Effect of quercetin on tension development by skinned fibres from frog skeletal muscle

1985 ◽  
Vol 6 (2) ◽  
pp. 189-195 ◽  
Author(s):  
Nagomi Kurebayashi ◽  
Yasuo Ogawa
Keyword(s):  
Skeletal Muscle ◽  
Skinned Fibres ◽  
Frog Skeletal Muscle ◽  
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.

scholarly journals Time necessary for tension development in frog skeletal muscle.

1999 ◽  
Vol 39 (supplement) ◽  
pp. S189
Author(s):  
H. Tanaka ◽  
T. Kobayashi ◽  
Y. Takezawa ◽  
Y. Sugimoto ◽  
K. Wakabayashi
Keyword(s):  
Skeletal Muscle ◽  
Frog Skeletal Muscle ◽  
Tension Development

scholarly journals Mechanical Threshold As a Factor in Excitation-Contraction Coupling

1969 ◽  
Vol 54 (3) ◽  
pp. 352-368 ◽  
Author(s):  
Stuart R. Taylor ◽  
Hanna Preiser ◽  
Alexander Sandow
Keyword(s):  
Skeletal Muscle ◽  
Electromechanical Coupling ◽  
Divalent Cations ◽  
Direct Action ◽  
Type A ◽  
Frog Skeletal Muscle ◽  
Tension Development ◽  
Contraction Coupling ◽  
Mechanical Threshold ◽  
Coupling Processes

I-, CH3SO4-, and ClO4-, like other previously studied type A twitch potentiators (Br-, NO3-, SCN-, and caffeine), lower the mechanical threshold in K depolarization contractures of frog skeletal muscle. In potentiated twitches, I-, Br-, CH3SO4-, ClO4, and SCN, as already reported for NO3- and caffeine, slightly shorten the latent period (L) and considerably increase the rate of tension development (dP/dt) during the first few milliseconds of the contraction period. Divalent cations (8 mM Ca2+, 0.5–1.0 mM Zn2+ and Cd2+) raise the mechanical threshold of contractures, and correspondingly affect the twitch by depressing the tension output, increasing L, and decreasing the early dP/dt, thus acting oppositely to the type A potentiators. These various results form a broad, consistent pattern indicating that electromechanical coupling in the twitch is conditioned by a mechanical threshold as it is in the contracture, and suggesting that the lower the threshold, in reference to the raised threshold under the action of the divalent cations, the more effective is a given action potential in activating the twitch as regards especially both its early rate and peak magnitude of tension development. The results suggest that the direct action by which the various agents affect the level of the mechanical threshold involves effects on E-C coupling processes of the T tubular and/or the sarcoplasmic reticulum which control the release of Ca for activating contraction.

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