This work was supported by the National Institute of Diabetes and Digestive and Kidney Diseases Grant DK41315.

All procedures involving animals described in this manuscript were conducted according the National Institutes of Health Guide for the Care and Use of Laboratory Animals and the Institutional Animal Use and Care Committee at the University of Nevada.
NOTE: The model presented here consists of the removal of the detrusor muscle while the urothelium and SubU/LP remain intact (Figure 1B) to enable investigators direct access...

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	<li>Apodaca, G., Balestreire, E., Birder, L. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+uroepithelial-associated+sensory+web.">The uroepithelial-associated sensory web.</a> Kidney International. 72, 1057-1064 (2007).</li><li>Fry, C. H., Vahabi, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Role+of+the+Mucosa+in+Normal+and+Abnormal+Bladder+Function.">The Role of the Mucosa in Normal and Abnormal Bladder Function.</a> Basic and Clinical Pharmacology and Toxicology. , 57-62 (2016).</li><li>Merrill, L., Gonzalez, E. J., Girard, B. M., Vizzard, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Receptors,+channels,+and+signalling+in+the+urothelial+sensory+system+in+the+bladder.">Receptors, channels, and signalling in the urothelial sensory system in the bladder.</a> Nature Reviewes Urology. 13, 193-204 (2016).</li><li>Ferguson, D. R., Kennedy, I., Burton, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ATP+is+released+from+rabbit+urinary+bladder+epithelial+cells+by+hydrostatic+pressure+changes--a+possible+sensory+mechanism?.">ATP is released from rabbit urinary bladder epithelial cells by hydrostatic pressure changes--a possible sensory mechanism?.</a> Journal of Physiology. 505, 503-511 (1997).</li><li>Wang, E. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ATP+and+purinergic+receptor-dependent+membrane+traffic+in+bladder+umbrella+cells.">ATP and purinergic receptor-dependent membrane traffic in bladder umbrella cells.</a> Journal of Clinical Investigation. 115, 2412-2422 (2005).</li><li>Miyamoto, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+role+for+Piezo1+in+stretch-evoked+Ca(2)(+)+influx+and+ATP+release+in+urothelial+cell+cultures.">Functional role for Piezo1 in stretch-evoked Ca(2)(+) influx and ATP release in urothelial cell cultures.</a> Journal of Biological Chemistry. 289, 16565-16575 (2014).</li><li>Mochizuki, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+TRPV4+cation+channel+mediates+stretch-evoked+Ca2++influx+and+ATP+release+in+primary+urothelial+cell+cultures.">The TRPV4 cation channel mediates stretch-evoked Ca2+ influx and ATP release in primary urothelial cell cultures.</a> Journal of Biological Chemistry. 284, 21257-21264 (2009).</li><li>McLatchie, L. M., Fry, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ATP+release+from+freshly+isolated+guinea-pig+bladder+urothelial+cells:+a+quantification+and+study+of+the+mechanisms+involved.">ATP release from freshly isolated guinea-pig bladder urothelial cells: a quantification and study of the mechanisms involved.</a> BJU International. 115, 987-993 (2015).</li><li>Birder, L. A., Apodaca, G., de Groat, W. C., Kanai, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adrenergic-+and+capsaicin-evoked+nitric+oxide+release+from+urothelium+and+afferent+nerves+in+urinary+bladder.">Adrenergic- and capsaicin-evoked nitric oxide release from urothelium and afferent nerves in urinary bladder.</a> American Journal of Physiology Renal Physiology. 275, F226-F229 (1998).</li><li>Birder, L. A., Kanai, A. J., de Groat, W. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DMSO:+effect+on+bladder+afferent+neurons+and+nitric+oxide+release.">DMSO: effect on bladder afferent neurons and nitric oxide release.</a> Journal of Urology. 158, 1989-1995 (1997).</li><li>Birder, L. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vanilloid+receptor+expression+suggests+a+sensory+role+for+urinary+bladder+epithelial+cells.">Vanilloid receptor expression suggests a sensory role for urinary bladder epithelial cells.</a> Proceedings of the National Academy of Sciences U S A. 98, 13396-13401 (2001).</li><li>Birder, L. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Beta-adrenoceptor+agonists+stimulate+endothelial+nitric+oxide+synthase+in+rat+urinary+bladder+urothelial+cells.">Beta-adrenoceptor agonists stimulate endothelial nitric oxide synthase in rat urinary bladder urothelial cells.</a> Journal of Neuroscience. 22, 8063-8070 (2002).</li><li>Durnin, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+ex+vivo+bladder+model+with+detrusor+smooth+muscle+removed+to+analyse+biologically+active+mediators+released+from+the+suburothelium.">An ex vivo bladder model with detrusor smooth muscle removed to analyse biologically active mediators released from the suburothelium.</a> Journal of Physiology. 597, 1467-1485 (2019).</li><li>Yoshida, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-neuronal+cholinergic+system+in+human+bladder+urothelium.">Non-neuronal cholinergic system in human bladder urothelium.</a> Urology. 67, 425-430 (2006).</li><li>Beckel, J. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pannexin+1+channels+mediate+the+release+of+ATP+into+the+lumen+of+the+rat+urinary+bladder.">Pannexin 1 channels mediate the release of ATP into the lumen of the rat urinary bladder.</a> Journal of Physiology. 593, 1857-1871 (2015).</li><li>Collins, V. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=OnabotulinumtoxinA+significantly+attenuates+bladder+afferent+nerve+firing+and+inhibits+ATP+release+from+the+urothelium.">OnabotulinumtoxinA significantly attenuates bladder afferent nerve firing and inhibits ATP release from the urothelium.</a> BJU International. 112, 1018-1026 (2013).</li><li>Daly, D. M., Nocchi, L., Liaskos, M., McKay, N. G., Chapple, C., Grundy, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Age-related+changes+in+afferent+pathways+and+urothelial+function+in+the+male+mouse+bladder.">Age-related changes in afferent pathways and urothelial function in the male mouse bladder.</a> Journal of Physiology. 592, 537-549 (2014).</li><li>Durnin, L., Hayoz, S., Corrigan, R. D., Yanez, A., Koh, S. D., Mutafova-Yambolieva, V. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Urothelial+purine+release+during+filling+of+murine+and+primate+bladders.">Urothelial purine release during filling of murine and primate bladders.</a> American Journal of Physiology Renal Physiology. 311, F708-F716 (2016).</li><li>Gonzalez, E. J., Heppner, T. J., Nelson, M. T., Vizzard, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purinergic+signalling+underlies+transforming+growth+factor-beta-mediated+bladder+afferent+nerve+hyperexcitability.">Purinergic signalling underlies transforming growth factor-beta-mediated bladder afferent nerve hyperexcitability.</a> Journal of Physiology. 594, 3575-3588 (2016).</li></ol>

