{"95af4cf87ffa1c7f150a05deb8bb810dinspo5":{"DOI":"10.1152/japplphysiol.00782.2025","ISBN":"","ISSN":"1522-1601","URL":"http://dx.doi.org/10.1152/japplphysiol.00782.2025","abstract":"Smooth muscle (SM) exhibits rapid mechanical adaptation in response to various stimuli, posing challenges for reproducible experimental results and consistent material parameter determination in biomechanical modeling. Preconditioning involving repeated loading and unloading cycles are commonly used to stabilize mechanical responses prior to testing. However, their influence on tissue properties and data variability remains underexplored. This study compares the effects of three preconditioning routines – passive cycling (PCYC), no preconditioning (PNPC), and free contraction (PFC) – on the active and passive force responses of porcine urinary bladder (UB) SM tissue. Three tissue strips from 12 UBs were randomly assigned to one of the routines and underwent an identical protocol involving a passive stretch ramp and two isometric contractions (IC1, IC2) to evaluate active and passive force development. After PCYC, the tissue generated the highest active (IC2: 44.7 ± 29.4 kPa) and passive tensions (IC2: 5.6 ± 4.3 kPa), though it also showed the highest variance in active tension. PNPC resulted in the lowest variance in active tension with a coefficient of variation (CV) of 45%, and PFC showed the lowest variance in passive tension, CV = 57%. These findings imply that the decision for a certain preconditioning protocol influences the observed mechanical properties. In this context, PFC appears promising for minimizing passive force variability and preventing creep-induced lengthening. This could offer a more reliable foundation for subsequent experiments analyzing mechanical parameters. This study underscores the importance of customized preconditioning strategies to enhance consistency and comparability in SM research and organ modeling.","annote":"","author":[{"family":"Kiem","given":"Simon"},{"family":"Papenkort","given":"Stefan"},{"family":"Borsdorf","given":"Mischa"},{"family":"Böl","given":"Markus"},{"family":"Siebert","given":"Tobias"}],"citation-label":"Kiem_2026","collection-editor":[{"family":"Siebert","given":"Tobias"}],"collection-title":"","container-author":[{"family":"Siebert","given":"Tobias"}],"container-title":"Journal of Applied Physiology","documents":[],"edition":"","editor":[{"family":"Siebert","given":"Tobias"}],"event-date":{"date-parts":[["2026","03"]],"literal":"2026"},"event-place":"","id":"95af4cf87ffa1c7f150a05deb8bb810dinspo5","interhash":"ad5f2b6a3128f8eb0f36ab2826d465bb","intrahash":"95af4cf87ffa1c7f150a05deb8bb810d","issue":"","issued":{"date-parts":[["2026","03"]],"literal":"2026"},"keyword":"bladder material adaptation biological urinary contraction tissue free soft properties","misc":{"language":"English","issn":"1522-1601","preprinturl":"https://journals.physiology.org/doi/abs/10.1152/japplphysiol.00782.2025","doi":"10.1152/japplphysiol.00782.2025"},"note":"","number":"","page":"","page-first":"","publisher":"American Physiological Society","publisher-place":"","status":"","title":"Shaping Smooth Muscle Forces: The Role of Preconditioning in Urinary Smooth Muscle","type":"article-journal","username":"inspo5","version":"","volume":""},"2f25a1adb4eeebb5ccf477386453f217inspo5":{"DOI":"10.1007/s00424-025-03075-7","ISBN":"","ISSN":"1432-2013","URL":"https://doi.org/10.1007/s00424-025-03075-7","abstract":"Mechanical organ models are crucial for understanding organ function and clinical applications. These models rely on input data regarding smooth muscle properties, typically gathered from experiments involving stimulations at different muscle lengths. However, reproducibility of these experimental results is a major challenge due to rapid changes in active and passive smooth muscle properties during the measurement period. Usually, preconditioning of the tissue is employed to ensure reproducible behavior in subsequent experiments, but this process itself alters the tissue's mechanical properties. To address this issue, three protocols (P1, P2, P3) without preconditioning were developed and compared to preserve the initial mechanical properties of smooth muscle tissue. Each protocol included five repetitive experimental cycles with stimulations at a long muscle length, varying in the number of stimulations at a short muscle length (P1: 0, P2: 1, P3: 2 stimulations). Results showed that P2 and P3 successfully reproduced the initial active force at a long length over five cycles, but failed to maintain the initial passive forces. Conversely, P1 was most effective in maintaining constant passive forces over the cycles. These findings are supported by existing adaptation models. Active force changes