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Durnin L, Kwok B, Kukadia P, McAvera R, Corrigan RD, Ward SM, Zhang Y, Chen Q, Koh SD, Sanders KM, Mutafova-Yambolieva VN. An ex vivo bladder model with detrusor smooth muscle removed to analyse biologically active mediators released from the suburothelium. J Physiol 2018; 597:1467-1485. [PMID: 30289177 DOI: 10.1113/jp276924] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 10/02/2018] [Indexed: 12/15/2022] Open
Abstract
KEY POINTS Studies of urothelial cells, bladder sheets or lumens of filled bladders have suggested that mediators released from urothelium into suburothelium (SubU)/lamina propria (LP) activate mechanisms controlling detrusor excitability. None of these approaches, however, has enabled direct assessment of availability of mediators at SubU/LP during filling. We developed an ex vivo mouse bladder preparation with intact urothelium and SubU/LP but no detrusor, which allows direct access to the SubU/LP surface of urothelium during filling. Pressure-volume measurements during filling demonstrated that bladder compliance is governed primarily by the urothelium. Measurements of purine mediators in this preparation demonstrated asymmetrical availability of purines in lumen and SubU/LP, suggesting that interpretations based solely on intraluminal measurements of mediators may be inaccurate. The preparations are suitable for assessments of release, degradation and transport of mediators in SubU/LP during bladder filling, and are superior to experimental approaches previously used for urothelium research. ABSTRACT The purpose of this study was to develop a decentralized (ex vivo) detrusor smooth muscle (DSM)-denuded mouse bladder preparation, a novel model that enables studies on availability of urothelium-derived mediators at the luminal and anti-luminal aspects of the urothelium during filling. Urinary bladders were excised from C57BL6/J mice and the DSM was removed by fine-scissor dissection without touching the mucosa. Morphology and cell composition of the preparation wall, pressure-volume relationships during filling, and fluorescent dye permeability of control, protamine sulfate- and lipopolysaccharide-treated denuded bladders were characterized. The preparation wall contained intact urothelium and suburothelium (SubU)/lamina propria (LP) and lacked the DSM and the serosa. The utility of the model for physiological research was validated by measuring release, metabolism and transport of purine mediators at SubU/LP and in bladder lumen during filling. We determined asymmetrical availability of purines (e.g. ATP, ADP, AMP and adenosine) in lumen and at SubU/LP during filling, suggesting differential mechanisms of release, degradation and bilateral transurothelial transport of purines during filling. Some observations were validated in DSM-denuded bladder of the cynomolgus monkey (Macaca fascicularis). The novel model was superior to current models utilized to study properties of the urothelium (e.g. cultured urothelial cells, bladder mucosa sheets mounted in Ussing chambers or isolated bladder strips in organ baths) in that it enabled direct access to the vicinity of SubU/LP during authentic bladder filling. The model is particularly suitable for understanding local mechanisms of urothelium-DSM connectivity and for broad understanding of the role of urothelium in regulating continence and voiding.
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Affiliation(s)
- Leonie Durnin
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, NV, 89557-0575, USA
| | - Benjamin Kwok
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, NV, 89557-0575, USA
| | - Priya Kukadia
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, NV, 89557-0575, USA
| | - Roisin McAvera
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, NV, 89557-0575, USA
| | - Robert D Corrigan
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, NV, 89557-0575, USA
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, NV, 89557-0575, USA
| | - Ying Zhang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Qi Chen
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, NV, 89557-0575, USA
| | - Sang Don Koh
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, NV, 89557-0575, USA
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, NV, 89557-0575, USA
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