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Effect of phosphate and temperature on force exerted by white muscle fibres from dogfish.

Park-Holohan SJ, West TG, Woledge RC, Ferenczi MA, Barclay CJ, Curtin NA - J. Muscle Res. Cell. Motil. (2010)

Bottom Line: Effects of Pi (inorganic phosphate) are relevant to the in vivo function of muscle because Pi is one of the products of ATP hydrolysis by actomyosin and by the sarcoplasmic reticulum Ca(2+) pump.Pi sensitivity of force produced by dogfish fibres activated from the relaxed state was greater below normal body temperature (12 degrees C for dogfish) in agreement with what is known for other species.The force-temperature relationship for dogfish fibres (intact and permeabilized fibres activated from relaxed) showed that at 12 degrees C, normal body temperature, the force was near to its maximum value.

View Article: PubMed Central - PubMed

Affiliation: Molecular Medicine Section, National Heart and Lung Institute, Sir Alexander Fleming Building, Imperial College London, London, SW7 2AZ, UK.

ABSTRACT
Effects of Pi (inorganic phosphate) are relevant to the in vivo function of muscle because Pi is one of the products of ATP hydrolysis by actomyosin and by the sarcoplasmic reticulum Ca(2+) pump. We have measured the Pi sensitivity of force produced by permeabilized muscle fibres from dogfish (Scyliorhinus canicula) and rabbit. The activation conditions for dogfish fibres were crucial: fibres activated from the relaxed state at 5, 12, and 20 degrees C were sensitive to Pi, whereas fibres activated from rigor at 12 degrees C were insensitive to Pi in the range 5-25 mmol l(-1). Rabbit fibres activated from rigor were sensitive to Pi. Pi sensitivity of force produced by dogfish fibres activated from the relaxed state was greater below normal body temperature (12 degrees C for dogfish) in agreement with what is known for other species. The force-temperature relationship for dogfish fibres (intact and permeabilized fibres activated from relaxed) showed that at 12 degrees C, normal body temperature, the force was near to its maximum value.

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a Relationship between temperature and Pi sensitivity of force (=Δ Relative force/Δ log10 [Pi]). Experimental results shown as mean ± SE: Dogfish fibres activated from rigor (activation protocol 2), closed triangle; rabbit fibres activated from rigor (activation protocol 2), closed diamonds; dogfish fibres activated from relaxed state (activation protocol 1), open squares. Results from Coupland et al. (2001) for rabbit fibres activated from relaxed state, gray circles. The corresponding model predictions are shown as full lines and open triangle. b Summary of observations of the relationship between relative force and temperature. Relative force = force/maximum force. Coupland et al. (2001) broken gray line summary of observations of force produced by permeabilized rabbit fibres (no added Pi); intact fibre bundles from dogfish blackclosed circles; permeabilized fibres from dogfish activated from relaxed state (activation protocol 1), open squares. Full lines and open triangles are simulations from the model described in the text
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Fig4: a Relationship between temperature and Pi sensitivity of force (=Δ Relative force/Δ log10 [Pi]). Experimental results shown as mean ± SE: Dogfish fibres activated from rigor (activation protocol 2), closed triangle; rabbit fibres activated from rigor (activation protocol 2), closed diamonds; dogfish fibres activated from relaxed state (activation protocol 1), open squares. Results from Coupland et al. (2001) for rabbit fibres activated from relaxed state, gray circles. The corresponding model predictions are shown as full lines and open triangle. b Summary of observations of the relationship between relative force and temperature. Relative force = force/maximum force. Coupland et al. (2001) broken gray line summary of observations of force produced by permeabilized rabbit fibres (no added Pi); intact fibre bundles from dogfish blackclosed circles; permeabilized fibres from dogfish activated from relaxed state (activation protocol 1), open squares. Full lines and open triangles are simulations from the model described in the text

Mentions: Figure 4b (closed symbols) shows force produced by four bundles of intact fibres from dogfish tested in the range 2–20°C. Temperature strongly influenced force during isometric tetani at L0, but the dependence of force on temperature was non-linear. Reducing temperature below 12°C, the normal body temperature for dogfish, had a larger effect on force than increasing temperature did. Permeabilized dogfish fibres activated from the relaxed state (activation protocol 1) also show the effect of temperature on force. The results are included in Fig. 4b (open squares) and were very similar to those from intact fibres.Fig. 4


Effect of phosphate and temperature on force exerted by white muscle fibres from dogfish.

