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Bahareh Vahabi - One of the best experts on this subject based on the ideXlab platform.
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Data_Sheet_1_Modulation of Bladder Wall Micromotions Alters Intravesical Pressure Activity in the Isolated Bladder.PDF
2019Co-Authors: Basu Chakrabarty, Bahareh Vahabi, Dominika Bijos, Francesco Clavica, Anthony J. Kanai, Anthony E. Pickering, Christopher H. Fry, Marcus J. DrakeAbstract:Micromotions are phasic contractions of the bladder wall. During urine storage, such phasic activity has little effect on Intravesical Pressure, however, changed motile activity may underlie urodynamic observations such as detrusor overactivity. The potential for bladder motility to affect Pressure reflects a summation of the overall movements, comprising the initiation, propagation, and dissipation components of micromotions. In this study, the influence of initiation of micromotions was investigated using calcium activated chloride channel blocker niflumic acid, and the effect of propagation using blockers of gap junctions. The overall bladder tone was modulated using isoprenaline. Isolated tissue strips and whole bladder preparations from juvenile rats were used. 18β-glycyrrhetinic acid was used to block gap junctions, reducing the amplitude and frequency of micromotions in in vitro and ex vivo preparations. Niflumic acid reduced the frequency of micromotions but had no effect on the amplitude of Pressure fluctuations. Isoprenaline resulted in a reduction in Pressure fluctuations and a decrease in Pressure baseline. Using visual video data analysis, bladder movement was visible, irrespective of lack of Pressure changes, which persisted during bladder relaxation. However, micromotions propagated over shorter distances and the overall bladder tone was reduced. All these results suggest that phasic activity of the bladder can be characterised by a combination of initiation and propagation of movement, and overall bladder tone. At any given moment, Intravesical Pressure recordings are an integration of these parameters. This synthesis gives insight into the limitations of clinical urodynamics, where Intravesical Pressure is the key indicator of detrusor activity.
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estimation of bladder contractility from Intravesical Pressure volume measurements
Neurourology and Urodynamics, 2017Co-Authors: Christopher H. Fry, Bahareh Vahabi, Marcus J. Drake, Andrew Gammie, Paul Abrams, Darryl KitneyAbstract:© 2016 Wiley Periodicals, Inc. Aims: To describe parameters from urodynamic Pressure recordings that describe urinary bladder contractility through the use of principles of muscle mechanics. Methods: Subtracted detrusor Pressure and voided flow were recorded from patients undergoing filling cystometry. The isovolumetric increase of detrusor Pressure, P, of a voluntary bladder contraction before voiding was used to generate a plot of (dP/dt)/P versus P. Extrapolation of the plot to the y-axis and the x-axis generated a contractility parameter, vCE (the maximum rate of Pressure development) and the maximum isovolumetric Pressure, P0, respectively. Similar curves were obtained in ex vivo pig bladders with different concentrations of the inotropic agent carbachol and shown in a supplement. Results: Values of vCE, but not P0, diminished with age in female subjects. vCE was most significantly associated with the 20–80% duration of isovolumetric contraction t20–80; and a weaker association with maximum flow rate and BCI in women. P0 was not associated with any urodynamic variable in women, but in men was with t20–80 and isovolumetric Pressure indices. Conclusions: The rate of isovolumetric subtracted detrusor Pressure (t20–80) increase shows a very significant association with indices of bladder contractility as derived from a derived force–velocity curve. We propose that t20–80 is a detrusor contractility parameter (DCP). Neurourol. Urodynam. 36:1009–1014, 2017. © 2016 Wiley Periodicals, Inc.
