Biomaterial Database

Muscle enthalpy production and its relationship to actomyosin ATPase. 1987

E Homsher

During a maintained tetanus most of the energy liberated is produced by ATP hydrolysis at the cross-bridge. The energy produced by ATP hydrolysis by the sarcoplasmic reticulum is, however, a significant fraction (0.35) of the total. The energy liberation rate depends on a variety of factors (including the shortening velocity, sarcomere length, temperature, fiber type, and duration of contraction) and is, for the most part, consistent with current cross-bridge models. At the beginning of tetanic stimulation, a significant amount of heat (approximately 30 mJ/g) is produced by calcium binding reactions in the sarcoplasm. In the transition from an isometric to a shortening contraction, the cross-bridge cycling rate increases, and as much as 6 mJ/g of unexplained heat is produced. This unexplained heat appears to involve enthalpy changes accompanying a redistribution of cross-bridge intermediates, and it is reversed by high-energy phosphate splitting after the cessation of shortening. The mechanistic significance of these enthalpy changes remains to be elucidated.

UI	MeSH Term	Description	Entries
D009119	Muscle Contraction	A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.	Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D000205	Actomyosin	A protein complex of actin and MYOSINS occurring in muscle. It is the essential contractile substance of muscle.
D000251	Adenosine Triphosphatases	A group of enzymes which catalyze the hydrolysis of ATP. The hydrolysis reaction is usually coupled with another function such as transporting Ca(2+) across a membrane. These enzymes may be dependent on Ca(2+), Mg(2+), anions, H+, or DNA.	ATPases,Adenosinetriphosphatase,ATPase,ATPase, DNA-Dependent,Adenosine Triphosphatase,DNA-Dependent ATPase,DNA-Dependent Adenosinetriphosphatases,ATPase, DNA Dependent,Adenosinetriphosphatases, DNA-Dependent,DNA Dependent ATPase,DNA Dependent Adenosinetriphosphatases,Triphosphatase, Adenosine
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013816	Thermodynamics	A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed)	Thermodynamic