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Hashitani H, Mitsui R, Hirai Y, Tanaka H, Miwa-Nishimura K. Nitrergic inhibition of sympathetic arteriolar constrictions in the female rodent urethra. J Physiol 2024; 602:2199-2226. [PMID: 38656747 DOI: 10.1113/jp285583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 04/08/2024] [Indexed: 04/26/2024] Open
Abstract
During the urine storage phase, tonically contracting urethral musculature would have a higher energy consumption than bladder muscle that develops phasic contractions. However, ischaemic dysfunction is less prevalent in the urethra than in the bladder, suggesting that urethral vasculature has intrinsic properties ensuring an adequate blood supply. Diameter changes in rat or mouse urethral arterioles were measured using a video-tracking system. Intercellular Ca2+ dynamics in arteriolar smooth muscle (SMCs) and endothelial cells were visualised using NG2- and parvalbumin-GCaMP6 mice, respectively. Fluorescence immunohistochemistry was used to visualise the perivascular innervation. In rat urethral arterioles, sympathetic vasoconstrictions were predominantly suppressed by α,β-methylene ATP (10 μM) but not prazosin (1 μM). Tadalafil (100 nM), a PDE5 inhibitor, diminished the vasoconstrictions in a manner reversed by N-ω-propyl-l-arginine hydrochloride (l-NPA, 1 μM), a neuronal NO synthesis (nNOS) inhibitor. Vesicular acetylcholine transporter immunoreactive perivascular nerve fibres co-expressing nNOS were intertwined with tyrosine hydroxylase immunoreactive sympathetic nerve fibres. In phenylephrine (1 μM) pre-constricted rat or mouse urethral arterioles, nerve-evoked vasodilatations or transient SMC Ca2+ reductions were largely diminished by l-nitroarginine (l-NA, 10 μM), a broad-spectrum NOS inhibitor, but not by l-NPA. The CGRP receptor antagonist BIBN-4096 (1 μM) shortened the vasodilatory responses, while atropine (1 μM) abolished the l-NA-resistant transient vasodilatory responses. Nerve-evoked endothelial Ca2+ transients were abolished by atropine plus guanethidine (10 μM), indicating its neurotransmitter origin and absence of non-adrenergic non-cholinergic endothelial NO release. In urethral arterioles, NO released from parasympathetic nerves counteracts sympathetic vasoconstrictions pre- and post-synaptically to restrict arteriolar contractility. KEY POINTS: Despite a higher energy consumption of the urethral musculature than the bladder detrusor muscle, ischaemic dysfunction of the urethra is less prevalent than that of the bladder. In the urethral arterioles, sympathetic vasoconstrictions are predominately mediated by ATP, not noradrenaline. NO released from parasympathetic nerves counteracts sympathetic vasoconstrictions by its pre-synaptic inhibition of sympathetic transmission as well as post-synaptic arteriolar smooth muscle relaxation. Acetylcholine released from parasympathetic nerves contributes to endothelium-dependent, transient vasodilatations, while CGRP released from sensory nerves prolongs NO-mediated vasodilatations. PDE5 inhibitors could be beneficial to maintain and/or improve urethral blood supply and in turn the volume and contractility of urethral musculature.
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Affiliation(s)
- Hikaru Hashitani
- Department of Cell Physiology, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan
| | - Retsu Mitsui
- Department of Cell Physiology, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan
| | - Yuuna Hirai
- Department of Cell Physiology, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan
| | - Hidekazu Tanaka
- Department of Cell Physiology, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan
| | - Kyoko Miwa-Nishimura
- Department of Cell Physiology, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan
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Abelson B, Sun D, Que L, Nebel RA, Baker D, Popiel P, Amundsen CL, Chai T, Close C, DiSanto M, Fraser MO, Kielb SJ, Kuchel G, Mueller ER, Palmer MH, Parker-Autry C, Wolfe AJ, Damaser MS. Sex differences in lower urinary tract biology and physiology. Biol Sex Differ 2018; 9:45. [PMID: 30343668 PMCID: PMC6196569 DOI: 10.1186/s13293-018-0204-8] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 09/26/2018] [Indexed: 12/12/2022] Open
Abstract
Females and males differ significantly in gross anatomy and physiology of the lower urinary tract, and these differences are commonly discussed in the medical and scientific literature. However, less attention is dedicated to investigating the varied development, function, and biology between females and males on a cellular level. Recognizing that cell biology is not uniform, especially in the lower urinary tract of females and males, is crucial for providing context and relevance for diverse fields of biomedical investigation. This review serves to characterize the current understanding of biological sex differences between female and male lower urinary tracts, while identifying areas for future research. First, the differences in overall cell populations are discussed in the detrusor smooth muscle, urothelium, and trigone. Second, the urethra is discussed, including anatomic discussions of the female and male urethra followed by discussions of cellular differences in the urothelial and muscular layers. The pelvic floor is then reviewed, followed by an examination of the sex differences in hormonal regulation, the urinary tract microbiome, and the reticuloendothelial system. Understanding the complex and dynamic development, anatomy, and physiology of the lower urinary tract should be contextualized by the sex differences described in this review.
