scholarly journals Changes in the maximum speed of shortening of frog muscle fibres early in a tetanic contraction and during relaxation

1998 ◽  
Vol 507 (2) ◽  
pp. 511-525 ◽  
Author(s):  
R. K. Josephson ◽  
K. A. P. Edman
Keyword(s):  
Frog Muscle ◽  
Maximum Speed ◽  
Muscle Fibres ◽  
Tetanic Contraction ◽  
Speed Of Shortening

scholarly journals The influence of free calcium on the maximum speed of shortening in skinned frog muscle fibres.

1986 ◽  
Vol 380 (1) ◽  
pp. 257-273 ◽  
Author(s):  
F J Julian ◽  
L C Rome ◽  
D G Stephenson ◽  
S Striz
Keyword(s):  
Frog Muscle ◽  
Maximum Speed ◽  
Free Calcium ◽  
Muscle Fibres ◽  
Speed Of Shortening

scholarly journals The maximum speed of shortening in living and skinned frog muscle fibres.

1986 ◽  
Vol 370 (1) ◽  
pp. 181-199 ◽  
Author(s):  
F J Julian ◽  
L C Rome ◽  
D G Stephenson ◽  
S Striz
Keyword(s):  
Frog Muscle ◽  
Maximum Speed ◽  
Muscle Fibres ◽  
Speed Of Shortening

Use of dP/dt and rise time to estimate speed of shortening in muscle

1985 ◽  
Vol 249 (5) ◽  
pp. R510-R513 ◽  
Author(s):  
E. D. Stevens ◽  
J. M. Renaud
Keyword(s):  
Rise Time ◽  
Rate Of Change ◽  
Effect Of Temperature ◽  
Maximum Speed ◽  
Sartorius Muscle ◽  
Tetanic Contraction ◽  
Significant Difference ◽  
Temperature Experiment ◽  
The Relationship ◽  
Speed Of Shortening

We examined the relationship between the maximum speed of shortening at zero load (Vmax) and two variables occasionally used to estimate Vmax: maximal rate of change of force during an isometric tetanic contraction [(dP/dt)max] and reciprocal of one-half rise time (RHRT), the time to achieve one-half the maximal force during an isometric tetanic contraction. The relationship was examined in two experiments on isolated toad sartorius muscle: the effect of temperature and the effect of changing pHe (extracellular pH) to test the hypotheses that (dP/dt)max or RHRT can be used to estimate the magnitude of the effect of experimental variables on Vmax. In the temperature experiment both (dP/dt)max and RHRT could be used to estimate changes in Vmax. The effect of pH on Vmax was markedly overestimated by (dP/dt)max, but there was no significant difference between the magnitude of the changes in Vmax and RHRT. Our results, taken with the results of others, suggest that it is inappropriate to assume that the magnitude of the effect of a particular experimental protocol on Vmax can necessarily be predicted by measuring (dP/dt)max or RHRT.

Effects of intracellular acidification and varied temperature on force, stiffness, and speed of shortening in frog muscle fibers

2004 ◽  
Vol 287 (1) ◽  
pp. C106-C113 ◽  
Author(s):  
T. Radzyukevich ◽  
K. A. P. Edman
Keyword(s):  
High Temperature ◽  
Rana Temporaria ◽  
Muscle Fibers ◽  
Ringer Solution ◽  
Frog Muscle ◽  
Maximum Force ◽  
Maximum Speed ◽  
Ph Change ◽  
Tibialis Muscle ◽  
Speed Of Shortening

This study aimed to establish whether the temperature-dependent effect of acidification on maximum force observed in mammalian muscles also applies to frog muscle. Measurements of force, stiffness, and unloaded velocity of shortening in intact single muscle fibers from the anterior tibialis muscle of Rana temporaria were performed between 0 and 22°C during fused tetani in H2CO3-CO2-buffered Ringer solution with pH adjusted to 7.0 and 6.3, respectively. The force-to-stiffness ratio increased as a rectilinear function of temperature between 0 and 20°C at pH 7.0. Lowering the pH to 6.3 reduced the tetanic force by 13.5 ± 1.2 and 11.5 ± 1.4% at 2.8 and 20.5°C, respectively, with only a minor reduction in fiber stiffness. The maximum speed of shortening was decreased by lowered pH by 12.9 ± 1.5 and 7.8 ± 1.1% at low and high temperature, respectively. Acidification increased the time to reach 70% of maximum force by 18.0% at ∼2°C; the same pH change performed at ∼20°C in the same fibers reduced the rise time by 24.1%. The same increase in the rate of rise of force at high temperature was also found at normal pH after the fibers were fatigued by frequent stimulation. It is concluded that, in frog muscle, the force-depressant effect of acidification does not vary significantly with temperature. By contrast, acidification affects the onset of activation in a manner that is critically dependent on temperature.

