{"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":""},"eeb7eec4365e95de248e73401073785ainspo5":{"DOI":"10.1016/j.jbiomech.2024.112107","ISBN":"","ISSN":"0021-9290","URL":"http://dx.doi.org/10.1016/j.jbiomech.2024.112107","abstract":"As part of the digestive system, the stomach plays a crucial role in the health and well-being of an organism. It produces acids and performs contractions that initiate the digestive process and begin the break-up of ingested food. Therefore, its mechanical properties are of interest. This study includes a detailed investigation of strains in the porcine stomach wall during passive organ filling. In addition, the observed strains were applied to tissue samples subjected to biaxial tensile tests. The results show inhomogeneous strains during filling, which tend to be higher in the circumferential direction (antrum: 13.2%, corpus: 22.0%, fundus: 67.8%), compared to the longitudinal direction (antrum: 4.8%, corpus: 24.7%, fundus: 50.0%) at a maximum filling of 3500 ml. Consequently, the fundus region experienced the greatest strain. In the biaxial tensile experiments, the corpus region appeared to be the stiffest, reaching nominal stress values above 400 kPa in the circumferential direction, whereas the other regions only reached stress levels of below 50 kPa in both directions for the investigated stretch range. Our findings gain new insight into stomach mechanics and provide valuable data for the development and validation of computational stomach models.","annote":"","author":[{"family":"Papenkort","given":"Stefan"},{"family":"Borsdorf","given":"Mischa"},{"family":"Kiem","given":"Simon"},{"family":"Böl","given":"Markus"},{"family":"Siebert","given":"Tobias"}],"citation-label":"Papenkort_2024","collection-editor":[{"family":"Siebert","given":"Tobias"}],"collection-title":"","container-author":[{"family":"Siebert","given":"Tobias"}],"container-title":"Journal of Biomechanics","documents":[],"edition":"","editor":[{"family":"Siebert","given":"Tobias"}],"event-date":{"date-parts":[["2024","05"]],"literal":"2024"},"event-place":"","id":"eeb7eec4365e95de248e73401073785ainspo5","interhash":"252446e0dc715c88dc9bb6f9988761ec","intrahash":"eeb7eec4365e95de248e73401073785a","issue":"","issued":{"date-parts":[["2024","05"]],"literal":"2024"},"keyword":"Biaxial Biological Stress-strain-relationship mechanics stomach tissue Inspo testing tensile soft Porcine Organ","misc":{"language":"English","issn":"0021-9290","doi":"10.1016/j.jbiomech.2024.112107"},"note":"","number":"","page":"112107","page-first":"112107","publisher":"Elsevier BV","publisher-place":"","status":"","title":"Regional differences in stomach stretch during organ filling and their implications on the mechanical stress response","type":"article-journal","username":"inspo5","version":"","volume":"168"}}