Biomedical subjects

R M Levin

Publications and source records attributed to R M Levin.

At least 37 records · Page 2Linked to original sources

PubMed2000

Normal detrusor is more sensitive than hypertrophied detrusor to in vitro ischemia followed by re-oxygenation.

Partial outlet obstruction results in marked metabolic as well as contractile alterations. Specifically, the ratio of anaerobic to oxidative metabolism is significantly greater in hypertrophied than normal bladder smooth muscle, lactate dehydrogenase (LDH) and lactic acid production are increased, and the contractile apparatus is altered to allow for metabolically more efficient tension generation. In addition, contractile responses of hypertrophied bladder are apparently more resistant than those of normal bladder to hypoxia. In the current experiment, we studied the effects of in vitro ischemia (hypoxia + substrate deprivation) followed by an in vitro model of reperfusion (re-oxygenation + substrate replacement) on contractile responses of normal and hypertrophied urinary bladder strips. We used repetitive field stimulation (FS) during the hypoxic period as a model for hyperreflexia. The purpose of the current study was to compare the responses of normal and hypertrophied bladder smooth muscle to repetitive stimulation in the presence of in vitro ischemia followed by re-oxygenation and substrate replacement. Thirty-two rats were separated into four groups of eight each. The rats in groups 1 and 3 were subjected to partial outlet obstruction. Two weeks later, all rats were anesthetized; their bladders were isolated and cut into four strips. Each strip was mounted in an isolated bath, and after 1-hour incubation in Tyrode's solution containing glucose (in the presence of O(2)), contractile responses to FS, carbachol, and KCl were determined. After this first set of stimulations, the strips were incubated without glucose and in the presence of N(2) for 30 minutes and 1 hour (groups 1 and 2); and for 2 and 4 hours (groups 3 and 4). For groups 1 and 2, the tissues were stimulated at 5-minute intervals with FS at 32 Hz, 1-millisecond duration, 3-second trains (in vitro model of hyperreflexia). For groups 3 and 4, no stimulations were performed during the ischemic period. At the end of the ischemic period, all strips were washed and incubated for 1 hour in the presence of O(2) and with glucose. At the end of this incubation, all strips received a second set of stimulations. a) Partial outlet obstruction resulted in a significant increase in bladder weight. b) Responses to in vitro ischemia: After in vitro ischemia, contractile responses of both normal and hypertrophied tissues to FS were reduced to a significantly greater degree than were responses to carbachol and KCl. The rate of development of contractile dysfunction was significantly greater in normal bladder tissue strips than in hypertrophied bladder strips. c) Responses to repetitive stimulation: The rate of development of contractile dysfunction was significantly greater in all strips subjected to repetitive stimulation than in those not repetitively stimulated; in addition, normal bladder strips were more sensitive than hypertrophied strips to hypoxia and substrate deprivation-induced contractile dysfunction. The rate of contractile failure induced by in vitro ischemia followed by re-oxygenation and substrate replacement was significantly greater for normal bladder strips than for hypertrophied bladder strips. These results indicate that, after partial outlet obstruction, the hypertrophied tissue is more resistant than normal tissue to hypoxia and substrate deprivation.

Animals↗

PubMed2000

A scientific basis for the therapeutic effects of Pygeum africanum and Serenoa repens.