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physiological and pathophysiological implications of micromotion activity in urinary bladder function
Acta Physiologica, 2015Co-Authors: Bahareh Vahabi, Marcus DrakeAbstract:© 2014 Scandinavian Physiological Society. 'Micromotions' is a term signifying the presence of localized microcontractions and microelongations, alongside non-motile areas. The motile areas tend to shift over the bladder surface with time, and the Intravesical Pressure reflects moment-by-moment summation of the interplay between net contractile force generated by micromotions and general bladder tone. Functionally, the bladder structure may comprise modules with variable linkage, which supports presence of localized micromotions (no functional linkage between modules), propagating contractions (where emergence of linkage allows sequential activation) and the shifting of micromotions over time. Detrusor muscle, interstitial cells and intramural innervation have properties potentially relevant for initiating, coordinating and modulating micromotions. Conceptually, such activity could facilitate the generation of afferent activity (filling state reporting) in the absence of Intravesical Pressure change and the ability to transition to voiding at any bladder volume. This autonomous activity is an intrinsic property, seen in various experimental contexts including the clinical setting of human (female) overactive bladder. 'Disinhibited autonomy' may explain the obvious micromotions in isolated bladders and perhaps contribute clinically in neurological disease causing detrusor overactivity. Furthermore, any process that could increase the initiation or propagation of microcontractions might be anticipated to have a functional effect, increasing the likelihood of urinary urgency and detrusor overactivity respectively. Thus, models of bladder outlet obstruction, neurological trauma and ageing provide a useful framework for detecting cellular changes in smooth muscle, interstitial cells and innervation, and the consequent effects on micromotions.
Marcus J. Drake - One of the best experts on this subject based on the ideXlab platform.
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Data_Sheet_1_Modulation of Bladder Wall Micromotions Alters Intravesical Pressure Activity in the Isolated Bladder.PDF
2019Co-Authors: Basu Chakrabarty, Bahareh Vahabi, Dominika Bijos, Francesco Clavica, Anthony J. Kanai, Anthony E. Pickering, Christopher H. Fry, Marcus J. DrakeAbstract:Micromotions are phasic contractions of the bladder wall. During urine storage, such phasic activity has little effect on Intravesical Pressure, however, changed motile activity may underlie urodynamic observations such as detrusor overactivity. The potential for bladder motility to affect Pressure reflects a summation of the overall movements, comprising the initiation, propagation, and dissipation components of micromotions. In this study, the influence of initiation of micromotions was investigated using calcium activated chloride channel blocker niflumic acid, and the effect of propagation using blockers of gap junctions. The overall bladder tone was modulated using isoprenaline. Isolated tissue strips and whole bladder preparations from juvenile rats were used. 18β-glycyrrhetinic acid was used to block gap junctions, reducing the amplitude and frequency of micromotions in in vitro and ex vivo preparations. Niflumic acid reduced the frequency of micromotions but had no effect on the amplitude of Pressure fluctuations. Isoprenaline resulted in a reduction in Pressure fluctuations and a decrease in Pressure baseline. Using visual video data analysis, bladder movement was visible, irrespective of lack of Pressure changes, which persisted during bladder relaxation. However, micromotions propagated over shorter distances and the overall bladder tone was reduced. All these results suggest that phasic activity of the bladder can be characterised by a combination of initiation and propagation of movement, and overall bladder tone. At any given moment, Intravesical Pressure recordings are an integration of these parameters. This synthesis gives insight into the limitations of clinical urodynamics, where Intravesical Pressure is the key indicator of detrusor activity.
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estimation of bladder contractility from Intravesical Pressure volume measurements
Neurourology and Urodynamics, 2017Co-Authors: Christopher H. Fry, Bahareh Vahabi, Marcus J. Drake, Andrew Gammie, Paul Abrams, Darryl KitneyAbstract:© 2016 Wiley Periodicals, Inc. Aims: To describe parameters from urodynamic Pressure recordings that describe urinary bladder contractility through the use of principles of muscle mechanics. Methods: Subtracted detrusor Pressure and voided flow were recorded from patients undergoing filling cystometry. The isovolumetric increase of detrusor Pressure, P, of a voluntary bladder contraction before voiding was used to generate a plot of (dP/dt)/P versus P. Extrapolation of the plot to the y-axis and the x-axis generated a contractility parameter, vCE (the maximum rate of Pressure development) and the maximum isovolumetric Pressure, P0, respectively. Similar curves were obtained in ex vivo pig bladders with different concentrations of the inotropic agent carbachol and shown in a supplement. Results: Values of vCE, but not P0, diminished with age in female subjects. vCE was most significantly associated with the 20–80% duration of isovolumetric contraction t20–80; and a weaker association with maximum flow rate and BCI in women. P0 was not associated with any urodynamic variable in women, but in men was with t20–80 and isovolumetric Pressure indices. Conclusions: The rate of isovolumetric subtracted detrusor Pressure (t20–80) increase shows a very significant association with indices of bladder contractility as derived from a derived force–velocity curve. We propose that t20–80 is a detrusor contractility parameter (DCP). Neurourol. Urodynam. 36:1009–1014, 2017. © 2016 Wiley Periodicals, Inc.
