Biomedical subjects

Paul Chichester

Publications and source records attributed to Paul Chichester.

At least 19 recordsLinked to original sources

PubMed2007

The effects of cyclical oestrogen on bladder and urethral structure and function.

OBJECTIVE: To determine the effects of cycling oestrogen in rabbits, as oestrogen is essential for physiological maintenance and integrity of the female urogenital tract. MATERIALS AND METHODS: Changes in circulating oestrogen have marked effects on the bladder of experimental animals, with ovariectomy (Ovx) inducing smooth muscle (SM) and mucosal atrophy, increasing collagen synthesis and deposition, decreasing contractile function, mucosal and SM blood flow; oestrogen reverses these effects and increases bladder mass and SM density, primarily by stimulating angiogenesis and increasing blood flow. Twenty adult female New Zealand White rabbits were divided into five equal groups; group 1 served as the control group, and groups 2-5 had a bilateral Ovx. Group 2 received no oestradiol and was assessed 2 weeks after Ovx; groups 3-5 received 17-beta oestradiol from a subcutaneous slow-release tablet 2 weeks after Ovx, which remained in place for a subsequent 2-week period. Group 3 was then assessed after the 2 weeks on oestradiol. Groups 4 and 5 then had their oestradiol tablets removed for 2 weeks and group 4 was assessed after this period off oestradiol. Group 5 then received a new oestradiol tablet that was left in place for an additional 2 weeks. RESULTS: Both groups receiving oestrogen (3 and 5) had a statistically significantly greater bladder weight than both the control group and group 2. The volume fraction of SM paralleled the bladder weight, showing that oestrogen increased the volume fraction of SM whereas Ovx and low oestrogen decreased the SM fraction. The cross-sections of the urethra from groups 3 and 5 were significantly wider than those of either the control or group 1, also being consistent with the structural effects of oestrogen. Intra-arterial phenylephrine increased urethral pressure to a similar level in all groups. The urethral pressure response to intra-arterial acetylcholine shifted from contraction in the control to relaxation in the oestrogen-treated groups. Ovx resulted in a lower vascular density, whereas oestrogen resulted in a significant increase in vascular density (angiogenesis). CONCLUSIONS: Cyclical oestrogen had pronounced structural and pharmacological effects. Low oestrogen decreased the volume fraction of SM, increased collagen, and decreased vasculature, whereas oestrogen mediated a marked hypertrophy of the SM components, decreased the collagen component, and stimulated angiogenesis. Cyclical oestrogen also had marked effects on the responses to intra-arterial acetylcholine, shifting the response from contraction to relaxation.

Animals↗

PubMed2007

Role of nitric oxide in urinary bladder function: effect of L-arginine.

BACKGROUND: Evidence indicates that decreased blood flow to the bladder plays a major role in obstructive bladder dysfunction in the rabbit model of partial bladder outlet obstruction (PBOO), and that nitric oxide (NO) regulation of blood flow may be important in modulating the degree of obstructive bladder dysfunction. The specific aim of our study is to determine the effect of feeding rabbits a diet high in L-arginine on the response to PBOO. MATERIALS AND METHODS: Sixteen male NZ White rabbits were separated into 4 groups of 4 each. The rabbits in groups 1 and 3 underwent PBOO. The rabbits in groups 2 and 4 were sham-operated. For 1 week prior to surgery, and 2 weeks postoperatively, each rabbit in groups 1 and 2 was put on a diet containing 7% arginine. Rabbits in groups 3 and 4 were on a normal diet (0.76% arginine). RESULTS: PBOO resulted in a greater increase in bladder weight in the control group than the arginine group. PBOO resulted in a greater decrease in compliance in the control group than the arginine group. The contractile responses to all agents in the arginine control group were greater than in the control normal diet group. PBOO resulted in a greater decrease in the response to field stimulation in the control group than in the arginine group. CONCLUSIONS: These studies clearly demonstrate that feeding rabbits a diet high in L-arginine was beneficial for the control rabbits, and reduced the level of dysfunctions following PBOO.

Animals↗

PubMed2006

Estrogen induced functional hypertrophy and increased force generation of the female rabbit bladder.