In Europe, phytotherapeutic preparations have been prescribed for the treatment of symptomatic benign prostatic hyperplasia (BPH) for over 20 years [1-4]. In these countries, phytotherapeutic preparations represent approximately 1/3 of total sales of all therapeutic agents sold for the treatment of BPH. In France, and other countries, phytotherapeutic preparations are the most widely used drugs for the treatment of BPH. In Asia, Africa, and India, phytotherapy is considered a first-line treatment for BPH and has been utilized effectively for centuries. In the United States, the multimillion dollar sales of phytotherapeutic preparations for "the health of the prostate and bladder" attests to the widespread utilization of these agents [3, 4]. Two of the most popular phytotherapeutic agents that have undergone both clinical studies to determine their efficacy, and have been the subject of basic science studies to identify the mechanism(s) of action are Pygeum africanum (Tadenan), an extract from the bark of the African plum tree, and Serenoa repens (Permixon), a lipido-sterol extract of dwarf palm. Tadenan and Permixon are registered therapeutic agents of Debat Pharmaceuticals, and Pierre Fabre Medicament, respectively. Manufacture of both preparations are tightly controlled and subjected to strict quality control for stability of component composition. In regard to phytotherapeutic agents, each individual preparation (even from the same plant source) must be considered individually because of differences in the extraction techniques, preparation of products, composition, and biological activities. Thus, the clinical and biological activities of one preparation cannot be extrapolated to other preparations of the same plant source. Thus, studies described in this review which utilize the preparations that are manufactured by DEBAT (Pygeum africanum) or Pierre Fabre Medicament (Serenoa repens) are referred to by their trade names, Tadenan and Permixon, to differentiate them from other nonstandardized preparations of the same plants.

Androgen Antagonists↗

PubMed2000

Vascular response of the rabbit bladder to short term partial outlet obstruction.

Partial bladder outlet obstruction of the rabbit bladder results in a rapid increase in mass characterized by remodeling of the bladder wall. In this study we investigated the effect of partial outlet obstruction on microvessel density and distribution in the bladder wall immunohistochemically using CD31 as a marker for vascular endothelium, and on blood flow using a fluorescent microsphere technique. Transverse sections of bladder wall were examined after 0 (unobstructed), 1, 3, 5, 7, and 14 days of obstruction. The microvasculature of obstructed rabbit bladder mucosa and detrusor smooth muscle apparently increased relative to augmentation of these compartments, while new vessels appeared in the thickening serosa. These vascular changes correlated with results showing that, at 1 week after obstruction, blood flow (ml/min/g tissue) to the mucosa and detrusor was unchanged. Thickening of the serosa, apparent after 1 day of obstruction, began before its vascularization. Then, 1 week post-obstruction, there was significant microvessel formation in the transition region between the detrusor smooth muscle and the increasing serosa; after 2 weeks, the entire serosa was vascularized. The vascularization of the muscle-serosal transition region and then the remaining serosa apparently precedes fibroblast differentiation, providing blood supply and thus metabolic support for this process. All obstructed rabbit bladders in this study were in a state of compensated function based on their weights. Our working hypothesis is that blood flow per unit tissue mass is normal in compensated obstructed bladders, thus allowing for normal contractile function and cellular metabolism. The results of this study indicate the presence of an augmented microvasculature in compensated obstructed rabbit bladders that provides adequate blood perfusion for normal function.

Animals↗

PubMed2000

Regulation of the activity of choline acetyl transferase by lipoic acid.

The observations reported in this article demonstrate that lipoic acid strongly influences the activity of a purified preparation of choline acetyl transferase. The reduced form, dihydrolipoic acid, is a powerful activator of the enzyme while lipoic acid itself has an inhibitory effect and counteracts the stimulatory effect of dihydrolipoic acid. It is proposed that dihydrolipoic acid serves an essential function in the action of this enzyme and that the ratio of reduced to oxidized lipoic acid in the cell may play an important role in the regulation of the activity of the enzyme. The implications of these findings for cell function and acetyl choline formation are discussed.

Antioxidants↗

PubMed2000

Comparative physiology and biochemistry of rat and rabbit urinary bladder.

