Iwamoto H, Sugaya R, Takei T, Tsuchiya T
Department of Physiology, School of Medicine, Teikyo University, Tokyo, Japan.
Jpn J Physiol. 1988;38(6):887-95. doi: 10.2170/jjphysiol.38.887.
The time course of the ability of active shortening was compared to that of isometric contractile force during contraction-relaxation cycles of the pedal retractor muscle of Mytilus by measuring the maximal shortening velocity and the rate of force redevelopment after a quick release. The contractile force had its peak at 2 s after stimulus initiation and decayed with a half relaxation time of 8.3 s at 10 degrees C. At 6 s after stimulus initiation, both the maximal velocity of shortening and the rate of force redevelopment had decreased to 30% or less of the initial values, while 70% of peak force was retained. The results suggest a mechanism of economic force maintenance with a reduced rate of crossbridge cycling.
