Mitochondrial involvement in bladder function and dysfunction

Lower urinary tract dysfunction in adult patients with mitochondrial disease

AIMS

Mitochondrial diseases present with a spectrum of clinical features, usually with multiorgan involvement and are often characterized by a loss of smooth muscle function. Hence, we hypothesized that mitochondrial dysfunction may contribute to lower urinary tract (LUT) dysfunction.

METHODS

We performed a prospective cohort study at a single, quaternary, mitochondrial disease referral center, enrolling consecutive adult patients with genetically confirmed mitochondrial disease. Data regarding baseline characteristics and disease burden were gathered. LUT dysfunction was assessed using the International Consultation on Incontinence Modular Questionnaire-Lower Urinary Tract Symptoms (ICIQ-LUTS) questionnaire, bladder voiding efficiency (BVE), and bladder diaries. Patients with one or more features of LUT dysfunction were offered urodynamic testing.

RESULTS

A total of 109 patients were included. Twenty-six percent of patients manifested at least one feature of LUT dysfunction, which was objectively confirmed in all 14 patients who consented to urodynamic investigation. Disease burden, defined by the Newcastle Mitochondrial Disease Adult Scale (NMDAS), demonstrated a linear relationship with ICIQ-LUTS severity (P = .01), with a statistically significant relationship between NMDAS-gastrointestinal scores and LUTS scores (P < .001). Limitations include mutational heterogeneity across the patient cohort.

CONCLUSIONS

This is the largest study exploring LUT in patients with mitochondrial disease and supports previous smaller studies suggesting LUT dysfunction is underrecognized in patients with mitochondrial disease and impacts considerably on their quality of life. We propose a clinical guideline for identifying mitochondrial disease patients at risk of LUT dysfunction.

Risk factors for urinary tract infection in children with urinary urgency

Purpose

To identify which independent variable would be strong predictor of febrile urinary tract infection (UTI) in children and adolescents with overactive bladder.

Materials and Methods

A search was made of the institute's database for all patients diagnosed with overactive bladder over the preceding four years. Children and adolescents under 18 years of age with overactive bladder and no neurological or anatomical alterations of the lower urinary tract were included in the study. The independent variables were: sex, age, ethnicity (Brazilians of African descendence/others), the presence of urinary urgency, daytime incontinence, enuresis, frequent urination, infrequent voiding (≤3 voids/day), nocturia, holding maneuvers, straining to void, intermittent urinary flow, constipation and encopresis. An analysis was conducted to identify patients with febrile UTI and subsequently determine predictors of this condition. Univariate and multivariate analyses were performed.

Results

Overall, 326 patients (214 girls/112 boys) were evaluated. The mean age of the patients was 7.7±3.19 years (± standard deviation). The incidence of febrile UTI was 39.2%. Being female and infrequent voiding were factors significantly associated with febrile UTI, both in the univariate and multivariate analyses.

Conclusions

These results show that being female and infrequent voiding constituted significant risk factors for a diagnosis of febrile UTI in these children.

Comparative biochemical responses and antioxidant activities of the rabbit urinary bladder to whole grapes versus resveratrol

The objective of this study is to compare the antioxidant activity of a whole-grape suspension with the antioxidant activity or pure resveratrol on the effect of hydrogen peroxide (H2O2) on malondialdehyde (MDA) generation, choline acetyltransferase (ChAT) activity, calcium ATPase activity, and sarcoendoplasmic reticular ATPase (SERCA) of the male rabbit urinary bladder. MDA was used as a model for the effect of H2O2 on lipid peroxidation. ChAT, SERCA, and calcium ATPase were evaluated based on their importance in urinary bladder physiology and pathology. Four male rabbit bladders were used. Each bladder was separated into muscle and mucosa, frozen under liquid nitrogen and stored at -80 °C for biochemical evaluation. The effect of H2O2 on the enzymes listed above was determined in the presence and absence of either resveratrol or a whole-grape suspension. (1) Resveratrol was significantly more effective than the grape suspension at protecting the bladder muscle and mucosa against peroxidation as quantitated by MDA formation. (2) The grape suspension was significantly more effective at protecting ChAT activity against oxidative stress of the muscle than resveratrol. (3) Neither the grape suspension nor resveratrol were particularly effective at protecting the bladder muscle or mucosa calcium ATPase or SERCA against oxidative stress. (4) ChAT was significantly more sensitive to oxidative stress than either calcium ATPase or SERCA. These data support the idea that the grape suspension protects the mitochondria and nerve terminals to a significantly greater degree than resveratrol which suggests that the activities of the grape suspension are due to the combination of active components found in the grape suspension and not just resveratrol alone.

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.

