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Cheng F, Watton PN, Pederzani G, Kurobe M, Takaoka EI, Chapple C, Birder L, Yoshimura N, Robertson AM. A constrained mixture-micturition-growth (CMMG) model of the urinary bladder: Application to partial bladder outlet obstruction (BOO). J Mech Behav Biomed Mater 2022; 134:105337. [PMID: 35863296 PMCID: PMC9835014 DOI: 10.1016/j.jmbbm.2022.105337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 04/13/2022] [Accepted: 06/24/2022] [Indexed: 01/14/2023]
Abstract
We present a constrained mixture-micturition-growth (CMMG) model for the bladder. It simulates bladder mechanics, voiding function (micturition) and tissue adaptations in response to altered biomechanical conditions. The CMMG model is calibrated with both in vivo and in vitro data from healthy male rat urinary bladders (cystometry, bioimaging of wall structure, mechanical testing) and applied to simulate the growth and remodeling (G&R) response to partial bladder outlet obstruction (BOO). The bladder wall is represented as a multi-layered, anisotropic, nonlinear constrained mixture. A short time scale micturition component of the CMMG model accounts for the active and passive mechanics of voiding. Over a second, longer time scale, G&R algorithms for the evolution of both cellular and extracellular constituents act to maintain/restore bladder (homeostatic) functionality. The CMMG model is applied to a spherical membrane model of the BOO bladder utilizing temporal data from an experimental male rodent model to parameterize and then verify the model. Consistent with the experimental studies of BOO, the model predicts: an initial loss of voiding capacity followed by hypertrophy of SMC to restore voiding function; bladder enlargement; collagen remodeling to maintain its role as a protective sheath; and increased voiding duration with lower average flow rate. This CMMG model enables a mechanistic approach for investigating the bladder's structure-function relationship and its adaption in pathological conditions. While the approach is illustrated with a conceptual spherical bladder model, it provides the basis for application of the CMMG model to anatomical geometries. Such a mechanistic approach has promise as an in silico tool for the rational development of new surgical and pharmacological treatments for bladder diseases such as BOO.
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Affiliation(s)
- Fangzhou Cheng
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, United States
| | - Paul N Watton
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, United States; Department of Computer Science & Insigneo Institute for in silico Medicine, University of Sheffield, Sheffield, United Kingdom.
| | - Giulia Pederzani
- Department of Computer Science & Insigneo Institute for in silico Medicine, University of Sheffield, Sheffield, United Kingdom
| | - Masahiro Kurobe
- Department of Urology, University of Pittsburgh, Pittsburgh, United States
| | - Ei-Ichiro Takaoka
- Department of Urology, University of Pittsburgh, Pittsburgh, United States
| | - Chris Chapple
- Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, United Kingdom
| | - Lori Birder
- Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, United Kingdom; Department of Medicine, University of Pittsburgh, United States
| | - Naoki Yoshimura
- Department of Urology, University of Pittsburgh, Pittsburgh, United States
| | - Anne M Robertson
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, United States
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Upchurch WJ, Iaizzo PA. In vitro contractile studies within isolated tissue baths: Translational research from Visible Heart ® Laboratories. Exp Biol Med (Maywood) 2022; 247:584-597. [PMID: 35068214 PMCID: PMC9014520 DOI: 10.1177/15353702211070535] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/27/2023] Open
Abstract
The isolated tissue bath research methodology was first developed in 1904. Since then, it has been recognized as an important tool in pharmacology and physiology research, including investigations into neuromuscular disorders. The tissue bath is still used routinely as the instrument for performing the "gold standard" test for clinical diagnosis of malignant hyperthermia susceptibility - the caffeine-halothane contracture test. Our research group has utilized this tool for several decades for a range of research studies, and we are currently one of four North American diagnostic centers for determining susceptibility for malignant hyperthermia. This review provides a brief summary of some of the historical uses of the tissue bath. Important experimental considerations for the operation of the tissue bath are further described. Finally, we discuss the different studies our group has performed using isolated tissue baths to highlight the broad potential applications.