AIMS: Estrogen is essential for physiological maintenance of the female urogenital tract. It is believed that alterations in female sex hormones play a major role in the etiology and response to urinary tract dysfunctions. In animal studies, ovariectomy (Ovx) results in smooth muscle (SM) weakness and atrophy whereas estrogen supplementation reverses these effects. Our study seeks to establish the mechanisms by which estrogen augmentation results in increased contractility. METHODS: Twenty New Zealand White female rabbits were separated into five groups of four each. Group 1 served as control, rabbits of groups 2-5 were ovariectomized, group 2 ovariectomized received no estradiol, groups 3-5 were given 17-beta estradiol (1 mg/kg/day) by subcutaneous slow release tablet implant for 1, 3, and 7 days, respectively, beginning 2 weeks after Ovx. At the end of the experimental period, each rabbit was anesthetized and the urinary bladder was removed for contractile, histological, and biochemical studies. RESULTS: Ovx resulted in significantly decreased bladder contractile function, whereas bladders tested after estradiol administration showed increased contractility. Ovx resulted in a decrease in SM/collagen ratio, whereas estrogen resulted in an increase. The estrogen receptor (ER) density significantly increased following Ovx. After 1 day of estrogen treatment, the ER density decreased significantly below control levels, but rose progressively during the estrogen treatment. CONCLUSION: The present study demonstrates that estrogen supplementation mediates a "functional hypertrophy," that is a hypertrophy characterized by increased contractile responses to all forms of stimulation, and an increased ratio of SM/collagen.

Animals↗

PubMed2006

The immediate effect of castration on female rabbit bladder blood flow and tissue oxygenation.

BACKGROUND: The female urinary bladder is a target organ for estrogen. Reductions in circulating estrogen have been associated with urothelial and vaginal atrophy and bladder disorders including incontinence and increased incidence of bladder infections. We determined the effect of short-term ovariectomy on sex hormones, bladder blood flow, and tissue oxygenation in the rabbit model. MATERIALS AND METHODS: Female New Zealand White rabbits were ovariectomized and evaluated on 1, 3, and 7 days after ovariectomy. Tissue oxygenation (pO2) and blood flow were measured with oxylab system of real time measurements. Serum estrogen and progesterone were determined at sacrifice. Tissue hypoxia was localized histologically using Hypoxyprobe-1 immunohistochemistry. RESULTS: Short-term ovariectomy caused rapid decreases in serum estrogen and progesterone, significant decreases in urothelial oxygenation and blood flow. No significant decreases in blood flow or oxygenation were noted for the detrusor smooth muscle. Immunohistochemistry confirmed the presence of urothelial hypoxia at all times after ovariectomy. Bladder muscle did not demonstrate significant levels of hypoxia. CONCLUSION: The bladder urothelium is extremely sensitive to short-term ovariectomy, with significant urothelial hypoxia seen by post-ovariectomy day 1. Urothelial hypoxia may play a significant role in pelvic pain syndromes, incontinence, and increased susceptibility to bladder infection.

Animals↗

PubMed2006

Estrogen induces angiogenesis of the female rabbit bladder.

Postmenopausal bladder dysfunction has been speculated to involve decreased circulating estrogen levels. It is our hypothesis that estrogen induces bladder dysfunctions by modulating blood flow to the bladder, i.e. low estrogen reduces blood flow to the bladder, whereas high estrogen increases blood flow. Our previous studies have demonstrated that estrogen administration in female rabbits induces a 'functional hypertrophy' of the urinary bladder smooth muscle represented by increased smooth muscle mass, which corresponds to increased contractile responses to all forms of stimulation. The present study investigates the effect of estrogen on vasculature density and distribution. Twenty-four female New Zealand white rabbits were separated into six groups of four rabbits each. Group 1 served as controls. Groups 2-6 were ovariectomized. Two weeks after ovariectomy (Ovx), groups 3-6 were given 17-beta estradiol (1 mg/kg per day) by s.c. implant for 1, 3, 7, and 14 days respectively. Blood vessel density and distribution were evaluated by immunohistochemistry and quantitative image analyses. Ovx resulted in significant vascular degeneration and decreased density, whereas estradiol administration mediated a significant angiogenic effect characterized by increased vascular density, and distribution of new vasculature within the smooth muscle bundles of the detrusor. Estradiol-induced vasculogenesis corresponds with our previously demonstrated increase in blood flow to the bladder and increased contractility. The most interesting aspect of these studies is the increased vascularization localized within the muscle bundles rather than between the muscle bundles, which may be important in the link between estrogen and increased incidence of cancers.

Animals↗

PubMed2005

Effect of partial outlet obstruction on nitrotyrosine content and distribution within the rabbit bladder.