Parts of this work was previously published in the Journal of Physiology (PMCID: PMC6418748; DOI:10.1113/JP27692413). Permission has been granted by Wiley and Sons, Inc. for the use of materials from this publication. The authors have no financial or other conflicts to disclose.

The bladder has two functions: storage and voiding of urine. Normal operation of these functions requires proper mechanical sensing of intraluminal volume and pressure and transduction of signals through cells in the bladder wall to regulate detrusor muscle excitability. The bladder mucosa (urothelium) is believed to regulate bladder excitability by releasing a variety of signaling molecules in the SubU/LP that affect numerous cell types in the bladder wall. Currently, most attempts at characterization of urothelium-deri...

The purpose of this model is to enable direct access to the submucosal side of the bladder mucosa during different phases of bladder filling.
The bladder must refrain from premature contraction during filling and empty when critical volume and pressure are reached. Abnormal continence or voiding of urine are frequently associated with abnormal excitability of the detrusor smooth muscle (DSM) in the course of bladder filling. Excitability of DSM is determined by factors intrinsic to the smooth muscle cells and by influences generated by different cell types within the bladder wall. The wall of the urinary bladder consists of urothelium (mucosa), suburothelium (SubU)/lamina propria (LP), detrusor smooth muscle (DSM) and serosa (Figure 1A). The urothelium consists of umbrella cells (i.e., the outermost layer of the urothelium), intermediate cells, and basal cells (i.e., the innermost layer of the urothelium). Various types of cells, including interstitial cells, fibroblasts, afferent nerve terminals, small blood vessels, and immune cells reside in the SubU/LP. It is widely assumed that the bladder urothelium is a sensory organ that initiates reflex micturition and continence by releasing mediators into the submucosa that affect cells in the SubU/ LP and the DSM1,2,3. For the most part, such assumptions are based on studies that have demonstrated release of mediators: from pieces of mucosa exposed to changes in hydrostatic pressure4,5; from cultured urothelial cells exposed to stretch6,7, hypotonicity-induced cell swelling7 or drag forces8; from isolated bladder wall strips upon receptor or nerve activation9,10,11,12,13,14; and in bladder lumen at end of bladder filling15,16,17,18,19. While such studies were instrumental to demonstrate release of mediators upon mechanical stimulation of bladder wall segments or cultured urothelial cells, they need to be supported by direct evidence for release of mediators in the submucosa that is elicited by physiological stimuli that reproduce bladder filling. This is a challenging task given that the SubU/LP is located deep in the bladder wall hampering the straightforward access to the vicinity of SubU/LP during bladder filling.
