Urinary Bladder Detrusor Research Articles

The role of intracellular calcium and Rho kinase pathways in G protein-coupled receptor-mediated contractions of urinary bladder urothelium and lamina propria.

The influence of extracellular and intracellular calcium on smooth muscle contractile activity varies between organs. In response to G protein-coupled receptor (GPCR) stimulation, the urinary bladder detrusor muscle has shown a 70% dependence on extracellular calcium, whereas the urothelium and lamina propria (U&LP) has a 20%-50% dependence. However, as this only accounts for partial contractile activity, the contribution of intracellular calcium and calcium sensitization pathways remains unclear. This study assessed the role of intracellular signaling pathways on GPCR-mediated urinary bladder U&LP contraction. Porcine U&LP responses to activation of the Gq/11-coupled muscarinic, histamine, 5-hydroxytryptamine (serotonin), neurokinin, prostaglandin, and angiotensin II receptors were assessed with three selective inhibitors of store-released intracellular calcium, 2-aminoethyl diphenylborinate (2-APB), cyclopiazonic acid (CPA), and ruthenium red, and three Rho kinase inhibitors, fasudil, Y-27632, and GSK269962. There was no discernible impact on receptor agonist-induced contractions of the U&LP after blocking intracellular calcium pathways, suggesting that this tissue is more sensitive to alterations in the availability of extracellular calcium. However, an alternative mechanism of action for GPCR-mediated contraction was identified to be the activation of Rho kinase, such as when Y-27632 significantly reduced the GPCR-mediated contractile activity of the U&LP by approximately 50% (P < 0.05, n = 8). This suggests that contractile responses of the bladder U&LP do not involve a significant release of calcium from intracellular stores, but that Gq/11-coupled receptor activation causes calcium sensitization via Rho kinase. This study highlights a key role for Rho kinase in the urinary bladder, which may provide a novel target in the future pharmaceutical management of bladder contractile disorders.

The five primary prostaglandins stimulate contractions and phasic activity of the urinary bladder urothelium, lamina propria and detrusor

BackgroundInflammation is often associated with several bladder dysfunctions, including overactive bladder (OAB) and interstitial cystitis/bladder pain syndrome (IC/PBS). As such, inflammation of the bladder and the actions of inflammatory mediators may contribute to the development of urinary symptoms. This study assessed the actions of PGE2, PGF2, PGD2, TXA2, and PGI2 on urinary bladder urothelium with lamina propria (U&LP), and detrusor smooth muscle.MethodsStudies were carried out using isolated tissue baths, where strips of porcine bladder U&LP or detrusor were exposed to varying concentrations of prostaglandin agonists (1 μM and 10 μM).ResultsAll assessed prostaglandin agonists contracted both the U&LP and detrusor smooth muscle, with the rank order of contractile response effectiveness as: PGE2 > PGF2α > TXA2 > PGD2 > PGI2. In U&LP, treatment with PGE2 (10 μM) increased tonic contractions by 1.36 ± 0.09 g (n = 42, p < 0.001) and phasic contractions by 40.4 ± 9.6% (n = 42, p < 0.001). In response to PGF2α (10 μM), U&LP tonic contractions increased by 0.79 ± 0.06 g (n = 14, p < 0.001) and phasic activity by 13.3% ± 5.3% (n = 15, p < 0.05). In detrusor preparations, PGE2 (10 μM) increased tonic contractions by 1.32 ± 0.13 g (n = 38, p < 0.001) and PGF2α (10 μM) by 0.97 ± 0.14 g (n = 12, p < 0.001). Only 34% (n = 48) of all detrusor preparations exhibited spontaneous activity prior to the addition of any agonist at a frequency of 2.03 ± 0.12 cpm. In preparations that did not exhibit initial phasic activity, all of the prostaglandin agonists were capable of commencing phasic activity.ConclusionsThe urinary bladder U&LP and detrusor respond to a variety of prostaglandin agonists, with their activation resulting in direct contractions, as well as increases to spontaneous contractile activity. This study presents the prostaglandin receptor system as a potential therapeutic target for lower urinary tract dysfunction.

