Biomaterial Database

Cross-bridge behaviour in skinned smooth muscle of the guinea-pig taenia coli at altered ionic strength. 1988

H Arheden, and A Arner, and P Hellstrand

Department of Physiology and Biophysics, University of Lund, Sweden.

1. The effects of varied levels (25-300 mM) of ionic strength on mechanical properties and ATP hydrolysis rate of chemically skinned guinea-pig taenia coli fibres were investigated. 2. The tension development following activation by calcium (pCa 4.8), and relaxation following removal of calcium (pCa 9), were slower in 25 mM compared to 150 mM ionic strength. In fibres activated by thiophosphorylation of myosin light chains, by exposure to ATP-gamma-S, the tension development was rapid and independent of ionic strength. 3. The maximal shortening velocity (Vmax) was obtained from force-velocity relations determined by the quick-release method. The rate of ATP hydrolysis (JATP) was determined by measurement of pyruvate released from phosphoenolpyruvate (PEP). In order to obtain maximal Vmax and JATP at a Mg-ATP concentration of 1 mM, an ATP regenerating system was required. In thiophosphorylated fibres 2 mM-phosphocreatine (PCr) or 3.2 mM-PEP were adequate for maximal Vmax and JATP respectively. In calcium-activated fibres 5 mM-PCr was required for maximal Vmax. 4. The isometric force of thiophosphorylated fibres showed a biphasic dependence on ionic strength with a maximum at 90 mM. Vmax was essentially unchanged between 50 and 200 mM ionic strength. At 25 mM ionic strength, isometric force and Vmax were decreased by, respectively, about 15 and 25%. At 250 mM ionic strength, isometric force and Vmax were decreased by, respectively, 47 and 33%. 5. Vmax decreased with decreasing [Mg-ATP]. At [Mg-ATP] less than 0.1 mM there was no difference in Vmax between 35 and 150 mM ionic strength. At 250 mM ionic strength Vmax was lower than that at 150 mM at all [Mg-ATP]. 6. JATP during contraction in thiophosphorylated fibres at 35, 150 and 250 mM ionic strength was respectively, 0.62, 0.98 and 0.93 mumol g-1 min-1. The energetic tension cost (JATP/force) increased with ionic strength. 7. The force response to a quick stretch was investigated in the relaxed, contracted and rigor states at 25, 150 and 250 mM ionic strength. Stiffness in the relaxed state increased with speed of stretch and was higher the lower the ionic strength. In the contracted and rigor states, stiffness was also affected by ionic strength, but the relative effect in the contracted state was small.(ABSTRACT TRUNCATED AT 400 WORDS)

UI	MeSH Term	Description	Entries
D007537	Isometric Contraction	Muscular contractions characterized by increase in tension without change in length.	Contraction, Isometric,Contractions, Isometric,Isometric Contractions
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
D009130	Muscle, Smooth	Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)	Muscle, Involuntary,Smooth Muscle,Involuntary Muscle,Involuntary Muscles,Muscles, Involuntary,Muscles, Smooth,Smooth Muscles
D009994	Osmolar Concentration	The concentration of osmotically active particles in solution expressed in terms of osmoles of solute per liter of solution. Osmolality is expressed in terms of osmoles of solute per kilogram of solvent.	Ionic Strength,Osmolality,Osmolarity,Concentration, Osmolar,Concentrations, Osmolar,Ionic Strengths,Osmolalities,Osmolar Concentrations,Osmolarities,Strength, Ionic,Strengths, Ionic
D010725	Phosphocreatine	An endogenous substance found mainly in skeletal muscle of vertebrates. It has been tried in the treatment of cardiac disorders and has been added to cardioplegic solutions. (Reynolds JEF(Ed): Martindale: The Extra Pharmacopoeia (electronic version). Micromedex, Inc, Englewood, CO, 1996)	Creatine Phosphate,Neoton,Phosphocreatine, Disodium Salt,Phosphorylcreatine,Disodium Salt Phosphocreatine,Phosphate, Creatine
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
D006168	Guinea Pigs	A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.	Cavia,Cavia porcellus,Guinea Pig,Pig, Guinea,Pigs, Guinea
D006868	Hydrolysis	The process of cleaving a chemical compound by the addition of a molecule of water.
D000255	Adenosine Triphosphate	An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.	ATP,Adenosine Triphosphate, Calcium Salt,Adenosine Triphosphate, Chromium Salt,Adenosine Triphosphate, Magnesium Salt,Adenosine Triphosphate, Manganese Salt,Adenylpyrophosphate,CaATP,CrATP,Manganese Adenosine Triphosphate,MgATP,MnATP,ATP-MgCl2,Adenosine Triphosphate, Chromium Ammonium Salt,Adenosine Triphosphate, Magnesium Chloride,Atriphos,Chromium Adenosine Triphosphate,Cr(H2O)4 ATP,Magnesium Adenosine Triphosphate,Striadyne,ATP MgCl2
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