compared to that of normal controls.

MATERIALS AND METHODS

A total of 97 consecutive children with myelomeningocele and 32 with voiding pathology due to other etiologies underwent urodynamic testing, and 11 children with no bladder symptoms and sterile urine served as controls. Urinary basic fibroblast growth factor levels were assayed by enzyme-linked immunosorbent assay and normalized to urinary creatinine.

RESULTS

Mean urinary basic fibroblast growth factor was higher in bladder dysfunction from myelomeningocele (6,673 pg./gm. creatinine, p = 0.0015) and other etiologies (5,665 pg./gm. creatinine, p = 0.0025) compared with urine from normal bladders (2,995 pg./gm. creatinine). In the myelomeningocele group urinary tract infection was associated with higher urinary basic fibroblast growth factor than in sterile urine (9,214 versus 5,642 pg./gm. creatinine, p = 0.018). Patient age, gender, remote bladder surgery, clean intermittent catheterization, detrusor hyperreflexia, detrusor compliance, age adjusted pressure specific bladder volume, low grade reflux and degree of trabeculation did not correlate with levels of basic fibroblast growth factor (p > 0.05).

CONCLUSIONS

Urinary elevation of basic fibroblast growth factor, a critical mediator of wound repair, in children with voiding pathology and clinically abnormal bladders supports the paradigm that bladder dysfunction may result from generalized response-to-injury mechanisms. The role of fibrogenic cytokines, such as basic fibroblast growth factor, merits further directed investigation in bladder pathology.

Mesenchymal-epithelial interactions in the bladder

During bladder development, undifferentiated mesenchymal and epithelial cells undergo an orderly sequence of differentiation defined by the expression of smooth-muscle (alpha-actin, myosin, vinculin, desmin, vimentin, and laminin) and epithelial (cytokeratins 5, 7, 8, 14, 18 and 19) protein markers. This process requires mesenchymal-epithelial interactions with bladder epithelium (urothelium) necessary for the differentiation of bladder smooth muscle. Peptide growth factors such as keratinocyte growth factor (KGF) and transforming growth factors (TGF) alpha and beta are likely candidates as mediators of these mesenchymal-epithelial interactions. Transcripts for KGF, TGF alpha, and TGF beta are regulated during bladder development and during smooth-muscle hypertrophy secondary to bladder-outlet obstruction. Finally, two experimental bladder models--(1) partial outlet obstruction and (2) regeneration of bladder smooth muscle into an acellular tissue matrix--are described in the context of mesenchymal-epithelial interactions in the bladder.

Anatomic basis of micturition and urinary continence. Muscle systems in urinary bladder neck during ageing

Dorschner et al have described the unique function and form of several different muscle systems of the urinary bladder neck. If these systems have different functional responsibilities, then the muscles must undergo different ageing processes, as stated in the theory of function-dependent ageing. One characteristic of histologic ageing is the change over time in the proportion of muscle cells to connective tissue, a phenomenon we have demonstrated in both the ciliary muscle and in the two muscle systems of the small intestine. Using an SIS-Image Analysing System, we have now measured automatically the ratios of muscle cells to connective tissue in sections from several regions of the urinary bladder neck, taken from 50 male and 15 female cadavers. Our results confirm new functional explanations of the different muscle systems in the bladder neck. The relative volume of muscle cells in both the sphincter trigonalis m. and the dilator urethrae m. diminishes continuously with age. In the ejaculatorius m., however, the volume of muscle cells first increases until beginning at the end of the third decade, it decreases until senescence. As was presumed, the proportion of muscle cells in the detrusor vesicae m. does not decline during the later decades. The volume of muscle cells and fibers in both urethral sphincter muscles, however, decreases with age, beginning in early childhood.