Alterations in histamine responses between juvenile and adult urinary bladder urothelium, lamina propria and detrusor tissues

Inflammatory mediators may have a role in various lower urinary tract disorders. Histamine is known to induce significant increases in both the tension and frequency of spontaneous phasic contractions in both urothelium with lamina propria (U&LP) and detrusor muscle via the activation of H1 receptor in juvenile animal models. However, it is unclear whether age affects these contractile responses to histamine. This study assessed the histamine receptor subtypes mediating contraction in juvenile and adult porcine bladders and compared the urothelium with lamina propria and detrusor responses to histamine. Isolated tissue bath studies were conducted using strips of porcine U&LP and detrusor obtained from juvenile (6 months) and adult (3 years) animals exposed to histamine receptor agonists and antagonists. Treatment with histamine (100 µM) in U&LP of juvenile animals caused increases in baseline tension by 47.84 ± 6.52 mN/g (p < 0.001, n = 51) and by 50.76 ± 4.10 mN/g (p < 0.001, n = 55) in adult animals. Furthermore, the frequency of spontaneous phasic contractions was significantly enhanced in response to histamine in U&LP of both juvenile and adult tissues (p < 0.001 for both age groups). Treatment with an H2 agonist in U&LP of juvenile animals decreased baseline tension by 13.97 ± 3.45 mN/g (n = 12, p < 0.05), but had no effect in adult animals. Inhibition of H1 receptors resulted in significantly reduced contractile responses of U&LP and detrusor to histamine in both juvenile and adult animals (p < 0.05). Treatment with an H2 receptor antagonist significantly enhanced contractions in juvenile preparations (n = 10, p < 0.05) but had no effect in adult preparations (n = 8). In detrusor, treatment with histamine (100 µM) in juvenile tissues showed a significantly higher increase in baseline tension of 19.10 ± 4.92 mN/g (n = 51) when compared to adult tissues exhibiting increases of 8.21 ± 0.89 mN/g (n = 56, p < 0.05). The increases in the baseline tension were significantly inhibited by the presence of H1 receptor antagonists in both juvenile and adult detrusor preparations. Treatment with either the H2 receptor antagonist or agonist in detrusor had no effect on both juvenile and adult tissues. Therefore, the histamine receptor system may play an essential role in the maintenance of bladder function or in bladder dysfunction observed in some lower urinary tract disorders.

Histamine modulation of urinary bladder urothelium, lamina propria and detrusor contractile activity via H1 and H2 receptors

The mechanisms underlying bladder contractile disorders such as overactive bladder are not fully understood, and there is limited understanding of the receptor systems modulating spontaneous bladder contractions. We investigated the potential for histamine to have a role in mediating contractility of the urothelium with lamina propria (U&LP) or detrusor via the H1-H4 histamine receptor subtypes. Isolated strips of porcine U&LP or detrusor smooth muscle were mounted in gassed Krebs-bicarbonate solution and responses to histamine obtained in the absence and presence of selective receptor antagonists. The presence of histamine increases the frequency of U&LP spontaneous phasic contractions and baseline tensions. In response to histamine, H1-antagonists pyrilamine, fexofenadine and cyproheptadine were effective at inhibiting contractile responses. Cimetidine (H2-antagonist) enhanced increases in baseline tension in response histamine, whereas amthamine (H2-agonist) induced relaxation. Although thioperamide (H3/H4-antagonist) increased baseline tension responses to histamine, selective H1/H2-receptor antagonism revealed no influence of these receptors. In detrusor preparations, pyrilamine, fexofenadine and cyproheptadine were effective at inhibiting baseline tension increases in response to histamine. Our findings provide evidence that histamine produces contractile responses both in the U&LP and detrusor via the H1-receptor, and this response is significantly inhibited by activation of the H2-receptor in the U&LP but not the detrusor.

Muscle cells, nerves, fibroblasts and vessels in the detrusor of the rat urinary bladder.