PURPOSE: Evidence indicates that free radicals are etiological factors in obstructive bladder disease. However, it is not clear which species of reactive oxygen or nitrogen species mediate the damage. The current studies were designed to determine if partial outlet obstruction in rabbits results in the generation of nitrotyrosine (NT). MATERIALS AND METHODS: Sixteen rabbits were separated into four groups of four. The rabbits in groups 1 and 2 underwent sham operation while rabbits in groups 3 and 4 underwent partial outlet obstruction. The rabbits in groups 1 and 3 were evaluated after 1 week of obstruction and the rabbits in groups 2 and 4 were evaluated after 2 weeks of obstruction. A separate group of four controls were evaluated simultaneously with the sham and obstructed rabbits. Four rabbits from each group were evaluated after 1 and 2 weeks of obstruction. Four control rabbits were also evaluated. Isolated strips were evaluated for contractile responses and NT content of the mucosa and muscle were quantitated by Western blot analysis. RESULTS: (1) The mucosa contains both 42 and 62 kD proteins exhibiting a strong nitrotyrosine signal; the muscle presents a signal only at 62 kD. (2) The sham operations had no effect on nitrotyrosine distribution or content. (3) The nitrotyrosine of both mucosal proteins and the muscle protein are increased in the 1 week obstructed bladder; whereas, only the 62 kD signal is increased in the two week obstructed bladder mucosa. (4) The contractile response to FS are reduced to a significantly greater degree than the responses to carbachol, KCl, or ATP. CONCLUSIONS: These studies clearly demonstrated that partial outlet obstruction in rabbits results in significant increases in nitrotyrosine within the bladder and may contribute to the contractile dysfunctions mediated by partial outlet obstruction.

Animals↗

PubMed2005

Effect of ethanol on protection of urinary bladder function by grape suspensions.

OBJECTIVES: To compare the protective effects of grape suspensions prepared in an aqueous vehicle with grape suspensions prepared in an 8% ethanol vehicle in rabbits subjected to partial outlet obstruction. The hypothesis was that the presence of ethanol would increase the absorption of the beneficial components of the grape suspensions and thus increase their protective ability. The use of ethanol in these studies was not to simulate wine. METHODS: A total of 48 New Zealand white rabbits were separated into eight groups of 6 rabbits each. Groups 1 and 3 were pretreated by oral gavage for 3 weeks with grape suspensions in water; groups 2 and 4 were treated with vehicle. Groups 5 and 7 were treated with the grape suspensions in 8% ethanol, and groups 6 and 8 were treated with ethanol vehicle. Groups 1, 2, 5, and 6 underwent sham operations, and groups 3, 4, 7, and 8 underwent partial outlet obstruction. Three weeks after surgery, the rabbits were evaluated. RESULTS: The bladder weight had significantly increased in all obstructed groups. The contractile responses to field stimulation and carbachol were reduced in all obstructed groups, although the responses in both grape-treated groups were greater than both vehicle-treated groups. The contractile responses to potassium chloride were significantly reduced by partial outlet obstruction in both obstructed groups similarly. CONCLUSIONS: Both grape suspensions provided protection against obstructive-induced bladder dysfunction. The ethanol preparation of the grape suspension was not better than the aqueous preparation.

Animals↗

PubMed2005

Effect of strip length on the contractile dysfunction of bladder smooth muscle after partial outlet obstruction.

OBJECTIVES: Partial outlet obstruction mediates decreased contractile responses and increased collagen synthesis; however, it is not known to what extent the increased collagen contributes to contractile dysfunction. METHODS: Sixteen WNZ rabbits were divided into three groups: control, 2-week obstructed, and 2-week sham. Each rabbit was anesthetized, and the bladder was excised and cut into equal width strips of 0.5, 1.0, and 2.0-cm lengths. The contractile responses to field stimulation, carbachol, potassium chloride, and adenosine triphosphate were determined. At the end of the experiment, each strip was fixed in formalin and immunostained for collagen. RESULTS: The contractile responses for the control and sham strips were similar for all strip lengths. In obstructed tissue, the shorter strip lengths generated significantly more tension per cross-sectional area than did the longer strips. The collagen density and distribution were similar for the control and sham bladders. The obstructed bladders had significantly increased collagen deposits between and within the smooth muscle bundles and cells. CONCLUSIONS: Because the relationship between strip size and contraction were similar for field stimulation, carbachol, and potassium chloride, it is the increased density of connective tissue within and between the muscle bundles and fibers that interferes with contraction (ie, the greater the strip length, the greater the interference and the greater the contractile dysfunction). Therefore, both functional and structural alterations in the obstructed bladder participate in contractile dysfunction.

