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New Findings: What is the central question of this study?Overactive bladder is associated with enhanced spontaneous contractions, but their origins are unclear. The aim of this study was to characterize the accompanying ATP transients.What is the main finding and its importance?Spontaneous detrusor contractions were accompanied by transient increases of ATP, and their appearance was delayed by previous activation of efferent nerves to the detrusor. This indicates that spontaneous ATP release from nerve terminals supports spontaneous contractions. ATP is a functional excitatory neurotransmitter in human bladder only in pathologies such as overactive bladder. A potential drug target is revealed to manage this condition. Spontaneous contractions are characteristic of the bladder wall, but their origins remain unclear. Activity is reduced if the mucosa is removed but does not disappear, suggesting that a fraction arises from the detrusor. We tested the hypothesis that spontaneous detrusor contractions arise from spontaneous ATP release. Guinea‐pig detrusor strips, without mucosa, were superfused with Tyrode solution at 36°C. Preparations were subjected to electrical field stimulation (EFS; 3 s trains at 90 s intervals) to produce nerve‐mediated contractions, abolished by 1 µm TTX. Amperometric ATP electrodes on the preparation surface recorded any ATP released. Spontaneous contractions and ATP transients were recorded between EFS trains. Nerve‐mediated contractions were attenuated by atropine and α,β‐methylene ATP; in combination, they nearly abolished contractions, as did nifedipine. Contractions were accompanied by ATP transients that were unaffected by atropine but inhibited by TTX and greatly attenuated by nifedipine. Spontaneous contractions were accompanied by ATP transients, with a close correlation between the magnitudes of both transients. ATP and contractile transients persisted with TTX, atropine and nifedipine. Immediately after a nerve‐mediated contraction and ATP transient, there was a longer interval than normal before spontaneous activity resumed. Spontaneous contractions and ATP transients are proposed to arise from ATP leakage from nerve terminals innervating the detrusor. Extracellular ATP has a greater functional significance in humans who suffer from detrusor overactivity (spontaneous bladder contractions associated with incontinence) owing to its reduced hydrolysis at the nerve–muscle interface. This study shows the origin of spontaneous activity that might be exploited to develop a therapeutic management of this condition. [ABSTRACT FROM AUTHOR]

Selective serotonin reuptake inhibitors (SSRIs) affect the smooth muscle cells acting on voltage‐dependent channels for Na+, K+ and Ca2+, but their action is tissue and species specific. The aim of our study was to investigate effects of selective serotonin reuptake inhibitors on motility of the isolated fallopian tubes. Isolated preparations of isthmus and ampoule were taken from fallopian tubes of 20 women during hysterectomy due to uterine fibroids and then tested for reactivity on increasing concentrations of selective serotonin reuptake inhibitors. Escitalopram (from 0.9 × 10−9 M/L to 1.4 × 10−6 M/L) produced concentration‐dependent increase of spontaneous contractions of the isolated ampulla (EC50 = 1.20 ± 1.06 × 10−8 M/L, r = 0.580, P < 0.05) (F = 2.980, df1 = 6, df2 = 28, P < 0.05). Paroxetine (from 1.2 × 10−9 M/L to 5.1 × 10−5 M/L) produced concentration‐dependent increase of spontaneous contractions of the isolated isthmus (EC50 = 7.01 ± 3.50 × 10−8 M/L, r = 0.500, P < 0.05) (F = 2.350, df1 = 9, df2 = 40, P < 0.05). The SSRIs differ among themselves in regard to their potential to affect motility of the fallopian tubes. Escitalopram and paroxetine have clear stimulating effect which may interfere with functioning of the fallopian tubes, and potentially impair fertility if taken by women in reproductive period of life. The other SSRIs tested in the study did not produce significant effect throughout the concentration range used in the experiments. [ABSTRACT FROM AUTHOR]

Objectives To measure the effect of external heating on bladder wall contractile function, histological structure and expression of proteins related to tissue protection and apoptosis. Material and Methods In vitro preparations of bladder wall and ex vivo perfused pig bladders were heated from 37 to 42°C, 46 and 50°C for 15 min. Isolated preparations were heated by radiant energy and perfused bladders were heated by altering perfusate temperature. Spontaneous contractions or pressure variations were recorded, as well as responses to the muscarinic agonist carbachol or motor nerve excitation in vitro during heating. Tissue histology in control and after heating was analysed using haematoxylin and eosin staining and 4′-6-diamidino-2-phenylindole ( DAPI) nuclear labelling. The effects of heating on protein expression levels of (i) heat shock proteins HSP27- pSer82 and inducible- HSP70 and (ii) caspase-3 and its downstream DNA-repair substrate poly-[ ADP-ribose] polymerase ( PARP) were measured. Results Heating to 42°C reduced spontaneous contractions or pressure variations by ~70%; effects were fully reversible. There were no effects on carbachol or nerve-mediated responses. Tissue histology was unaffected by heating, and expression of heat shock proteins as well as caspase-3 and PARP were also unaltered. A TRPV1 antagonist had no effect on the reduction of spontaneous activity. Heating to 46°C had a similar effect on spontaneous activity and also reduced the carbachol contracture. Urothelial structure was damaged, caspase-3 levels were increased and inducible- HSP70 levels declined. At 50°C evoked contractions were abolished, the urothelium was absent and heat shock proteins and PARP expression was reduced with raised caspase-3 expression. Conclusions Heating to 42°C caused a profound, reversible and reproducible attenuation of spontaneous activity, with no tissue damage and no initiation of apoptosis pathways. Higher temperatures caused tissue damage and activation of apoptotic mechanisms. Mild heating offers a novel approach to reducing bladder spontaneous activity. [ABSTRACT FROM AUTHOR]