are primarily due to the addition or removal of contractile units in the contractile apparatus, while passive force changes mainly result from actin polymerization induced by contractions, leading to cytoskeletal stiffening. This study introduces a new method for obtaining reproducible smooth muscle parameters, offering a foundation for future research to replicate the mechanical properties of smooth muscle tissue without preconditioning.","annote":"","author":[{"family":"Kiem","given":"Simon"},{"family":"Papenkort","given":"Stefan"},{"family":"Borsdorf","given":"Mischa"},{"family":"Böl","given":"Markus"},{"family":"Siebert","given":"Tobias"}],"citation-label":"Kiem2025","collection-editor":[{"family":"Siebert","given":"Tobias"}],"collection-title":"","container-author":[{"family":"Siebert","given":"Tobias"}],"container-title":"Pfluegers Archiv - European Journal of Physiology","documents":[],"edition":"","editor":[{"family":"Siebert","given":"Tobias"}],"event-date":{"date-parts":[["2025","03","22"]],"literal":"2025"},"event-place":"","id":"2f25a1adb4eeebb5ccf477386453f217inspo5","interhash":"0aba6dffcddeb953c4db46121e64f033","intrahash":"2f25a1adb4eeebb5ccf477386453f217","issue":"","issued":{"date-parts":[["2025","03","22"]],"literal":"2025"},"keyword":"Urinary bladder Stimulation Stress–strain-relationship Biological tissue soft Adaptation","misc":{"language":"English","issn":"1432-2013","doi":"10.1007/s00424-025-03075-7"},"note":"","number":"","page":"","page-first":"","publisher":"","publisher-place":"","status":"","title":"Reproducibility of smooth muscle mechanical properties in consecutive stretch and activation protocols","type":"article-journal","username":"inspo5","version":"","volume":""},"86d35e263b284d088ad36a772e8c40b6inspo5":{"DOI":"10.1016/j.jmbbm.2022.105347","ISBN":"","ISSN":"","URL":"https://doi.org/10.1016%2Fj.jmbbm.2022.105347","abstract":"Insight into the global deformation of the urinary bladder during passive and active phases is crucial for understanding the biomechanics and function of the organ. Therefore, in the present study, the three-dimensional deformations of the porcine urinary bladder were investigated using 10 cameras in ex vivo experiments. Voltages between 20 V and 40 V were applied to induce contraction without outflow (isovolumetric) and against different back pressures (isobaric). The fluid volume in the bladder and the fluid volume pushed out of the bladder in the active state were measured. During filling, a roughly constant pressure of 2.5–4 cmH2O was measured for a large volume range, followed by a steep increase. Overall, the urinary bladder shape changes from elliptical to spherical in the active phase, resulting in a more homogeneous stress field. The active pressure decreases with increasing volume, while the actively generated stress increases up to 65 kPa at the maximum volume examined. Smaller filling volumes and lower back pressures allowed complete emptying, whereas higher back pressures prevent full emptying from larger filling states. Finally, a recently developed three-dimensional model was used to describe the active and passive bladder characteristics in order to qualitatively represent the mechanical properties. Overall, this study provides for the first time a comprehensive experimental data set at organ level that leads to an improved understanding of load transfer mechanisms within the urinary bladder and serves to validate corresponding models.","annote":"","author":[{"family":"Trostorf","given":"Robin"},{"family":"Orcajo","given":"Enrique Morales"},{"family":"Pötzke","given":"Amelie"},{"family":"Siebert","given":"Tobias"},{"family":"Böl","given":"Markus"}],"citation-label":"Trostorf_2022","collection-editor":[{"family":"Siebert","given":"Tobias"}],"collection-title":"","container-author":[{"family":"Siebert","given":"Tobias"}],"container-title":"Journal of the Mechanical Behavior of Biomedical Materials","documents":[],"edition":"","editor":[{"family":"Siebert","given":"Tobias"}],"event-date":{"date-parts":[["2022","09"]],"literal":"2022"},"event-place":"","id":"86d35e263b284d088ad36a772e8c40b6inspo5","interhash":"032878f78a28d5cf534daf6847ed894d","intrahash":"86d35e263b284d088ad36a772e8c40b6","issue":"","issued":{"date-parts":[["2022","09"]],"literal":"2022"},"keyword":"organ experiments Whole modelling characteristics Urinary bladder Active Ex Inspo Siebert vivo","misc":{"doi":"10.1016/j.jmbbm.2022.105347"},"note":"","number":"","page":"105347","page-first":"105347","publisher":"Elsevier BV","publisher-place":"","status":"","title":"A pilot study on active and passive ex vivo characterisation of the urinary bladder and its impact on three-dimensional modelling","type":"article-journal","username":"inspo5","version":"","volume":"133"}}