OBJECTIVE: To compare directly the biochemistry and contractile responses of rat and rabbit bladder to different stimuli. Materials and methods Sexually mature male New Zealand White rabbits and Sprague Dawley rats were compared. Each bladder was excised while the animal was anaesthetized; longitudinal bladder strips were cut and then mounted in an organ bath. Tension (2 g) was placed on all strips and each underwent field stimulation (FS) for a total of 20 s at 1-32 Hz, 1 ms and 80 V and was exposed to carbachol (100 micromol/L), ATP (2 mmol/L) and KCl (120 mmol/L). The tension was monitored continually using a polygraph and data stored digitally in a computer. The responses to each stimulus were determined as the maximum tension generated, maximum rate of tension generation and duration to a maximum response. The Ca2+- ATPase activity of the rat and rabbit bladder was determined. Bladder pressures were then predicted from the strip data using Laplace's law and compared with published values. RESULTS: Contractile responses (per unit tissue mass) of rat bladder strips were significantly greater than those of rabbit bladder strips at all frequencies of FS and to carbachol, KCl and ATP. The rate of contractile force generated by rat bladder strips in response to all stimuli were significantly greater than that generated by rabbit strips. Rabbit bladder strips took significantly longer to generate maximum tension than did rat bladder strips in response to pharmacological stimuli. In response to FS, rat strips took significantly longer than rabbit strips to generate maximum tension. Although the predicted rat bladder pressures were significantly greater than those for rabbit, the predicted pressures for both the rat and rabbit were significantly lower than the pressure responses of the isolated whole bladder model. The contractile data correlated well with the Ca2+-ATPase activity data; rat bladder had seven times the enzyme activity of rabbit bladder. CONCLUSION: Per unit mass, rat bladder is capable of generating more than five times the tension of rabbit bladder. Similarly, the rate of tension generation by rat bladder is three to five times greater than that by rabbit bladder. The duration to maximum tension generated in response to FS compared with pharmacological stimuli was affected by the inherent difference in the rate of contractile response to electrical activation compared with agents which diffuse through tissue, and by the difference in size between rat and rabbit bladder smooth muscle cells.

Adenosine Triphosphate↗

PubMed2000

Acral steatocystoma multiplex.

Steatocystoma multiplex (SM) is characterized by multiple, widespread cutaneous cystic lesions. These lesions can appear virtually anywhere on the body but are more common in areas where the pilosebaceous apparatus is well developed, such as the trunk (especially the presternal area), neck, axilla, inguinal region, scalp, and proximal extremities. We present a case of a woman with predominantly acrally located SM. To the best of our knowledge, a predominantly acral distribution has never been reported. We hypothesize that this patient's phenotype may be due to her genetic predisposition, possibly involving a familial defect in keratin 17, in combination with "ectopic" acral sebaceous follicles.

Adult↗

PubMed2000

Intermittent catheterization limits rabbit bladder dysfunction in response to partial outlet obstruction.

INTRODUCTION: The initial response of the urinary bladder to outflow partial obstruction consists of distension, followed by a rapid increase in mass and concomitant functional adaptations. Subsequently, an indeterminate period of stabilized function and little increase in mass occurs (compensation). Finally, bladder mass again progressively increases, accompanied by deleterious changes in bladder morphology, biochemistry and pharmacology, and progressive loss of function (decompensation). The reported study was designed to determine whether limiting the level of bladder distension, using intermittent catheterization (IntCath), could protect the bladder from decompensation. MATERIALS AND METHODS: Sixteen male New Zealand White rabbits were separated into 4 groups of 4 rabbits each: control, control with IntCath, obstructed, and obstructed with IntCath. IntCath was performed with the animals under inhalation anesthesia. An 8 Fr. catheter was inserted through the urethra into the bladder every 8 hours and the urine drained. After 14 days of obstruction, bladders were removed from all rabbits; longitudinal strips were cut from the bladder body and suspended in individual organ baths. Contractile responses to field stimulation (FS), KCl, ATP, and carbachol were measured. RESULTS: There were no significant differences between control rabbits and controls with IntCath in bladder weights, compliance, and contractile responses to all stimuli. Bladder weights of both obstructed groups increased significantly compared to those of both control groups. Bladder weights of obstructed rabbits increased to a significantly greater extent than did those of obstructed rabbits with IntCath. Bladder compliance in the obstructed group was significantly lower than compliance in both control groups and in obstructed rabbits with IntCath. Both obstructed groups exhibited significantly decreased contractile responses to FS, ATP and KCl, compared to control groups. The response of the obstructed group with IntCath to FS and carbachol was significantly greater than the responses of the obstructed group without IntCath. CONCLUSIONS: These findings show that limiting distension with IntCath reduces the magnitudes of the increased bladder mass, the loss of bladder wall elasticity (compliance), and the impaired contractile responses which occur secondary to outflow obstruction.

