FORCE-LOAD-VELOCITY RELATION AND THE INTERNAL LOAD OF TETANIZED FROG CARDIAC MUSCLE

Effect of muscle length on the force-velocity relationship of tetanized cardiac muscle.

Cat papillary muscles were tetanized with repetitive electrical stimulation in the presence of 10 ITIM caffeine and 10 mM calcium. Velocities were measured during the plateau of tetanus with quick releases to isotonic loads. The course of isotonic shortening was independent of time in the contraction cycle for at least 2 seconds after the attainment of peak isometric force. The force-velocity r...

The force-velocity relation and stepwise shortening in cardiac muscle.

A series of experiments was carried out to determine the effects of load variation on the character of stepwise shortening. We imposed afterloaded isotonic contractions on rat ventricular trabeculae, and measured the effect of load on pause duration, i.e., on the duration of the periods during which there was no sarcomere shortening. Sarcomere lengths were measured by optical diffraction. Incre...

Evidence that the velocity of sarcomere shortening in single frog atrial cardiac cells is load dependent.

Recent experiments using laser diffraction techniques to determine the time course and extent of sarcomere shortening in thin bundles of cardial tissue have given results which suggest that the velocity of sarcomere shortening in cardiac muscle is independent of the developed force (Nassar et al., 1974; Krueger and Pollack, 1975). However, the anatomical complexity of the intact tissue preclude...

Evidence That the Velocity of Sarcomere Shortening in Single Frog Atrial Cardiac Cells is Load Dependent

during isometric contraction. J Physiol (Lond) 251: 627-643 Krueger JW, Wittenberg BA (1978) Dynamics of myofilament sliding in single intact cardiac muscle cells (abstr). Circulation 58: (suppl II): 33 Lapicque L (1907) Recherches quantitative sur l'excitation electriquer des nerfs traitee comme une polarisation. J Physiol (Paris) 9: 620-635 Manring A, Nassar R, Johnson EA (1977) Light diffrac...

The relation between force and velocity in human muscle.