All the cells of rat detrusor muscle fall into one of five ultrastructural types: muscle cells, fibroblasts, axons and glia, and vascular cells (endothelial cells and pericytes). The tissue is ~79% cellular and 21% non-cellular. Muscle cells occupy 72%, nerves ~4% (1/3 axons, 2/3 glia), and fibroblast >3% of space. Muscle cells (up to 6 µm across and ~600 µm long, packed to almost 100,000 per mm2) have surface-to-volume ratio of 2.4 µm2/µm3 ~93% of cell volume is contractile apparatus, 3.1% mitochondria and 2.5% nucleus. Cell profiles are irregular but sectional area decreases regularly towards either end of the cell. Muscle cells are gathered into bundles (the mechanical units of detrusor), variable in length and size, but of constant width. The musculature is highly compact (without fascia or capsule) with smooth outer surfaces and extensive association and adhesion between its cells. Among many types of intercellular contact and junction, digitations are very common, each muscle cell issuing minute finger-like processes that abut on adjacent cells. Sealed apposition are wide areas of specialized contact, possibly forming a chamber between two muscle cells, distinct from the extracellular space at large (stromal space). The innervation is very dense, virtually all intramuscular axons being varicose (including afferent ones). There are identifiable neuro-muscular junctions on each muscle cell, often several junctions on a single cell. There are also unattached terminals. Fibroblasts (involved in the production of collagen), ~1% of the total number of cells, do not make specialized contacts.

Analysis of spontaneous depolarization-linked hyperpolarizations in mouse detrusor smooth muscle cells

Background: Urinary bladder detrusor smooth muscle cells exhibit spontaneous electrical activities comprising various signal types. Aims and Objectives: This article introduces and analyzes a rare category of signals observed in such activity, named spontaneous depolarization-linked hyperpolarization (sDLH). Materials and Methods: A mouse model was used in the study, where all the occurrences of sDLHs were pooled together from multiple intracellular recording sessions. Four features – (i) resting membrane potential (RMP) (R, in mV), (ii) depolarization amplitude (D, in mV), (iii) hyperpolarization amplitude (H, in mV), and (iv) time course of the hyperpolarization (T, in ms) – were evaluated from all sDLHs. Results: The analysis of results indicated that (a) the signals appear more frequently in cells with higher RMP, (b) the depolarization amplitudes seem to be distributed randomly and have no correlation with other features, (c) hyperpolarization amplitudes show two distinct clusters and exhibit strong correlation with the RMP, and (d) time course of hyperpolarization phase shows no distinct groups and is distributed in a window larger than that of any other signals seen in the intracellular recordings. With the help of the results obtained from the analysis, a hypothesis for the biophysical origin of these signals is proposed. Conclusions: This needs to be tested experimentally, and if proved right, would help extend the boundaries of our current understanding of the detrusor smooth muscle system.

Experimental Electrophysiological and Pressure Responses of Urinary Bladder Detrusor to Lumbar to Sacral Nerve Rerouting - An Animal Study with Negative Results

Background/Aims/Objectives: To verify the transfer of evoked potentials through anastomosis of an experimentally created micturition reflex arc and to detect said potentials directly on the detrusor and sphincter of rabbit urinary bladder. Methods: During 2013-2015, 17 rabbits were operated upon and measurement followed during reoperation 3-16 months later. Suitable ventral spinal roots were electrophysiologically detected following laminectomy, and a somatic-central nervous system-autonomic micturition reflex arc was created. During reoperation, the ventral root was stimulated above and below the anastomosis, the evoked potentials on the bladder detrusor and sphincter were measured, and intravesical pressure was monitored. Results: With stimulation above the anastomosis, 9 animals (53%) displayed a urinary bladder detrusor response and 7 (41%) a sphincter response. Four rabbits (24%) had elevated intravesical pressure. During the control stimulation below the anastomosis, we detected a detrusor response in 7 animals (41%), a sphincter response in 5 (29%), and elevated pressure in 4 (24%). Neither induction of micturition nor decrease in external sphincter activity occurred. Conclusions: Creation of a somatic-CNS-autonomic reflex arc is technically possible. However reflex activity transferring through the anastomosis is detectable on the detrusor only in some individuals, and is unable to induce a micturition reflex with or without accompanying detrusor-sphincter dyssynergia.

Botulinum toxin type A injection on different positions of the bladder in female bladder pain syndrome/interstitial cystitis

Objectives To compare the different effects caused by different injection sites in bladder, in cases of female bladder pain syndrome/interstitial cystitis (BPS/IC) cured by botulinum toxin type A injection. Methods 60 cases were randomly divided into two groups. Cases of group A accepted botulinum toxin type A injection only on detrusor.Cases of group B accepted botulinum toxin type A injection on detrusor and trigone of urinary bladder.The following parameters were recorded to evaluate the effects after 8 weeks: average urination frequency, Maximum voiding, PUF scores and QOL scores. Results These parameters of two groups had no statistical differences before accepting treament. Efficacy in both groups obviously improved after treatment. Efficacy of group B improved more obviously than group A. Conclusions Botulinum toxintype A injection on bladder is a new effective method for female interstitial cystitis. Injection on detrusor and trigone of urinary bladder is better than injection only on detrusor. Key words: Cystitis, Interstitial; Pain; Syndrome; Botulinum Toxin Type A

