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  • 1
    Electronic Resource
    Electronic Resource
    The mechanical properties of polyneuronally innervated, myotomal muscle fibres isolated from a teleost fish (Myoxocephalus scorpius) (1988)
    Springer
    Pflügers Archiv 412 (1988), S. 524-529 
    Details
    ISSN: 1432-2013
    Keywords: Muscle contraction ; Fish ; Myotomal muscle ; Force-velocity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Single or small bundles of fibres were isolated from the abdominal myotomes of the sculpinMyoxocephalus scorpius, a teleost with a polyneuronal pattern of fast muscle innervation. Fibres responded to a supra-threshold stimulus with an all-or-none twitch. Tetanic fusion frequency at 3°C was 40–60 Hz, and the twitch tetanus ratio 0.70. Maximum isometric tension was 281 kN m−2. Similar isometric contractile properties were obtained from the focally innervated fast muscle fibres of another teleost, the eel,Anguilla anguilla. The response of sculpin fibres to stretch during tetanus was similar to that reported for frog twitch fibres. A 5% stretch of 25–50 ms duration increased force to 1.4P 0 which decayed to a steady level 5–10% above that of a control tetanus. The force-velocity relationship was also studied. Maximum contraction velocity was 4.75 Ls−1. Force-velocity data were not adequately described by a simple hyperbola. Alternative methods of curve fitting have been explored and discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582542
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  • 2
    Electronic Resource
    Electronic Resource
    Temperature and the energy cost of oscillatory work in teleost fast muscle fibres (1991)
    Springer
    Pflügers Archiv 419 (1991), S. 177-183 
    Details
    ISSN: 1432-2013
    Keywords: Temperature ; Fish muscle ; Oscillatory work ; Energetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Bundles of 20–30 fast muscle fibres were isolated from the abdominal myotomes of the short-horned sculpin (Myoxocephalus scorpius L.). The energy cost of contraction was measured during oscillatory work at 4 °C and 15 °C following treatment with iodoacetate and nitrogen gas to block glycolysis and aerobic metabolism. Isolated fibres were subjected to sinusoidal length changes about in situ resting length and stimulated at a selected phase in the strain cycle. Preliminary experiments with untreated preparations established the strain amplitude and stimulation parameters required to maximize work output over a range of cycle frequencies at 4 °C and 15 °C. Following oscillatory work, treated preparations were rapidly frozen, freeze-dried and the concentrations of phosphocreatine (PCr), creatine, adenosine 5′-triphosphate (ATP), adenosine 5′- di- and mono-phosphate and inosine 5-monophosphate measured by high performance liquid chromatography. The concentration of PCr declined in proportion to the total work done for up to 64 cycles without a significant change in ATP. Maximum power output was produced at a cycle frequency of 5 Hz at 4 °C (14–18 W/kg) and 17 Hz at 15 °C (23–27 W/kg). The rate of utilization of PCr per cycle was independent of temperature. However, since work per cycle was higher at 4 °C (2.7–3.7 mJ/g wet weight) than 15 °C (1.2–1.6 mJ/g wet weight), the energetic cost of contraction decreased with increasing temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00373004
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  • 3
    Electronic Resource
    Electronic Resource
    Further studies on the adaptation of fish myofibrillar ATPases to different cell temperatures (1977)
    Springer
    Pflügers Archiv 371 (1977), S. 257-262 
    Details
    ISSN: 1432-2013
    Keywords: Cell temperature ; Environmental temperature ; Fish ; Myofibrillar ATPase ; Temperature compensation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Previous studies on fish Mg2+Ca2+ activated myofibrillar ATPases have been extended to species inhabiting diverse thermal environments. Cold adapted ATPases have considerably higher catalytic centred activities at low temperatures than warm adapted ATPases. Differences in cell temperature have also lead to evolutionary modifications in thermodynamic activation parameters. The free energies (ΔG2+), enthalpies (ΔH2+) and entropies (ΔS2+) of activation of the Mg2+Ca2+ myofibrillar ATPase are positively correlated with adaptation temperature. Myofibrils with CaATP−2 as substrate in the absence of Mg2+ will hydrolyse ATP by a mechanism not associated with fibril shortening. Differences in activation enthalpies (ΔHH) between cold and warm adapted Ca2+-activated myofibrillar ATPases are less pronounced than for the physiological ATPase. Furthermore the Ca2+-activated ATPase showed no relationship between environmental temperature and substrate turnover number or free energy of activation (ΔG2+).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00586266
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  • 4
    Electronic Resource
    Electronic Resource
    Evolutionary adaptation of muscle power output to environmental temperature: force-velocity characteristics of skinned fibres isolated from antarctic, temperate and tropical marine fish (1985)
    Springer
    Pflügers Archiv 405 (1985), S. 136-140 
    Details
    ISSN: 1432-2013
    Keywords: Muscle ; Temperature ; Mechanics ; Forcevelocity ; Skinned fibres ; Antarctic fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract 1. Single fast fibres were isolated from the myotomal muscles of icefish (Chaenocephalus aceratus Lönnberg, Antarctica), North Sea Cod (Gadus morhua L.) and Pacific Blue Marlin (Makaira nigricans Wakiya, Hawaii). Fibres were chemically skinned with the non-ionic detergent Brij-58. 2. Maximum tensions (Po, kN m−2) developed at the characteristic body temperature of each species are 231 for icefish (−1°C), 187 for cod (8°C) and 156 for marlin (20°C). At 0°CPo is 7 times higher for fibres from the icefish than from the marlin. 3. Fibres from icefish and cod failed to relax completely following activations at temperatures above approximately 12°C. The resultant post-contraction force is associated with a proportional increase in stiffness, suggesting the formation of a population of Ca-insensitive cross bridges. 4. At 0°C there is little interspecific variation in unloaded contraction velocity (V max) among the three species.V max (muscle lengths s−1) at normal body temperatures are 0.9 for icefish (−1°C), 1.0 for cod (8°C) and 3.4 for marlin (20°C). 5. The force-velocity (P-V) relationship becomes progressively more curved with increasing temperature for all three species. 6. Maximum power output for the fast muscle fibres from the Antarctic species at −1°C is around 60% of that of the tropical fish at 20°C. Evolutionary temperature compensation of muscle power output appears largely to involve differences in the ability of cross bridges to generate force.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00584534
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