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Biomedical subjects

R M Levin

Publications and source records attributed to R M Levin.

At least 91 records · Page 5Linked to original sources
PubMed1996

Comparative response of rabbit bladder smooth muscle and mucosa to anoxia.

Recent studies indicate that the mucosa of the urinary bladder plays a major role in the maintenance of normal bladder function. Previous studies have demonstrated that rabbit bladder mucosa has higher rates of basal glycolysis and oxidative phosphorylation than that of bladder smooth muscle. The current study compares the response of rabbit bladder mucosa and smooth muscle compartments to anoxia. The results demonstrate that the rate of high energy phosphate degradation of the mucosa is significantly greater than the rate of high energy phosphate degradation of the smooth muscle. The implication is that the mucosa would be significantly more sensitive to ischemia than the smooth muscle of the bladder. This hypothesis may be extremely relevant to conditions such as interstitial cystitis and recurrent urinary bladder infections, in which ischemia has been implicated in their etiology.

Adenosine Triphosphate↗
PubMed1996

Properties of Ca2(+)-Mg2+ ATP-ase in rabbit bladder muscle and mucosa: effect of urinary outlet obstruction.

The contractile response of the smooth muscle of the urinary bladder is dependent upon both the entrance of extracellular calcium through receptor-operated calcium channels and the stimulated release of calcium from the sarcoplasmic reticulum. In addition, partial outlet obstruction induces marked alterations in the utilization of intracellular calcium. Although calcium ATP-ase provides the energy for the translocation of intracellular free calcium into storage sites within the sarcoplasmic reticulum, very little is known about the properties of this enzyme in bladder muscle and mucosa. As an initial study, divalent ion specific ATP-ase activity was measured in extracts of rabbit bladder muscle and mucosa from control animals and from rabbits following partial urinary outlet obstruction. In both normal bladder muscle and mucosa, magnesium and calcium ions were equally effective in activating the enzyme. Seven days following partial urinary outlet obstruction, the ATP-ase activity in both bladder muscle and mucosa was significantly depressed by over 70%. The degree of the decreased enzyme activities observed within the muscularis and mucosa would indicate that specific membrane functions supported by divalent-ion-ATP-ase are dysfunctional. This hypothesis is supported by marked alterations in the utilization of intracellular calcium following partial outlet obstruction and the marked dysfunctions in both mucosal permeability and bacterial adherence to mucosa observed following partial outlet obstruction.

Animals↗
PubMed1996

Age-related differential susceptibility to calcium channel blocker and low calcium medium in rat detrusor muscle: response to field stimulation.

The influences of aging on the response of urinary bladder detrusor smooth muscle in response to neurogenic stimulation (electric field stimulation) were investigated in rats aged 3-4 months (young) and 18-20 months (old). In addition, age-associated changes in calcium homeostasis were evaluated by comparing the basal intracellular free calcium concentration ([Ca2+]i), the change of [Ca2+]i in response to field stimulation, the contractile response at different extracellular calcium concentrations (Ca2+ = 1.8, 0.6, and 0 mM), and the sensitivity to the L-type calcium channel blocker. In both groups, the frequency-response curve in response to field stimulation (1-32 Hz) was similar. The contractile response to field stimulation was biphasic (phasic and tonic). The phasic/tonic ratio at different frequencies was similar between the two groups. The contractile responses were equally inhibited by atropine (1 microM) and preincubation with alpha, beta-methylene ATP (50 microM). Tetrodotoxin (1 microM) virtually abolished the responses to field stimulation in both groups. The biphasic components showed different sensitivities to diltiazem and low calcium. The tonic component was more readily inhibited by diltiazem, whereas the phasic component was more sensitive to low calcium medium. In general, the response to lower frequency stimulations was more sensitive to both diltiazem and low calcium. The aged group was more sensitive to the inhibitory effects of both low calcium and diltiazem. In Ca2(+)-free medium, the contractile response to higher frequency (e.g., 32 Hz) was temporarily preserved in most of the preparations. This response disappeared after repeated stimulation. The magnitude of this Ca2(+)-free response to 32 Hz stimulation was significantly lower in the aged group than in the young group (18.1 +/- 1.4 vs.29.1 +/- 3.2% of the control response in normal Tyrode medium, P < 0.05). The basal [Ca2+]i levels were similar in the two groups (young: 131 +/- 12 nM, n = 5; old: 118 +/- 10 nM, n = 4, P > 0.05). The magnitude and time course of the [Ca2+]i response to field stimulation were also similar in the two groups. It is concluded that aging seems to have little effect on the neuromuscular activities of rat urinary bladder. However, the calcium homeostasis may be altered as evidenced by the increased sensitivity to diltiazem and low extracellular calcium.