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Affiliation(s)
- Weston J Upchurch
- Department of Surgery, University of
Minnesota, Minneapolis, MN 55455, USA
- Bioinformatics and Computational
Biology Program, University of Minnesota, Minneapolis, MN 55455, USA
| | - Paul A Iaizzo
- Department of Surgery, University of
Minnesota, Minneapolis, MN 55455, USA
- Bioinformatics and Computational
Biology Program, University of Minnesota, Minneapolis, MN 55455, USA
- Institute for Engineering in Medicine,
University of Minnesota, Minneapolis, MN 55455, USA
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3
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Borsdorf M, Tomalka A, Stutzig N, Morales-Orcajo E, Böl M, Siebert T. Locational and Directional Dependencies of Smooth Muscle Properties in Pig Urinary Bladder. Front Physiol 2019; 10:63. [PMID: 30787883 PMCID: PMC6372509 DOI: 10.3389/fphys.2019.00063] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 01/21/2019] [Indexed: 12/11/2022] Open
Abstract
The urinary bladder is a distensible hollow muscular organ, which allows huge changes in size during absorption, storage and micturition. Pathological alterations of biomechanical properties can lead to bladder dysfunction and loss in quality of life. To understand and treat bladder diseases, the mechanisms of the healthy urinary bladder need to be determined. Thus, a series of studies focused on the detrusor muscle, a layer of urinary bladder made of smooth muscle fibers arranged in longitudinal and circumferential orientation. However, little is known about whether its active muscle properties differ depending on location and direction. This study aimed to investigate the porcine bladder for heterogeneous (six different locations) and anisotropic (longitudinal vs. circumferential) contractile properties including the force-length-(FLR) and force-velocity-relationship (FVR). Therefore, smooth muscle tissue strips with longitudinal and circumferential direction have been prepared from different bladder locations (apex dorsal, apex ventral, body dorsal, body ventral, trigone dorsal, trigone ventral). FLR and FVR have been determined by a series of isometric and isotonic contractions. Additionally, histological analyses were conducted to determine smooth muscle content and fiber orientation. Mechanical and histological examinations were carried out on 94 and 36 samples, respectively. The results showed that maximum active stress (pact ) of the bladder strips was higher in the longitudinal compared to the circumferential direction. This is in line with our histological investigation showing a higher smooth muscle content in the bladder strips in the longitudinal direction. However, normalization of maximum strip force by the cross-sectional area (CSA) of smooth muscle fibers yielded similar smooth muscle maximum stresses (165.4 ± 29.6 kPa), independent of strip direction. Active muscle properties (FLR, FVR) showed no locational differences. The trigone exhibited higher passive stress (ppass ) than the body. Moreover, the bladder exhibited greater ppass in the longitudinal than circumferential direction which might be attributed to its microstructure (more longitudinal arrangement of muscle fibers). This study provides a valuable dataset for the development of constitutive computational models of the healthy urinary bladder. These models are relevant from a medical standpoint, as they contribute to the basic understanding of the function of the bladder in health and disease.
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Affiliation(s)
- Mischa Borsdorf
- Institute for Sport and Exercise Science, Department of Movement and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - André Tomalka
- Institute for Sport and Exercise Science, Department of Movement and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Norman Stutzig
- Institute for Sport and Exercise Science, Department of Movement and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Enrique Morales-Orcajo
- Institute of Solid Mechanics, Department of Mechanical Engineering, Technical University of Braunschweig, Braunschweig, Germany
| | - Markus Böl
- Institute of Solid Mechanics, Department of Mechanical Engineering, Technical University of Braunschweig, Braunschweig, Germany
| | - Tobias Siebert
- Institute for Sport and Exercise Science, Department of Movement and Exercise Science, University of Stuttgart, Stuttgart, Germany