Here, we illustrate a decentralized (ex vivo) murine bladder model with the detrusor muscle removed13 that was developed to facilitate studies on local mechanisms of mechanotransduction that participate in the signaling between the bladder urothelium, DSM and other cell types in the bladder wall. This approach is superior to using flat bladder wall sheets, bladder wall strips or cultured urothelial cells because it allows direct measurements in the vicinity of SubU/LP of urothelium-derived mediators that are released or formed in response to physiological pressures and volumes in the bladder and avoids potential phenotypic changes in cell culture. It can be used to measure availability, release, metabolism and transurothelial transport of mediators in SubU/LP at different stages of bladder filling (Figure 1B). The preparation can also be used to examine urothelial signaling and mechanotransduction in models of overactive and underactive bladder syndromes.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>CaCl2</td>
			<td>Fisher</td>
			<td>C79</td>
			<td>Source flexible</td>
		</tr>
		<tr>
			<td>Dextrose</td>
			<td>Fisher</td>
			<td>D16</td>
			<td>Source flexible</td>
		</tr>
		<tr>
			<td>Dissecting pins</td>
			<td>Fine Science Tools</td>
			<td>26002-20</td>
			<td>Source flexible</td>
		</tr>
		<tr>
			<td>Infusion Pump</td>
			<td>Kent Scientific</td>
			<td>GenieTouch</td>
			<td>Source flexible</td>
		</tr>
		<tr>
			<td>KCl</td>
			<td>Fisher</td>
			<td>P217</td>
			<td>Source flexible</td>
		</tr>
		<tr>
			<td>KH2PO4</td>
			<td>Fisher</td>
			<td>P284</td>
			<td>Source flexible</td>
		</tr>
		<tr>
			<td>Light source</td>
			<td>SCHOTT ACEI</td>
			<td></td>
			<td>Source flexible</td>
		</tr>
		<tr>
			<td>Microscope</td>
			<td>Olympus SZX7</td>
			<td></td>
			<td>Flexible to use any scope</td>
		</tr>
		<tr>
			<td>MgCl2</td>
			<td>Fisher</td>
			<td>M33</td>
			<td>Source flexible</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Fisher</td>
			<td>S671</td>
			<td>Source flexible</td>
		</tr>
		<tr>
			<td>NaHCO3</td>
			<td>Fisher</td>
			<td>S233</td>
			<td>Source flexible</td>
		</tr>
		<tr>
			<td>Needles 25G</td>
			<td>Becton Dickinson</td>
			<td>305122</td>
			<td>Source flexible</td>
		</tr>
		<tr>
			<td>Organ bath</td>
			<td>Custom made</td>
			<td></td>
			<td>Flexible source; We made it from Radnoti dissecting dish</td>
		</tr>
		<tr>
			<td>PE-20 tubing</td>
			<td>Intramedic</td>
			<td>427405</td>
			<td>Source flexible</td>
		</tr>
		<tr>
			<td>Pressure transducer</td>
			<td>AD instrument</td>
			<td></td>
			<td>Source flexible</td>
		</tr>
		<tr>
			<td>S&#38;T Forceps</td>
			<td>Fine Science Tools</td>
			<td>00632-11</td>
			<td>Source flexible</td>
		</tr>
		<tr>
			<td>Software pressure-volume</td>
			<td>AD Instruments</td>
			<td>Power lab</td>
			<td></td>
		</tr>
		<tr>
			<td>Suture Nylon, 6-0</td>
			<td>AD surgical</td>
			<td>S-N618R13</td>
			<td>Source flexible</td>
		</tr>
		<tr>
			<td>Suture Silk, 6-0</td>
			<td>Deknatel via Braintree Scientific, Inc.</td>
			<td>07J1500190</td>
			<td>Source flexible</td>
		</tr>
		<tr>
			<td>Syringes 1 ml</td>
			<td>Becton Dickinson</td>
			<td>309602</td>
			<td>Source flexible</td>
		</tr>
		<tr>
			<td>Vannas Spring Scissors</td>
			<td>Fine Science Tools</td>
			<td>15000-08</td>
			<td>Source flexible</td>
		</tr>
		<tr>
			<td>Water circulator</td>
			<td>Baxter</td>
			<td>K-MOD 100</td>
			<td>Source flexible</td>
		</tr>
	</tbody>
</table>