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partial outlet obstruction enhances modular autonomous activity in the isolated rat bladder
The Journal of Urology, 2003Co-Authors: Marcus J. Drake, Karlerik Andersson, Petter Hedlund, I J Harvey, Raj Kumar Pandita, James GillespieAbstract:Purpose: Autonomous bladder activity can take the form of localized micromotions (MMs), suggesting that the detrusor may be arranged into component modules, of which each is capable of contracting autonomously. We examined MMs in isolated whole rat bladder and the effects of partial bladder outlet obstruction as a model of detrusor overactivity (DO) to ascertain whether altered modular activity could be an etiological factor in DO. Materials and Methods: A total of 12 adult female Sprague-Dawley rats underwent obstruction or sham operation for 1 or 4 weeks. Bladders were microsurgically removed and mounted in whole organ tissue baths. Recordings of Intravesical Pressure and simultaneous registration of intramural contractions were performed under standardized conditions. Results: Prior to filling MMs took the form of localized contractions near the vesicoureteral junction in sham operated animals and multifocal microcontractions in obstructed animals. Intravesical volume increases were associated with a change in localized MMs to propagated contraction waves. In sham operated animals stretch resulted in increased MM frequency but decreased amplitude. After obstruction stretch elicited highly coordinated MMs and enhanced Intravesical Pressure transmission. The time since surgery did not alter observations in the sham or obstructed group. Conclusions: Detrusor muscle in isolated bladders under conditions modeling urine storage may have a functional modular arrangement with the basolateral region most active prior to filling. Peripheral factors determining Intravesical Pressure include the number of modules active, coordination and intramural tension at other sites. After bladder outlet obstruction more modules are active at baseline and their coordination is enhanced by stretch, leading to increased Pressure fluctuations. Such changes may contribute to the development of DO.
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autonomous activity in the isolated guinea pig bladder
Experimental Physiology, 2003Co-Authors: Marcus J. Drake, I J Harvey, James GillespieAbstract:Phasic changes in Pressure have been reported to occur in the bladder which are not associated with micturition. Spontaneous Intravesical Pressure changes can be recorded from bladders in vitro or bladders in vivo isolated from the central nervous system suggesting that the bladder itself is capable of autonomous activity. Experiments using isolated cells and muscle strips indicate that the smooth muscle can generate spontaneous activity. Whether this is the origin of phasic changes in the intact organ remains unknown. The present study set out to establish the presence and characteristics of autonomous activity in the isolated guinea pig bladder. Multiple-point motion analysis and concurrent Intravesical Pressure recording were used to identify and quantify spontaneous and evoked activity. Highly complex autonomous activity was observed in unstimulated bladders. This activity comprised localised micro-contractions in single or multiple discrete regions, waves of activity and micro-stretches. Low-amplitude phasic 'micro-transients' were seen in the Intravesical Pressure trace in association with micro-contractions. Incremental increases in the Intravesical volume recruited additional areas of activity. Atropine and tetrodotoxin had no effect on the micro-transients or micro-contractions. Exposure to the muscarinic agonist arecaidine (10-300 nM) initially increased the incidence of micro-contractions which subsequently became co-ordinated into phasic Pressure rises and contraction waves, interspersed with periods of total quiescence. The findings describe the generation and co-ordination of autonomous activity in the bladder wall and also demonstrate complex phasic activity. This approach has shown the importance of assessing the integrative properties of the entire organ in studies of the physiology and patho-physiology of the bladder.
Robert M Levin - One of the best experts on this subject based on the ideXlab platform.
