caa a22 4500 47574473X CHVBK 20180406123510.0 cr unu---uuuuu 170329e20000101xx s 000 0 eng 10.1023/A:1005619014170 doi (NATIONALLICENCE)springer-10.1023/A:1005619014170 Measured and modeled properties of mammalian skeletal muscle: III. the effects of stimulus frequency on stretch-induced force enhancement and shortening-induced force depression [Elektronische Daten] [Ian Brown, Gerald Loeb] Stretch-induced force enhancement and shortening-induced force depression were examined in fast-twitch feline caudofemoralis muscle at 37∘C. These phenomena were induced by applying ramp length changes during the first 100-200 ms of an otherwise isometric contraction. The effects of various stimulus frequencies ranging from 30 to 120 pps were investigated over lengths ranging from 0.85 to 1.15 L 0. Distributed asynchronous stimulation of bundles of ventral roots was employed to produce smooth contractions at sub-tetanic stimulus frequencies in whole muscle. Of the two components of force enhancement identified by Noble (1992) we observed only the transient component that decays with time; we did not observe residual force enhancement. The force depression that we observed was symmetrical in almost all respects to the transient force enhancement, and was unlike the shortening-induced de-activation and residual force depression identified by Edman (Edman, 1975; Edman et al., 1993). Both transient force enhancement and depression were independent of work, load and activation. Reversals in the direction of ramp length changes following either an initial stretch or initial shortening were shown to cancel the effects of both transient force enhancement and transient force depression. The distances over which these cancellations could be achieved were different for the lengthening and shortening effects. This asymmetry can be reconciled with the predictions of Huxley's original cross-bridge mechanism by incorporating the recent suggestion that myosin heads can interact with multiple actin binding sites during a single ‘working' stroke. We conclude that the types of force enhancement/depression that are most likely to be encountered under physiological conditions are the transient effects observed here, but that even these will have relatively little effect on force production during most natural behaviors. Kluwer Academic Publishers, 2000 Brown Ian The MRC Group in Sensory-Motor Neuroscience, Department of Physiology, Queen's University, K7L 3N6, Kingston, ON, Canada aut Loeb Gerald The MRC Group in Sensory-Motor Neuroscience, Department of Physiology, Queen's University, K7L 3N6, Kingston, ON, Canada aut Journal of Muscle Research & Cell Motility Kluwer Academic Publishers 21/1(2000-01-01), 21-31 0142-4319 21:1<21 2000 21 10974 https://doi.org/10.1023/A:1005619014170 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1005619014170 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Brown Ian The MRC Group in Sensory-Motor Neuroscience, Department of Physiology, Queen's University, K7L 3N6, Kingston, ON, Canada aut NATIONALLICENCE 700 1- Loeb Gerald The MRC Group in Sensory-Motor Neuroscience, Department of Physiology, Queen's University, K7L 3N6, Kingston, ON, Canada aut NATIONALLICENCE 773 0- Journal of Muscle Research & Cell Motility Kluwer Academic Publishers 21/1(2000-01-01), 21-31 0142-4319 21:1<21 2000 21 10974 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer