Catherine Schuler

Coenzyme Q10 diminishes ischemia–reperfusion induced apoptosis and nerve injury in rabbit urinary bladder

Ischemia/reperfusion (I/R) can significantly change the nerve function of the bladder, thus resulting in detrusor weakness and overactivity. CoQ10 is a lipid‐soluble cofactor found naturally in the mitochondria and has been reported to have neuroprotective and antiapoptosis effects. The aim of this study is to determine if CoQ10 can protect bladders subjected to I/R injury.

Comparative evaluation of antioxidant reactivity within obstructed and control rabbit urinary bladder tissue using FRAP and CUPRAC assays

Partial urinary bladder outlet obstruction mediates cyclic ischemia and reperfusion resulting in the generation of both reactive oxygen species and reactive nitrogen species. It is theorized that with an increase in the level of free radicals, the level of protective antioxidants should decrease. To test this hypothesis, two electron transfer assays, the FRAP method and the CUPRAC method, were used to determine the level of antioxidant reactivity of obstructed and control bladder tissue. The results showed that the CUPRAC assay detected a significant decrease in the reactivity of antioxidants found within the obstructed bladder tissue as compared to the control bladder tissue in both the muscle and mucosa. The FRAP assay did not detect any difference between the muscle and mucosa of the obstructed and control bladder tissue.

Partial outlet obstruction in rabbits: Duration versus severity

Oxidative stress is a major etiology of obstructed bladder dysfunction. The major goal of the current study was to correlate the level of oxidative stress with both the severity and duration of obstruction.

Effect of co-enzyme Q10 and alpha-lipoic acid on response of rabbit urinary bladder to repetitive stimulation and in vitro ischemia.

OBJECTIVES To determine the efficacy of coenzyme Q10 (CoQ10) and alpha-lipoic acid (alpha-LA), either alone or in combination, to protect the contractile responses of the rabbit urinary bladder from damage caused by repetitive stimulation in the presence or absence of in vitro ischemia. METHODS Four groups of New Zealand white rabbits (4 per group) were treated with vehicle (group 1), CoQ10 (group 2), alpha-LA (group 3), or CoQ10 plus alpha-LA (group 4) for 2 weeks. At the end of the treatment period, eight longitudinal strips from each rabbit bladder body were placed in oxygenated Tyrodes solution with glucose (normal physiologic medium). The strips were stimulated by field stimulation, carbachol, and KCl, and the responses were recorded. One half of the strips were switched for 1 hour to Tyrodes solution with no glucose equilibrated with nitrogen (ischemia medium). Simultaneously, all strips were subjected to 1 h of repetitive field stimulation followed by 1 hour of recovery in normal physiologic medium, and the responses to all stimuli were recorded again. RESULTS CoQ10 showed no protective effect. Alpha-LA resulted in increased contractile responses of the control bladder and showed a moderate protective effect for all forms of stimulation. The combination, however, showed a significantly greater increase in the contraction of the control bladder and a greater protective effect than alpha-LA alone. CONCLUSIONS The combination of alpha-LA and CoQ10 treatment enhanced the contractile response in normal medium and diminished the contractile dysfunction induced by repetitive field stimulation and ischemia.

Effect of partial bladder outlet obstruction and reversal on rabbit bladder physiology and biochemistry: duration of recovery period and severity of function

To use a rabbit model of partial bladder outlet obstruction (BOO) to investigate the point at which obstructive bladder dysfunction becomes irreversible.

Differential Expression of Vascular Endothelial Growth Factor, and Angiopoietin 1 and 2 in Functionally Divergent Experimental Rabbit Models of Bladder Hypertrophy

PURPOSE Partial bladder outlet obstruction or ovariectomy with subsequent estrogen replenishment induces bladder hypertrophy in rabbits and yet the functional outcomes of these procedures differ. We investigated whether these models might be distinguished by differential expression of the genes controlling angiogenesis. MATERIALS AND METHODS Groups of male rabbits underwent sham surgery or partial bladder outlet obstruction for 1 or 2 weeks. Groups of females underwent sham surgery, ovariectomy or ovariectomy plus estrogen for 1 or 2 weeks. Bladders from each group were weighed and assayed for the contractile response, smooth muscle content and vascular density. Mucosa and muscle layers were separated and RNA from the fractions was assayed by quantitative real-time polymerase chain reaction to measure the relative expression of vascular endothelial growth factor, and angiopoietin 1 and 2 mRNA. RESULTS Male bladders with partial outlet obstruction had attributes that typified hypertrophy with a loss of contractile function. Vascular endothelial growth factor expression was up-regulated in the mucosa and muscle layers but the effect was most pronounced in mucosa. Angiopoietin 1 expression was significantly up-regulated in muscle. Female bladders with ovariectomy plus estrogen had attributes that typified bladder hypertrophy with increased contractile function. Vascular endothelial growth factor expression was up-regulated early in mucosa but more highly and consistently increased in muscle. Angiopoietin 1 and 2 expression was not significantly affected. CONCLUSIONS Although these models have similar outcomes with regard to bladder hypertrophy, they have opposite functional outcomes that coincide with compartmental differences in the expression of genes involved in the regulation of angiogenesis. The disparity in gene expression might explain the difference in the functional outcomes.

