Economic force maintenance in a phasic smooth muscle of mollusca.
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.
Iwamoto
H
H
Department of Physiology, School of Medicine, Teikyo University, Tokyo, Japan.
Sugaya
R
R
Takei
T
T
Tsuchiya
T
T
D000818:Animals; D049872:Bivalvia / Q000502:physiology*; D004558:Electric Stimulation; D066298:In Vitro Techniques; D007537:Isometric Contraction; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000502:physiology*; D013997:Time Factors