Biomaterial Database

The mechanical activity of chick embryonic myocardial cell aggregates. 1981

W T Clusin, and W E Hamilton, and D V Nelson

1. Simultaneous recordings of membrane potential and edge movement were obtained in spontaneously beating chick embryonic myocardial cell aggregates, which are known to behave as an isopotential syncytium.2. The time course of edge movement was similar in different aggregates, and in different regions of the same aggregate.3. Peak amplitude was increased by 10(-6)m-ouabain, and by rapid reduction of the external sodium concentration.4. Peak amplitude was decreased during single premature action potentials, but sustained rapid pacing produced an ascending staircase.5. Depolarizing current pulses increased both the amplitude and duration of the contraction, and caused potentiation of the next spontaneous beat. Edge displacement during a series of pulses was a monotonic function of membrane potential.6. Edge movement between action potentials (diastolic movement) was well fitted by an exponential with a mean time constant of 69 msec. Diastolic edge movement was due to a weak, slowly decaying contractile force, which was demonstrated in cells grown on a linear-elastic nylon bristle.7. The time course of diastolic edge movement remained constant, or nearly constant, during variations in peak amplitude that resulted from prematurity of the action potential, exposure to 10(-6)m-ouabain, spontaneous mechanical alternans, or prolongation of the action potential by current pulses.8. In contrast, reduction of the external sodium concentration produced marked, selective slowing of the diastolic edge movement. Similar slowing occurred during cooling and during staircase. Diastolic edge movement was selectively accelerated when the preceding interbeat interval was prolonged by a hyperpolarizing current pulse.9. The above observations are consistent with the hypothesis that edge displacement is a monotonic function of contractile force.10. The slow relaxation between action potentials probably reflects removal of intracellular calcium across the surface membrane in exchange for sodium. Changes in the rate of calcium removal may play a role in the regulation of contractility in this tissue.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D009200	Myocardial Contraction	Contractile activity of the MYOCARDIUM.	Heart Contractility,Inotropism, Cardiac,Cardiac Inotropism,Cardiac Inotropisms,Contractilities, Heart,Contractility, Heart,Contraction, Myocardial,Contractions, Myocardial,Heart Contractilities,Inotropisms, Cardiac,Myocardial Contractions
D009206	Myocardium	The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.	Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
D010042	Ouabain	A cardioactive glycoside consisting of rhamnose and ouabagenin, obtained from the seeds of Strophanthus gratus and other plants of the Apocynaceae; used like DIGITALIS. It is commonly used in cell biological studies as an inhibitor of the NA(+)-K(+)-EXCHANGING ATPASE.	Acocantherin,G-Strophanthin,Acolongifloroside K,G Strophanthin
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
D002465	Cell Movement	The movement of cells from one location to another. Distinguish from CYTOKINESIS which is the process of dividing the CYTOPLASM of a cell.	Cell Migration,Locomotion, Cell,Migration, Cell,Motility, Cell,Movement, Cell,Cell Locomotion,Cell Motility,Cell Movements,Movements, Cell
D002642	Chick Embryo	The developmental entity of a fertilized chicken egg (ZYGOTE). The developmental process begins about 24 h before the egg is laid at the BLASTODISC, a small whitish spot on the surface of the EGG YOLK. After 21 days of incubation, the embryo is fully developed before hatching.	Embryo, Chick,Chick Embryos,Embryos, Chick
D006321	Heart	The hollow, muscular organ that maintains the circulation of the blood.	Hearts
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential
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