Biophysical Processes in a Urinary Bladder Detrusor Smooth Muscle Cell during Rehabilitation Stimulation of Parasympathetic Efferents: a Simulation Study

In a computer model of an urinary bladder detrusor (UBD) smooth muscle cell (SMC), we investigated coupled changes in the membrane potential (MP), partial transmembrane currents, and intracellular calcium concentration ([Ca2 +]i), caused by parasympathetic stimulation. The respective data should help to determine the biophysical basis for the choice of parameters of medical rehabilitation electrical stimulation of the UBD. Ionotropic and metabotropic effects of such stimulation having different latency periods (LPs) were simulated by, respectively, an increase in the conductivity of purinoreceptor channels of the sarcolemma and a delayed (by 70 msec) increase in the permeability of calcium channels of the sarcoplasmic reticulum (store) sensitive to inositol triphosphate (IP3), the end-product of a chain of reactions triggered by activation of muscarinic cholinergic receptors. The modeled SMC responded to single stimulation by generation of action potential (AP) close in its parameters to those in the prototype. Application of long series of identical stimuli caused, after a transient interval, forced stationary oscillations of the MP and [Ca2 +]i. The magnitudes of the latter decreased, and the mean level increased with shortening of the interstimulus intervals (ISIs). It was found that the stimulation outcome needing prior experimental refining was determined by such parameters of the parasympathetic action as the durations of the purine and muscarinic components and the delay between these components. It has been shown that, during stimulation with ISIs shorter than the above-mentioned delay, the subsiquent stimulus activates P2X channels before expiration of the delay of the IP3-channel activation evoked by the preceding stimulus. This is actually equivalent to shortening of the interval between successive activations of P2X- and IP3-channels. Simple quantitative expressions were obtained for the parameters of stimulation; a given difference in the LPs of purine and muscarinic effects of parasympathetic stimulation allowed us to calculate the ISIs providing more efficient rehabilitation stimulation of the UBD parasympathetic nerves.

Impact of the Ratio of Metabotropic and Ionotropic Components of Parasympathetic Action on the Excitability of a Urinary Bladder Smooth Muscle Cell: a Simulation Study

On a computer model of a smooth muscle cell (SMC) of the urinary bladder detrusor (UBD) having a corresponding set of ion channels and intracellular signaling mechanisms, we investigated the influence of ionotropic (purine, P) and metabotropic (muscarinic, M) components of the parasympathetic stimulus on the membrane potential of the cell and Ca2+ concentration inside it ([Ca2+]i). The P and M components of the stimulus were simulated, respectively, by the increasing conductivity of P2X receptor channels of the SMC membrane (G P2X) and the permeability of calcium channels of the sarcoplasmic reticulum activated by inositol triphosphate (P IP3), considering that IP3 is the end product of the metabotropic chain starting from the M3 cholinergic receptors. The G P2X and P IP3 values, latent periods (LPs) of their activation, and relations of the above parameters were chosen in such a mode that application of a single stimulus evoked the SMC response with the P and M components close to those of the prototype. The normal magnitude and LP of the M component of the concentration response (calcium transient) were significantly greater than the respective parameters of the P component; the M component was accompanied by generation of an action potential (AP) with after-processes analogous to those of the prototype. A decrease in the P IP3 simulating a deficiency of M3 receptors observed under a few pathological conditions led to a decrease in the electric and concentration SMC responses, down to full elimination of AP generation and changes in [Са2+]i. Under such conditions, a significant increase in the G P2X could provide a [Са2+]i increase to a nearly normal level. Using paired parasympathetic stimulation with different interstimulus intervals, ΔТ, allowed us to obtain a situation where the M response to the first stimulus (M1) was preceded by the P response to the second stimulus (P2) with a short adjustable interval. The use of such stimulation with certain values of the ΔТ and conductivity of purinergic channels G P2X can compensate for the attenuation of the M component, due to interaction of the latter with the P component caused by the second stimulus. Thus, pathological attenuation of the M component of the parasympathetic stimulation effect can be compensated in clinical practice (at least partly) by applying purinomimetics and/or paired stimulation.