Aging↗
PubMed1996

Effect of ischemia of the rabbit bladder on Ca-Mg-activated ATP-ase activity.

This investigation is concerned with the effect of ischemia on the activity of Ca-Mg-stimulated ATP-ase in rabbit bladder tissue. White New Zealand male rabbits were used for the experiments. Ischemia was produced by clamping of the vesical arteries. After 1 and 2 hours the clamps were removed, and the animals were sacrificed 2 days later. The bladders were removed, and the muscle and mucosal parts of the bladders were separated. In some experiments with 2-hour ischemia the animals were allowed to recover for 7 days. Homogenates were made of the muscle and mucosal tissue and separated by differential centrifugation into three parts: 1) an initial particulate fraction obtained by low-speed centrifugation; 2) a supernate fraction free of mitochondria; and 3) a mitochondrial-rich fraction. ATP-ase activity was determined in the different fractions in the presence of magnesium or calcium as the activating ion, and the results were expressed as nmols/mg protein/minute. The following results were obtained: with the supernates, ischemia was found to produce a marked inhibition of enzyme activity that was large and significant in muscle tissue after 1 hour and in mucosal tissue after 2 hours. Seven days after termination of 1 hour of ischemia, the ATP-ase activity of the muscle fraction had been partially restored towards normal. Activity of ATP-ase when measured in the particulate fraction was less sensitive to the effect of ischemia; a significant diminution of enzyme activity in preparations from muscle was seen only after 2 hours of ischemia, and no inhibition was observed with mucosal tissue. ATP-ase of muscle mitochondria was severely inhibited by ischemia, and the effect of 1 hour of ischemia was not reversed 7 days after the insult. Mitochondria from mucosal tissue were affected to only a small extent by ischemia. In all cases, results were similar whether magnesium or calcium was used for activation of the enzyme.

Animals↗
PubMed1996

Effects of partial outlet obstruction on bladder-strip sensitivity to glucose deprivation: an in vitro study in the rat.

Partial outlet obstruction has been shown to result in contractile and metabolic dysfunctions. Specifically, there is a greater reduction in the response to field stimulation (FS) in comparison with the responses to bethanechol and KCl, a greater reduction in the tonic response to stimulation in comparison with the phasic response, and a reduction in oxidative metabolism of glucose accompanied by an increase in the glycolytic metabolism of glucose. The specific aim of the current study was to correlate the effects of partial outlet obstruction on the contractile responses of isolated strips of bladder smooth muscle to repetitive stimulation in the presence and absence of glucose. Adult male Sprague-Dawley rats were subjected to partial outlet obstruction by the surgical placement of silk ligatures around the urethra. After 2 weeks, each rate was anesthetized, the bladder was excised, and isolated strip studies were performed. These studies demonstrated that the maximal phasic response to FS was significantly decreased in the obstructed strips as compared with controls, with no difference being noted for responses to bethanechol or KCl; the tonic responses to all forms of stimulation were significantly decreased after obstruction, with the tonic response to FS being decreased to a greater degree than were the tonic responses to bethanechol and KCl; and in the absence of glucose, the tonic responses of control strips to all forms of stimulation were reduced to a greater degree than were the phasic responses. These studies demonstrate that the tonic response to FS is extremely sensitive to fatigue induced by repetitive stimulation.

