The mechanical properties of polyneuronally innervated, myotomal muscle fibres isolated from a teleost fish (Myoxocephalus scorpius)

1988 ◽  
Vol 412 (5) ◽  
pp. 524-529 ◽  
Author(s):  
J. D. Altringham ◽  
I. A. Johnston
Keyword(s):  
Mechanical Properties ◽  
Teleost Fish ◽  
Muscle Fibres ◽  
Myoxocephalus Scorpius ◽  
Myotomal Muscle

scholarly journals Activation of Multiply Innervated Fast and Slow Myotomal Muscle Fibres of the Teleost Myoxocephalus Scorpius

1988 ◽  
Vol 140 (1) ◽  
pp. 313-324 ◽  
Author(s):  
J. D. ALTRINGHAM ◽  
I. A. JOHNSTON
Keyword(s):  
Action Potentials ◽  
Spinal Nerve ◽  
Resting Potential ◽  
Muscle Fibres ◽  
Significant Difference ◽  
Slow Muscle Fibres ◽  
Myoxocephalus Scorpius ◽  
Nerve Muscle ◽  
Myotomal Muscle ◽  
Tetanic Tension

A nerve-muscle preparation from the sculpin Myoxocephalus scorpius was used to study the membrane response of fast and slow muscle fibres to stimulation of the spinal nerves. There was no significant difference between resting potential in fast (−81.9mV) and slow fibres (−80.8mV). Fast fibres responded to a suprathreshold stimulus in the spinal nerve with an action potential. Overshoots of up to +32 mV were recorded. Both junction potentials and overshooting action potentials were observed in the slow fibres. The twitch/tetanus characteristics of myotomal muscle were investigated using isolated bundles of ‘live’ fast and slow fibres. Both fibre types responded to a single stimulus with a mechanical twitch. Fused tetani were obtained at around 50Hz in fast fibres and 20 Hz in slow fibres. In the slow fibres, tetanic tension increased with frequency up to around 50Hz. At frequencies giving maximum tetanic tension, the twitch/tetanus ratio was 0.70 for fast fibres and 0.29 for slow ones. These results are discussed with reference to the polyneuronal/multiterminal innervation pattern of the myotomal muscle in teleost fish and its role in locomotion.

scholarly journals Plasticity of muscle contractile properties following temperature acclimation in the marine fish Myoxocephalus scorpius

1995 ◽  
Vol 198 (1) ◽  
pp. 193-201 ◽  
Author(s):  
T A Beddow ◽  
I A Johnston
Keyword(s):  
High Temperatures ◽  
Power Output ◽  
Temperature Acclimation ◽  
Contractile Properties ◽  
Muscle Fibres ◽  
Contraction Speed ◽  
High K ◽  
Myoxocephalus Scorpius ◽  
Myotomal Muscle ◽  
Muscle Contractile

Live fibre bundles were isolated from the fast myotomal muscle of short-horned sculpin (Myoxocephalus scorpius L.) and isometric contractile properties and the force­velocity (P­V) relationship determined at 5, 10 and 15 °C. Experiments were carried out on winter- and summer-caught sculpins and on individuals acclimated for 6­8 weeks to either 5 or 15 °C (12 h:12 h light:dark). Maximum tetanic tension (P0) in fibres from 15 °C-acclimated fish increased from 125 kN m-2 at 5 °C to 282 kN m-2 at 15 °C (R10=2.3). For 5 °C-acclimated fish, P0 was 139 kN m-2 at 5 °C, but fell to 78 kN m-2 at 15 °C, consistent with a partial failure of excitation­contraction coupling at high temperatures. Peak force at 15 °C was increased 2.2 times following depolarisation with a high-K+ solution, but was unaffected by the addition of caffeine and/or eserine to the Ringer's solution. The results from winter- and summer-caught fish were similar to those from 5 °C- and 15 °C-acclimated sculpins respectively. In 15 °C-acclimated fish, the power output of muscle fibres calculated from the P­V relationship was 55 W kg-1 at 5 °C and 206 W kg-1 at 15 °C. The P­V relationship at 5 °C was significantly less curved in muscle fibres from 5 °C- than from 15 °C-acclimated fish. After normalizing the curves for P0 and Vmax, it was found that the change in curvature was sufficient to produce a 40 % increase in relative power output at 5 °C in cold-acclimated fish. The maximum contraction speed of muscle fibres at 15 °C was 2.4 times higher in 15 °C- than in 5 °C-acclimated fish. It was concluded that acclimation modifies the contractile properties of fast muscle fibres at both low and high temperatures.