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Affiliation(s)
- Benjamin Abelson
- Glickman Urological and Kidney Institute, Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Daniel Sun
- Glickman Urological and Kidney Institute, Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Lauren Que
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | | | - Dylan Baker
- UConn Center on Aging, University of Connecticut, 263 Farmington, Farmington, CT, USA
| | - Patrick Popiel
- Department of Obstetrics, Gynecology & Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
| | - Cindy L Amundsen
- Department of Obstetrics and Gynecology, Division of Urogynecology and Reconstructive Surgery, Duke University, Durham, NC, USA
| | - Toby Chai
- Department of Obstetrics, Gynecology & Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA.,Department of Urology, Yale School of Medicine, New Haven, CT, USA
| | | | - Michael DiSanto
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, NJ, USA
| | - Matthew O Fraser
- Department of Surgery, Division of Urology, Duke University Medical Center, Durham, NC, USA
| | - Stephanie J Kielb
- Department of Urology and Obstetrics and Gynecology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - George Kuchel
- UConn Center on Aging, University of Connecticut, 263 Farmington, Farmington, CT, USA
| | - Elizabeth R Mueller
- Department of Urology, Loyola University Chicago, Maywood, IL, USA.,Department of Obstetrics/Gynecology, Loyola University Chicago, Maywood, IL, USA
| | - Mary H Palmer
- School of Nursing, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Candace Parker-Autry
- Department of Obstetrics and Gynecology, Wake Forest School of Medicine, Winston-Salem, NC, USA.,Department of Urology, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Alan J Wolfe
- Department of Microbiology and Immunology, Loyola University Chicago, Health Sciences Division, Stritch School of Medicine, Maywood, IL, 60153, USA
| | - Margot S Damaser
- Glickman Urological and Kidney Institute, Cleveland Clinic Foundation, Cleveland, OH, USA. .,Department of Biomedical Engineering, Lerner Research Institute, The Cleveland Clinic, 9500 Euclid Avenue, ND20, Cleveland, OH, 44195, USA. .,Louis Stokes Cleveland VA Medical Center, Cleveland, OH, USA.
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Teng M, Kervinio F, Moutounaïck M, Miget G, Charlanes A, Chesnel C, Le Breton F, Amarenco G. Review of pelvic and perineal neuromuscular fatigue: Evaluation and impact on therapeutic strategies. Ann Phys Rehabil Med 2018; 61:345-351. [PMID: 30017491 DOI: 10.1016/j.rehab.2018.06.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 06/15/2018] [Accepted: 06/16/2018] [Indexed: 11/16/2022]
Abstract
BACKGROUND Pelvic floor fatigue is known by its clinical consequences (fecal incontinence, stress urinary incontinence, pelvic organ prolapse), but there are still few studies on the subject. OBJECTIVE This article presents an overview of the current knowledge of pelvic and perineal fatigue, focusing on its assessment and consequences in terms of evaluation and therapeutic strategies, to propose an evaluation that could be routinely performed. METHODS We performed a systematic review of the literature in MEDLINE via PubMed and Cochrane Library databases by using the keywords pelvic floor, muscular fatigue, physiopathology, stress urinary incontinence, pelvic organ prolapse, fecal incontinence, physical activity, and pelvic rehabilitation. We included reports of systematic reviews and retrospective and prospective studies on adult humans and animals in English or French published up to April 2018 with no restriction on start date. RESULTS We selected 59 articles by keyword search, 18 by hand-search and 3 specific guidelines (including the 2009 International Continence Society recommendations); finally 45 articles were included; 14 are described in the Results section (2 reviews of 6 and 20 studies, and 12 prospective observational or cross-over studies of 5 to 317 patients including 1 of animals). Perineal fatigue can be assessed by direct assessment, electromyography and spectral analysis and during urodynamics. Because pelvic floor fatigue assessments are not evaluated routinely, this fatigability is not always identified and is often falsely considered an exclusive pelvic floor weakness, as suggested by some rehabilitation methods that also weaken the pelvic floor instead of enhancing it. CONCLUSION Pelvic floor fatigue is not evaluated enough on a routine basis and the assessment is heterogeneous. A better knowledge of pelvic floor fatigue by standardized routine evaluation could lead to targeted therapeutic strategies.