Animals↗

PubMed2000

Correlation between the structure and function of the rabbit urinary bladder following partial outlet obstruction.

PURPOSE: To understand the relationship between contractile and structural changes in the obstructed bladder, rabbit bladder was partially obstructed for up to 70 days and alterations in tension response to field stimulation and carbachol were compared with alterations in ultrastructure and innervation of detrusor smooth muscle (SM). The effect of partial outlet obstruction on the physiological responses to field stimulation (FS) (nerve mediated contraction) and carbachol (receptor mediated contraction) were correlated with the structure and innervation of the detrusor smooth muscle (SM) of the same animal during a 70 day period. MATERIALS AND METHODS: 28 rabbits were subjected to 1 to 70 days of mild partial outlet obstruction. Sham operated rabbits were euthanized at 7, 14, 28, and 70 days post-obstruction. At each time period, isolated strips of bladder body were mounted in individual baths and the contractile response to FS and carbachol determined. Three additional strips from each bladder were fixed for electron microscopy. RESULTS: Bladder mass increased rapidly during the first 7 days after obstruction, was constant for the next 7 days, and then continued to increase gradually. Dysfunction of the contractile response to FS was noted as early as 3 days and progressively increased over the 70-day study period. The decrease in the response to FS increased at a significantly faster rate than the decrease in the contractile response to carbachol. In ultrastructure studies, at 3 and 7 days post-obstruction the majority of SM cells displayed the characteristics of hypertrophy. At 28 days some SM cells displayed loosely packed myofilaments and an irregular distribution of sarcoplasmic dense bodies. At 70 days swollen mitochondria were present in all cell types of the bladder wall. Evidence of axonal degeneration was first observed at 7 days post-obstruction and became more extensive thereafter. No evidence of mitotic figures, nerve growth cones or regenerating SM cells was observed. CONCLUSIONS: Prolonged partial bladder outflow obstruction is accompanied by a progressive decrease in contractility of SM. The present study describes the structural damage that occurs in the bladder wall in response to partial outlet obstruction and correlates these observations with the contractile dysfunction with which it is associated. Furthermore, mitochondrial damage in vessels and fibroblasts is suggestive of bladder wall ischemia.

Animals↗

PubMed2000

Improved contractility of obstructed bladders after Tadenan treatment is associated with reversal of altered myosin isoform expression.

PURPOSE: Tadenan is a plant extract from Pygeum africanum used in the treatment of benign prostatic hyperplasia, to protect the bladder from contractile dysfunction induced by partial bladder outlet obstruction (BOO). The aim of the present study was to determine whether the Tadenan-induced return of detrusor contractility affects the expression of myosin isoforms, which differ at the C-terminal (SM1 and SM2) and the N-terminal regions (SM-A and SM-B). MATERIALS AND METHODS: Four groups of New Zealand White rabbits (3 to 5 kg., 4 to 6 rabbits per group) were either partially obstructed by ligation of the urethra (groups 1 and 2) or not obstructed (groups 3 and 4). After 2 weeks, rabbits from groups 2 and 4 received Tadenan in peanut oil (vehicle) orally at 100 mg. /kg./day for 3 weeks and rabbits in groups 1 and 3 received vehicle only. Rabbits were sacrificed and bladders were removed and weighed. Contractility studies were performed on isolated strips of detrusor and the remaining muscular layer from the bladder body was used to study the expression of myosin heavy chain (MHC) isoforms at mRNA (SM1, SM2, SM-A, and SM-B) and the protein (SM1 and SM2) levels by RT-PCR and SDS-PAGE analyses, respectively. RESULTS: Tadenan significantly reduced the effect of BOO on bladder mass. The diminished contractile response to field stimulation and carbachol secondary to urethral obstruction was significantly reversed by Tadenan treatment. The relative ratios for MHC isoforms were altered at the mRNA (SM2:SM1 and SM-A:SM-B) and protein (SM2:SM1) levels in obstruction. Upon treatment with Tadenan, the ratio of these isoforms returned to normal, as shown at the mRNA levels. In addition, the altered relative ratio of SM2:SM1 at the protein level also returned to nearly normal values after treatment. CONCLUSIONS: Improvement of obstruction-induced contractile dysfunction of the detrusor following treatment with Tadenan is associated with changes in the expression of myosin isoforms. The alteration in the expression of myosin isoforms associated with obstruction-induced hypertrophy is reversed close to normal in the detrusor smooth muscle from Tadenan-treated obstructed rabbits.