scholarly journals Temperature and the Force-Velocity Relationship of Live Muscle Fibres from the Teleost Myoxocephalus Scorpius

1989 ◽  
Vol 144 (1) ◽  
pp. 437-448 ◽  
Author(s):  
KAREN S. LANGFELD ◽  
JOHN D. ALTRINGHAM ◽  
IAN A. JOHNSTON
Keyword(s):  
Power Output ◽  
Muscle Power ◽  
Muscle Fibres ◽  
Velocity Relationship ◽  
Force Velocity ◽  
Myoxocephalus Scorpius ◽  
Relationship Of ◽  
Myotomal Muscle ◽  
Best Fit ◽  
Tetanic Tension

Small bundles of fast fibres were isolated from the myotomal muscle of the teleost Myoxocephalus scorpius. The temperature-dependence of isometric contractile properties and the force-velocity (P-V) relationship were studied. Fibres were found to deteriorate above 18°C, and the force plateau during tetanic stimulation was not maintained above 15°C. Twitch and tetanic tension (P0) showed optima at around 8°C. Force-velocity curves were fitted using either Hill's hyperbolic equation or a hyperbolic-linear equation (hyp-lin). The best fit to the data was provided by the hyp-lin equation, which gave consistently higher values for unloaded contraction velocity (Vmax): 4.3, 8.1 and 9.5 muscle lengths s−1 at 1, 8 and 12°C, respectively. The P-V relationship was found to become progressively more curved at higher temperatures. Muscle power output calculated from the hyp-lin equation was 123 W kg−1 at 1°C and 256 W kg−1 at 8°C. Curves normalized for P0 and Vmax at each temperature show that the change in curvature is sufficient to increase the relative power output of the muscle by around 15% on decreasing the temperature from 8 to 1°C.

EFFICIENCY OF ENERGY CONVERSION DURING SINUSOIDAL MOVEMENT OF WHITE MUSCLE FIBRES FROM THE DOGFISH SCYLIORHINUS CANICULA

1993 ◽  
Vol 183 (1) ◽  
pp. 137-147 ◽  
Author(s):  
N. A. Curtin ◽  
R. C. Woledge
Keyword(s):  
Power Output ◽  
High Efficiency ◽  
Fibre Length ◽  
Dry Mass ◽  
Energy Output ◽  
Maximum Efficiency ◽  
Muscle Fibres ◽  
Work Output ◽  
Sinusoidal Movement ◽  
Myotomal Muscle

Net work output and heat production of white myotomal muscle fibres from the dogfish were measured during complete cycles of sinusoidal movement at 12°C. The peak-to-peak movement was about 9 % of the muscle fibre length; three stimuli at 32 ms intervals were given in each mechanical cycle. The frequency of movement and the timing of the stimulation were varied for each preparation to find the optimal conditions for power output and those optimal for efficiency (the ratio of net work output to total energy output as heat+work). To achieve either maximum power or maximum efficiency, the tetanus must start while the muscle fibres are being stretched, before the beginning of the shortening part of the mechanical cycle. The highest power output, averaged over one cycle, was 0.23+/−0.014 W g-1 dry mass (+/−s.e.m., N=9, 46.9+/−2.8 mW g-1 wet mass) and was produced during movement at 3.5 Hz. The highest efficiency, 0.41+/−0.02 (+/−s.e.m., N=13), occurred during movements at 2.0-2.5 Hz. This value is higher than the efficiency previously measured during isovelocity shortening of these fibres. The implications of the high efficiency for crossbridge models of muscle contraction are discussed.

