Biomedical subjects

Catherine Whitbeck

Publications and source records attributed to Catherine Whitbeck.

28 records · Page 2Linked to original sources

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

Oral Kohki Tea and its protective effect against in vitro ischemic damage to the bladder.

AIMS: Results of several studies indicate that ischemia/reperfusion (I/R) is an etiological factor in the contractile dysfunctions induced by partial bladder outlet obstruction in animal models. In support of this hypothesis, pretreatment of rabbits with Kohki Tea (Engelhardtia chrysolepis), a Japanese herbal drink very high in antioxidant activity, significantly reduced the contractile dysfunctions induced by partial outlet obstruction. The current study was designed to determine if pretreating rabbits with Kohki Tea could protect the bladder against the contractile damage induced by in vitro ischemia followed by re-oxygenation. METHODS: Forty-eight New Zealand White rabbits were separated into two groups of 24; Group 1 was pretreated by oral gavage for 3 weeks with Kohki Tea and Group 2 received vehicle (water). Each rabbit was anesthetized with pentobarbital. The urinary bladder was rapidly removed and eight longitudinal muscle strips were cut from the bladder body. Each strip was mounted in a separate 15-ml bath containing Tyrode's solution with glucose (1 mg/ml) and maintained at 37 degrees C. All strips were equilibrated for 30 min with a gas mixture of 95% O2 and 5% CO2. At the end of this period of time, all strips were stimulated with field stimulation (FS) carbachol and KCl. After the last wash, the aeration was changed to hypoxic mixture (nitrogen-CO2) without glucose. At the end of 2 hr, the aeration was changed back to the normal 95% O2 and 5% CO2, and glucose was added to the buffer. After 1 hr of re-oxygenation, a second set of stimulations was performed. In order to represent hyperreflexia, the strips were stimulated at 32-Hz FS at 5-min intervals during the hypoxic period in half of the in vitro experiments. RESULTS: The results showed that Kohki Tea pretreatment protected the bladder's response to FS from the detrimental effects of repetitive stimulation and the detrimental effects of both in vitro ischemia and repetitive stimulation on the contractile responses to carbachol and KCl. CONCLUSIONS: These data are consistent with the concept that Kohki Tea acts by protecting the bladder from cellular damage caused by hypoxia and the generation of free radicals.

Administration, Oral↗

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

Inhibition of hyperreflexia by vaginally administered oxybutynin: a novel rabbit model.

PURPOSE: The rabbit has proved to be an excellent model in which to study lower urinary tract function and pathological mechanisms involved in specific forms of lower urinary tract dysfunctions, including those involved with partial outlet obstruction (benign prostatic hyperplasia), erectile dysfunction, bladder instability and ischemic bladder disease. The current study describes a model of bladder instability induced in female rabbits and its use in developing a novel form of vaginal treatment for this instability. MATERIALS AND METHODS: A total of 18 female New Zealand White rabbits were used for this experiment. Each rabbit was anesthetized and the carotid artery was cannulated for blood pressure monitoring. The bladder dome was catheterized for monitoring bladder pressure and for cystometry. A ligature was placed around the urethra just distal to the bladder neck to prevent leakage through the urethra and generate unstable bladder contractions. After initial cystometry the bladder was emptied and then filled to 30 ml. Acetylcholine (Ach) was administered into the vesical artery at 15-minute intervals for 2 hours. Hyperreflexia usually developed within 30 minutes. Vaginal oxybutynin (low and high dose) was applied and the effect on cystometry, the response to Ach, and the amplitude and frequency of hyperreflexia was determined. RESULTS: Each dose of oxybutynin increased bladder capacity and improved compliance. The high oxybutynin dose completely inhibited the response to Ach and significantly decreased micturition pressure. The high dose decreased uninhibited bladder contraction peak pressure in a time dependent manner to a greater extent than it decreased uninhibited contraction frequency. The low dose of oxybutynin had no effect on micturition pressure, significantly inhibited the response to Ach and hyperreflexia amplitude to approximately 40% of control values, and had little effect on hyperreflexia frequency. CONCLUSIONS: Vaginally delivered oxybutynin was effective in improving bladder compliance, inhibiting intra-arterial Ach stimulated bladder contractions and significantly decreasing the amplitude of hyperreflexia. Vaginal oxybutynin had a more potent effect on the evoked response to Ach and on hyperreflexia than it did on micturition pressure.