scholarly journals Potentiometric measurement of membrane action potentials in frog muscle fibres

1966 ◽  
Vol 183 (1) ◽  
pp. 152-166 ◽  
Author(s):  
B. Frankenhaeuser ◽  
B. D. Lindley ◽  
R. S. Smith
Keyword(s):  
Action Potentials ◽  
Frog Muscle ◽  
Muscle Fibres ◽  
Membrane Action ◽  
Potentiometric Measurement

Maximum shortening speed of motor units of various types in cat lumbrical muscles

1993 ◽  
Vol 69 (2) ◽  
pp. 442-448 ◽  
Author(s):  
J. Petit ◽  
M. Chua ◽  
C. C. Hunt
Keyword(s):  
Motor Unit ◽  
Inverse Correlation ◽  
Motor Units ◽  
Maximum Speed ◽  
Single Motor Units ◽  
Maximal Speed ◽  
Contraction Times ◽  
Isometric Twitch ◽  
Lumbrical Muscles ◽  
Speed Of Shortening

1. Isotonic shortening of cat superficial lumbrical muscles was studied during maximal tetanic contractions of single motor units of identified types. For each motor unit, the maximal speed of contraction, Vmax, was determined by extrapolating to zero the hyperbolic relation between applied tension and speed of shortening. 2. The maximal speeds of shortening of motor units formed a continuum with the highest velocities observed for the fast fatigable motor units and the lowest for the slow motor units. 3. On average, the maximum speed of shortening increased with the tetanic tension developed by the motor units. 4. In motor units with isometric twitch contraction times less than 35 ms, these times showed a significant inverse correlation with Vmax. Progressively longer contraction times were associated with rather small changes in Vmax. 5. The implications of these findings on the speed of muscle shortening during motor-unit recruitment are discussed.

The spindle and extrafusal innervation of a frog muscle

1957 ◽  
Vol 146 (924) ◽  
pp. 416-430 ◽  
Keyword(s):  
Muscle Fibre ◽  
Short Distance ◽  
Frog Muscle ◽  
Muscle Fibres ◽  
Intrafusal Muscle ◽  
Intrafusal Fibre ◽  
Unmyelinated Axons ◽  
Intrafusal Fibres ◽  
Break Up ◽  
Tonic System

In the frog muscle, ext. long. dig. IV, there are two or three spindle systems. Each consists of a bundle of intrafusal muscle fibres with two, three or four discrete encapsulated sensory regions distributed in mechanical series along it. A sensory region is usually comprised of the coiled branches of one afferent axon. These embrace the intrafusal fibres and ultimately form long fine varicose endings on or near them. The intrafusal striations appear to be lost for a short distance within the sensory region, and in this region the intrafusal fibre nuclei crowd together. The ‘small’ extrafusal efferents break up into trusses of fine unmyelinated axons and terminate as ‘grape’ end-plates, several of which can occur on the same muscle fibre. This is the ‘tonic’ system. The ‘large’ extrafusal efferents terminate as ‘Endbiischel’ end-plates on muscle fibres not supplied by grape endings. This is the ‘twitch’ system. Both ‘grape' and ‘twitch’ end-plates occur on the intrafusal bundle (probably on separate fibres) between the sensory regions. They are supplied by branches of ‘small’ or ‘large’ axons respectively, which also innervate extrafusal fibres. Thus like the extrafusals the intrafusal bundle is composed of ‘tonic’ and ‘twitch’ muscle fibres. This situation contrasts with that of the mammal, where extrafusals are exclusively ‘twitch’ fibres and intrafusals ‘tonic’.

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