Effect of hydrogen peroxide on rabbit urinary bladder citrate synthase activity in the presence and absence of a grape suspension

PURPOSE

The etiology of obstructive bladder dysfunction includes free radical damage to mitochondria. Feeding rabbits a standardized grape suspension protects the ability of the bladder to contract and empty in part by preventing mitochondrial damage, thus maintaining smooth muscle and mucosal metabolism. The objective of the current study is to determine the direct effect of this grape suspension on the response of mitochondria to the oxidative effects of hydrogen peroxide.

MATERIALS AND METHODS

Six male rabbits were anesthetized with sodium pentobarbital and the bladders excised. Four full thickness strips were obtained for contractile studies and the balance separated into smooth muscle and mucosa compartments by blunt dissection. The effect of hydrogen peroxide on the contractile response to field stimulation was quantitated. Each tissue was homogenized and the effects of increasing concentrations of hydrogen peroxide in the presence and absence of grape suspension on citrate synthase activity was determined.

RESULTS

Citrate synthase activity was significantly higher in the mucosa than in the muscle. The grape suspension had no effect on control citrate synthase activity. However, the grape suspension provided significant protection of both smooth muscle and mucosal citrate synthase activity.

CONCLUSIONS

These studies support the conclusion that the grape suspension provides direct protection of mitochondrial function.

Etiology, epidemiology, and natural history of benign prostatic hyperplasia

Historically, benign prostatic hyperplasia (BPH) has been a major focus of urologic practice and surgery. But a simplistic causal relationship among prostatic enlargement, progressive obstruction, lower urinary tract symptoms, retention, and complications of retention has been challenged by recognition of the incomplete overlap of prostatic enlargement with symptoms and obstruction. The result has been a greater focus on symptoms than prostatic enlargement and a shift from surgery to medical treatment. Therefore, the question can be asked whether BPH per se, the glandular enlargement as it contributes to bladder dysfunction, or hyperplastic enlargement as a biomarker for generalized lower urinary tract dysfunction are concerns. This article addresses these issues.

The beneficial effect of coenzyme Q10 and lipoic acid on obstructive bladder dysfunction in the rabbit

PURPOSE

Recent evidence indicates that ischemia and reperfusion are major etiological factors in the bladder dysfunction that occurs after partial bladder outlet obstruction. Coenzyme Q10 and alpha-lipoic acid are found naturally in mitochondria and act as potent antioxidants. We investigated the beneficial effects of coenzyme Q10 plus alpha-lipoic acid in a rabbit model of bladder outlet obstruction.

MATERIALS AND METHODS

Twenty male rabbits were divided into 5 groups. Group 1 served as control and group 2 received three weeks of coenzyme Q10 plus alpha-lipoic acid supplementation. Rabbits in group 3 underwent surgical partial bladder outlet obstruction for duration of four weeks and groups 4 and 5 were obstructed for seven weeks. In group 5, coenzyme Q10 plus alpha-lipoic acid supplementation was given following 4 weeks obstruction and continued till the end of the seven weeks. The contractile responses to various agents were determined. The protein nitration and carbonylation levels were studied by immunoblotting. Nerve function was determined by choline acetyltransferase activity and nerve density.

RESULTS

The contractile responses to different forms of stimulations, including field stimulation, ATP, carbachol and KCl all showed decreases following 4 and 7 weeks obstruction. Treatment with coenzyme Q10 plus alpha-lipoic acid significantly restored contractile responses to all forms of stimulation. Treatment also had mitochondrial and neuronal effects and reduced protein nitration and carbonylation. Histologically there was less detrusor muscle hypertrophy.

CONCLUSIONS

The current study clearly demonstrates that coenzyme Q10 and alpha-lipoic acid supplementation can improve bladder function after outlet obstruction.

Urinary bladder contraction and relaxation: physiology and pathophysiology

The detrusor smooth muscle is the main muscle component of the urinary bladder wall. Its ability to contract over a large length interval and to relax determines the bladder function during filling and micturition. These processes are regulated by several external nervous and hormonal control systems, and the detrusor contains multiple receptors and signaling pathways. Functional changes of the detrusor can be found in several clinically important conditions, e.g., lower urinary tract symptoms (LUTS) and bladder outlet obstruction. The aim of this review is to summarize and synthesize basic information and recent advances in the understanding of the properties of the detrusor smooth muscle, its contractile system, cellular signaling, membrane properties, and cellular receptors. Alterations in these systems in pathological conditions of the bladder wall are described, and some areas for future research are suggested.

THE MOLECULAR GENETIC BASIS OF MITOCHONDRIAL MALFUNCTION IN BLADDER TISSUE FOLLOWING OUTLET OBSTRUCTION

PURPOSE

Bladder dysfunction following partial outlet obstruction is a frequent consequence of benign prostatic hyperplasia and an increasingly common problem given the aging of the general population. Recent studies from this and other groups have begun to elucidate the molecular bases for the well described physiological malfunctions that characterize this clinical entity. We summarized and synthesized that information.