Analysis of Variance↗
PubMed1996

Comparative studies on urethral function.

Urethral pressure profiles (in vivo), opening pressures, and flow rates at opening pressure (in vitro) were determined for female, male, pregnant, ovariectomized (OVX), OVX and then estrogen-treated, and OVX and then progesterone-treated rabbits. Using the isolated whole-urethra preparation, we determined the opening pressures and flow rates as well as the effects of 250 microM phenylephrine, 250 microM bethanechol, and 120 mM KCl on the urethral opening pressure and flow rate. The results demonstrated that (1) the urethral pressure profiles were similar for male and female rabbits, (2) ovariectomy and pregnancy decreased the urethral pressure profiles, (3) estrogen therapy partially reversed the effect of ovariectomy on the urethra, and (4) progesterone therapy had little effect on the urethral pressure profile. With regard to opening pressure and flow, (1) flow at opening pressure was lower in the male than in the female; (2) the opening pressure was increased by ovariectomy; (3) phenylephrine and KCl stimulated a greater response in the male than in the female, whereas the response to bethanechol was significantly lower in the male than in the female; (4) the male had the greatest resistance to flow among all the groups; and (5) ovariectomy increased the resistance to flow and estrogen treatment reversed the effect of ovariectomy. In conclusion, ovariectomy had significant effects on urethral function that were reversed by estrogen therapy but not by progesterone therapy.

Adrenergic alpha-Agonists↗
PubMed1996

Effect of alteration in the extracellular potassium and calcium on field-stimulated relaxation of the rabbit corpus cavernosum.

Changes in extracellular potassium or calcium concentration can alter the calcium equilibrium between intracellular and extracellular calcium pools in smooth muscle. The current study was designed to investigate the effect of alterations in the extracellular potassium and calcium concentrations, primarily on field-stimulated relaxation of the corpus cavernosum. The results can be summarized as follows: 1. Increasing extracellular calcium at constant potassium mediated a moderate increase in the contractile response to phenylephrine; 2. Increasing extracellular potassium at constant calcium did not affect the contractile response to phenylephrine; 3. Increasing the concentration of extracellular calcium at constant potassium resulted in an increase in field-stimulated relaxation only at low frequency stimulation; 4. Increasing the concentration of extracellular potassium at constant calcium resulted in a marked increase in field-stimulated relaxation, especially prominent at high-frequency stimulation; 5. Increasing the extracellular potassium concentration at constant calcium, or increasing the calcium at constant potassium, had no significant effects on the relaxant effects of ATP and bethanechol; 6. Our findings suggest that, within the corpus cavernosum, neuronal release or synthesis of nitric oxide depends, at least in part, on intracellular bioavailability of calcium.

Adrenergic alpha-Agonists↗
PubMed1996

Effect of thapsigargin on the contractile response of the normal and obstructed rabbit urinary bladder.

Excitation-contraction coupling is achieved by translocation of calcium from the extracellular space as well as by the release of calcium from intracellular stores. Thapsigargin has been shown to selectively block the sarcoplasmic Ca-ATPase, thereby preventing the reuptake of calcium into intracellular stores and the participation of these calcium storage sites in the contractile response to stimulation. The current study determined the effect of thapsigargin on the contractile response to field stimulation, bethanechol, and KCl in control rabbit bladders and bladders obtained from rabbits subjected to partial outlet obstruction. Partial bladder outlet obstruction resulted in a marked increase in bladder mass and in significant decreases in the contractile response to field stimulation, bethanechol, and KCl. Thapsigargin (5-40 microM) had no effect on the contractile responses of bladder strips isolated from control rabbits to field stimulation, bethanechol, or KCl. However, bladder strips isolated from obstructed rabbits showed a significant concentration-dependent decrease in the contractile response to field stimulation in the presence of thapsigargin. Thapsigargin had no effect on the contractile responses of bladder strips isolated from obstructed rabbits to either bethanechol or KCl. In general, the data described in this study support our current hypothesis: as smooth muscle cells enlarge (hypertrophy) and the cell volume increases, there is an increased dependence on the release of intracellular calcium from the sarcoplasmic reticulum to mediate the contractile response to field stimulation.