Animals↗

PubMed2005

Effect of age on rabbit bladder function and structure following partial outlet obstruction.

PURPOSE: We determined whether young and old rabbits respond differently to partial bladder outlet obstruction. MATERIALS AND METHODS: A total of 16 male New Zealand White rabbits were separated into 2 groups of 8 each. Group 1 consisted of young rabbits (age 7 weeks) and group 2 consisted of old rabbits (age 2 years). Four rabbits per group underwent partial outlet obstructions and 4 underwent sham operation. Four weeks following surgery individual bladder strips were used for contractile studies and the remaining tissue was examined histologically. RESULTS: Contractile responses to all forms of stimulation between the young and old sham operated groups were similar. Contractile responses to all forms of stimulation were significantly decreased to the same degree in the 2 obstructed groups. However, the rate of tension generation to field stimulation was decreased to a significantly greater degree in young vs old bladders. Although young and old bladders showed smooth muscle hypertrophy, older rabbits showed significantly greater thickening of the serosa than young rabbits. Young rabbits showed significant inflammation, hemorrhage and expansion of the lamina propria, whereas old rabbits showed none of these characteristics. CONCLUSIONS: Although there were only minor differences in the physiological response of young and old bladders to obstruction, young rabbits showed a significantly greater degree of histological damage. This may have been due to the thinner wall and greater sensitivity to distention.

Aging↗

PubMed2005

Protective effects of grape suspension on in vivo ischaemia/reperfusion of the rabbit bladder.

OBJECTIVE: To investigate the potential protective effect of a grape suspension in a rabbit model of in vivo bilateral ischaemia/reperfusion (I/R), which is a causal factor in obstructive bladder dysfunction. MATERIALS AND METHODS: Six groups of four New Zealand White rabbits were treated by twice-daily gavage with aqueous grape suspension (groups 1-3) or sugar-water vehicle (groups 4-6) for 3 weeks. Groups 1 and 4 then received bilateral ischaemia for 2 h, and groups 2 and 5 received bilateral ischaemia for 2 h and reperfusion (recovery) for 1 week. Groups 3 and 6 were controls (sham-operated). The effects on cystometry, in vitro contractile responses, and morphology were evaluated. RESULTS: Ischaemia resulted in significant reductions in the contractile responses to all forms of stimulation in vehicle-fed rabbits, whereas there were no reductions in grape-fed rabbits. Contractile responses were significantly reduced in both I/R groups, but significantly more in vehicle-fed than in grape-fed rabbits. Immunohistochemical studies showed less hypoxia in the bladders of grape-fed rabbits than in vehicle-fed rabbits for both ischaemia-only and I/R groups. CONCLUSIONS: Feeding rabbits with grape suspension provided significant protection against the hypoxic effects of bilateral ischaemia and I/R.

Animals↗

PubMed2005

Effect of nitric oxide synthase inhibition on changes induced by estradiol in bladders from ovariectomized rabbits.

PURPOSE: Our current study was designed to determine whether estradiol-induced increases in bladder blood flow could be inhibited by N(omega)-nitro-L-arginine methyl ester (L-NAME), and thus whether nitric oxide was involved in estrogen-linked female bladder blood flow alterations. MATERIALS AND METHODS: Sixteen female New Zealand White rabbits were separated into 4 groups of 4 rabbits each. (1) Sham group received sham operation and injections of vehicle (peanut oil). (2) Ovariectomy (OVX) group received ovariectomies and injections of vehicle. (3) Ovariectomy+estrogen (OVX+E) group received ovariectomy and injections of 17beta-estradiol (1 mg/kg) dissolved in peanut oil. (4) Ovariectomy+estradiol+L-NAME (OVX+E+L-NAME) group received ovariectomies and injections of 17beta-estradiol and L-NAME. All treatments were continued for 4 weeks. At 4 weeks after treatment, each rabbit was anesthetized and cystometries were performed. After cystometry, blood flow to the detrusor muscle and mucosa was determined by standard fluorescent microsphere infusion technique. Then four longitudinal detrusor strips and two rings of descending thoracic aorta were mounted in individual 15 ml baths containing oxygenated Tyrode's solution at 37 degrees C. Contractile responses to several agents were determined. Full-thickness sections of detrusor were fixed and embedded in paraffin for alpha-actin immunostaining. RESULTS: In the bladder: (1) Estradiol resulted in an increases in bladder weight and blood flow; L-NAME inhibited these increases. (2) OVX resulted in a decreased cystometric capacity; estradiol resulted in increased capacity which was attenuated by L-NAME treatment. (3) OVX resulted in significantly decreased contractile responses to all forms of stimulation; estradiol resulted in significantly increased contractile responses which were attenuated by L-NAME treatment. (4) OVX resulted in a significant decrease in the volume-fraction of smooth muscle in the detrusor; estradiol resulted in a significant increase which was attenuated by L-NAME. CONCLUSIONS: These findings strongly support the hypothesis that nitric oxide plays a major role in the alterations in blood flow mediated by changing circulating estrogen and that these changes mediate at least in part the cystometric and contractile changes induced by alterations in circulating estrogen.

