Inward barium current and excitation-contraction coupling in frog twitch muscle fibres

1993 ◽  
Vol 14 (2) ◽  
pp. 158-166 ◽  
Author(s):  
Sylvie Blaineau ◽  
Vincent Jacquemond ◽  
Bruno Allard ◽  
Jacqueline Amsellem ◽  
Marie Jo Moutin ◽  
...  
Keyword(s):  
Muscle Fibres ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling

Temperature Effects on Neuromuscular Transmission (Opener Muscle of Crayfish, Astacus Leptodactylus)

1981 ◽  
Vol 94 (1) ◽  
pp. 251-268
Author(s):  
LUDWIG FISCHER ◽  
ERNST FLOREY
Keyword(s):  
Decay Time ◽  
Neuromuscular Transmission ◽  
Membrane Conductance ◽  
Resting Potential ◽  
Muscle Fibres ◽  
Astacus Leptodactylus ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Temperature Range ◽  
Parallel Change

In experiments on the opener muscle of the third walking legs of crayfish (Astacus leptodactylus) it was found that the mechanical tension developed in response to repetitive stimulation of the single motor axon increases over the entire temperature range from 30 down to 0°C. In contrast to this, the tension elicited by depolarizing single muscle fibres decreases with decreasing temperature; the threshold for excitation-contraction coupling is not significantly altered. With decreasing temperature the resting potential decreases (up to 2 mV/°C) but the amplitude and decay time of the e.p.s.p.'s increase. The time constant, λ, of e.p.s.p. decay has a Q10 of less than −2 in the range above 15 °C but reaches a value of −7 between 10 and 0°C. This pattern of temperature dependence is fully accounted for by a parallel change of membrane resistance and its reciprocal, the membrane conductance. The corresponding activation energies computed from λ-values approximate 3 kcal/mol at high temperature and 46 kcal/mol in the low temperature range. The combined effects of a lowered resting potential, an increased amplitude, and especially an increased decay time of e.p.s.p.s result in a drastic enhancement of the depolarization reached during summation of e.p.s.p.s as the temperature is decreased. These effects overcompensate the declining effectiveness of excitation-contraction coupling so that the entire process of neuromuscular transmission becomes more and more effective as the temperature declines. In order to reach the same tension lower frequencies of nerve stimulation are needed at lower temperatures.

Electromechanical Coupling II. The Effect of Perchlorate Upon Excitation-Contraction Coupling in Frog Skeletal Muscle Fibres

1982 ◽  
Vol 37 (7-8) ◽  
pp. 707-708
Author(s):  
Michael Gomolla ◽  
Gernot Gottschalk ◽  
Hans-Christoph Lüttgau
Keyword(s):  
Skeletal Muscle ◽  
Electromechanical Coupling ◽  
Muscle Fibres ◽  
Frog Skeletal Muscle ◽  
Large Shift ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Inactivation Process ◽  
Skeletal Muscle Fibres ◽  
Kinetics Of

Abstract In single skeletal muscle Fibres perchlorate causes a large shift of the potential dependence of contraction activation to more negative potentials without a corresponding alteration in the kinetics of the inactivation process.

G.P.12.02 T-tubule disorganisation and defective excitation–contraction coupling in muscle fibres lacking myotubularin lipid phosphatase

2009 ◽  
Vol 19 (8-9) ◽  
pp. 635-636
Author(s):  
L. Al-Qusairi ◽  
N. Weiss ◽  
C. Berbey ◽  
N. Messaddeq ◽  
C. Kretz ◽  
...  
Keyword(s):  
Muscle Fibres ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Lipid Phosphatase

Evidence for an essential role for calcium in excitation-contraction coupling in skeletal muscle

1964 ◽  
Vol 160 (981) ◽  
pp. 504-512 ◽  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibre ◽  
Calcium Ions ◽  
Essential Role ◽  
Mechanical Response ◽  
Frog Heart ◽  
Muscle Fibres ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Spontaneous Action

The events and processes that link the electrical events which occur at the surface of a muscle fibre with the contractile process that takes place within the fibre, have been a continuing source of interest. Recently attention has been concentrated on the role played by calcium ions in linking these two events. As often happens in physiological investigations, the idea that calcium ions play an essential role in excitation-contraction coupling is not new. As long ago as 1883 Ringer demonstrated that the frog heart fails to contract and remains relaxed when calcium ions are absent from its perfusion fluid. Later it was shown that under this condition the rhythmic spontaneous action potentials of this preparation are still present in an only slightly modified form (Mines 1913). It was known at that time that the depolarization of the muscle fibre membrane is the electrical event responsible for initiating the mechanical response (Biedermann 1896) and although this point has been disputed from time to time, the evidence presently available makes it obvious that this is the case. One explanation of these observations is that the action potential or depolarization permits or promotes the movement of calcium ions from the surface to the interior of the muscle fibre and that these ions then initiate the mechanical response. A working hypothesis of this type was proposed by Sandow (1952). However, until fairly recently the only direct evidence supporting such an hypothesis was the demonstration by Heilbrunn & Wiercinski (1947) that calcium was the only physiologically occurring cation which would cause shortening when injected into bits of skeletal muscle fibres in low concentrations. This effect was later confirmed under more physiological conditions by Niedergerke (1955). Although there is considerable evidence of recent origin showing that calcium ions play an essential role in coupling in smooth and cardiac muscles, for the sake of brevity attention will be concentrated on skeletal muscle in the present discussion.

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