Animals↗

PubMed2000

Rabbit urinary bladder blood flow changes during the initial stage of partial outlet obstruction.

PURPOSE: The rabbit urinary bladder's early response to partial outlet obstruction includes bladder wall remodeling with marked urothelial and fibroblast hyperplasia (1 day) and smooth muscle hypertrophy (3-5 days) resulting in a 4-5 fold increase in bladder mass within 7 days. In this study, we examined the effect of partial outlet obstruction on bladder blood flow during the initial period of rapid growth (1-7 days). MATERIALS AND METHODS: Each New Zealand White rabbit was partially obstructed by tying a 2-0 silk ligature loosely around the vesical outlet. After 0 (unoperated), 4 hours, 1, 3, or 7 days of obstruction, 5 rabbits per group were anesthetized and the carotid and femoral arteries cannulated with polyethylene tubing. Additional rabbits receiving sham surgeries were treated like obstructed animals at 4 hours and 1 day post-obstruction (5/group). Using standard methods, fluorescent microspheres were infused through the right carotid artery. Bladder and right kidney were rapidly removed upon completion of sphere infusion; bladder mucosa and muscle were separated. Sphere densities in detrusor, mucosa, and kidney were measured by Interactive Medical Technologies, Ltd. A section of each detrusor tissue was fixed in formalin and immunostained for smooth muscle alpha-actin. RESULTS: Mucosal blood flow (0.20 +/- 0.03 ml./min./gm.) was approximately 4-fold greater than that of detrusor (0.05 +/- 0.01 ml./min./gm.). Sham surgery caused a significant increase in bladder blood flow at 4 hours post-obstruction that returned to control levels by 1 day. Both mucosal and muscle blood flows were slightly higher in rabbit bladders obstructed for 4 hours than in sham-operated rabbits, and substantially greater in those obstructed for 1 day: 0.68 +/- 0.13 ml./min./gm. (mucosa) and 0.26 +/- 0.04 ml./min./gm. (muscle). Blood flows returned to control values by 3 days post-obstruction and remained constant through 7 days. Kidney blood flow was unchanged. Although bladder weight increased 4-fold after 7 days of obstruction, the volume fraction of smooth muscle (transverse section) remained constant at approximately 40%. CONCLUSIONS: Blood flow was approximately 4-fold greater in bladder mucosa than in muscle, which may relate to the significantly higher metabolic rate and lower high energy phosphate concentration of mucosa than muscle. Partial outlet obstruction resulted in a significant increase in blood flow at 1 day post-obstruction, which coincides temporally with the early cellular hyperplasia and hypertrophy of obstructed rabbit bladder. This increase in blood flow may be an essential factor for the initial increase in bladder mass. By three days, the blood flow per gram of tissue returned to control levels. The mechanisms relating to the changes in blood flow induced by partial outlet obstruction are currently under investigation.

Animals↗

PubMed1999

Effect of diltiazem and pinacidil on the response of the rabbit urinary bladder to repetitive stimulation and in vitro ischemia.

