Limits...
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.

Show MeSH

Related in: MedlinePlus

Summaries of the relationship between relative force and log10 [Pi] where [Pi] is in units of mmol l−1. Forces were expressed relative to that produced at the lowest [Pi] to which the fibre was exposed. Mean ± SEM. a Dogfish fibres. Results for activation from the relaxed state (activation protocol 1): open circles, 5°C (n = 30); open triangles, 12°C (n = 20); open squares, 20°C (n = 10). Activation from rigor (activation protocol 2): closed triangles, 12°C (n = 16–18). b Rabbit fibres. Activation from rigor (activation protocol 2): closed diamonds, 20°C (n = 18); closed triangles, 35°C (n = 11–24). Rabbit fibre results from Coupland et al. (2001): gray squares, 20°C; gray circles, 35°C. Regression lines are shown for each set of results
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2908752&req=5

Fig3: Summaries of the relationship between relative force and log10 [Pi] where [Pi] is in units of mmol l−1. Forces were expressed relative to that produced at the lowest [Pi] to which the fibre was exposed. Mean ± SEM. a Dogfish fibres. Results for activation from the relaxed state (activation protocol 1): open circles, 5°C (n = 30); open triangles, 12°C (n = 20); open squares, 20°C (n = 10). Activation from rigor (activation protocol 2): closed triangles, 12°C (n = 16–18). b Rabbit fibres. Activation from rigor (activation protocol 2): closed diamonds, 20°C (n = 18); closed triangles, 35°C (n = 11–24). Rabbit fibre results from Coupland et al. (2001): gray squares, 20°C; gray circles, 35°C. Regression lines are shown for each set of results

Mentions: The example records in Fig. 1 show that force produced by dogfish fibres was influenced by temperature and [Pi]. Force increases abruptly when temperature is increased after 8 s of activation. Force was less in the solution with added Pi (20 mmol l−1, broken lines in Fig. 1) than with no added Pi (full lines). In each experiment there was a repeat test with one of the solutions; the repeat measurements were averaged and then force with 20 mmol l−1 added Pi was expressed relative to force without added Pi. The results from all 30 experiments of this type are summarized in Fig. 3a (open symbols), where the relative force is plotted against the logarithm of the total Pi concentration, that is the background level plus any added Pi (see Methods). The effect of Pi on force is greater at 5°C than at either 12 or 20°C; the effect is almost the same at the two higher temperatures.Fig. 3


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)

Summaries of the relationship between relative force and log10 [Pi] where [Pi] is in units of mmol l−1. Forces were expressed relative to that produced at the lowest [Pi] to which the fibre was exposed. Mean ± SEM. a Dogfish fibres. Results for activation from the relaxed state (activation protocol 1): open circles, 5°C (n = 30); open triangles, 12°C (n = 20); open squares, 20°C (n = 10). Activation from rigor (activation protocol 2): closed triangles, 12°C (n = 16–18). b Rabbit fibres. Activation from rigor (activation protocol 2): closed diamonds, 20°C (n = 18); closed triangles, 35°C (n = 11–24). Rabbit fibre results from Coupland et al. (2001): gray squares, 20°C; gray circles, 35°C. Regression lines are shown for each set of results
© Copyright Policy
Related In: Results  -  Collection

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

Fig3: Summaries of the relationship between relative force and log10 [Pi] where [Pi] is in units of mmol l−1. Forces were expressed relative to that produced at the lowest [Pi] to which the fibre was exposed. Mean ± SEM. a Dogfish fibres. Results for activation from the relaxed state (activation protocol 1): open circles, 5°C (n = 30); open triangles, 12°C (n = 20); open squares, 20°C (n = 10). Activation from rigor (activation protocol 2): closed triangles, 12°C (n = 16–18). b Rabbit fibres. Activation from rigor (activation protocol 2): closed diamonds, 20°C (n = 18); closed triangles, 35°C (n = 11–24). Rabbit fibre results from Coupland et al. (2001): gray squares, 20°C; gray circles, 35°C. Regression lines are shown for each set of results
Mentions: The example records in Fig. 1 show that force produced by dogfish fibres was influenced by temperature and [Pi]. Force increases abruptly when temperature is increased after 8 s of activation. Force was less in the solution with added Pi (20 mmol l−1, broken lines in Fig. 1) than with no added Pi (full lines). In each experiment there was a repeat test with one of the solutions; the repeat measurements were averaged and then force with 20 mmol l−1 added Pi was expressed relative to force without added Pi. The results from all 30 experiments of this type are summarized in Fig. 3a (open symbols), where the relative force is plotted against the logarithm of the total Pi concentration, that is the background level plus any added Pi (see Methods). The effect of Pi on force is greater at 5°C than at either 12 or 20°C; the effect is almost the same at the two higher temperatures.Fig. 3

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