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Affiliation(s)
- Maëlys Teng
- GRC 01, GREEN - groupe de recherche clinique en neuro-urologie, hôpital Tenon, Sorbonne université, AP-HP, 75020 Paris, France; Service de neuro-urologie, hôpital Tenon, AP-HP, 4, rue de la Chine, 75020 Paris, France.
| | - Florian Kervinio
- GRC 01, GREEN - groupe de recherche clinique en neuro-urologie, hôpital Tenon, Sorbonne université, AP-HP, 75020 Paris, France; Service de neuro-urologie, hôpital Tenon, AP-HP, 4, rue de la Chine, 75020 Paris, France
| | - Mirella Moutounaïck
- GRC 01, GREEN - groupe de recherche clinique en neuro-urologie, hôpital Tenon, Sorbonne université, AP-HP, 75020 Paris, France; Service de neuro-urologie, hôpital Tenon, AP-HP, 4, rue de la Chine, 75020 Paris, France
| | - Gabriel Miget
- GRC 01, GREEN - groupe de recherche clinique en neuro-urologie, hôpital Tenon, Sorbonne université, AP-HP, 75020 Paris, France; Service de neuro-urologie, hôpital Tenon, AP-HP, 4, rue de la Chine, 75020 Paris, France
| | - Audrey Charlanes
- GRC 01, GREEN - groupe de recherche clinique en neuro-urologie, hôpital Tenon, Sorbonne université, AP-HP, 75020 Paris, France; Service de neuro-urologie, hôpital Tenon, AP-HP, 4, rue de la Chine, 75020 Paris, France
| | - Camille Chesnel
- GRC 01, GREEN - groupe de recherche clinique en neuro-urologie, hôpital Tenon, Sorbonne université, AP-HP, 75020 Paris, France; Service de neuro-urologie, hôpital Tenon, AP-HP, 4, rue de la Chine, 75020 Paris, France
| | - Frédérique Le Breton
- GRC 01, GREEN - groupe de recherche clinique en neuro-urologie, hôpital Tenon, Sorbonne université, AP-HP, 75020 Paris, France; Service de neuro-urologie, hôpital Tenon, AP-HP, 4, rue de la Chine, 75020 Paris, France
| | - Gérard Amarenco
- GRC 01, GREEN - groupe de recherche clinique en neuro-urologie, hôpital Tenon, Sorbonne université, AP-HP, 75020 Paris, France; Service de neuro-urologie, hôpital Tenon, AP-HP, 4, rue de la Chine, 75020 Paris, France
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Tsumori T, Tsumiyama W. Sexual and Regional Differences in Myosin Heavy Chain Expression in the Rat External Urethral Sphincter. Anat Rec (Hoboken) 2017; 300:2058-2069. [PMID: 28667697 DOI: 10.1002/ar.23627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 04/13/2017] [Accepted: 04/20/2017] [Indexed: 11/11/2022]
Abstract
The external urethral sphincter is a unique striated muscle surrounding the urethra that plays a crucial role in urinary continence, and a comprehensive understanding of its morphology is needed to determine the pathophysiology underlying urinary incontinence and find suitable therapies. Differences between the sexes and among species regarding the fiber types present remain controversial. This study used triple immunofluorescence labeling to visualize one slow (Type 1) and two fast (Types 2A and 2B) myosin isoforms in rat external urethral sphincters from both sexes. Type 2A fibers predominated throughout the sphincter and Type 2B fibers were restricted to the proximal one-third of the external urethral sphincter in the female rats. Type 1 fibers were present adluminally and were concentrated in the proximal and distal segments of the sphincter. While most of the male external urethral sphincter comprised Type 2B fibers, Type 2A fibers intermingled among these fibers in the proximal