Sexually dimorphic effects of early life stress in rat pups on urinary bladder detrusor muscle contractility in adulthood.

BackgroundPainful bladder syndrome/interstitial cystitis (PBS/IC) is a chronic disorder that is commonly seen in women who report a history of adversity in early life. Here, we test the hypothesis that early life stress (ELS) induces sexually dimorphic abnormalities in urinary bladder smooth muscle function in adulthood.MethodsMale and female rat pups were conditioned on postnatal (PN) days 8–12 with either a “predictable or “unpredictable” odor-shock, or odor only control treatment. In adulthood, urinary bladder function was assessed in vivo via urine spot analysis and in vitro via contractile responses to electrical field stimulation (EFS) and membrane depolarization with potassium chloride (KCl).ResultsIn adulthood, we found that female rats exposed to unpredictable ELS showed a significant (p < 0.05) increase in urine voiding volume compared to predictable ELS or controls. We also found that detrusor muscle contractile responses to EFS were significantly (p < 0.001) decreased following unpredictable ELS in adult female rats compared to the predictable ELS or controls. In male rats exposed to ELS, there was no difference in voiding volume or EFS-induced contractility between groups. In adulthood, the myogenic smooth muscle response to KCl was not significantly different between groups. Histological analysis from adult female and male rats revealed no differences in the appearance of the urinary bladder in rats exposed to ELS.ConclusionsIn summary, our findings provide evidence to support abnormalities in the nerve-mediated contractile responses of the detrusor smooth muscle in adult female rats following ELS. We speculate that these sexually dimorphic alterations in urinary bladder function may account, at least in part, for the female predominance of PBS/IC.

Biophysical Processes in a Urinary Bladder Detrusor Smooth Muscle Cell during Rehabilitation Electrostimulation: a Simulation Study

The work was aimed at the search for approaches to solving the problem of biophysically reasonable selection of the parameters of electrical stimulation of smooth muscle cells (SMCs) of the urinary bladder detrusor (UBD). Such stimulation is widely used in the rehabilitation of patients with surgical correction of congenital malformations accompanied by total or partial deficiency of the M2/M3 cholinergic receptors in the UBD. A computer model built on the basis of experimental data on ion channels and pumps of the sarcolemma and mechanisms of regulation of the intracellular calcium concentration ([Ca22+]i), providing both electrogenesis and the contractile function of the cell inherent to the biological prototype, was used. We studied changes in the membrane potential, partial transmembrane currents, and [Ca2+]i, caused by depolarizing current pulses applied with constant frequencies and combined in “packs” or “envelopes” typical of the protocols of rehabilitation stimulation; the stimuli had constant or trapezoid-modulated amplitudes. The examined UBD SMC responded to a single pulse by generation of the action potential (AP) close in its properties to the prototype. Stimulation by both packs and envelopes of identical pulses eventually led to the establishing of equal forced electrical and concentration oscillations with the parameters depending on the duration of interpulse intervals (IPIs). Such oscillations caused by stimulation with 5- and 50-msec-long IPIs, typical of the rehabilitation protocols and comparable with the durations of the absolute and relative refractoriness of the model SMC, significantly differed in the pattern of the regenerative responses (APs) and in the range and mean levels of depolarization shifts of the membrane potential and those of [Ca2+]i, which were greater at high-frequency stimulation. In the case of short IPIs, [Ca2+]i, having no time to return to the basal level, oscillated within a range of values which in other excitable cells are considered to exceed significantly the physiological norm. These data emphasize the necessity to estimate the exact kinetic characteristics of the mechanisms underlying the inflow and extrusion of Ca2+ in the UBD SMC necessary for a biophysically justified choice of the parameters of rehabilitation stimulation that would prevent possible cytotoxic side effects associated with excessively long-lasting high levels of [Ca2+]i. Essential for the observed processes and, therefore, requiring targeted studies, was such a parameter of UBD SMCs as the reversal potential for Ca2+-dependent chloride current (E Cl); this current is activated, in particular, by parasympathetic action on the M2/M3 receptors. When high-frequency oscillations of the membrane potential periodically exceeded the E Cl level, the mentioned current changed its main (depolarizing) direction to the opposite (hyperpolarizing) one.