The effect of repetitive stimulation, in the presence and absence of diltiazem or pinacidil, on the contractile responses of isolated strips of rabbit bladder detrusor to field stimulation and carbachol, after 2 hr of incubation in a medium that serves as an in vitro model of ischemia (oxygen and substrate depleted Tyrode's solution), was determined. Our results are summarized as follows: a) The magnitude of the contractile dysfunctions after in vitro ischemia was enhanced by repetitive stimulation. b) Pre-incubation of isolated strips of detrusor with diltiazem (50 microM) inhibited the contractile responses to field stimulation (FS) and carbachol by 43 and 50%, respectively. Pinacidil (100 microM) inhibited the contractile responses to FS and carbachol by 37 and 32%, respectively. c) Neither diltiazem nor pinacidil protected the bladder strips against the effects of 2 hr of incubation in in vitro ischemia medium. However, d) both pinacidil and diltiazem reduced the level of contractile dysfunctions induced by repetitive stimulation. In conclusion, the contractile response to FS was significantly more sensitive to in vitro ischemia and repetitive stimulation than was the contractile response to carbachol. Both diltiazem and pinacidil protected the contractile responses to FS and carbachol from the degenerative effects of repetitive stimulation, but not from the effects of in vitro ischemia.

Animals↗

PubMed1999

Fatty acid profiles in normal and obstructed rabbit bladder smooth muscle and mucosa.

Partial bladder outlet obstruction results in progressive loss in contractile and specific cellular and subcellular membrane functions. There is evidence that ischemic activation of proteolytic and lipolytic enzymes play a major role in the etiology of bladder dysfunction secondary to partial outlet obstruction. The specific aims of the current study were to determine the fatty acid profiles in normal rabbit bladder smooth muscle and mucosa and to determine the effect of partial outlet obstruction on the distribution and content of free and total fatty acids. Fatty acids were isolated by extraction from obstructed and normal bladder smooth muscle and mucosal homogenates, and samples were analyzed by gas chromatography. All samples contained palmitic, stearic, oleic, linoleic, and arachidonic acids. A 100% increase in total fatty acid concentration was observed in the obstructed bladder muscle tissue relative to normal bladders, although the concentration of total arachidonic acid remained constant in the two groups. Significantly higher levels of free arachidonic acid were observed in the obstructed bladder muscle group compared to the normal group. No changes were observed in fatty acid concentrations or distributions in bladder mucosa. These data show that fatty acid composition is altered as a result of bladder obstruction and support the idea that obstruction increases the activity of lipase activity and/or decreases acyl transferase activity. Neurourol. Urodynam. 18:697-711, 1999.

Animals↗

PubMed1999

Subcellular distribution of free fatty acids, phospholipids, and endogenous lipase activity of rabbit urinary bladder smooth muscle and mucosa.

OBJECTIVES: The urinary bladder wall can be separated into two major compartments: the urothelium (mucosa) and the detrusor smooth muscle. Specific dysfunctions of both layers have been linked to ischemia, which may induce significant cellular and subcellular membrane damage via the activation of selective calcium dependent and independent hydrolytic enzymes. Preliminary to investigating changes in cell membrane composition induced by ischemia, we measured the free fatty acid (FFA) and phospholipid (PL) content of normal rabbit bladder muscle and mucosal cellular and subcellular membranes, and characterized the endogenous lipase activity. METHODS: Rabbit bladders were excised and the muscle and mucosal layers separated; each layer was homogenized, then fractionated by differential centrifugation. Endogenous lipase activity of the homogenates, and FFA and PL concentrations of the homogenates and subcellular fractions were measured. RESULTS: (1) The basal FFA concentration of the mucosal homogenates was 5 times that of the muscle homogenates. (2) The basal PL concentrations of the two tissues were similar. (3) Subcellular studies: FFA concentration was greatest in the mitochondrial fraction of both compartments. In the mucosa, PL concentration was significantly greater in the mitochondria and microsomes than in the other fractions; in the smooth muscle, the PL concentration was highest in the mitochondria. (4) The maximal endogenous lipase activity was 10 times higher in the mucosal homogenates than in the muscle homogenates. CONCLUSIONS: These results are consistent with those of previous studies which indicate that the mucosa is metabolically more active than the resting smooth muscle, which may cause the mucosa to be significantly more sensitive than the muscle to hypoxic/ischemic damage.