Animals↗
PubMed1996

Comparative effects of intravesical versus extravesical administration of ZD6169 and cromakalim on the response of the in vitro rat whole bladder to field stimulation.

Potassium channel openers are currently being evaluated for their inhibitory effect on hyperreflexia. Increasing potassium permeability results in a hyperpolarization of the smooth muscle membrane and a reduction in calcium entry. This stabilizes the membrane and should result in the reduction of spontaneous contractile activity. Potassium channel agonists have been shown to be effective in the reduction of hyperreflexia secondary to outlet obstruction in rats, and certainly have been shown to reduce the contractile response of isolated tissues to a number of different agonists. In addition, intravesical administration of potassium channel openers have been shown to be effective against hyperreflexia (in rabbits) using intravesical administration, although relatively high concentrations had to be employed. Using an in vitro whole bladder model (rat), our current study compares the potency and efficacy of intravesical versus extravesical administration of two potassium channel openers for the inhibition of field-stimulated contraction. The results demonstrate that (1) the extracellular administration of ZD6169 and cromakalim were equally effective inhibitors of the contractile response to field stimulation, (2) low frequency stimulation was inhibited to a significantly greater degree than high frequency stimulation, (3) intravesical administration of ZD6169 was equally effective at inhibiting the response to low frequency field stimulation when compared to extravesical administration, (4) intravesical administration was less effective than extravesical administration at high frequency stimulation (although the inhibition was still statistically significant), and (5) intravesical administration of cromakalim did not inhibit field stimulation.

Amides↗
PubMed1996

Physiological effects of a novel bioactive agent.

Urinary bladder smooth muscle contraction can be evaluated using field stimulation (neurohumoral transmission), carbachol (muscarinic stimulation), and KCl (direct membrane depolarization). We recently evaluated the activity of a novel organic chemical, macrocycle-1, on the contractile responses of the bladder to field stimulation, carbachol, and KCl. Isolated strips of rabbit bladder were mounted in individual baths containing 7.5 ml Tyrode's solution. The response to FS (1-32 Hz), carbachol (1 mumol/l), and KCl (120 mmol/l) were determined in the presence and absence of 3 different concentrations of macrocycle-1. Maximal tension, the rate of tension generation, the time to maximal tension, and the rate of decay following maximal tension were determined. The results can be summarized as follows: (1) In the absence of macrocycle-1, maximal tension and the maximal and mean rate of tension generation increased with frequency, whereas the time to maximal tension was constant. The rate of decay of tension following maximum tension was greater for 8, 16 and 32 Hz as compared to 1 or 2 Hz. (2) The maximal response to KCl was lower than either FS or carbachol. The maximal rates of tension generation for carbachol and KCl were lower than that of FS; and the rate of tension generation for KCl was lower than that of carbachol. The time to maximal stimulation for KCl was greater than that of either carbachol or FS. (3) Macrocycle-1 had a greater inhibitory effect on KCl stimulation than on carbachol stimulation; and a greater inhibitory effect on KCl and carbachol stimulation than on FS. (4) The rate of tension generation was more sensitive to macrocycle-1 inhibition than was the maximal tension responses to all methods of stimulation. Our current hypothesis is that macrocycle-1 is acting as an intracellular calcium buffer whose affinity constant and association rate does not interfere with rapid intracellular release mechanisms (FS) while it inhibits slow intracellular calcium release mechanisms (carbachol and KCl).

Animals↗
PubMed1996

Genetic and cellular response to unilateral ischemia of the rabbit urinary bladder.