Excitability Characteristics of a Urinary Bladder Detrusor Smooth Muscle Cell as a Basis for Choosing Parameters of Rehabilitation Electrostimulation: A Simulation Study

Electrical stimulation targeted at smooth muscle cells (SMCs) of the urinary bladder detrusor (UBD) is used in a complex of rehabilitation procedures performed during treatment of neurourological diseases, in particular of those associated with the deficiency of М2/М3 acetylcholine receptors modifying the efficacy of parasympathetic innervation of these cells. The choice of parameters of such stimulation meets difficulties because of limited knowledge about biophysical and physiological processes induced in the stimulated cells. Certain information about such processes can be obtained with the use of a UBD SMC computer model built according to the data of biological experiments characterizing ion channels, ion exchangers, and other mechanisms regulating the intracellular calcium concentration ([Ca2+] i ) typical of the prototype. We explored the standard characteristics of the electrical excitability of the model SMC (“strength – duration” relationship for the threshold current and dynamics of the refractoriness following generation of action potentials, APs), as well as coupled changes in the membrane potential, partial transmembrane currents, and [Ca2+] i values evoked by depolarizing current pulses. In some computational experiments, such stimulation was performed under conditions of a higher conductivity of purinergic ionotropic receptor channels, thereby mimicking the action of purinomimetics. The model UBD SMC generated APs with parameters close to those of the prototype; AP generation was accompanied by long periods of absolute and relative refractoriness (up to 30 and 600 msec, respectively). The relative refractoriness period included an early phase (AP half-recovery lasting about 220 msec) and a late phase; each of these phases included “fast” and “slow” components with the time constants differing from each other by an order of magnitude. These time characteristics of the refractoriness were determined by the kinetic characteristics of the processes of activation/inactivation of voltage- and calcium-dependent ion channels and by those of the [Ca2+] i return to the basal level under the action of a set of Са2+ extrusion mechanisms. An important UBD SMC biophysical parameter was also the reversal potential (E Cl) for calcium-dependent chloride current (which is activated, in particular, due to the parasympathetic action on М2/М3 receptors). This current changed its main “depolarizing” direction to the hyperpolarizing one when the membrane potential exceeded the E Cl level.

Inhibitory effect of curcumin on the contractility of isolated caprine detrusor muscle.

Curcumin is a naturally occurring compound which has been used in traditional medicine in India for a long time. This study investigated the ability of curcumin to inhibit the contractility of isolated caprine (goat) detrusor muscle. The ability of three concentrations of curcumin (30, 100 and 300 µM) to inhibit the 100 µM acetylcholine-induced contractility of the isolated caprine urinary bladder detrusor muscle was investigated. The effect of raising the concentration of acetylcholine from 100, 200 and 400 µM to overcome the curcumin-induced inhibition of detrusor contractility and the effects of the reversal agents tetraethylammonium, a potassium channel blocker (100 µM), glibenclamide, an ATP-sensitive potassium channel blocker (10 µM), and propranolol, a beta adrenergic receptor blocker (1 µM), on the inhibitory effect of detrusor contractility was also studied. Curcumin caused a concentration-dependent inhibition of acetylcholine-induced contractility of the isolated detrusor muscle which was statistically significant at all three concentrations of curcumin used. This inhibition was partially overcome by raising the concentration of ACh to 200 and 400 µM. The inhibition was overcome by the concurrent administration of tetraethylammonium. Glibenclamide reversed the inhibitory effect of 100 µM curcumin, but not that of 300 µM curcumin. Propranolol reversed the inhibitory effect of 100 µM curcumin but not that of 300 µM curcumin. These results suggest that curcumin inhibited the contractions of the isolated detrusor muscle. The results further suggest that the inhibitory effect is mediated by various mechanisms: stimulation of beta adrenergic receptors; an anticholinergic effect; and the opening of ATP-sensitive potassium channels.