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Chakrabarty B, Bijos DA, Vahabi B, Clavica F, Kanai AJ, Pickering AE, Fry CH, Drake MJ. Modulation of Bladder Wall Micromotions Alters Intravesical Pressure Activity in the Isolated Bladder. Front Physiol 2019; 9:1937. [PMID: 30687132 PMCID: PMC6335571 DOI: 10.3389/fphys.2018.01937] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 12/21/2018] [Indexed: 12/20/2022] Open
Abstract
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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Affiliation(s)
- Basu Chakrabarty
- School of Physiology, Pharmacology and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - Dominika A Bijos
- Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom.,Southmead Hospital, Bristol Urological Institute, Bristol, United Kingdom
| | - Bahareh Vahabi
- Department of Applied Sciences, University of West England, Bristol, Bristol, United Kingdom
| | - Francesco Clavica
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Anthony J Kanai
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Anthony E Pickering
- School of Physiology, Pharmacology and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom.,Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Christopher H Fry
- School of Physiology, Pharmacology and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - Marcus J Drake
- Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom.,Southmead Hospital, Bristol Urological Institute, Bristol, United Kingdom
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Seydewitz R, Menzel R, Siebert T, Böl M. Three-dimensional mechano-electrochemical model for smooth muscle contraction of the urinary bladder. J Mech Behav Biomed Mater 2017; 75:128-146. [DOI: 10.1016/j.jmbbm.2017.03.034] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 03/22/2017] [Accepted: 03/31/2017] [Indexed: 11/25/2022]
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Importance of contraction history on muscle force of porcine urinary bladder smooth muscle. Int Urol Nephrol 2016; 49:205-214. [DOI: 10.1007/s11255-016-1482-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 12/07/2016] [Indexed: 01/13/2023]
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Sacco E, Bientinesi R, Bassi P, Currò D. Pharmacological methods for the preclinical assessment of therapeutics for OAB: an up-to-date review. Int Urogynecol J 2016; 27:1633-1644. [DOI: 10.1007/s00192-016-2977-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 02/04/2016] [Indexed: 11/24/2022]
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Speich JE, Southern JB, Henderson S, Wilson CW, Klausner AP, Ratz PH. Adjustable passive stiffness in mouse bladder: regulated by Rho kinase and elevated following partial bladder outlet obstruction. Am J Physiol Renal Physiol 2011; 302:F967-76. [PMID: 22205227 DOI: 10.1152/ajprenal.00177.2011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Detrusor smooth muscle (DSM) contributes to bladder wall tension during filling, and bladder wall deformation affects the signaling system that leads to urgency. The length-passive tension (L-T(p)) relationship in rabbit DSM can adapt with length changes over time and exhibits adjustable passive stiffness (APS) characterized by a L-T(p) curve that is a function of both activation and strain history. Muscle activation with KCl, carbachol (CCh), or prostaglandin E(2) at short muscle lengths can increase APS that is revealed by elevated pseudo-steady-state T(p) at longer lengths compared with prior T(p) measurements at those lengths, and APS generation is inhibited by the Rho Kinase (ROCK) inhibitor H-1152. In the current study, mouse bladder strips exhibited both KCl- and CCh-induced APS. Whole mouse bladders demonstrated APS which was measured as an increase in pressure during passive filling in calcium-free solution following CCh precontraction compared with pressure during filling without precontraction. In addition, CCh-induced APS in whole mouse bladder was inhibited by H-1152, indicating that ROCK activity may regulate bladder compliance during filling. Furthermore, APS in whole mouse bladder was elevated 2 wk after partial bladder outlet obstruction, suggesting that APS may be relevant in diseases affecting bladder mechanics. The presence of APS in mouse bladder will permit future studies of APS regulatory pathways and potential alterations of APS in disease models using knockout transgenetic mice.
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Affiliation(s)
- John E Speich
- Mechanical and Nuclear Engineering, Virginia Commonwealth University, 401 West Main St., Richmond, VA 23284-3015, USA.