Analysis of Variance↗

PubMed2004

Protection of urinary bladder function by grape suspension.

Urinary bladder dysfunction secondary to BPH is a major affliction of aging men. A rabbit model of partial outlet obstruction was used to evaluate the ability of a standardized grape suspension to protect the bladder against obstructive bladder dysfunction.Twenty-four New Zealand White rabbits were separated into four groups of six rabbits each. Groups 1 and 3 were pretreated by oral gavage for 3 weeks with a standardized grape suspension suspended in water; groups 2 and 4 were treated with vehicle. Groups 1 and 3 received sham operations after 3 weeks of treatment; groups 2 and 4 received partial outlet obstruction by surgically placing a silk ligature loosely around the urethra. At 3 weeks following surgery, in vivo and in vitro bladder functions were evaluated. Based on both in vivo and in vitro studies, the grape suspension significantly reduced the severity of obstructed bladder dysfunction. This is consistent with the hypothesis that ischemia is a major etiological factor in obstructive dysfunction, and treatment with antioxidants and membrane stabilization compounds such as those in the grape suspension can be effective in the treatment of obstructive bladder pathology.

Adrenergic alpha-Antagonists↗

PubMed2004

Effects of castration on female rabbit bladder physiology and morphology.

OBJECTIVES: To determine the effect of ovariectomy on bladder blood flow and oxygen tension. Women are subject to bladder dysfunctions that occur less frequently in men. These include interstitial cystitis (syndrome of urgency, frequency, and pain on distension), incontinence, and bladder infections. It is believed that alterations in female sex hormones play a major role in mediating these abnormalities. We believe that alterations in estrogen can have marked effects on the blood flow to the bladder. METHODS: We divided 20 female rabbits into two equal groups: ovariectomized and sham operated. Six weeks later, the bladder of each rabbit was evaluated for bladder capacity, compliance, permeability, blood flow, tissue hypoxia, morphology, and smooth muscle contraction. RESULTS: Ovariectomy resulted in decreased bladder compliance; decreased blood flow to the bladder mucosa and uterus, a smaller decrease in blood flow to the bladder smooth muscle, and mucosal hypoxia; and statistically significant thinning of the bladder mucosa and increased mucosal permeability. CONCLUSIONS: Ovariectomy resulted in decreased blood flow and hypoxia to the bladder mucosa and a mildly decreased blood flow to the smooth muscle. The decreased blood flow and hypoxia may be related to the age-related uropathologic findings in postmenopausal women.

Age Factors↗

PubMed2004

Role of angiogenesis in bladder response to partial outlet obstruction.

Benign prostatic hyperplasia (BPH) is a disease that has its etiology in the abnormal growth of the adult human prostate gland that accompanies the aging process in men. The symptomatic presentation of this disease, however, is related largely to degenerative changes in the bladder that occur as a result of the increasing urethral resistance and partial bladder outlet obstruction (PBOO) caused by the growing prostate gland. BPH is characterized by bladder hypertrophy, significant decreases in urinary flow and compliance, presence of residual urine after voiding, voiding urgency and incontinence (). Obstructed bladder dysfunction secondary to BPH is a slow, progressive disease that is so strongly associated with human aging that it is an expected occurrence of the male aging process. Although the symptoms of BPH are usually not life threatening, they effect an extremely negative quality of life for men who suffer from them. However, many men delay seeking medical treatment for early BPH since bladder function can remain relatively normal as the hypertrophying bladder initially compensates for the progressive increase in urethral resistance caused by prostatic obstruction. The limited changes in micturition pressure and flow characteristics that occur during compensated function are not usually disabling enough to motivate seeking medical attention, which, often, is not sought until the symptoms become typical of advanced disease. Recent advances in detection methods enable identification of patients with significant BPH during compensation before the bladder becomes dysfunctional (decompensated). A more complete understanding of the disease processes that underlie the loss of bladder function associated with BPH might enable the development of treatments that better protect these early-stage BPH patients from the more debilitating aspects of the disease. This review updates the understanding of obstructive bladder dysfunction via the use of animal models.

