title: Experiments and mechanochemical modeling of smooth muscle contraction: significance of filament overlap.
abstract: The main function of smooth muscle is to maintain/regulate the size of different hollow organs through contraction and relaxation. The magnitude of the active force during contraction is dependent on the number of attached cross-bridges, which can be linked to the overlap between the thin and thick filaments. The relevance of filament overlap and the active cross-bridges in smooth muscle is investigated through a mechanical model founded on Hill's three-element model. The mechanical model describes a sarcomere-equivalent contractile unit supported by structural observations with a distinct filament overlap and a realistic framework for the filament sliding behavior based on force-velocity experiments. The mechanical model is coupled to the four-state latch-model by Hai and Murphy to capture the electromechanical activation from intracellular calcium concentration to load-bearing cross-bridges. The model is fitted to isometric experiments performed on the pig carotid media and on isotonic quick-release experiments found in the literature. The proposed coupled mechanochemical model with the description of the filament overlap, which has a significant influence on the results, is able to predict isometric experimental data performed at different muscle lengths. The relevance of the filament overlap and the load-bearing cross-bridges is investigated through the model by simulating additional scenarios that has been documented in the literature.
authors: Royal Institute of Technology (KTH), Department of Solid Mechanics, School of Engineering Sciences, Osquars Backe 1, 100 44 Stockholm, Sweden.
authors: Saeil C
authors: SC
authors: Murtada
authors: Anders
authors: A
authors: Arner
authors: Gerhard A
authors: GA
authors: Holzapfel
mesh_terms: D008841:Actin Cytoskeleton / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D007537:Isometric Contraction / Q000502:physiology*; D040542:Mechanotransduction, Cellular / Q000502:physiology; D008954:Models, Biological; D009130:Muscle, Smooth / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation; D013314:Stress, Mechanical; D034421:Sus scrofa
chemical_list: D002118:Calcium