Park-Holohan SJ, West TG, Woledge RC, Ferenczi MA, Barclay CJ, Curtin NA - J. Muscle Res. Cell. Motil. (2010)

a Relationship between temperature and Pi sensitivity of force (=Δ Relative force/Δ log10 [Pi]). Experimental results shown as mean ± SE: Dogfish fibres activated from rigor (activation protocol 2), closed triangle; rabbit fibres activated from rigor (activation protocol 2), closed diamonds; dogfish fibres activated from relaxed state (activation protocol 1), open squares. Results from Coupland et al. (2001) for rabbit fibres activated from relaxed state, gray circles. The corresponding model predictions are shown as full lines and open triangle. b Summary of observations of the relationship between relative force and temperature. Relative force = force/maximum force. Coupland et al. (2001) broken gray line summary of observations of force produced by permeabilized rabbit fibres (no added Pi); intact fibre bundles from dogfish blackclosed circles; permeabilized fibres from dogfish activated from relaxed state (activation protocol 1), open squares. Full lines and open triangles are simulations from the model described in the text
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2908752&req=5

Fig4: a Relationship between temperature and Pi sensitivity of force (=Δ Relative force/Δ log10 [Pi]). Experimental results shown as mean ± SE: Dogfish fibres activated from rigor (activation protocol 2), closed triangle; rabbit fibres activated from rigor (activation protocol 2), closed diamonds; dogfish fibres activated from relaxed state (activation protocol 1), open squares. Results from Coupland et al. (2001) for rabbit fibres activated from relaxed state, gray circles. The corresponding model predictions are shown as full lines and open triangle. b Summary of observations of the relationship between relative force and temperature. Relative force = force/maximum force. Coupland et al. (2001) broken gray line summary of observations of force produced by permeabilized rabbit fibres (no added Pi); intact fibre bundles from dogfish blackclosed circles; permeabilized fibres from dogfish activated from relaxed state (activation protocol 1), open squares. Full lines and open triangles are simulations from the model described in the text
Mentions: Figure 4b (closed symbols) shows force produced by four bundles of intact fibres from dogfish tested in the range 2–20°C. Temperature strongly influenced force during isometric tetani at L0, but the dependence of force on temperature was non-linear. Reducing temperature below 12°C, the normal body temperature for dogfish, had a larger effect on force than increasing temperature did. Permeabilized dogfish fibres activated from the relaxed state (activation protocol 1) also show the effect of temperature on force. The results are included in Fig. 4b (open squares) and were very similar to those from intact fibres.Fig. 4

Bottom Line: Effects of Pi (inorganic phosphate) are relevant to the in vivo function of muscle because Pi is one of the products of ATP hydrolysis by actomyosin and by the sarcoplasmic reticulum Ca(2+) pump.Pi sensitivity of force produced by dogfish fibres activated from the relaxed state was greater below normal body temperature (12 degrees C for dogfish) in agreement with what is known for other species.The force-temperature relationship for dogfish fibres (intact and permeabilized fibres activated from relaxed) showed that at 12 degrees C, normal body temperature, the force was near to its maximum value.

View Article: PubMed Central - PubMed

Affiliation: Molecular Medicine Section, National Heart and Lung Institute, Sir Alexander Fleming Building, Imperial College London, London, SW7 2AZ, UK.

ABSTRACT
Effects of Pi (inorganic phosphate) are relevant to the in vivo function of muscle because Pi is one of the products of ATP hydrolysis by actomyosin and by the sarcoplasmic reticulum Ca(2+) pump. We have measured the Pi sensitivity of force produced by permeabilized muscle fibres from dogfish (Scyliorhinus canicula) and rabbit. The activation conditions for dogfish fibres were crucial: fibres activated from the relaxed state at 5, 12, and 20 degrees C were sensitive to Pi, whereas fibres activated from rigor at 12 degrees C were insensitive to Pi in the range 5-25 mmol l(-1). Rabbit fibres activated from rigor were sensitive to Pi. Pi sensitivity of force produced by dogfish fibres activated from the relaxed state was greater below normal body temperature (12 degrees C for dogfish) in agreement with what is known for other species. The force-temperature relationship for dogfish fibres (intact and permeabilized fibres activated from relaxed) showed that at 12 degrees C, normal body temperature, the force was near to its maximum value.

Show MeSH
Related in: MedlinePlus