PURPOSE: Previous studies have demonstrated that partial outlet obstruction and acute overdistension of the rabbit bladder rapidly stimulate the activation of similar patterns of gene expression. Since bladder overdistension has been shown to reduce the blood flow of the bladder and since unilateral ischemia of rabbit bladder has been found to induce similar physiologic and histologic changes to the bladder as found in association with partial outlet obstruction, we tested whether experimental ischemia of the rabbit bladder could induce the same molecular response. MATERIAL AND METHODS: Unilateral ischemia was created by surgically ligating the major arteries entering the rabbit bladder to one side. Bladders were recovered from control rabbits and from rabbits at 1 hour, 8 hours, 1, 3, or 7 days after unilateral ischemia and were divided into ischemic and nonischemic portions. These tissues were used for in vitro 35S-methionine and 3H-thymidine incorporation assays. Ribonucleic acids extracted from these tissues were examined by Northern blot assay for the expression of a number of different mRNA transcripts. RESULTS: 1) Bladder DNA synthesis was elevated 4-fold at 24 hours after ischemia; 2) protein synthesis was increased 2-fold at 8 and 24 hours after ischemia; 3) early response genes (c-fos and c-jun) mRNAs were induced by 1 hour of ischemia; hsp-70 mRNA was highly induced by 8 hours of ischemia, and bFGF mRNA was elevated 3- to 5-fold by 8 hours of ischemia. CONCLUSION: The early molecular response of rabbit bladder to ischemia is similar to responses observed in bladder overdistension or partial outlet obstruction.

Animals↗
PubMed1996

Protective effect of Tadenan on bladder function secondary to partial outlet obstruction.

PURPOSE: Tadenan (DEBAT, Paris, France) is a pharmaceutical agent used in the treatment of benign prostatic hyperplasia (BPH). The specific aim of this study was to determine if pretreatment of rabbits with Tadenan reduced either the hypertrophic response of the bladder to partial outlet obstruction or the accompanying contractile dysfunction. MATERIALS AND METHODS: Twenty-five male New Zealand rabbits (3 to 5 kg.) were separated into 5 groups of 5 rabbits each. Each rabbit in groups 1,2, and 3 received Tadenan orally at 1, 10 and 100 mg./kg./day for 3 weeks. Group 4 received vehicle only (peanut oil); Group 5 were controls. The bladders were evaluated (in vitro studies) after 2 weeks of obstruction. RESULTS: 1) Tadenan did not reduce the effect of partial outlet obstruction on bladder mass. 2) Tadenan pretreatment resulted in a significant protective effect on the contractile responses to field stimulation, bethanechol and KCl. CONCLUSIONS: These results clearly demonstrate that Tadenan pretreatment protected the bladder from the contractile dysfunctions induced by partial outlet obstruction.

Adenosine Triphosphate↗
PubMed1996

The decompensated detrusor I: the effects of bladder outlet obstruction on the use of intracellular calcium stores.

PURPOSE: As in other smooth muscle groups, extracellular calcium influx as well as the release of calcium from intracellular storage sites or sarcoplasmic reticulum occur in response to receptor stimulation. The relative participation of extracellular influx versus intracellular release has recently been shown to be influenced by developmental stage and obstruction. Partial bladder outlet obstruction results in marked hypertrophy of the bladder and produces alterations in contractile function. To understand better how this contractile dysfunction after outlet obstruction is influenced by intracellular calcium handling we tested the effects of 2 drugs with known effects on the sarcoplasmic reticulum. MATERIALS AND METHODS: We evaluated ryanodine, which blocks the release of calcium from the sarcoplasmic reticulum, and thapsigargin, which blocks the ability of the sarcoplasmic reticulum to pump cytosolic calcium back into the storage sites. Rabbit bladders were obstructed for different periods, after which detrusor muscle strips were harvested and contractile performance was evaluated in the absence and presence of ryanodine and thapsigargin. RESULTS: In the early phases of outlet obstruction the release of intracellular calcium increased significantly. With prolonged obstruction and detrusor decompensation the intracellular storage sites lost the ability to contribute to the generation of contractile force. CONCLUSIONS: Alterations in the calcium handling ability of the smooth muscle cell appear to have an important role in the process of decompensation of bladder function in infravesical obstruction.

