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We examined the tension responses to ramp shortening and lengthening over a range of velocities (0.1–5 L 0/s) and at 20°C and 30°C in tetanized intact fibre bundles from a rat fast (flexor hallucis brevis) muscle; fibre length (L 0) was 2.2 mm and sarcomere length ∼2.5 μm. The tension change during ramp releases as well as ramp stretches showed an early(More)
In experiments on small bundles of intact fibers from a rat fast muscle, in vitro, we examined the decline in force in repeated tetanic contractions; the aim was to characterize the effect of shortening and of temperature on the initial phase of muscle fatigue. Short tetanic contractions were elicited at a control repetition rate of 1/60 s, and fatigue was(More)
We examined the tension change induced by a rapid temperature jump (T-jump) in shortening and lengthening active muscle fibres. Experiments were done on segments of permeabilized single fibres (length (L0) approximately 2 mm, sarcomere length 2.5 microm) from rabbit psoas muscle; [MgATP] was 4.6 mm, pH 7.1, ionic strength 200 mm and temperature(More)
The aim of the present study was to examine the temperature dependence of active force in lengthening and shortening muscle. Experiments were done, in vitro, on bundles of intact fibres (fibre length L0 ~2 mm; sarcomere length ~2.5 μm) isolated from a rat fast muscle (flexor hallucis brevis) and a ramp length change of 5–7 % L0 was applied on the plateau of(More)
Analysis of tension responses to ramp length changes in muscle can provide important information about the crossbridge cycle. During a ramp length change, the force response of an active muscle shows an early change in slope (the P₁ transition) followed by a later, gradual change in slope (the P₂ transition). Modeling shows that the first transition(More)
We examined, over a wide range of temperatures (10–35°C), the isometric tension and tension during ramp shortening at different velocities (0.2–4 L 0/s) in tetanized intact fibre bundles from a rat fast (flexor hallucis brevis) muscle; fibre length (L 0) was 2.2 mm and sarcomere length ~2.5 μm. During a ramp shortening, the tension change showed an initial(More)
We examined the tension responses to ramp shortening and rapid temperature jump (<0.2 ms, 3-4 degrees C T-jump) in maximally Ca(2+)-activated rabbit psoas muscle fibres at 8-9 degrees C (the fibre length (L(0)) was approximately 1.5 mm and sarcomere length 2.5 microm). The aim was to investigate the strain sensitivity of crossbridge force generation in(More)
................................................................................................................................................. ii ACKNOWLEDGEMENTS .......................................................................................................................... v 1. CHAPTER 1 CONCLUSIONS(More)
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