Details

Autor(en) / Beteiligte

• Lieber, Richard L.
• Binder‐Markey, Benjamin I

Titel

Biochemical and structural basis of the passive mechanical properties of whole skeletal muscle

Ist Teil von

• The Journal of physiology, 2021-08, Vol.599 (16), p.3809-3823

Ort / Verlag

England: Wiley Subscription Services, Inc

Erscheinungsjahr

2021

Quelle

MEDLINE

Beschreibungen/Notizen

• Passive mechanical properties of whole skeletal muscle are not as well understood as active mechanical properties. Both the structural basis for passive mechanical properties and the properties themselves are challenging to determine because it is not clear which structures within skeletal muscle actually bear passive loads and there are not established standards by which to make mechanical measurements. Evidence suggests that titin bears the majority of the passive load within the single muscle cell. However, at larger scales, such as fascicles and muscles, there is emerging evidence that the extracellular matrix bears the major part of the load. Complicating the ability to quantify and compare across size scales, muscles and species, definitions of muscle passive properties such as stress, strain, modulus and stiffness can be made relative to many reference parameters. These uncertainties make a full understanding of whole muscle passive mechanical properties and modelling these properties very difficult. Future studies defining the specific load bearing structures and their composition and organization are required to fully understand passive mechanics of the whole muscle and develop therapies to treat disorders in which passive muscle properties are altered such as muscular dystrophy, traumatic laceration, and contracture due to upper motor neuron lesion as seen in spinal cord injury, stroke and cerebral palsy. figure legend Schematic representation of passive load bearing at various skeletal muscle scales. In the sarcomere (upper left), load is borne by the giant elastic protein titin and, to a lesser extent, desmin. The myofilaments actin and myosin are responsible for active force production. Sarcomeres in series (myofibrils) connect to the fibre surface at specialized focal adhesions called costameres at which desmin and other cytoskeletal proteins converge (upper right). Muscle fibres are embedded in a connective tissue matrix (lower left) composed primarily of basal lamina collagen type IV. At larger scales, passive load is borne in the perimysium (lower right) by perimysial cables that seem to be composed of collagen types 1 and 3 and this is where the majority of passive load is borne.