Animals↗
PubMed1996

The decompensated detrusor II: evidence for loss of sarcoplasmic reticulum function after bladder outlet obstruction in the rabbit.

PURPOSE: While it may lack the classic morphological pattern in striated muscle systems, there is ample evidence that smooth muscle also contains sarcoplasmic reticulum. These intracellular storage sites release calcium into the cytosol to generate contractile force in response to various stimuli. A major component of the sarcoplasmic reticulum is an adenosine triphosphate dependent ion pump, which serves to drive free calcium out of the cytosol back into this intracellular reservoir. This ion pump serves to maintain the intracellular calcium storage sites, and also as a marker of the sarcoplasmic reticulum. MATERIALS AND METHODS: Muscle strip studies were performed to stratify the data into 3 major groups (controls, and compensated and decompensated obstructions) based on physiological performance. These were correlated with biochemical and molecular determinations of sarcoplasmic endoplasmic reticulum calcium, magnesium-adenosinetriphosphatase expression. RESULTS: Our results demonstrate a remarkable loss of sarcoplasmic endoplasmic reticulum calcium-adenosinetriphosphatase activity in the decompensated group and a moderate loss in the compensated group. CONCLUSIONS: These data provide molecular support for our previous physiological studies in which we demonstrated an important role for intracellular calcium storage and release with normal bladder smooth muscle function. These data strongly support our contention that contractile dysfunction in bladder smooth muscle following outlet obstruction is partially mediated by changes in the mechanisms of intracellular calcium homeostasis.

Animals↗
PubMed1996

Effects of tadenan pretreatment on bladder physiology and biochemistry following partial outlet obstruction.

PURPOSE: Tadenan is a pharmaceutical agent used in the treatment of BPH. Prior studies demonstrated that pretreatment of rabbits with Tadenan significantly reduced the contractile dysfunction following two weeks of partial outlet obstruction. The specific aim of the present study was to determine the effect of Tadenan pretreatment on the time course of the response to partial outlet obstruction and correlate the effect of Tadenan on the contractile responses to field stimulation, bethanechol, and KCl with both mitochondrial enzyme activity (citrate synthase) and sarcoplasmic reticular function (calcium-ATP'ase activity). MATERIALS AND METHODS: Sixty male New Zealands white rabbit (3 to 5 kg.) were separated into 12 groups of 5 rabbits each. Each rabbit in groups 1-6 received Tadenan orally at 100 mg./kg./day for three weeks; each rabbit in groups 7-12 received vehicle (peanut oil). Each rabbit in groups 2-6 and 8-12 received a partial outlet obstruction as described below. One group of Tadenan treated and one group of vehicle-treated rabbits were euthanized at 1, 3, 5, 7, and 14 days following partial outlet obstruction. The non-obstructed groups were studied after 4 weeks of drug or vehicle treatment. Each bladder was rapidly removed and weighed, and 3 longitudinal strips prepared and mounted in individual baths for contractile studies. The remainder of the bladder was frozen for biochemical analysis. The contractile responses to field stimulation, bethanechol, and KCl were determined; and the enzyme activities of citrate synthase (marker for mitochondrial function) and calcium-ATP'ase (marker for sarcoplasmic reticulum) were determined. RESULTS: 1) Tadenan did not reduce the effect of partial outlet obstruction on bladder mass. 2) Although the contractile responses to forms of stimulation were reduced at 1 day following partial outlet obstruction, Tadenan pretreatment resulted in a significant protective effect on the contractile responses to field stimulation, bethanechol, and KCl at 3, 5, 7, and 14 days of obstruction. 3) The activities of both citrate synthase and calcium ATP'ase were reduced significantly at 1 day following obstruction for both Tadenan treated and vehicle treated groups. The activities of both enzymes returned to near normal levels at 7 and 14 days for the Tadenan groups whereas the activities of both enzymes remained significantly reduced in the vehicle treated groups. CONCLUSIONS: These results clearly demonstrate that Tadenan pretreatment protected the bladder from both the contractile and metabolic dysfunctions induced by partial outlet obstruction.