one-third of the sphincter, and a few Type 1 fibers were present that were restricted to the adluminal region of the proximal segment. The fiber-type compositions and their areal densities changed in both sexes after gonadectomy. The areal density of the Type 1 fibers increased significantly in the ovariectomized females, especially in the distal segment. In the orchidectomized males, the areal densities of the Types 1 and 2A fibers increased significantly, but that of the Type 2B fibers decreased. These results indicate that myosin heavy chain expression in the rat external urethral sphincter is sexually dimorphic and shows regional differences. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 300:2058-2069, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Toshiko Tsumori
- Departments of Nursing, Faculty of Health and Welfare, Prefectural University of Hiroshima, Mihara, Japan
| | - Wakako Tsumiyama
- Physical Therapy, Faculty of Health and Welfare, Prefectural University of Hiroshima, Mihara, Japan
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Ragionieri L, Ravanetti F, Gazza F, Botti M, Ivanovska A, Cacchioli A. Morphological analysis of the urethral muscle of the male pig with relevance to urinary continence and micturition. J Anat 2015; 228:511-9. [PMID: 26573248 DOI: 10.1111/joa.12415] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/13/2015] [Indexed: 01/12/2023] Open
Abstract
To investigate whether the pig could be considered a suitable model to study lower urinary tract function and dysfunction, the pelvic urethra of 24 slaughtered male pigs were collected, and the associated muscles were macroscopically, histologically and histochemically analyzed. In cross-sections of the urethra, a muscular complex composed of an inner layer of smooth muscle and an outer layer of striated muscle that are not separated by fascial planes was observed. A tunica muscularis, composed of differently oriented smooth muscle bundles, is only evident in the proximal part of the pelvic urethra while, in the remaining part, it contributes to form the prostatic fibromuscular stroma. The striated urethral muscle surrounds the pelvic urethra in a horseshoe-like configuration with a dorsal longitudinal raphe, extending from the bladder neck to the central tendon of perineum. Proximally to the bladder, it is constituted of slow-twitch and fast-twitch myofibers of very small diameter, and embedded in an abundant collagen and elastic fiber net. Moving caudally it is gradually encircled and then completely substituted by larger and compact myofibers, principally presenting circular orientation and fast-twitch histochemical characteristics. So, like in humans, the cranial tract of the muscular system surrounding the pelvic urethra is principally composed of smooth musculature. The striated component cranially may have a role in blocking retrograde ejaculation, while the middle and caudal tracts may facilitate urine and semen flow, and seem especially concerned with the rapid and forceful urethral closure during active continence. Some differences in the morphology and structure between pigs and humans seem due to the different morphology of the 'secondary' sexual organs that develop from the urethral wall and to the different effect of gravity on the mechanics of the urinary system in quadruped and bipedal mammals.