Aims To examine the effects of the α1A-adrenoceptor antagonist, tamsulosin, on spontaneous contractile and electrical activity in the guinea-pig prostate gland. Methods The effects of tamsulosin (0.1 and 0.3 nM) were investigated in adult and ageing male guinea pig prostate glands using conventional tension recording and electrophysiological intracellular microelectrode recording techniques. Results Tamsulosin reduced spontaneous activity, and had different age-dependent effects on adult and ageing guinea pigs at different concentrations. 0.1 nM tamsulosin caused a significantly greater reduction of spontaneous contractile and electrical activity in ageing guinea pigs in comparison to adult guinea pigs. In contrast, 0.3 nM tamsulosin had a significantly greater reduction of spontaneous contractile and electrical activity in adult guinea pigs in comparison to ageing guinea pigs. Conclusions This study demonstrates that tamsulosin can modulate spontaneous myogenic stromal contractility and the underlying spontaneous electrical activity; tamsulosin does not block spontaneous activity. This reduction in spontaneous activity suggests that downstream cellular mechanisms underlying smooth muscle tone are being targeted, and these may represent novel therapeutic targets to better treat benign prostatic hyperplasia. Neurourol. Urodynam. 34:482-488, 2015. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The use of clonidine, a selective agonist of α2-adrenoceptors, is related to the fertility impairment. Thus, it has been described that changes in the epididymal function are related to the loss of fertility. Therefore, this study was sought to further evaluate the effects of clonidine in the rat distal cauda epididymis contractions and its consequence in the sperm parameters. The in vitro effects of clonidine in the isolated distal cauda epididymis were evaluated by pharmacological experiments. The consecutive contractile responses for clonidine in distal cauda epididymis showed desensitization. The noradrenaline-induced contractions were desensitized after in vitro clonidine pre-treatment (10−5 m for 10 min). Clonidine was unable to alter the noradrenaline contractions if the in vitro pre-treatment was made in the presence of idazoxan (α2-adrenoceptor antagonist), whereas prazosin (α1-adrenoceptor antagonist) was ineffective. Moreover, the in vitro clonidine pre-treatment increased frequency and amplitude of spontaneous contraction of distal cauda epididymis. In addition, to induce in vivo desensitization of α2-adrenoceptors, male Wistar rats were treated with crescent doses of clonidine and distal cauda of epididymis contraction and sperm parameters were analyzed. The in vivo treatment with clonidine diminished the potency of the contractions induced by adrenergic agonists and augmented the frequency and amplitude of spontaneous contraction of distal cauda epididymis. This treatment also altered the sperm transit time in epididymis, epididymal sperm reserves, sperm lipid peroxidation, and antioxidant enzymes activity. The results suggest that clonidine was able to affect the sperm quantity and quality by decreasing the transit time related to the increase in the frequency and amplitude of spontaneous contractions in epididymis, although the contractions induced by adrenergic agonists were desensitized. [ABSTRACT FROM AUTHOR]

Aims To highlight novel experimental approaches that test if the Myogenic Hypothesis remains viable as a contributor to the aetiology of detrusor overactivity. Methods To summarise the conclusions of a workshop held under the auspices of ICI-RS in 2013. Results Several theories may explain the pathology of detrusor overactivity and include a myogenic theory with fundamental changes to detrusor muscle excitation-contraction coupling. The isolated bladder displays micromotions that do not normally translate into significant changes of intravesical pressure. However, their amplitude and frequency are altered in animal models of bladder dysfunction. The origin of micromotions, if they generate significant changes of intravesical pressure and contribute to urinary tract sensations remain unanswered. Within the myocyte, changes to contractile protein phosphorylation through accessory proteins and cytoplasmic regulatory pathways occur in lower urinary tract pathologies associated with detrusor overactivity. Furthermore, myocytes isolated from overactive human bladders generate greater spontaneous activity, but a complete description of changes to ionic currents remains to be characterised. Finally, several growth factors, including mechano-growth factor, are released when bladder wall stress is increased, as with outflow obstruction. However the phenotype of the transformed detrusor myocytes remains to be measured. Conclusions A number of lines of evidence suggest that the Myogenic Hypothesis remains viable as a contributor to detrusor overactivity. Neurourol. Urodynam. 33:577-580, 2014. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