Adenosine Triphosphate↗
PubMed1995

Hyperplasia in the rabbit bladder urothelium following partial outlet obstruction. Autoradiographic evidence.

Previous experiments have shown that adult male rabbits subjected to partial outlet obstruction or overdistension and acutely labeled, 24 h later, in vivo or in vitro with 3H-Thymidine(3H-TdR) show high levels of incorporated radioactivity in bladder epithelium when they are visualized with autoradiography. To test the hypothesis that such labeling represents the onset of a wave of proliferation (that is, true hyperplasia), we injected 3H-TdR subcutaneously in two normal and three partially obstructed New Zealand White male rabbits on each of days One, Two or Three following obstruction. Bladders were excised on the seventh day(D) following obstruction or the sixth day after injection of normals. Under these conditions, cells labeled with 3H-TdR had the opportunity to proliferate, after labelling, for 6(OneD and Normals), 5(TwoD) or 4(ThreeD) days respectively. After processing tissues for autoradiography, normal bladders showed only trace levels of labeling. Animals exposed to 3H-TdR one day after obstruction, when large numbers of basal cells of the urothelium are known to incorporate 3HTdR (i.e., synthesize DNA), showed labeling in most layers of the urothelium seven days after injection, but levels of labeling in bladders injected TwoD or ThreeD were lower than those injected OneD after obstruction. The smaller numbers of urothelial cells labeled by 3H-TdR in TwoD bladders were found in clusters where one or two alternate or adjacent layers of cells were labeled. Obstructed animals injected ThreeD after surgery showed even less labeling. This evidence clearly supports the hypothesis that DNA synthesis that occurs in the urothelium within 24 h after obstruction is followed by proliferation, because by the seventh day, labeling can be found at all levels of the urothelium. The decline of labeling in TwoD and ThreeD animals suggests that the proliferative stimulus probably operates only during the first 24 h after insult. The data suggest that a substantial fraction of the urothelium enters one or more rounds of proliferation following obstruction and support the contention that hyperplasia does occur.

Animals↗
PubMed1995

Assessment of stress gene mRNAs (HSP-27, 60 and 70) in obstructed rabbit urinary bladder using a semi-quantitative RT-PCR method.

Stress proteins (HSPs) participate in the cellular response to various stresses including hyperthermia, hypoxia and injury. A previous work using northern blot analysis demonstrated increased expression of stress protein 70 (HSP-70) in rabbit bladder tissue subjected to partial outlet obstruction. In order to determine if the increased expression was specific for HSP-70 or, alternatively, indicated a generalized stress protein response, a modified quantitative RT-PCR technique was used to quantitate HSP mRNAs (HSP-27, 60, and 70) in normal and obstructed rabbit urinary bladder tissues. The results show the following: 1) The modified semi-quantitative RT-PCR is a sensitive and reproducible technique for detecting mRNA in bladder tissue. 2) Constitutive levels of HSP-27, HSP-60, and HSP-70 mRNAs were detected in control bladder tissues; the relative signal intensity was highest for HSP-70 and lowest for HSP-27. 3) A transient increase in HSP mRNAs was observed after obstruction; the mRNAs of HSP-27, 60 and 70 increased 4.3-, 5.6-, and 2.4-fold, respectively, at 24 h following obstruction, then gradually returned to control levels by the end of one week post-obstruction and remained stable up to 14 days post-obstruction. These data indicate that the modified quantitative RT-PCR is a useful technique for detecting mRNA in bladder tissue; the stress response which occurs in rabbit urinary bladder tissue following partial outlet obstruction is a general phenomenon.

Animals↗