منابع مشابه
Regulation of Cardiac Muscle Contractility
The heart's physiological performance, unlike that of skeletal muscle, is regulated primarily by variations in the contractile force developed by the individual myocardial fibers. In an attempt to identify the basis for the characteristic properties of myocardial contraction, the individual cardiac contractile proteins and their behavior in contractile models in vitro have been examined. The lo...
متن کاملMaximum Velocity as an Index of Contractility in Cardiac Muscle
The use of maximum velocity of shortening (Vmas) as an index of contractility has been based on the assumption that Vraox of muscle fibers is equivalent t° Vmax of the contractile element. It is shown here that such equivalence applies to the two-element model of skeletal muscle but not to three-element models of cardiac muscle. Analysis of published data in terms of the Voigt and Maxwell three...
متن کامل2-deoxy-ATP enhances contractility of rat cardiac muscle.
To investigate the kinetic parameters of the crossbridge cycle that regulate force and shortening in cardiac muscle, we compared the mechanical properties of cardiac trabeculae with either ATP or 2-deoxy-ATP (dATP) as the substrate for contraction. Comparisons were made in trabeculae from untreated rats (predominantly V1 myosin) and those treated with propylthiouracil (PTU; V3 myosin). Steady-s...
متن کاملImmobilized catecholamine and cocaine effects on contractility of cardiac muscle.
Isoproterenol, norepinephrine, and epinephrine covalently bound to glass beads exert a positive inotropic effect on isometrically contracting papillary muscles from cats. Immobilized isoproterenol maintains increases in force and velocity of contraction for more than 5 hr. 1 muM Cocaine potentiates the action of immobilized norepinephrine, isoproterenol, and epinephrine, but not of isoprotereno...
متن کاملCardiac contractility modulation by non-excitatory currents: studies in isolated cardiac muscle.
BACKGROUND Myocardial contractility can be altered using voltage clamp techniques by modulating amplitude and duration of the action potential resulting in enhanced calcium entry in the cell of isolated muscle strips (Non-Excitatory Currents; NEC). Extracellular electrical stimuli delivered during the absolute refractory period (Cardiac Contractility Modulation; CCM) have recently been shown to...
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ژورنال
عنوان ژورنال: The Journal of Physiology
سال: 1966
ISSN: 0022-3751
DOI: 10.1113/jphysiol.1966.sp007931