The effect of changing free Ca2+ on light diffraction intensity and correlation with tension development in skinned fibers of frog skeletal muscle

1983 ◽  
Vol 397 (3) ◽  
pp. 243-247 ◽  
Author(s):  
Toshiharu Oba ◽  
Ken Hotta
Keyword(s):  
Skeletal Muscle ◽  
Light Diffraction ◽  
Skinned Fibers ◽  
Frog Skeletal Muscle ◽  
Diffraction Intensity ◽  
Tension Development

The Threshold for Potassium-Induced Contractures of Frog Skeletal Muscle. Potentiation of Potassium-Induced Contractures by Preexposure to Subthreshold Potassium Concentrations

1972 ◽  
Vol 50 (1) ◽  
pp. 37-44 ◽  
Author(s):  
E. C. Vos ◽  
G. B. Frank
Keyword(s):  
Skeletal Muscle ◽  
Potassium Concentration ◽  
Ringer Solution ◽  
Frog Skeletal Muscle ◽  
Contractile Apparatus ◽  
Tension Development ◽  
Eventual Loss ◽  
Active Processes ◽  
Muscle Potentiation ◽  
Small Bundle

A brief exposure (about 10–30 s) of a frog's toe muscle or a small bundle of fibers from the semi-tendinosus muscle to just subthreshold potassium concentrations potentiated contractures subsequently produced by exposing the muscles to a potassium concentration slightly above the threshold. The contractures thus potentiated had greater maximum tensions, and greater rates of tension development and relaxation than control contractures elicited by the same final potassium concentration. The resistance to stretch (R.T.S.) in the first few seconds of the potentiated contractures was about twice that of control contractures. Maximum potentiation occurred with preexposures of about 30 s; longer preexposures led to a decrease of potentiation and eventually to a depression of the contracture. The potentiation was not immediately abolished when the muscle was reexposed to Ringer solution but persisted for 2 min or longer (the 'washout effect'). It was concluded that exposing a muscle to low subcontracture threshold concentrations of potassium for a few seconds primes the intracellular contractile apparatus, probably by causing an increased sarcoplasmic concentration of Ca2+ ions, resulting in a potentiation of subsequently induced submaximal potassium contractures. The increase in metabolism (or 'Solandt effect') seen under these conditions is temporally related to the decline and eventual loss of the potentiation and is probably a reflection of active processes involved in reducing the sarcoplasmic concentration of Ca2+ ions.

The Effect of Lanthanum on Excitation–Contraction Coupling in Frog Skeletal Muscle

1974 ◽  
Vol 52 (6) ◽  
pp. 1126-1135 ◽  
Author(s):  
D. J. Parry ◽  
A. Kover ◽  
G. B. Frank
Keyword(s):  
Skeletal Muscle ◽  
Action Potential ◽  
Muscle Membrane ◽  
Frog Skeletal Muscle ◽  
Tension Development ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Reduced Rate ◽  
Caffeine Contractures

Exposure of frog toe muscles to 1 mM La3+ results in a decrease in amplitude and rate of tension development of potassium contractures and twitches. At this concentration La3+ also inhibits the uptake of calcium, both in the resting condition and during stimulation. Caffeine contractures are unaffected even after a 5-min pre-exposure to La3+. The depolarization induced by various concentrations of K+ is reduced by about 10 mV as is the amplitude of the action potential. The rate of rise of the action potential is reduced by about 40% after 1 min in La3+ Ringer. Neither the decreased amplitude nor the reduced rate of depolarization is considered to be sufficient to explain the inhibition of tension development. It is suggested that La3+ partially uncouples excitation from contraction by preventing the release of a trigger-Ca2+ fraction from some site on the muscle membrane. This fraction normally plays a role in excitation–contraction coupling, although some tension may still be developed in the absence of a trigger-Ca2+ influx.

Hg2+-induced contracture in mechanically skinned fibers of frog skeletal muscle

1985 ◽  
Vol 63 (9) ◽  
pp. 1070-1074 ◽  
Author(s):  
Takako Aoki ◽  
Toshiharu Oba ◽  
Ken Hotta
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Sulfhydryl Groups ◽  
Skinned Fibers ◽  
Frog Skeletal Muscle ◽  
Semitendinosus Muscle ◽  
Skinned Fiber ◽  
Brij 58 ◽  
Develop Tension

In mechanically skinned fibers of the semitendinosus muscle of bullfrogs, we examined the role of membrane sulfhydryl groups on Ca2+ release from the sarcoplasmic reticulum (SR). Hg2+, a sulfhydryl reagent (20–100 μM), induced a repetitive contracture of skinned fibers, and this contracture did not occur in skinned fibers in which the SR had been disrupted by treatment with a detergent (Brij 58). Procaine (10 mM), Mg2+ (5 mM), or dithiothreitol (1 mM) blocked the Hg2+-induced contracture. Ag+ or p-chloromercuribenzenesulfonic acid produced similar contractures to that induced by Hg2+. We conclude that Hg2+ releases Ca2+ from SR of a skinned fiber by modifying sulfhydryl groups on the SR membrane, and suggest that the Ca2+ released by Hg2+ may trigger a greater release of Ca2+ from SR to develop tension.

X-ray diffraction from tropoin extracted skinned fibers of frog skeletal muscle.

2000 ◽  
Vol 40 (supplement) ◽  
pp. S63
Author(s):  
M. Yamaguchi ◽  
T. Takemori ◽  
N. Yagi ◽  
S. Morimoto
Keyword(s):  
Skeletal Muscle ◽  
Skinned Fibers ◽  
Frog Skeletal Muscle ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Characteristics of Ca2+- and Mg2+-induced tension development in chemically skinned smooth muscle fibers.

1978 ◽  
Vol 72 (1) ◽  
pp. 1-14 ◽  
Author(s):  
K Saida ◽  
Y Nonomura
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Striated Muscle ◽  
Muscle Fibers ◽  
Skinned Fibers ◽  
Tension Development ◽  
Contractile System ◽  
Myosin Interaction ◽  
Myosin B ◽  
Muscle Myosin

Chemically skinned fibers from guinea pig taenia caecum were prepared by saponin treatment to study the smooth muscle contractile system in a state as close to the living state as posible. The skinned fibers showed tension development with an increase of Ca2+ in the solution, the threshold tension occurring as 5 X 10(-7) M Ca2+. The maximal tension induced with 10(-4) M Ca2+ was as large and rapid as the potassium-induced contracture in the intact fibers. The slope of the pCa tension curve was less steep than that of skeletal muscle fibers and shifted in the direction of lower pCa with an increase of MgATP. The presence of greater than 1 mM Mg2+ was required for Ca2+-induced contraction in the skinned fibers as well as for the activation of ATPase and superprecipitation in smooth muscle myosin B. Mg2+ above 2 mM caused a slow tension development by itself in the absence of Ca2+. Such a Mg2+-induced tension showed a linear relation to concentrations up to 8 mM in the presence of MgATP. Increase of MgATP concentration revealed a monophasic response without inhibition of Ca2+-induced tension development, unlike the biphasic response in striated muscle. When MgATP was removed from the relaxing solution, the tension developed slowly and slightly, even though the Mg2+ concentrations was fixed at 2 mM. These results suggest a substantial difference in the mode of actin-myosin interaction between smooth and skeletal muscle.

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