Animals↗

PubMed1999

Effect of partial outflow obstruction on the distribution of free fatty acids and phospholipids in the rabbit bladder.

The urinary bladder is separated into two distinct components, the mucosal epithelium (urothelium) and the underlying detrusor smooth muscle. Specific bladder dysfunctions such as partial outlet obstruction may contribute to the breakdown and damage of cell membranes. The major component of cell membranes is phospholipids, and the release of free fatty acids (FFA) from membrane phospholipids is suggestive of degradative lipase activity. The current investigation is concerned with the effect of partial outlet obstruction on the subcellular distribution of free fatty acids and phospholipids (PL) in rabbit bladder muscle and mucosa. Partial outlet obstructions were surgically created in mature male New Zealand White rabbits by standard methodology. At 2 weeks following surgery, rabbits were euthanized and the bladders, removed and separated into smooth muscle and mucosa. Muscle and mucosa were homogenized and separated by differential centrifugation to obtain separate subcellular fractions including plasma membranes, mitochondria, microsomes, and cytosol. The homogenate and supernatant fraction, free of membranes, were also saved. The free-fatty-acid (FFA) and choline-containing phospholipid (PL) content and the rate of generation of FFA were quantitated using in vitro enzymatic colorimetric methods. Relative to controls there was a significant increase in the FFA content of the obstructed smooth muscle and an increase in the PL content of the obstructed mucosa. There was an increase in FFA content in the mitochondrial fraction and a decrease in the supernatant of the obstructed smooth muscle. The PL content was reduced in the obstructed smooth muscle microsomal and supernatant fractions and was increased in the supernatant fraction of the mucosa. Endogenous lipase activity among control bladders was more than 10-fold greater in mucosa than in muscle. The FFA generation of the smooth muscle was significantly reduced by partial outlet obstruction. In conclusion, partial outlet obstruction causes bladder dysfunction due to activation of enzymes that hydrolyze cellular and subcellular membranes. The increase in endogenous lipase activity and generation of FFA among obstructed bladders indicates that the pathological state affects the membrane structure needed for normal bladder function.

Animals↗

PubMed1999

Biochemical evaluation of obstructive bladder dysfunction in men secondary to BPH: a preliminary report.

OBJECTIVES: In the rabbit, two of the major cellular alterations that mediate bladder dysfunction secondary to partial outlet obstruction are a decreased ability of the sarcoplasmic reticulum (SR) to store and release Ca2+, and mitochondrial dysfunction. The objective of the current study was to determine whether SR and mitochondrial dysfunctions are associated with symptomatic benign prostatic hyperplasia (BPH) in men. METHODS: Bladder biopsies were obtained from men with symptomatic BPH and from age-matched men with no urologic dysfunction. Each biopsy was analyzed for the following enzyme activities: malate dehydrogenase and citrate synthase (mitochondrial markers) and the sarcoplasmic reticular enzyme Ca2+ -dependent adenosine triphosphatase (ATPase). These values were compared with the enzyme activities of control rabbit bladder smooth muscle and bladder smooth muscle obtained from rabbits subjected to 2 weeks of partial outlet obstruction. RESULTS: The enzymatic activities of all three enzymes are significantly lower in human bladder smooth muscle than in rabbit bladder smooth muscle. The maximal activities of all three enzymes are significantly lower in human bladder samples obtained from men with diagnosed obstructive uropathy than in men of equal age with no urologic dysfunction. CONCLUSIONS: These studies demonstrate that similar to the response of the rabbit to partial outlet obstruction, obstructive dysfunction secondary to BPH is characterized by mitochondrial and SR dysfunction.