OBJECTIVE To investigate the influence of the mucosa on the inhibitory effects of the ATP-sensitive potassium channel (KATP channel) opener, cromakalim, on the spontaneous contractions of pig bladder strips from the bladder dome and trigone. Little is known about the influence of the mucosa on spontaneous contractions and whether the nature of these contractions differs between the bladder dome and trigone. MATERIALS AND METHODS Paired longitudinal strips of female pig bladders were isolated from the dome and trigone. The mucosa was removed from one strip per pair and tissues were set up in organ baths. Spontaneous activity was allowed to develop and recorded, and then cumulative concentration–response curves to cromakalim were obtained. The time needed for spontaneous contractions to develop, the frequency and amplitude of spontaneous contractions, and the effect of cromakalim were analysed. The strips of mucosa removed from the dome to produce denuded strips were also analysed by immunofluorescence using antibodies specific for vimentin and α-smooth muscle actin (α-SMA). RESULTS In the dome removal of the mucosa delayed the development of spontaneous contractions compared with mucosa-intact strips, whilst the trigone strips developed spontaneous contractions soon after set up in the organ baths irrespective of the presence or absence of mucosa. In the dome, cromakalim was more potent in suppressing spontaneous contractions when the mucosa was absent; whilst in the trigone the effects of cromakalim were similar in mucosa-intact and denuded strips. Upon examination of the strips of mucosa by immunofluorescence these strips were shown to contain cells positive for α-SMA or vimentin and cells positive for both, suggesting the presence of not only urothelium but also suburothelium and some detrusor smooth muscle bundles. CONCLUSION In the dome, the urothelium and suburothelium reduce the inhibitory effect of cromakalim on spontaneous contractions, whilst in the trigone these structures appear to have little influence. The mechanism for generating spontaneous contractions in the intact strips seems to be linked to the urothelium and suburothelium in the dome but not in the trigone. [ABSTRACT FROM AUTHOR]

In the current issue of Microcirculation, studies by Kurtz et al. [12] and Nizamutdinova et al. [18] together provide new evidence supporting a role for histamine as an endothelial-derived molecule that inhibits lymphatic muscle contraction. In particular, Nizamutdinova et al. show that the effects of flow-induced shear stress on lymphatic endothelium are mediated by both nitric oxide and histamine, since only blockade of both prevents contraction strength and frequency from being altered by flow. Separately, Kurtz et al. used confocal microscopy to determine a preferential expression of histamine receptors on the lymphatic endothelium and demonstrated that histamine applied to spontaneously contracting collecting lymphatics inhibits contractions. Previous studies disagreed on whether histamine stimulates or inhibits lymphatic contractions, but also used differing concentrations, species, and preparations. Together these new reports shed light on how histamine acts within the lymphatic vasculature, but also raise important questions about the cell type on which histamine exerts its effects and the signaling pathways involved. This editorial briefly discusses the contribution of each study and its relevance to lymphatic biology. [ABSTRACT FROM AUTHOR]

The use of clonidine, a selective agonist of α2-adrenoceptors, is related to the fertility impairment. Thus, it has been described that changes in the epididymal function are related to the loss of fertility. Therefore, this study was sought to further evaluate the effects of clonidine in the rat distal cauda epididymis contractions and its consequence in the sperm parameters. The in vitro effects of clonidine in the isolated distal cauda epididymis were evaluated by pharmacological experiments. The consecutive contractile responses for clonidine in distal cauda epididymis showed desensitization. The noradrenaline-induced contractions were desensitized after in vitro clonidine pre-treatment (10(-5) M for 10 min). Clonidine was unable to alter the noradrenaline contractions if the in vitro pre-treatment was made in the presence of idazoxan (α2-adrenoceptor antagonist), whereas prazosin (α1-adrenoceptor antagonist) was ineffective. Moreover, the in vitro clonidine pre-treatment increased frequency and amplitude of spontaneous contraction of distal cauda epididymis. In addition, to induce in vivo desensitization of α2-adrenoceptors, male Wistar rats were treated with crescent doses of clonidine and distal cauda of epididymis contraction and sperm parameters were analyzed. The in vivo treatment with clonidine diminished the potency of the contractions induced by adrenergic agonists and augmented the frequency and amplitude of spontaneous contraction of distal cauda epididymis. This treatment also altered the sperm transit time in epididymis, epididymal sperm reserves, sperm lipid peroxidation, and antioxidant enzymes activity. The results suggest that clonidine was able to affect the sperm quantity and quality by decreasing the transit time related to the increase in the frequency and amplitude of spontaneous contractions in epididymis, although the contractions induced by adrenergic agonists were desensitized., (© 2014 American Society of Andrology and European Academy of Andrology.)