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Sadegh MK, Ekman M, Rippe C, Sundler F, Wierup N, Mori M, Uvelius B, Swärd K. Biomechanical properties and innervation of the female caveolin-1-deficient detrusor. Br J Pharmacol 2011; 162:1156-70. [PMID: 21091642 DOI: 10.1111/j.1476-5381.2010.01115.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND PURPOSE Caveolin-1-deficiency is associated with substantial urogenital alterations. Here, a mechanical, histological and biochemical characterization of female detrusors from wild-type and caveolin-1-deficient (KO) mice was made to increase the understanding of detrusor changes caused by lack of caveolae. EXPERIMENTAL APPROACH Length-tension relationships were generated, and we recorded responses to electrical field stimulation, the muscarinic receptor agonist carbachol and the purinoceptor agonist ATP. Tyrosine nitration and the contents of caveolin-1, cavin-1, muscarinic M₃ receptors, phospholipase C(β1), muscle-specific kinase (MuSK) and L-type Ca(2+) channels were determined by immunoblotting. Innervation was assessed by immunohistochemistry. KEY RESULTS Bladder to body weight ratio was not changed, nor was there any change in the optimum circumference for force development. Depolarization- and ATP-induced stress was reduced, as was carbachol-induced stress between 0.1 and 3 µM, but the supramaximal relative (% K(+)) response to carbachol was increased, as was M₃ expression. The scopolamine-sensitive component of the electrical field stimulation response was impaired, and yet bladder nerves contained little caveolin-1. The density of cholinergic nerves was unchanged, whereas CART- and CGRP-positive nerves were reduced. Immunoblotting revealed loss of MuSK. CONCLUSIONS AND IMPLICATIONS Ablation of caveolae in the female detrusor leads to generalized impairment of contractility, ruling out prostate hypertrophy as a contributing factor. Cholinergic neuroeffector transmission is impaired without conspicuous changes in the density of cholinergic nerves or morphology of their terminals, but correlating with reduced expression of MuSK.
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Abstract
Maintenance of normal lower urinary tract function is a complex process that requires coordination between the central nervous system and the autonomic and somatic components of the peripheral nervous system. This article provides an overview of the basic principles that are recognized to regulate normal urine storage and micturition, including bladder biomechanics, relevant neuroanatomy, neural control of lower urinary tract function, and the pharmacologic processes that translate the neural signals into functional results. Finally, the emerging role of the urothelium as a sensory structure is discussed.
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11
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Almasri AM, Ratz PH, Speich JE. Length adaptation of the passive-to-active tension ratio in rabbit detrusor. Ann Biomed Eng 2010; 38:2594-605. [PMID: 20387122 DOI: 10.1007/s10439-010-0021-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Accepted: 03/19/2010] [Indexed: 02/04/2023]
Abstract
The passive and active length-tension (L-T (p) and L-T (a)) relationships in airway, vascular, and detrusor smooth muscles can adapt with length changes and/or multiple contractions. The present objectives were to (1) determine whether short-term adaptation at one muscle length shifts the entire L-T (a) curve in detrusor smooth muscle (DSM), (2) compare adaptation at shorter versus longer lengths, and (3) determine the effect of adaptation on the T (p)/T (a) ratio. Results showed that multiple KCl-induced contractions on the descending limb of the original L-T (a) curve adapted DSM strips to that length and shifted the L-T (a) curve rightward. Peak T (a) at the new length was not different from the original peak T (a), and the L-T (p) curve shifted rightward with the L-T (a) curve. Multiple contractions on the ascending limb increased both T (a) and T (p). In contrast, multiple contractions on the descending limb increased T (a) but decreased T (p). The T (p)/T (a) ratio on the original descending limb adapted from 0.540 +/- 0.084 to 0.223 +/- 0.033 (mean +/- SE, n = 7), such that it was not different from the ratio of 0.208 +/- 0.033 at the original peak T (a) length, suggesting a role of length adaptation may be to maintain a desirable T (p)/T (a) ratio as the bladder fills and voids over a broad DSM length range.
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Affiliation(s)
- Atheer M Almasri
- Department of Mechanical Engineering, Virginia Commonwealth University, 401 West Main Street, P.O. Box 843015, Richmond, VA 23284-3015, USA
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12
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Speich JE, Almasri AM, Bhatia H, Klausner AP, Ratz PH. Adaptation of the length-active tension relationship in rabbit detrusor. Am J Physiol Renal Physiol 2009; 297:F1119-28. [PMID: 19675182 DOI: 10.1152/ajprenal.00298.2009] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Studies have shown that the length-tension (L-T) relationships in airway and vascular smooth muscles are dynamic and can adapt to length changes over a period of time. Our prior studies have shown that the passive L-T relationship in rabbit detrusor smooth muscle (DSM) is also dynamic and that DSM exhibits adjustable passive stiffness (APS) characterized by a passive L-T curve that can shift along the length axis as a function of strain history and activation history. The present study demonstrates that the active L-T curve for DSM is also dynamic and that the peak active tension produced at a particular muscle length is a function of both strain and activation history. More specifically, this study reveals that the active L-T relationship, or curve, does not have a unique peak tension value with a single ascending and descending limb, but instead reveals that multiple ascending and descending limbs can be exhibited in the same DSM strip. This study also demonstrates that for DSM strips not stretched far enough to reveal a descending limb, the peak active tension produced by a maximal KCl-induced contraction at a short, passively slack muscle length of 3 mm was reduced by 58.6 +/- 4.1% (n = 15) following stretches to and contractions at threefold the original muscle length, 9 mm. Moreover, five subsequent contractions at the short muscle length displayed increasingly greater tension; active tension produced by the sixth contraction was 91.5 +/- 9.1% of that produced by the prestretch contraction at that length. Together, these findings indicate for the first time that DSM exhibits length adaptation, similar to vascular and airway smooth muscles. In addition, our findings demonstrate that preconditioning, APS and adaptation of the active L-T curve can each impact the maximum total tension observed at a particular DSM length.