Animals↗

PubMed1999

Sucrose diuresis protects rat bladder from outlet partial obstruction-induced contractile dysfunction.

OBJECTIVES: Evidence is accumulating that bladder dysfunction caused by experimental partial obstruction of the bladder outlet can be reduced or reversed by treatment that results in upregulation of bladder function, even in the presence of obstruction. Inducing diuresis in rats or rabbits results in a significant increase in bladder mass and increased contractility in response to stimulation. The objective of the present study was to determine whether diuresis-induced amplification of bladder function in the rat could protect the bladder from contractile dysfunctions caused by partial outlet obstruction. METHODS: Thirty-two rats were separated into four groups of 8 rats each. Groups 2 and 4 were fed 5% sucrose instead of water; groups 1 and 3 were fed only water. Three weeks later, partial outlet obstructions were created in groups 3 and 4. After 4 weeks of obstruction, all bladders were rapidly excised and cut into longitudinal strips; each strip was mounted in an isolated muscle bath for contractile studies. RESULTS: Sucrose-induced diuresis caused a moderate but significant increase in bladder mass. Partial outlet obstruction stimulated significant increases in bladder mass in both water-drinking and sucrose-drinking groups; the bladder mass of sucrose-drinking rats, however, increased less than that of water-drinking rats. In water-drinking rats, partial outlet obstruction resulted in significantly decreased bladder strip contractility in vitro in response to field stimulation (1 to 32 Hz), carbachol (0.1 to 22 microM), and KCl (120 mM). After 3 weeks of sucrose-induced diuresis, partial obstruction of the rat bladder outlet did not result in decreased in vitro contractile responses to any form of stimulation applied. CONCLUSIONS: Sucrose-induced diuresis caused an increase in bladder mass and an increase in contractile strength, consequently protecting the rat bladder from the contractile dysfunctions that usually follow partial outlet obstruction.

Animals↗

PubMed1999

Correlation of calcium-activated ATPase activity, lipid peroxidation, and the contractile response of rabbit corporal smooth muscle treated with in vitro ischemia.

Oxygen and glucose are critical to support the survival and integrity of all smooth muscles. Hypoxia alone has been demonstrated to suppress the contractile response of corporal smooth muscle, and one might expect simultaneous deprivation of oxygen and glucose (in vitro model of ischemia) to exert more serious damage to corporal smooth muscle contraction. The effect of in vitro ischemia on the pharmacological responses of isolated rabbit corporal smooth muscle was correlated with the level of tissue lipid peroxidation. The effects of in vitro ischemia were as follows: (1) In vitro ischemia resulted in an 85% reduction in the contractile response to phenylephrine; (2) more than a 50% reduction in the activity of thapsigargin-sensitive calcium-activated ATPase activity of the microsomes (sarcoplasmic reticulum [SR]); (3) more than a fourfold increase in the tissue concentration of thiobarbituric acid reactive substances (TBARS) (level of lipid peroxidation). In conclusion, stimulation of lipid peroxidation in part may be responsible for the decrease in thapsigargin-sensitive calcium-activated ATPase activity of the SR (SERCA), and the correlated decrease in the contractile response to phenylephrine in response to ischemia.

Adenosine Triphosphatases↗

PubMed1999

Identification of components of Prunus africana extract that inhibit lipid peroxidation.

Extractive and chromatographic separations were performed on V-1326, a chloroform extract from the bark of Prunus africana (also referred to as Pygeum africanum), which is used to treat the symptoms associated with benign prostate hyperplasia (BPH). The relative amounts of eleven identified constituents in crude V-1326 and in separated fractions were determined using gas chromatographic analysis. The ability of V-1326 and its separated fractions to inhibit ferrous ion-induced stimulation of lipid peroxidation in microsomal preparations from rabbit livers was evaluated. The extract, V-1326, and fractions containing high levels of myristic acid potently inhibited lipid peroxidation.

Biological Assay↗