Administration, Intravaginal↗

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

Effectiveness of vaginally administered oxybutynin on rabbit bladder function.

OBJECTIVES: To demonstrate the effectiveness of vaginally delivered oxybutynin on bladder function. Oxybutynin has been used for treatment of urge urinary incontinence for more than 20 years. METHODS: Thirty female New Zealand White rabbits were used for this experiment. Each rabbit was anesthetized, and the carotid artery was cannulated for blood pressure monitoring. The bladder dome was catheterized for both monitoring of bladder pressure and cystometry. After initial cystometry, acetylcholine (ACh) was injected into the vesical artery at 15-minute intervals for 4 hours. Cystometry was performed at the 2-hour mark and at the end of each experiment (4 hours). After the third ACh administration, vaginal or oral oxybutynin was given and the effect on the response to ACh, blood pressure, and cystometry was observed. RESULTS: The high dose of oxybutynin completely inhibited the response to ACh and significantly inhibited the micturition reflex. A 45% inhibition of micturition pressure occurred at the intermediate dose. Little effect on compliance after the low dose and a significant increase in compliance after the mid-dose occurred. Both the low and intermediate doses of oxybutynin reduced the response to ACh to approximately 50% of control. No blood pressure effects of vaginal oxybutynin were noted for any concentration. Oral oxybutynin showed very similar effects to that of the intermediate vaginal dose. CONCLUSIONS: Vaginally delivered oxybutynin was effective in decreasing bladder compliance and inhibiting intra-arterial ACh-stimulated bladder contractions with little or no effect on the vascular effect of ACh.

Acetylcholine↗

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↗

PubMed2002

Effect of doxazosin on rat urinary bladder function after partial outlet obstruction.

Hypoxia induced by partial outlet obstruction is believed to play a major role in both the hypertrophic and degenerative effects of partial outlet obstruction. Doxazosin (dox) is a clinically effective alpha-adrenergic antagonist used in the treatment of symptomatic benign prostatic hyperplasia (BPH). Although the major therapeutic effect of the agent is believed to occur on the smooth muscle components of the prostate by reducing prostatic urethral resistance and thus improving emptying, dox may have part of its clinical action via effects mediated by other actions, including via spinal alpha-adrenergic receptors or direct effects on the bladder, possibly via inhibition of vascular alpha receptors. The specific aim of the current study was to determine whether dox pretreatment on rats affects blood flow to the bladder and reduces the level of bladder dysfunction induced by partial outlet obstruction. In part 1, eight rats were separated into two groups of four rats each. Group 1 received oral administration of dox (30 mg/kg) for 4 weeks; group 2 received vehicle (5% dimethyl sulfoxide). After 4 weeks of treatment, blood flow studies were performed using fluorescent microspheres and the bladders excised, frozen, and submitted to Interactive Medical Technologies (IMT) for blood flow analysis. In part 2, 32 adult male rats were separated into four groups of eight rats each. Groups 1 and 2 received oral administration of dox (30 mg/kg) for 4 weeks, groups 3 and 4 received vehicle (5% dimethyl sulfoxide). At 4 weeks, the rats in groups 1 and 3 received partial outlet obstructions and treatment continued for an additional 2 weeks. After 6 weeks of treatment (total), each rat was anesthetized, the bladder excised, weighed, and isolated strips mounted and contractility studies performed. 1) Four weeks pretreatment of rats with dox increased blood flow to the bladder in both the control and obstructed groups. 2) Partial outlet obstruction induced a mild decrease in blood flow. 3) The magnitude of the increased bladder weight in the vehicle-treated obstructed group was significantly greater than in the dox-treated obstructed group. 4) Partial outlet obstruction resulted in significant decreases in the contractile response to field stimulation in both treated and non-treated rats. The magnitude of the decreased response was significantly greater in the non-treated rats. 5) The response to potassium chloride was significantly reduced by partial outlet obstruction in the vehicle-treated group but not in the dox-treated group. 6) The time to maximal tension was significantly increased in response to carbachol, adenosine triphosphate, and potassium chloride. However, the magnitude of the increase was significantly greater for the vehicle-treated obstructed groups stimulated by potassium chloride than for the dox-treated groups. Dox treatment of rats increased blood flow to the bladder and reduced the severity of the response to partial outlet obstruction. These beneficial effects would be due to pharmacological effects on alpha-adrenergic systems outside those present in the prostate. These include effects on blood flow to the bladder, effects on the micturition centers of the central nervous system, spinal reflexes, and alpha-adrenergic receptors in the urethra and bladder.

