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 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.

scholarly journals The different intracellular action potentials of fast and slow muscle fibres

1985 ◽  
Vol 60 (6) ◽  
pp. 539-547 ◽  
Author(s):  
Willemien Wallinga-De Jonge ◽  
Frans L.H Gielen ◽  
Peter Wirtz ◽  
Paul De Jong ◽  
Jan Broenink
Keyword(s):  
Action Potentials ◽  
Slow Muscle ◽  
Muscle Fibres ◽  
Fast And Slow Muscle ◽  
Slow Muscle Fibres ◽  
Intracellular Action

Neuromuscular Physiology of the Longitudinal Muscle of the Earthworm, Lumbricus Terrestris

1974 ◽  
Vol 60 (2) ◽  
pp. 445-452
Author(s):  
C. D. DREWES ◽  
R. A. PAX
Keyword(s):  
Longitudinal Muscle ◽  
Ionic Composition ◽  
Lumbricus Terrestris ◽  
Physiological Saline ◽  
Body Fluids ◽  
Resting Potential ◽  
Muscle Fibres ◽  
The Mean ◽  
Nerve Muscle ◽  
Increased Susceptibility

1. An earthworm saline commonly used in previous investigations of earthworm neuromuscular physiology has been shown to be inappropriate for such studies because the ionic composition of the saline does not correspond to that of earthworm body fluids. 2. Problems encountered when using this saline include: increased excitability of motor axons innervating the longitudinal muscle, a decrease in the amplitude of external electrical responses of the muscle, an increased susceptibility of longitudinal muscle fibres to injury spiking, and a decrease in resting potentials of longitudinal muscle fibres (to a mean of -36.1 mV). 3. Such problems have been overcome by the development of a new physiological saline whose composition closely corresponds to the ionic composition of earthworm body fluids. 4. In the new saline responses of the nerve-muscle preparation remain stable for more than 1 h. 5. Resting potentials of longitudinal muscle fibres are also stable with time, the mean resting potential being -47.9 mV.

Inhibition by a actinomycin D of the denervation-induced action potential in frog slow muscle fibres

1973 ◽  
Vol 184 (1074) ◽  
pp. 91-95 ◽  
Keyword(s):  
Sciatic Nerve ◽  
Action Potential ◽  
Action Potentials ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Slow Muscle ◽  
Muscle Fibres ◽  
Na Channels ◽  
Potential Mechanism ◽  
Slow Muscle Fibres

Pyriformis muscles of the frog were denervated by section of the sciatic nerve. About three weeks later all slow muscle fibres examined had become capable of generating action potentials. However, the action potential mechanism failed to develop if actinomycin D was injected early after the operation. It is suggested that RNA synthesis is required for the formation of ‘Na channels’ in the membrane of denervated slow muscle fibres.

Muscle growth in the Antarctic teleost, Notothenia neglecta (Nybelin)

1991 ◽  
Vol 3 (1) ◽  
pp. 29-33 ◽  
Author(s):  
John C. Battram ◽  
Ian A. Johnston
Keyword(s):  
Muscle Fibre ◽  
Muscle Growth ◽  
Somatic Growth ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Slow Muscle ◽  
Muscle Fibres ◽  
Slow Muscle Fibres ◽  
The Antarctic ◽  
Myotomal Muscle

A histochemical and electron microscopy study was carried out on muscle growth in demersal stages of the Antarctic teleost Notothenia neglecta Nybelin. The total number of myotomal muscle fibres was similar in fish ranging in body mass from 11.9g to 889g. Post-anal myotomes contained around 17,000 slow muscle fibres and 70,000 fast muscle fibres. Myosatellite cells were extremely rare. The diameter of fast fibres varied from <10μm to 130μm in the smallest, and from >40μm to 450μm in the largest fish studied. Slow muscle fibre diameters in the largest fish ranged from >30μm to 260μm. Even the largest diameter slow fibres contained significant numbers of mitochondria, which suggests that the diffusion of oxygen does not limit metabolism. The results confirm that muscle fibre hyperplasia ceases prior to the demersal stages of the life history, and that subsequent muscle growth is entirely via the hypertrophy of existing fibres. Comparative studies suggest that this may be one of the factors contributing to the relatively slow rate of somatic growth in this species.

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