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increased blood flow after catheterization and drainage in the chronically obstructed rabbit urinary bladder
Urology, 2001Co-Authors: Annette Schroder, Barry A Kogan, Jeremy Lieb, Robert M LevinAbstract:Abstract Objectives. To determine the effect of drainage on rabbit bladder blood flow after 4 weeks of partial outlet obstruction. Previous studies have shown that catheterization and drainage of the urinary bladder in control rabbits resulted in a significant nitric oxide-induced increase of blood flow to the bladder. It was also shown that 4 weeks’ partial outlet obstruction caused a significant decrease in blood flow to the bladder. Methods. Male New Zealand White rabbits underwent partial outlet obstruction by standard methods. After 4 weeks, the blood flow to the bladder muscle and mucosa was determined by a microsphere technique. Within 1 to 2 minutes after transurethral catheterization and complete drainage of the bladder, the blood flow was again determined. Unobstructed animals served as controls. Four other control animals underwent a repetitive blood flow study during 10 minutes to determine the time frame of blood flow changes after drainage. Blood flow was also measured in 2 control rabbits after transurethral catheterization without drainage and in 2 control rabbits after drainage by suprapubic puncture. To exclude the possibility that increased Intravesical Pressure alters the blood flow measurements, the relationship between the Intravesical volume and the bladder Pressure was examined in the obstructed rabbits. Results. After drainage of the bladder, the blood flow to the bladder muscle increased 4.5-fold in the decompensated obstructed group (bladder weights greater than 15 g) and 2.5-fold in the compensated animals (bladder weights less than 5 g) and control animals. Blood flow to the mucosa followed the same pattern but without reaching significance. Blood flow returned to near baseline values within 5 minutes. Catheterization without drainage did not alter the blood flow. In contrast, drainage by puncture increased the blood flow significantly. Higher Intravesical volumes increased the Intravesical Pressure slightly, but after opening the abdominal fascia, the Intravesical Pressure did not change with increasing volumes. Conclusions. Although the previously shown decreased blood flow to the bladder smooth muscle may be an etiologic factor in bladder contractile dysfunction secondary to partial outlet obstruction, the bladder does have the ability to increase the blood flow after drainage. This ability could be a compensatory and possibly protective mechanism after outlet obstruction.
Marcus Drake - One of the best experts on this subject based on the ideXlab platform.
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physiological and pathophysiological implications of micromotion activity in urinary bladder function
Acta Physiologica, 2015Co-Authors: Bahareh Vahabi, Marcus DrakeAbstract:© 2014 Scandinavian Physiological Society. 'Micromotions' is a term signifying the presence of localized microcontractions and microelongations, alongside non-motile areas. The motile areas tend to shift over the bladder surface with time, and the Intravesical Pressure reflects moment-by-moment summation of the interplay between net contractile force generated by micromotions and general bladder tone. Functionally, the bladder structure may comprise modules with variable linkage, which supports presence of localized micromotions (no functional linkage between modules), propagating contractions (where emergence of linkage allows sequential activation) and the shifting of micromotions over time. Detrusor muscle, interstitial cells and intramural innervation have properties potentially relevant for initiating, coordinating and modulating micromotions. Conceptually, such activity could facilitate the generation of afferent activity (filling state reporting) in the absence of Intravesical Pressure change and the ability to transition to voiding at any bladder volume. This autonomous activity is an intrinsic property, seen in various experimental contexts including the clinical setting of human (female) overactive bladder. 'Disinhibited autonomy' may explain the obvious micromotions in isolated bladders and perhaps contribute clinically in neurological disease causing detrusor overactivity. Furthermore, any process that could increase the initiation or propagation of microcontractions might be anticipated to have a functional effect, increasing the likelihood of urinary urgency and detrusor overactivity respectively. Thus, models of bladder outlet obstruction, neurological trauma and ageing provide a useful framework for detecting cellular changes in smooth muscle, interstitial cells and innervation, and the consequent effects on micromotions.
Christopher H. Fry - One of the best experts on this subject based on the ideXlab platform.