a decentralized (ex vivo) murine bladder model with the detrusor muscle removed for direct access to the suburothelium during bladder filling

Previous studies have established the release of chemical substances from flat bladder mucosa sheets affixed in Ussing chambers and exposed to changes in hydrostatic pressure or mechanical stretch and from cultured urothelial cells upon hydrostatic pressure changes, stretch, cell swelling, or drag forces, and in bladder lumen at end of filling. Such findings led to the assumption that these mediators are also released in suburothelium (SubU)/lamina propria (LP) during bladder filling, where they affect cells deep in the bladder wall to ultimately regulate bladder excitability. There are at least two obvious limitations in such studies: 1) none of these approaches provide direct information about the presence of mediators in SubU/LP, and 2) the stimuli used are not physiological and do not recapitulate authentic filling of the bladder. Here, we discuss a procedure that enables direct access to the suburothelial surface of the bladder mucosa in the course of bladder filling. The murine detrusor-free preparation we created closely resembles filling of the intact bladder and allows pressure-volume studies to be performed on the bladder in the absence of confounding signaling from spinal reflexes and detrusor smooth muscle. Using the novel detrusor-free bladder model, we recently demonstrated that intravesical measurements of mediators cannot be used as a proxy to what has been released or present in the SubU/LP during bladder filling. The model enables examination of urothelium-derived signaling molecules that are released, generated by metabolism and/or transported into the SubU/LP during the course of bladder filling to transmit information to neurons and smooth muscle of the bladder and regulate its excitability during continence and micturition.

The wall of murine detrusor-free bladder preparation is intact and contains all layers except the DSM and serosa. Proof-of-principle studies demonstrated that the DSM-free bladder wall includes urothelium and SubU/LP while the tunica muscularis and the serosa are absent (Figure 2)13.
Filling of the detrusor-free bladder approximates normal bladder filling. <strong cl...

Watch this Scientific Journal Video about A Decentralized Ex Vivo Murine Bladder Model with the Detrusor Muscle Removed for Direct Access to the Suburothelium during Bladder Filling at JoVE.com

A Decentralized Ex Vivo Murine Bladder Model with the Detrusor Muscle Removed for Direct Access to the Suburothelium during Bladder Filling

The detrusor-free bladder model enables direct access to the suburothelium to study local mechanisms for regulation of biologically active mediator availability in suburothelium/lamina propria during storage and voiding of urine. The preparation closely resembles filling of an intact bladder and allows pressure-volume studies to be performed without systemic influences.

A Decentralized (Ex Vivo) Murine Bladder Model with the Detrusor Muscle Removed for Direct Access to the Suburothelium during Bladder Filling

Previous studies have established the release of chemical substances from flat bladder mucosa sheets affixed in Ussing chambers and exposed to changes in ...