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Affiliation(s)
- John E Speich
- Department of Mechanical Engineering, Virginia Commonwealth University, 401 W. Main St., PO Box 843015, Richmond, VA 23284-3015, USA.
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Speich JE, Dosier C, Borgsmiller L, Quintero K, Koo HP, Ratz PH. Adjustable passive length-tension curve in rabbit detrusor smooth muscle. J Appl Physiol (1985) 2007; 102:1746-55. [PMID: 17234807 DOI: 10.1152/japplphysiol.00548.2006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Until the 1990s, the passive and active length-tension (L-T) relationships of smooth muscle were believed to be static, with a single passive force value and a single maximum active force value for each muscle length. However, recent studies have demonstrated that the active L-T relationship in airway smooth muscle is dynamic and adapts to length changes over a period of time. Furthermore, our prior work showed that the passive L-T relationship in rabbit detrusor smooth muscle (DSM) is also dynamic and that in addition to viscoelastic behavior, DSM displays strain-softening behavior characterized by a loss of passive stiffness at shorter lengths following a stretch to a new longer length. This loss of passive stiffness appears to be irreversible when the muscle is not producing active force and during submaximal activation but is reversible on full muscle activation, which indicates that the stiffness component of passive force lost to strain softening is adjustable in DSM. The present study demonstrates that the passive L-T curve for DSM is not static and can shift along the length axis as a function of strain history and activation history. This study also demonstrates that adjustable passive stiffness (APS) can modulate total force (35% increase) for a given muscle length, while active force remains relatively unchanged (4% increase). This finding suggests that the structures responsible for APS act in parallel with the contractile apparatus, and the results are used to further justify the configuration of modeling elements within our previously proposed mechanical model for APS.
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Affiliation(s)
- John E Speich
- Dept. of Mechanical Engineering, Virginia Commonwealth University, Richmond, VA 23284-3015, USA.
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14
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Pagala M, Lehman DS, Morgan MP, Jedwab J, Wise GJ. Physiological fatigue of smooth muscle contractions in rat urinary bladder. BJU Int 2006; 97:1087-93. [PMID: 16643497 DOI: 10.1111/j.1464-410x.2006.06136.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To characterize the physiological fatigue in bladder smooth muscles that can occur within 60 s of stimulation, which is closer to the duration of normal voiding. MATERIALS AND METHODS Longitudinal and transverse strips of rat bladder were used; the muscles were mounted in an in vitro multi-muscle chamber, and the decline in contractile tension recorded during continuous electrical stimulation at frequencies of 5-30 Hz for 60 s. The effect of muscle length on fatigue was assessed by monitoring the decline in tension during 30 Hz stimulation at rest length, and at 60% and 100% stretched lengths of the bladder strips. To assess some of the factors involved in the development of fatigue, tension responses of fatigued muscles were monitored on exposure to 80 mm potassium or 1 microm bethanechol. RESULTS In both longitudinal and transverse bladder strips stimulated at 30 Hz, peak contractile tension declined to 50% of original after approximately 33 s, and to 30% after 60 s of stimulation. After 10 s rest, 60% of the original tension was recovered. Increasing the frequency of fatigue stimulation from 5 to 30 Hz significantly increased the extent of the decline in tension and reduced the time to a 50% decrease in tension. Stretching the bladder strips from rest length to 100% stretched length significantly reduced the extent of tension decline and increased the time to a 50% decrease in tension. Exposure of fatigued muscles to high potassium or bethanechol generated more tension than electrical stimulation. CONCLUSION Contractile fatigue occurs in both longitudinal and transverse strips of the bladder smooth muscles within the duration of normal voiding. Increasing the frequency of stimulation from 5 to 30 Hz increased the degree and rate of fatigue. Stretching the bladder strips from rest length by 60-100% reduced the degree and rate of fatigue. Bladder fatigue may be caused by decreased depolarization of the smooth muscle membranes, reduced release of acetylcholine from presynaptic nerve terminals, or by other yet undetermined mechanisms.