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Data_Sheet_1_Modulation of Bladder Wall Micromotions Alters Intravesical Pressure Activity in the Isolated Bladder.PDF
2019Co-Authors: Basu Chakrabarty, Bahareh Vahabi, Dominika Bijos, Francesco Clavica, Anthony J. Kanai, Anthony E. Pickering, Christopher H. Fry, Marcus J. DrakeAbstract:Micromotions are phasic contractions of the bladder wall. During urine storage, such phasic activity has little effect on Intravesical Pressure, however, changed motile activity may underlie urodynamic observations such as detrusor overactivity. The potential for bladder motility to affect Pressure reflects a summation of the overall movements, comprising the initiation, propagation, and dissipation components of micromotions. In this study, the influence of initiation of micromotions was investigated using calcium activated chloride channel blocker niflumic acid, and the effect of propagation using blockers of gap junctions. The overall bladder tone was modulated using isoprenaline. Isolated tissue strips and whole bladder preparations from juvenile rats were used. 18β-glycyrrhetinic acid was used to block gap junctions, reducing the amplitude and frequency of micromotions in in vitro and ex vivo preparations. Niflumic acid reduced the frequency of micromotions but had no effect on the amplitude of Pressure fluctuations. Isoprenaline resulted in a reduction in Pressure fluctuations and a decrease in Pressure baseline. Using visual video data analysis, bladder movement was visible, irrespective of lack of Pressure changes, which persisted during bladder relaxation. However, micromotions propagated over shorter distances and the overall bladder tone was reduced. All these results suggest that phasic activity of the bladder can be characterised by a combination of initiation and propagation of movement, and overall bladder tone. At any given moment, Intravesical Pressure recordings are an integration of these parameters. This synthesis gives insight into the limitations of clinical urodynamics, where Intravesical Pressure is the key indicator of detrusor activity.
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estimation of bladder contractility from Intravesical Pressure volume measurements
Neurourology and Urodynamics, 2017Co-Authors: Christopher H. Fry, Bahareh Vahabi, Marcus J. Drake, Andrew Gammie, Paul Abrams, Darryl KitneyAbstract:© 2016 Wiley Periodicals, Inc. Aims: To describe parameters from urodynamic Pressure recordings that describe urinary bladder contractility through the use of principles of muscle mechanics. Methods: Subtracted detrusor Pressure and voided flow were recorded from patients undergoing filling cystometry. The isovolumetric increase of detrusor Pressure, P, of a voluntary bladder contraction before voiding was used to generate a plot of (dP/dt)/P versus P. Extrapolation of the plot to the y-axis and the x-axis generated a contractility parameter, vCE (the maximum rate of Pressure development) and the maximum isovolumetric Pressure, P0, respectively. Similar curves were obtained in ex vivo pig bladders with different concentrations of the inotropic agent carbachol and shown in a supplement. Results: Values of vCE, but not P0, diminished with age in female subjects. vCE was most significantly associated with the 20–80% duration of isovolumetric contraction t20–80; and a weaker association with maximum flow rate and BCI in women. P0 was not associated with any urodynamic variable in women, but in men was with t20–80 and isovolumetric Pressure indices. Conclusions: The rate of isovolumetric subtracted detrusor Pressure (t20–80) increase shows a very significant association with indices of bladder contractility as derived from a derived force–velocity curve. We propose that t20–80 is a detrusor contractility parameter (DCP). Neurourol. Urodynam. 36:1009–1014, 2017. © 2016 Wiley Periodicals, Inc.
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The validation of a functional, isolated bladder model from a large animal
Frontiers Media S.A., 2012Co-Authors: Brian Andrew Parsons, Christopher H. Fry, Marcus John Drake, Andrew Egammie, Bahareh EvahabiAbstract:Characterising the integrative physiology of the bladder requires whole organ preparations. The purpose of this study was to validate an isolated large animal (pig) bladder preparation, through arterial and Intravesical drug administration, Intravesical Pressure recording and filming of surface micromotions. Female pig bladders were obtained from the local abattoir and arterially perfused in vitro. Arterial and Intravesical Pressures were recorded at varying volumes. Bladder viability was assessed histologically and by monitoring inflow and outflow pH. Arterial drug administration employed boluses introduced into the perfusate. Intravesical administration involved slow instillation and a prolonged dwell-time. Surface micromotions were recorded by filming the separation of surface markers concurrently with Intravesical Pressure measurement. Adequate perfusion to all bladder layers was achieved for up to eight hours; there was no structural deterioration nor alteration in inflow and effluent perfusate pH. Arterial drug administration (carbachol and potassium chloride) showed consistent dose-dependent responses. Localised movements (micromotions) occurred over the bladder surface, with variable correlation with fluctuations of Intravesical Pressure. The isolated pig bladder is a valid approach to study integrative bladder physiology. It remains viable when perfused in vitro, responds to different routes of drug administration and provides a model to correlate movements of the bladder wall directly to variation of Intravesical Pressure