MATERIALS AND METHODS

Using modern methods of molecular genetics, including real-time polymerase chain reaction, real-time reverse transcriptase-polymerase chain reaction and others, as well as traditional experimental techniques such as electron microscopy we and others examined the transcriptional profile, morphology, etc of bladder smooth muscle mitochondria in experimental models of outlet obstruction.

RESULTS

Data from many studies have demonstrated that aberrant gene expression in the mitochondrial and mitochondria related nuclear genetic systems underlies the loss of compliance and other attributes of bladder dysfunction following outlet obstruction. Such aberrant transcriptional characteristics engender loss of function in the electron transport and oxidative phosphorylation systems. Morphological studies of mitochondria in the animal model systems support this conclusion.

CONCLUSIONS

In large part the loss of function in bladder smooth muscle following outlet obstruction results from the attenuation of mitochondrial energy production. In this article we reviewed and synthesized all available experimental observations relevant to this problem and we suggest future lines of inquiry that should prove fruitful in developing new strategies to treat the condition.

Role of mitochondria in the generation of spontaneous activity in detrusor smooth muscles of the Guinea pig bladder

PURPOSE

The rhythmic electrical activity of gastrointestinal smooth muscles is associated with mitochondrial Ca2+ handling. We examined the role of mitochondria in the generation of spontaneous activity in detrusor smooth muscles.

MATERIALS AND METHODS

Changes in the membrane potential and intracellular Ca2+ concentration ([Ca2+]i) were measured in detrusor smooth muscles of the guinea pig using conventional microelectrode techniques and Fura-PE3 (Calbiochem, San Diego, California) fluorescence, respectively.

RESULTS

Detrusor smooth muscle cells showed spontaneous action potentials and associated transient increases in [Ca2+]i (Ca transients). The mitochondrial protonophore CCCP (carbonyl cyanide m-chlorophenyl hydrazone) (10 microM) depolarized the membrane, increased [Ca2+]i and caused activation followed by suppression of action potentials and Ca transients. High K solution potassium concentration ([K+]o = 30 mM) depolarized the membrane and increased [Ca2+]i to levels similar to those produced by 10 microM CCCP but this depolarization did not suppress action potentials. Nifedipine (10 microM) decreased the amplitude of CCCP induced increases in [Ca2+]i by about 50%. CCCP induced increases in [Ca2+]i were further reduced by about 70% in Ca2+-free solution and by about 30% in the presence of 10 microM SKF96365, a blocker for store operated Ca entry. In the presence of 10 microM nifedipine and 10 microM cyclopiazonic acid, CCCP induced [Ca2+]i responses were suppressed to about 25% of control values. Under these conditions repetitive applications of 10 microM acetylcholine chloride successively decreased [Ca2+]i responses and finally failed to increase [Ca2+]i. Subsequent CCCP failed to elevate [Ca2+]i.

CONCLUSIONS

These results suggest that mitochondria have an important role in Ca2+ buffering in bladder smooth muscles. Mitochondrial Ca2+ is presumably supplied by Ca2+ transport from internal stores and also by capacitative calcium entry through nonselective cation channels. Mitochondrial Ca2+ handling may also be critical for the generation of spontaneous activity in detrusor smooth muscle.

Loss of mitochondrial DNA in rabbit bladder smooth muscle following partial outlet obstruction results from lack of organellar DNA replication

When the rabbit bladder outlet is partially obstructed, the relative amount of mitochondrial (mt) DNA per cell in bladder smooth muscle falls rapidly. In order to assess whether this loss of organellar genome results from attenuation of mt DNA replication, we cloned portions of rabbit genes specifying the single-strand binding (SSB) protein required for initiation of mt DNA replication, and the catalytic subunit of DNA polymerase gamma (pol gamma), the replication enzyme itself. We then designed primer-probe systems for real-time RT-PCR (TaqMan) analyses for each gene. These were used to assess mRNA in preparations from bladder smooth muscle and mucosa from rabbits subjected to surgical obstruction of the bladder outlet for up to 14 days. mRNA from the pol gamma gene remained essentially at control level in smooth muscle and mucosa in all samples. In mucosa, mRNA from the SSB protein gene remained virtually at control levels in all samples, as did mt genome copy number. In smooth muscle, however, levels of this mRNA declined by >95% within 3 days of obstruction and remained at that level through 14 days; this attenuation of SSB protein mRNA paralleled the loss of mt DNA in the same smooth muscle samples. Thus, lack of mt SSB protein, and consequently attenuated mt DNA replication, is a primary factor in the loss of mt genome copies in bladder smooth muscle after outlet obstruction in the rabbit model of benign bladder dysfunction.