Animals↗

PubMed2003

Focal hypoxia of the obstructed rabbit bladder wall correlates with intermediate decompensation.

AIMS: We showed that partial obstruction of the rabbit bladder outlet caused decreases in detrusor blood flow that were directly proportional to the level of decompensation present. Bladder decompensation is characterized by decreases in detrusor contractility, mitochondrial function, and sarco/endoplasmic reticulum calcium ATPase (SERCA) activity in obstructed rabbits. The current study was designed to create bladder decompensation and to relate its characteristic dysfunctions to the presence or absence of hypoxia in the obstructed rabbit bladder wall. Tissue hypoxia was visualized immunohistochemically after administration of a hypoxia probe in vivo. METHODS: Twelve New Zealand White rabbits were separated into two groups. The rabbits in group 1 received sham operations; the rabbits in group 2 received partial outlet obstructions by standard methods. Four weeks after surgery, each rabbit received an intraperitoneal injection of aqueous Hypoxyprobe-1, which forms protein adducts in cells having O(2) concentrations less than 14 microM. Two hours after injection, the rabbit was anesthetized and the bladder exposed through a midline incision. One full-thickness bladder strip was cut and immediately placed in fixative for immunohistochemical recognition and visualization of Hypoxyprobe-1-protein adducts. The remaining bladder was then excised, and three additional strips were cut for contractility studies. The remainder of the bladder was frozen for biochemical and slot-blot analyses. RESULTS: Bladder weight was increased fourfold after obstruction, and significant contractile and biochemical dysfunctions were observed that indicated an intermediate level of decompensation. Immunohistochemical visualization revealed focal areas of moderate to severe hypoxia in the detrusor smooth muscle (SM) and subserosal regions of these bladders. No hypoxia was observed in the obstructed bladder mucosa, consistent with the absence of biochemical dysfunction in this compartment, or in unobstructed bladders. Slot-blot analyses confirmed the presence of significant Hypoxyprobe-1-protein adducts in the detrusor of the obstructed bladder, whereas none were present in the control bladder detrusors. CONCLUSIONS: Partial outlet obstruction of rabbit bladders resulted in focal areas of moderate to severe hypoxia in the detrusor SM and subserosal regions concomitant with increased bladder mass, decreased contractile function, and selective metabolic dysfunctions of the SM consistent with an intermediate stage of decompensation. The metabolic characteristics of the normoxic mucosa were normal a were those of unobstructed bladders.

Adenosine Triphosphate↗

PubMed2003

Structural and vascular response of normal and obstructed rabbit whole bladders to distension.

OBJECTIVES: To investigate the structural and morphologic effect of distension after partial outlet obstruction in rabbits. METHODS: Thirty male New Zealand white rabbits were separated into two groups: control (sham) and partial outlet obstruction (3 weeks). Three rabbits from each group were distended to 5%, 25%, 50%, 100%, and 125% of capacity. Each bladder was fixed at the volume in buffered formalin for 6 to 8 hours. Sections of dorsal and ventral bladder were blocked, and cross sections were evaluated. Quantitative morphometry was performed, and CD31 immunohistochemistry was used to characterize the vascularity. RESULTS: Partial outlet obstruction resulted in increased bladder weight and capacity and increased thickness of the mucosa, submucosa, detrusor, and serosa. In the control bladder, the greatest thinning was seen between 5% and 25% capacity, and in the obstructed group, the greatest thinning occurred between 25% and 50%. The level of vascular collapse was significantly greater for the control bladders than for the obstructed bladders at all levels of distension. Finally, the obstructed bladders showed a significantly greater level of vascularity in the submucosa than the control bladders. CONCLUSIONS: Normal bladder distension resulted in significant morphologic changes when the bladder was distended to 25% of capacity but changed relatively little between 25% and 125%. However, distension of the obstructed bladder resulted in significant morphologic changes when the bladder was distended from 25% to 50% of capacity but changed relatively little between 50% and 125%.