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Affiliation(s)
- Luisa Ragionieri
- Department of Veterinary Sciences, University of Parma, Parma, Italy
| | | | - Ferdinando Gazza
- Department of Veterinary Sciences, University of Parma, Parma, Italy
| | - Maddalena Botti
- Department of Veterinary Sciences, University of Parma, Parma, Italy
| | - Ana Ivanovska
- Department of Veterinary Sciences, University of Parma, Parma, Italy
| | - Antonio Cacchioli
- Department of Veterinary Sciences, University of Parma, Parma, Italy
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Lim SH, Wang TJ, Tseng GF, Lee YF, Huang YS, Chen JR, Cheng CL. The distribution of muscles fibers and their types in the female rat urethra: cytoarchitecture and three-dimensional reconstruction. Anat Rec (Hoboken) 2013; 296:1640-9. [PMID: 23832822 DOI: 10.1002/ar.22740] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 05/16/2013] [Indexed: 12/27/2022]
Abstract
An attempt to explore urethral cytoarchitecture including the distribution of smooth muscles and fast and slow striated muscles of adult female Sprague Dawley rat--a popular model in studying lower urinary tract function. Histological and immunohistochemical stainings were carried out to investigate the distribution of urethral muscle fibers and motor end plates. The urethral sphincter was furthermore three-dimensionally reconstructed from serial histological sections. The mucosa at the distal urethra was significantly thicker than that of other segments. A prominent inner longitudinal and outer circular layer of smooth muscles covered the proximal end of urethra. Thick circular smooth muscles of the bladder neck region (urethral portion) decreased significantly distalward and longitudinal smooth muscles became 2- to 3-fold thicker in the rest of the urethra. An additional layer of striated muscles appeared externally after neck region (urethra) and in association with motor end plates ran throughout the remaining urethra as the striated sphincter layer. Most striated muscles were fast fibers while relatively fewer slow fibers often concentrated at the periphery. A pair of extraneous striated muscles, resembling the human urethrovaginal sphincter muscles, connected both sides of mainly the distal vagina to the dorsal striated muscles in the wall of the middle urethra. The tension provided by this pair of muscles, and in conjunction with the striated sphincter of the urethral wall, was likely to function to suspend the middle urethra and facilitates its closure. Comprehensive morphological data of urethral sphincter offers solid basis for researchers conducting studies on dysfunction of bladder outlet.
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Affiliation(s)
- Seh Hong Lim
- Department of Veterinary Medicine, College of Veterinary Medicine, National Chung-Hsing University, Taichung, Taiwan
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Schabrun SM, Stafford RE, Hodges PW. Anal sphincter fatigue: Is the mechanism peripheral or central? Neurourol Urodyn 2011; 30:1550-6. [DOI: 10.1002/nau.21162] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2011] [Accepted: 05/03/2011] [Indexed: 11/07/2022]
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Deffieux X, Hubeaux K, Dick J, Ismael SS, Raibaut P, Amarenco G. Urine leakage related to physical fatigue in women with urinary stress incontinence. J Obstet Gynaecol Res 2009; 35:738-45. [DOI: 10.1111/j.1447-0756.2008.01000.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Deffieux X, Hubeaux K, Faivre E, Raibaut P, Ismael S, Fernandez H, Amarenco G. Sacral reflexes and urinary incontinence in women: New concepts. Ann Phys Rehabil Med 2009; 52:256-68. [DOI: 10.1016/j.rehab.2008.12.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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10
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Deffieux X, Hubeaux K, Porcher R, Ismael SS, Raibaut P, Amarenco G. Decrease in urethral pressure following repeated cough efforts: A new concept for pathophysiology of stress urinary incontinence. Int J Urol 2007; 14:1019-24. [PMID: 17956530 DOI: 10.1111/j.1442-2042.2007.01887.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Xavier Deffieux
- Pierre & Marie Curie University; Urodynamics Laboratory, Rothschild Hospital, AP-HOP, 33 boulevard de Picpus, Paris Cedex 12, France.
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Deffieux X, Hubeaux K, Damphousse M, Raibaut P, Sheikh Ismael S, Thoumie P, Amarenco G, Lapeyre E, Jousse M. Fatigue neuromusculaire périnéale. ACTA ACUST UNITED AC 2006; 49:331-6, 413-7. [PMID: 16698109 DOI: 10.1016/j.annrmp.2006.03.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2006] [Accepted: 03/22/2006] [Indexed: 10/24/2022]
Abstract
AIM The physiology of urinary continence during stress is complex and the role of passive and active mechanisms remains unclear. Coughing leads to a contraction of urethral rhabdomyosphincter and pelvic floor muscles leading to a positive urethro-vesical gradient and continence. Neuromuscular fatigue can involve all striated muscles, including rhabdomyosphincter, peri-urethral and pelvic floor muscles. This article reviews results of studies assessing perineal muscular fatigue in urinary incontinence. MATERIALS AND METHODS A systematic review of the literature (Medline, Pascal and Embase) with use of the MESH keywords fatigue, stress, urinary incontinence, pelvic floor, urethra, urethral pressure, and muscle. RESULTS Animal models have shown that the pelvic muscles (iliococcygeus and pubococcygeous) exhibit more neuromuscular fatigue than classical skeletal striated muscles (i.e. soleus muscle). Although the human external urethral sphincter is considered to be a highly fatigue-resistant muscle with its high proportion of slow muscle fibers, repeated coughing seems to lead to decreased urethral pressure in numerous women affected with stress urinary incontinence. In this case, "urethral fatigue" might be a possibility. CONCLUSIONS Although few studies have focused on perineal muscular fatigue, such increased fatigue in pelvic floor muscles may play a role in the pathophysiologic features of stress urinary incontinence in women.