scholarly journals Differences in temperature dependence of muscle contractile properties and myofibrillar ATPase activity in a cold-temperature fish

1984 ◽  
Vol 111 (1) ◽  
pp. 179-189 ◽  
Author(s):  
I. A. Johnston ◽  
B. D. Sidell
Keyword(s):  
Atpase Activity ◽  
Test Method ◽  
Muscle Fibres ◽  
Contraction Velocity ◽  
Mechanical Constraints ◽  
Force Velocity ◽  
Skinned Fibre ◽  
Myoxocephalus Scorpius ◽  
Two Parameters ◽  
Triton X

Single muscle fibres were isolated from the fast myotomal muscle of the teleost Myoxocephalus scorpius L. and chemically skinned with 1% Brij. Maximum Ca2+-activated force (P0) increased from 14.5 +/− 1.1 N cm-2 at 2 degrees C to 19.1 +/− 1.8 N cm-2 at 15 degrees C (mean +/− S.E.). Maximum contraction velocity was determined by Hill's slack-test method (V0) and by extrapolation from force-velocity (P-V) relationships (Vmax). There was a linear relation between log10 V0 and temperature below 15 degrees C (Q10 = 1.9, P less than 0.01). The force-velocity characteristics of the fibres were determined at 2 degrees C and 20 degrees C. Points below 0.6 P0 on the P-V curve could be fitted by a linear form of Hill's equation. Extrapolated Vmax values were 0.55 muscle lengths s-1 (L0 s-1) at 2 degrees C and 1.54 L0 s-1 at 20 degrees C. Curvature of the P-V relationship was independent of temperature. The Mg2+, Ca2+-ATPase activity of Triton-X 100 extracted myofibrils was determined under similar ionic conditions to those used in skinned fibre experiments. (Ionic strength 0.16 mmol l-1, pMgATP 2.5). A linear relationship between log10 ATPase and temperature was only obtained below 15 degrees C (P less than 0.001). Above 15 degrees C, the Q10 for ATPase decreased significantly. The Q10(0–15 degrees C) for ATPase activity (3.9) was significantly higher than for unloaded contraction velocity. Supercontraction of isolated myofibrils to very short sarcomere lengths and differences in the mechanical constraints for crossbridge cycling between the preparations probably account for the lack of proportionality between these two parameters.

scholarly journals Power Output and Force-Velocity Relationship of Live Fibres from White Myotomal Muscle of the Dogfish, Scyliorhinus Canicula

1988 ◽  
Vol 140 (1) ◽  
pp. 187-197 ◽  
Author(s):  
N. A. CURTIN ◽  
R. C. WOLEDGE
Keyword(s):  
Power Output ◽  
Maximum Velocity ◽  
Muscle Fibres ◽  
Fish Length ◽  
Skinned Fibres ◽  
Step Method ◽  
Velocity Relationship ◽  
Velocity Of Shortening ◽  
Force Velocity ◽  
Myotomal Muscle

The relationship between force and velocity of shortening and between power and velocity were examined for myotomal muscle fibre bundles from the dogfish. The maximum velocity of shortening, mean value 4.8 ± 0.2 μms−1 half sarcomere−1 (±S.E.M., N = 13), was determined by the ‘slack step’ method (Edman, 1979) and was found to be independent of fish length. The force-velocity relationship was hyperbolic, except at the high-force end where the observations were below the hyperbola fitted to the rest of the data. The maximum power output was 91 ± 14 W kg−1 wet mass (±S.E.M., N = 7) at a velocity of shortening of 1.3 ± 0.13μms−1 halfsarcomere−1 (±S.E.M., N = 7). This power output is considerably higher than that previously reported for skinned fibres (Bone et al. 1986). Correspondingly the force-velocity relationship is less curved for intact fibres than for skinned fibres. The maximum swimming speed (normalized for fish length) predicted from the observed power output of the muscle fibres decreased with increasing fish size; it ranged from 12.9 to 7.8 fish lengths s−1 for fish 0155–0.645m in length.

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