Biomaterial Database

Sarcomere length effects on the Sr2+- and Ca2+-activation curves in skinned frog muscle fibres. 1979

D G Moisescu, and R Thieleczek

1. A procedure recently described to produce rapid changes in [Ca2+] and [Sr2+] within the whole cross-section of skinned muscle preparations (Moisescu, D.G. (1976) Nature 262, 610--613, and Moisescu, D.G. and Thieleczek, R. (1978) J. Physiol. 275, 241--262) has enabled us to obtain whole Ca2+- or Sr2+-activation curves at different sacromere lengths with the same preparation. 2. The maximal isometric force response was found to be very similar in Ca2+-and Sr2+-buffered solutions for otherwise identical conditions. 3. The change in sarcomere length between approx. 2.2 and 2.6 micron reversibly shifted both the Ca2+- and the Sr2+-activation curves by approx. 0.1 log units towards lower concentrations of the activator, without affecting their shape. However, the change in sarcomere length in the range above 2.6 micron did not have an effect upon the relative isometric force response-pCa (and -pSr) relationship. 4. All the Ca2+- and Sr2+-activation curves present a similar steepness and indicate that the relative isometric force increases from approx. 10 to 90% if the concentration of the activator is increased 3-fold. 5. The half time for force development in these experiments did not appear to be influenced by the length of the sarcomeres. 6. A potentiometric method for determining the apparent affinity constants of Ca2+, Mg2+ and Sr2+ to EGTA and ATP under various conditions is described.

UI	MeSH Term	Description	Entries
D008274	Magnesium	A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
D008433	Mathematics	The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Mathematic
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
D011893	Rana esculenta	An edible species of the family Ranidae, occurring in Europe and used extensively in biomedical research. Commonly referred to as "edible frog".	Pelophylax esculentus
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D004533	Egtazic Acid	A chelating agent relatively more specific for calcium and less toxic than EDETIC ACID.	EGTA,Ethylene Glycol Tetraacetic Acid,EGATA,Egtazic Acid Disodium Salt,Egtazic Acid Potassium Salt,Egtazic Acid Sodium Salt,Ethylene Glycol Bis(2-aminoethyl ether)tetraacetic Acid,Ethylenebis(oxyethylenenitrile)tetraacetic Acid,GEDTA,Glycoletherdiamine-N,N,N',N'-tetraacetic Acid,Magnesium-EGTA,Tetrasodium EGTA,Acid, Egtazic,EGTA, Tetrasodium,Magnesium EGTA
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
D001001	Anura	An order of the class Amphibia, which includes several families of frogs and toads. They are characterized by well developed hind limbs adapted for jumping, fused head and trunk and webbed toes. The term "toad" is ambiguous and is properly applied only to the family Bufonidae.	Bombina,Frogs and Toads,Salientia,Toad, Fire-Bellied,Toads and Frogs,Anuras,Fire-Bellied Toad,Fire-Bellied Toads,Salientias,Toad, Fire Bellied,Toads, Fire-Bellied
D013324	Strontium	An element of the alkaline earth family of metals. It has the atomic symbol Sr, atomic number 38, and atomic weight 87.62.