Animals↗

PubMed2003

Acute intravesical infusion of a cobalt solution stimulates a hypoxia response, growth and angiogenesis in the rat bladder.

PURPOSE: Experimental partial bladder outlet obstruction of rats induces a bladder growth and remodeling process similar to that in humans with benign prostatic hyperplasia. Previously we have proposed that bladder hypoxia associated with partial bladder outlet obstruction is a stimulus of this bladder growth process. We report our results of testing the acute effects of a simple chemical agent (cobaltous ion) known to mimic hypoxia in the rat bladder. We measured its ability to effect bladder gene expression, angiogenesis and growth processes. MATERIALS AND METHODS: Adult rats were divided into 2 groups. One group (controls) received intravesical saline 3 times for 30 minutes in 6 days and the other received intravesical saline with 100 microM. CoCl(2) at the same times. All animals also received continuous infusion of BrdU for the 6-day period through an implanted osmotic pump. Portions of the bladders from these rats were fixed, sectioned, stained for microscopic analysis and immunohistochemically stained to identify BrdU positive cells and vascular elements via factor VIII staining. Other portions were frozen, extracted for proteins and the proteins were comparatively analyzed for the expression of hypoxia inducible factor-1alpha and vascular endothelial growth factor on Western blots. RESULTS: Bladders infused with CoCl(2) showed extensive expansion of the submucosal region, which was significant compared with that in saline infused bladders. Cells in this expanded region as well as cells within the urothelium were found to be extensively labeled with BrdU, in contrast to control bladders, which had rare BrdU labeled cells in any region. Immunohistochemical analysis for factor VIII showed that the submucosal region of cobalt treated rats contained numerous small vessels and microvessels that were not apparent in controls. These cellular changes were consistent with our finding of increased hypoxia inducible factor-1alpha and vascular endothelial growth factor protein expression in cobalt treated bladders compared with controls. CONCLUSIONS: Acute intravesical instillation of cobalt ion solution into the rat bladder initiated a hypoxia response accompanied by increased bladder angiogenesis and growth. This finding supports the idea that hypoxia is a stimulus for bladder growth subsequent to partial bladder outlet obstruction.

Administration, Intravesical↗

PubMed2003

The effect of ovariectomy and estradiol on rabbit bladder smooth muscle contraction and morphology.

PURPOSE: The bladder can be considered a target organ for the actions of estrogen. Decreases in circulating estrogen after menopause have been associated with bladder dysfunctions, including incontinence and detrusor instability. We determined the effects of estrogen on rabbit bladder contractile function and morphology. MATERIALS AND METHODS: Female New Zealand White rabbits were ovariectomized or sham operated and treated with vehicle or estradiol (1 mg/kg weekly) for 5 weeks. Serum estradiol concentration was monitored every 2 weeks. After treatment each rabbit was anesthetized, the bladder was catheterized, cystometry was performed, and the bladder was removed for contractile and morphological studies. Apoptosis in paraffin embedded rabbit bladder tissue was detected using in situ end-labeling, specifically terminal deoxynucleotidyl-transferase nick end labeling or the TUNEL assay. RESULTS: Ovariectomy resulted in a 50% decrease in circulating estrogen and estradiol treatment resulted in a 5-fold increase. Ovariectomy had no significant effects on bladder capacity, micturition pressure or bladder weight; whereas estradiol treatment resulted in significant increases in bladder capacity and bladder weight. Ovariectomy resulted in a decreased rate of tension generation in response to field stimulation, carbachol and KCl. Estradiol resulted in increased contractile responses to FS and carbachol, and an increased rate of tension generation for carbachol and KCl. Histologically ovariectomy resulted in significant urothelial apoptosis, which was not present in the sham operated or estradiol treated groups. Estradiol treatment resulted in the appearance of large cytoplasmic vacuoles in the urothelium and significant smooth muscle hypertrophy. CONCLUSIONS: These findings demonstrate that bladder function and structure can be significantly affected by modulating the circulating estrogen level. In addition, estrogen given in pharmacological doses can have a significant hypertrophic effect on bladder smooth muscle, resulting in increased contractile function.

Animals↗