Biophysical Mechanism of Parasympathetic Excitation of Urinary Bladder Smooth Muscle Cells: a Simulation Study

Using the Hodgkin-Huxley formalism, we developed a computer model of a smooth muscle cell (SMC) of the urinary bladder detrusor; the model included the main types of ion channels and pumps, as well as intracellular calcium regulatory mechanisms inherent in the prototype cell. The biophysical mechanisms of generation of action potentials (APs) necessary for initiation of muscle contraction and those of calcium transients in response to parasympathetic activation of metabotropic М2/М3-cholinoreceptors and co-activation of Р2Х-purinoreceptors were investigated. The simulated SMC in response to a depolarizing current pulse generated an AP that was, by a number of indices, similar to real APs and was also accompanied by a transient elevation of the intracellular calcium concentration. We demonstrated a possibility of generation of such APs in response to a transient increase in the conductivity of channels of calcium-dependent chloride current accompanied by increase in the conductivity of channels associated with Р2Х-receptors (the conductivity ratio was 95 to 5 % and similar to that in the prototype). For the AP generation, temporal relations of the processes of increases in the mentioned conductances simulating the final effect of activation of М2/М3- and Р2Х-receptors were significant. These results obtained on the rather simplified model allow researchers to use the latter as an appropriate starting point for the development of more detailed models (in particular, those representing cascades of metabolic reactions triggered by a parasympathetic action).

The association of lyme disease with loss of sexual libido and the role of urinary bladder detrusor dysfunction.

PurposeThe primary aim was to carry out a pilot study to compare the loss of sexual libido between a group of Lyme disease patients and a group of matched controls. The secondary aim was to evaluate whether loss of libido in Lyme disease patients is associated with urinary bladder detrusor dysfunction.MethodsA group of 16 serologically positive Lyme disease patients and 18 controls were queried directly about loss of libido.ResultsThe 2 groups were matched with respect to age, sex, body mass index, and mean arterial blood pressure. None of the 34 subjects was taking medication that might affect sexual libido or had undergone a previous operative procedure involving the genitourinary tract. Of the 16 Lyme disease patients, 8 (50%) had no loss of libido, and of the 18 controls, none had loss of libido (P<0.001). In the Lyme disease patient group, there was no statistically significant relationship between loss of libido and urinary bladder detrusor dysfunction (P=0.61).ConclusionsThis pilot study suggested an association between Lyme disease and loss of libido. Moreover, this loss of libido did not seem to be associated with urinary bladder detrusor dysfunction. Given these results, we recommend further studies to confirm the association.

Berberine improves neurogenic contractile response of bladder detrusor muscle in streptozotocin-induced diabetic rats

Ethnopharmacological relevanceCoptidis Rhizoma has been used to treat diabetes mellitus for more than 1400 years in China. Berberine, one of the main alkaloids of Coptidis Rhizoma, is a principal antidiabetic component of Coptidis Rhizoma. To investigate the effects of berberine on impaired neurogenic contractility of detrusor muscle from urinary bladder of rats with early stage diabetes. Materials and methodsThe detrusor muscle strips were isolated from urinary bladders of streptozotocin-induced diabetic rats, 5% sucrose-induced diuretic rats or normal rats, and were placed in organ bath. The contractions induced by electrical field stimulation (EFS), carbachol, KCl, adenosine triphosphate, and the effects of berberine on those contractions were measured. ResultsThe EFS- or KCl-induced contraction of detrusor muscle was significantly decreased in diabetic rats as compared with diuretic or normal rats. Atropine and suramin inhibited EFS-induced contraction. In diabetic rats, the atropine sensitive components were decreased in EFS-induced contraction of detrusor muscle, and the adenosine triphosphate-induced contraction was significantly increased. The carbachol-induced contrations were not different among groups. Berberine significantly potentiated EFS-induced contractions of detrusor muscle both from normal and diabetic rats, but the potentiated effect of BBR was more sensitive to atropine in diabetic rats. Berberine also potentiated adenosine triphosphate-induced contraction of detrusor muscle, but did not change carbachol- or KCl-induced contraction. ConclusionThe neurogenic contraction of urinary bladder detrusor muscle is decreased while purinergic contraction of bladder detrusor muscle is increased in rats with early stage diabetes. Berberine increases the neurogenic contractile response to EFS possibly via both presynaptic increasing neurotransmitters release and postsynaptic potentiation of purinergic transmitter-regulated response in rat urinary bladder detrusor; and in diabetic rats, berberine increases neurogenic contractile response mainly via the presynaptic increasing acetylcholine release.

Expression of β-Adrenoceptor Subtypes in Urothelium, Interstitial Cells and Detrusor of the Human Urinary Bladder.