Adenosine Triphosphate↗

PubMed2002

Cyr61 and CTGF are molecular markers of bladder wall remodeling after outlet obstruction.

Cysteine-rich protein (Cyr61) and connective tissue growth factor (CTGF) are key immediate early growth factors with functions in cell proliferation, differentiation, and extracellular matrix synthesis. Studies were performed to assess the gene expression profile of Cyr61 and CTGF in rat urinary bladder during growth in response to partial outlet obstruction. The mRNA levels of Cyr61 as determined by ribonuclease protection assay increased sharply after 1 day and remained elevated throughout the time period of the obstruction. This correlates well with increased bladder weight. The CTGF mRNA levels seemed to peak within the second week of the urethral obstruction and correlate well with increased type I collagen mRNA. The expression pattern of either Cyr61 or CTGF proteins corroborated that of their respective mRNAs. Immunohistochemical analyses showed that immunoreactivity of Cyr61 was confined to detrusor smooth muscle and that of CTGF was detected within both detrusor muscle and lamina propria layers. These data strongly indicate the involvement of Cyr61 and CTGF in bladder wall remodeling as a result of the outlet obstruction.

Angiotensin II↗

PubMed2002

Effect of oral Kohki tea on bladder dysfunction induced by severe partial outlet obstruction.

PURPOSE: Extracts of the leaves of Engelhardtia chrysolepis, a subtropical plant that grows wild in southern China, have been used medicinally in east Asia for hundreds of years. A standard extract named Kohki tea (Maruzen Pharmaceuticals, Onomichi City, Japan) is sold over the counter in Japan as a sweet tea shown to confer many beneficial effects on general health and well-being. The tea contains strong antioxidants, including several dihydroflavonol glycosides. The results of previous studies show that natural products with antioxidant activities provide protective effects on the bladder of rabbits with partial outlet obstruction. We determined in vivo and in vitro whether oral pretreatment of rabbits with Kohki tea protects the bladder from dysfunction induced by partial outlet obstruction. MATERIALS AND METHODS: A total of 28 New Zealand White rabbits were separated into 4 groups of 7 each. Rabbits in groups 1 and 2 were treated by gavage with 100 mg./kg. Kohki tea daily in distilled water, while those in groups 3 and 4 were given distilled water. After 4 weeks of daily oral administration each rabbit was sedated, the bladder was catheterized and cystometry was performed at a filling rate of 1 ml. per minute. At the completion of cystometry the rabbits were immediately anesthetized. Moderate outlet obstruction was created in groups 1 and 3, and sham surgery was performed in groups 2 and 4. Treatment was continued for an additional 4 weeks, when each rabbit was sedated and cystometry was repeated. After cystometry the bladder was exposed through a midline incision, excised, weighed and 4 strips of bladder body were cut for contractility studies. The balance of the bladder was separated between smooth muscle and mucosa by blunt dissection, frozen in liquid nitrogen and stored at -70C for biochemical analyses. RESULTS: Partial outlet obstruction stimulated similar increases in the bladder weight of all obstructed rabbits. Partial outlet obstruction resulted in a significant decrease in bladder compliance in all obstructed animals. However, the bladder of obstructed rabbits given Kohki tea were significantly more compliant than those given water. Voiding pressures in the control group and the obstructed group given distilled water were approximately equal, while obstructed rabbits given Kohki tea showed significantly higher maximal voiding pressure. The contractile responses to all forms of stimulation were reduced by obstruction to a significantly greater degree in the rabbits not given tea than in those given tea. Sarcoplasmic reticulum Ca2+-adenosine triphosphatase enzyme activity of the bladder was significantly reduced in obstructed rabbits given vehicle but activity was not reduced in obstructed rabbits given Kohki tea. CONCLUSIONS: Kohki tea had a significant protective effect on bladder function, contractile responses and bladder biochemistry in rabbits with moderate to severe partial outlet obstruction.

Animals↗