Effect of estrogen and ovariectomy on response of the female rabbit urinary bladder to two forms of in vitro oxidative stress

Introduction and hypothesisThere are several lower urinary tract dysfunctions (LUTD) that are more common in women than in men including incontinence, interstitial cystitis, and recurrent urinary tract infection. There is increasing evidence that these dysfunctions are associated with reduced blood flow, ischemia, hypoxia, and reperfusion resulting in free radical generation and oxidative damage. The goal of the current study was to determine if the level of circulating estrogen affects the response of the bladder muscle and mucosa to two in vitro models of oxidative stress: Incubation in the presence of hydrogen peroxide (H2O2) is the first model; the second is ischemia followed by reperfusion which results in the direct production of damaging free radicals. The motivation for this study is the current literature linking female-related LUTD with oxidative stress.MethodsEighteen female New Zealand white rabbits were divided into three groups: control, ovariectomized, and ovariectomized receiving continuous estrogen. Eight bladder strips from each of three rabbits per group were taken for in vitro ischemia/reperfusion (I/R) physiological experiments, while eight strips from the three remaining rabbit bladders per group were taken for in vitro H2O2 experiments. All tissue was analyzed for total antioxidant activity (AA) and malondialdehyde (MDA) levels. In addition, the organ bath buffer was also analyzed for AA.ResultsIn vitro H2O2 was found to target the nerve, muscarinic receptor, and membrane equally causing more damage to bladder tissue than in vitro I/R. Ovariectomy resulted in lower contractility and higher lipid peroxidation. However, estrogen supplementation following ovariectomy protected the bladder against both models of oxidative stress by maintaining contractile responses to stimulation and decreasing lipid peroxidation.ConclusionsThe primary conclusion from this study is high estrogen protects the bladder from oxidative stress, whereas low estrogen makes the bladder more susceptible.

Cyclical estrogen and free radical damage to the rabbit urinary bladder

Introduction and hypothesisThere are a number of lower urinary tract dysfunctions (LUTD) that occur primarily in women. Our hypothesis is that cyclical estrogen will produce LUTD in part by the generation of free radicals and oxidative damage to cellular and subcellular membranes.MethodsTwenty female rabbits were divided into five groups: control, ovariectomized (Ovx), Ovx receiving continuous estrogen, Ovx receiving cyclical estrogen ending off estrogen, and Ovx receiving cyclical estrogen ending on estrogen. Statistical analyses used ANOVA followed by the Tukey analysis for individual differences.ResultsHigh estrogen increased bladder mass, contraction, compliance, and blood flow and decreased oxidative damage. Low estrogen decreased bladder mass, contraction, compliance, and blood flow and increased oxidative damage.ConclusionsThe decreased blood flow associated with increased oxidative damage demonstrates that cyclical damage to cellular membranes occurs. This supports the hypothesis that cycling estrogen may play a role in the etiology of LUTD of women.

The Effect of 2- and 4-Week Ovariectomy on Female Rabbit Urinary Bladder Function

OBJECTIVES To evaluate the effect ovariectomy (OVX) after 2 and 4 weeks on bladder function and biochemistry of the adult female rabbit urinary bladder. METHODS Twelve mature female rabbits were divided into 3 groups: control, 2-week ovariectomized, and 4-week ovariectomized. At the end of the experimental period, the following studies were performed: contractile studies on isolated strips; examinations of the activity of citrate synthase (a marker for mitochondrial function) and thapsigargin-sensitive calcium ATPase (a marker for sarcoplasmic reticular calcium uptake function); and quantification of Rho-kinase (ROK) alpha and beta and myosin light chain kinase by Western blot analyses. RESULTS By 28 days after OVX, there were significant decreases in bladder weight, contractile responses, and citrate synthase and sarcoplasmic reticular calcium uptake activity. In addition, by 28 days following OVX the relative concentration of ROK alpha was significantly increased, whereas ROK beta concentration was significantly decreased. Myosin light chain kinase was significantly reduced. CONCLUSIONS Our study demonstrated that OVX contributed significantly to chronically decreased contractile function in the detrusor muscle of the female rabbit bladder, and this decrease, in turn, was mediated by decreased mitochondrial and sarcoplasmic reticulum function. These specific bladder dysfunctions could be related to the demonstrated decreased blood flow to the bladder muscle and mucosa and the increased generation of free radicals. Changes in smooth muscle regulatory proteins, especially myosin light chain kinase, may also play a role in contractile dysfunctions.

Effect of severity and duration of bladder outlet obstruction on catalase and superoxide dismutase activity

To study the effects of partial bladder outlet obstruction on the cells anti‐oxidant defense mechanisms, superoxide dismutase and catalase, in order to elucidate how the bladder responds to oxidative stress.