We examined whether interstitial cells (ICs) of the human urinary bladder expressed β-adrenoceptor (AR) subtypes, and semiquantitatively compared the staining intensity among urothelium, ICs and detrusor muscles. Paraffin sections of the human urinary bladder were obtained from histologically normal areas of formalin-fixed specimens removed for bladder carcinoma. Double-labeling immunohistochemical methods using antibodies against each β-AR subtype and vimentin were performed to identify ICs of the human urinary bladder. The staining intensity of β-ARs was semiquantitatively compared among urothelium, ICs and detrusor muscles. Further, gender-related difference or age-related correlation in the staining intensity of β-ARs was compared in the same cell types. The expression of β1 -, β2 -, and β3 -AR was observed in vimentin-positive ICs localized in suburothelium, between detrusor muscle bundles, and within these bundles of the human urinary bladder. The rank order of the staining intensity was urothelium > ICs = detrusor muscles in β1 -AR, urothelium > ICs > detrusor muscles in β2 -AR, whereas its order was ICs = detrusor muscles > urothelium in β3 -AR. Except for urothelial β1 -AR, there was no gender-related difference in the signal intensity of β-ARs in the urothelium, ICs or detrusor muscles. Age negatively correlated with the signal intensity of all β-AR subtypes. β-ARs were expressed in vimentin-positive ICs of the human urinary bladder. As for β2 - and β3 -AR, there was no gender-related difference or age-related correlation in urothelium, ICs and detrusor muscles. In the human urinary bladder, β-ARs expressed in ICs may play a role in bladder physiology.

Urinary Bladder Detrusor Dysfunction Symptoms in Lyme Disease

PurposeSymptoms of urinary bladder detrusor dysfunction have been rarely reported in Lyme disease. The aim was to carry out the first systematic study to compare the prevalence of such symptoms in a group of Lyme disease patients and a group of matched controls.MethodsA questionnaire relating to detrusor function was administered to 17 serologically positive Lyme disease patients and to 18 control subjects.ResultsThe two groups were matched in respect of age, sex, body mass, and mean arterial blood pressure. None of the 35 subjects was taking medication which might affect urinary function and none had undergone a previous operative procedure on the lower urinary tract. Six of the Lyme patients (35%) and none of the controls (0%) had symptoms of detrusor dysfunction (P<0.01).ConclusionsThis first systematic controlled study confirms that Lyme disease is associated with urinary bladder detrusor dysfunction. Further evaluation of detrusor function is warranted in this disease.

Changes in Urinary Bladder Smooth Muscle Contractility and the Role of Rho Kinase and Isoprostane after Partial Bladder outlet Obstruction in rats

Objective: Bladder outlet obstruction is a common urological problem that associatedwith many cellular changes and remodeling of urinary bladder detrusor smoothmuscle. This study was designed to determine the changes in Rho kinase (ROCK) andisoprostane levels in urinary bladder homogenate after partial bladder outletobstruction (PBOO); and to evaluate the contractile response of isolated rat detrusormuscle after PBOO. Methods: The present work was carried out on 30 male albinorats that were divided into 3 groups (10 rats/group): group I: consisted of normalrats, they were sham operated and considered as control group, group II: consisted ofrats that were undergone PBOO for 14days, group III: consisted of rats that wereundergone PBOO for 28 days. The following parameters were assessed in rats of allgroups: urinary bladder weight, levels of both Rho kinase and isoprostane in thetissues of urinary bladder as well as the contractile response of detrusor muscle bothspontaneously and in response to acetyl choline. Results: The present study revealeda significant increase in the weight of urinary bladder in rats of PBOO of group IIand III as compared to sham operated control of group I. There was a significantincrease in the mean value of Rho kinase and isoprostane in the tissue of the urinarybladder after obstruction. 14 days after obstruction was associated with a significantincrease in the mean value of Rho kinase which was significantly high compared togroup I (sham operated rats) and group III (28days of obstruction), 28 days ofobstruction was associated with decrease in the mean value of Rho kinase comparedto 14 days of obstruction, however, its value was above the control. Regarding thecontractile response, PBOO was associated with increased spontaneous activity ofdetrusor muscle and increased tonic response to acetyl choline which wassignificantly high after 14 and 28 days of obstruction compared to the control.Conclusion: The results of the present study demonstrated that Rho kinase andisoprostane levels were elevated after bladder outlet obstruction and that Rho kinasecould play a crucial role in the regulation of rat urinary bladder smooth musclecontraction and tone. Therefore, Rho kinase inhibitors may prove to betherapeutically useful in the treatment of lower urinary tract disorders associatedwith changes in the physiology of bladder smooth muscle contractility.