Our bladder model with a removed detrusor muscle is a new experimental approach to studying simultaneously the availability of urothelial mediators in the lamia propria and bladder lumen during bladder filling. This model can provide new insights into the signaling mechanisms between urothelium, suburothelium, and detrusor muscle that regulate bladder excitability during filling. Begin by placing the intact murine bladder specimen into a dissecting dish under a dissection microscope containing 10 degrees celsius oxygenated KBS and cleaning out the connective and fat tissues around the bladder.Pin a small portion of the dome of the isolated bladder all the way through the outermost edge of the detrusor muscle far from the innermost edge of the muscle that faces the suburothelium lamia propria to a sylgard covered dissecting dish filled with KBS, and pin the ureters and bladder neck to display the intact bladder preparation. Using fine-tipped forceps, gently pull a piece of the serosa at the corner between the ureter and the bladder body and adjust the light of the microscope to increase the transparency and to distinguish the margin of the submucosa underneath the detrusor muscle. To avoid perforating the preparation wall, be sure to cut away the detrusor muscle only while the lateral edge of the bladder mucosa is clearly visible.Using fine-tipped scissors, begin cutting the bladder wall along the inner surface of the detrusor muscle layer while gently pulling the cut segment away from the preparation taking care that the lateral edge of the mucosa can be observed while avoiding touching the edge of the tissue. Leave a small piece of the detrusor muscle on top of the bladder dome to allow preparation to be immobilized during the remaining steps of the protocol and fill a two centimeter piece of 20 polyethylene tubing with 37 degree celsius oxygenated KBS. After inserting the catheter into the orifice of the bladder urethra, gently push the catheter until the catheter tip reaches the approximate middle of the bladder.Then secure the catheter in the surrounding tissue of the bladder neck with a double loop 6.0 nylon suture. After checking the tissue for leaks, place the denuded bladder preparation into a three milliliter chamber of 37 degree celsius water jacketed organ dish with a sylgard bottom and secure the catheter to the side of the chamber so that the preparation does not float above the surface of the perfusion solution. Connect the bladder catheter to a piece of polyethylene 20 tubing connected to a three-way stopcock and an infusion syringe filled with 37 degree celsius oxygenated KBS and start the infusion pump to fill the bladder with KBS taking care to monitor the filling volume in the intravesical pressure during the filling.To detect mediators within the suburothelium lamina propria aspect of the preparation, collect aliquots of the bath solution at various appropriate experimental time points and process the samples according to the planned downstream analysis. The denuded bladder preparation wall contains the urothelium and suburothelium but not detrusor smooth muscle. The pressure volume relationships are remarkably similar in the intact and denuded preparations.The suitability of the model for measuring urothelium-derived mediators that are released in the suburothelium lamina propria side during filling can be tested by measuring the release of purine mediators into the solution bathing the suburothelium lamina propria of the denuded preparation. As demonstrated, negligible amounts of purines can be detected in a bath containing an isolated bladder preparation with an intact detrusor muscle;whereas the amounts of these purines are significantly higher in samples collected from the bath containing a denuded bladder preparation. Notably, the distribution of purines and metabolites in samples collected from the lumen and the suburothelium lamina propria at the end of filling differ significantly.Addition of atheno ATP, a highly fluorescent analog of ATP, to the suburothelial side of the detrusor-free preparation results in a decrease in atheno ATP and an increase in the atheno ATP products, atheno ADP, atheno AMP, and atheno ADO. Likewise, the addition of atheno ATP to the lumen preparation results in a decrease in atheno ATP and an increase in atheno ADP, atheno AMP, and atheno ADO in the lumen. Further, the addition of atheno ATP to the suburothelium lamina propria side of the denuded preparation results in the appearance of atheno AMP and atheno ADO within the lumen.Likewise, adding atheno ATP to the lumen results in the appearance of atheno AMP and atheno ADO in the suburothelium lamina propria. Following this procedure, the availability of excitatory and inhibitory mediators can be measured at the lamina propria and in the bladder lumen at different stages of bladder filling. Bilateral transurethral transport of mediators and metabolism of mediators can also be studied using this model.Using this new bladder model will result in new understanding of intrinsic, local mechanosensitive signaling between the urothelium and detrusor smooth muscle that control bladder excitability in health and disease.

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7.1K visualizações.  University of Nevada Reno School of Medicine. Nosso modelo de bexiga com um músculo detrusor removido é uma nova abordagem experimental para estudar simultaneamente a disponibilidade de mediadores uroteliais na propria lamia e lúmen da bexiga durante o preenchimento da bexiga. Este modelo pode fornecer novas percepções sobre os mecanismos de sinalização entre urotélio, suburotélio e músculo detrusor que regulam a excitabilidade da bexiga durante o preenchimento. Comece colocando a amostra intacta da bexiga murina em um prato de...