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Affiliation(s)
- Muarli Pagala
- Division of Urology, Department of Surgery, Maimonides Medical Center, Brooklyn, New York 11219, USA.
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15
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Liu G, Daneshgari F. Alterations in neurogenically mediated contractile responses of urinary bladder in rats with diabetes. Am J Physiol Renal Physiol 2005; 288:F1220-6. [PMID: 15687244 DOI: 10.1152/ajprenal.00449.2004] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Diabetic bladder dysfunction (DBD) is among the most common and bothersome complications of diabetes mellitus. Autonomic neuropathy has been counted as the cause of DBD. In the present study, we compared the alterations in the neurogenically mediated contractile responses of urinary bladder in rats with streptozocin-induced diabetes, 5% sucrose-induced diuresis, and age-matched controls. Male Sprague-Dawley rats were divided into three groups: 9-wk diabetic rats, diuretic rats, and age-matched controls. Micturition and morphometric characteristics were evaluated using metabolic cage and gross examination of the bladder. Bladder detrusor muscle strips were exposed to either periodic electrical field stimulation (EFS) or to EFS in the presence of atropine, alpha,beta-methylene adrenasine 5'-triphosphate, or tetrodotoxin. The proportions of cholinergic, purinergic, and residual nonadrenergic-noncholinergic (NANC) components of contractile response were compared among the three groups of animals. Diabetes caused a significant reduction of body weight compared with diuresis and controls, although the bladders of diabetic and diuretic rats weighed more than the controls. Both diabetes and diuresis caused significant increase in fluid intake, urine output, and bladder size. Diabetes and diuresis caused similarly increased response to EFS and reduced response to cholinergic component compared with controls. However, the purinergic response was significantly smaller in diuretic bladder strips compared with controls but not in diabetic rats. A residual NANC of unknown origin increased significantly but differently in diabetics and diuretics compared with controls. In conclusion, neurogenically mediated bladder contraction is altered in the diabetic rat. Diabetic-related changes do not parallel diuretic-induced changes, indicating that the pathogenesis of DBD needs further exploration.
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Affiliation(s)
- Guiming Liu
- Glickman Urological Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
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Andersson KE, Arner A. Urinary bladder contraction and relaxation: physiology and pathophysiology. Physiol Rev 2004; 84:935-86. [PMID: 15269341 DOI: 10.1152/physrev.00038.2003] [Citation(s) in RCA: 607] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The detrusor smooth muscle is the main muscle component of the urinary bladder wall. Its ability to contract over a large length interval and to relax determines the bladder function during filling and micturition. These processes are regulated by several external nervous and hormonal control systems, and the detrusor contains multiple receptors and signaling pathways. Functional changes of the detrusor can be found in several clinically important conditions, e.g., lower urinary tract symptoms (LUTS) and bladder outlet obstruction. The aim of this review is to summarize and synthesize basic information and recent advances in the understanding of the properties of the detrusor smooth muscle, its contractile system, cellular signaling, membrane properties, and cellular receptors. Alterations in these systems in pathological conditions of the bladder wall are described, and some areas for future research are suggested.
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Affiliation(s)
- Karl-Erik Andersson
- Dept. of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
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17
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Longhurst PA, Uvelius B. Pharmacological techniques for the in vitro study of the urinary bladder. J Pharmacol Toxicol Methods 2001; 45:91-108. [PMID: 11687378 DOI: 10.1016/s1056-8719(01)00133-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- P A Longhurst
- Department of Basic and Pharmaceutical Sciences, Albany College of Pharmacy, Albany, NY 12208-3492, USA.
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