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Affiliation(s)
- X Deffieux
- Laboratoire d'Urodynamique et d'Explorations Neurophysiologiques du Périnée, Service de Rééducation Neurologique, Hôpital Rothschild, APHP, 75012 Paris, France.
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Lehtoranta M, Streng T, Yatkin E, Paranko J, Kolts I, Talo A, Santti R. Division of the male rat rhabdosphincter into structurally and functionally differentiated parts. ACTA ACUST UNITED AC 2006; 288:536-42. [PMID: 16604534 DOI: 10.1002/ar.a.20318] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In order to understand the structure-function relationship in the male rat rhabdosphincter, the 3D structure of the striated muscle and associated dense connective tissue was reconstructed from representative serial sections cut from the proximal urethra harboring the muscle. The 3D structure was correlated with electromyography (EMG) of the rhabdosphincter, urodynamic parameters (bladder pressure and flow rate), and longitudinal contraction force of the proximal urethra. The muscular component of the rhabdosphincter consisted of a homogeneous population of the fast-twitch-type fibers. In the cranial part, striated muscle formed a complete ring encircling the urethra, deferent ducts, and ducts from seminal vesicles and prostatic lobes. Toward the middle part, the amount of densely packed connective tissue lacking type III collagen increased anteriorly and posteriorly and penetrated the muscular ring that became divided first posteriorly and then anteriorly into two symmetrical halves. In the caudal part, a thin midsagittal dense connective tissue septum remained posteriorly. EMG recordings suggested that the rhabdosphincter muscle was functionally divided into two parts. Unlike the cranial and middle parts, the caudal part did not show the first depolarization peak. It appears that rapid oscillatory oblique-to-circular muscular contractions proceeding in craniocaudal direction in the cranial and middle part draw the anterior wall supported by arch-like dense connective tissue closer to the posterior wall supported by a more rigid rhomboidal raphe. Longitudinal contractions of the urethra are possibly evoked from the proximal and caudal parts of rhabdosphincter. These could lead to simultaneous increase in urethral pressure ensuring rapid urine flow rate. The caudal part could augment the opening of urethral lumen during oscillatory voiding.
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Affiliation(s)
- Mari Lehtoranta
- Department of Anatomy, Institute of Biomedicine, University of Turku, Turku, Finland
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Tokunaka S, Fujii H, Hashimoto H, Yachiku S. Proportions of fiber types in the external urethral sphincter of young nulliparous and old multiparous rabbits. UROLOGICAL RESEARCH 1993; 21:121-4. [PMID: 8503148 DOI: 10.1007/bf01788830] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The proportions of fast and slow myosin molecules in specimen's of the external urethral sphincter (EUS) from 6 young nulliparous (6-month-old) and 6 old multiparous (2-year-old) rabbits were studied using myosin heavy chain electrophoresis. The percentages of fast and slow myosin molecules were 80.4 +/- 4.5% and 19.6 +/- 4.5% in the EUS from nulliparas, and 68.7 +/- 6.3% and 31.3 +/- 6.3% in the EUS from multiparas. The difference between the two groups was significant (P < 0.01). We suggest that a selective decrease in the volume of type 2 (fast) muscle fibers and/or conversion of type 2 to type 1 (slow) muscle fibers had taken place in the EUS of old multiparas. The proportional change in the constituent muscle fibers of the EUS with aging may play a role in human genuine stress incontinence.
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Affiliation(s)
- S Tokunaka
- Department of Urology, Asahikawa Medical College, Japan
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