Determinants of work produced by skeletal muscle: potential limitations of activation and relaxation

1997 ◽  
Vol 273 (3) ◽  
pp. C1049-C1056 ◽  
Author(s):  
V. J. Caiozzo ◽  
K. M. Baldwin
Keyword(s):  
Skeletal Muscle ◽  
Length Change ◽  
Small Strain ◽  
Mechanical Work ◽  
Slow Skeletal Muscle ◽  
Loop Technique ◽  
Force Velocity ◽  
The Difference ◽  
Kinetics Of ◽  
Work Loop

The objective of this study was to estimate the limitations imposed by the kinetics of activation and relaxation on the ability of slow skeletal muscle to produce mechanical work. These estimates were made by the following methods: 1) using the work loop technique and measuring the actual mechanical work (WA) produced by rat soleus muscles (n = 6) at four different frequencies (0.5, 1, 2, and 4 Hz) and seven different amplitudes of length change (1, 2, 3, 4, 5, 6, and 7 mm); 2) determining the force-velocity relationships of the soleus muscles and using this data to quantify the theoretical mechanical work (WT) that could be produced under the work loop conditions described above; and 3) subtracting WA from WT. The difference between WT and WA was interpreted to represent limitations imposed by activation and relaxation. Under certain conditions (high frequency, small strain), factors controlling the kinetics of activation and relaxation reduced the mechanical work of the soleus muscle by approximately 60%. Hence, activation and relaxation collectively represent important factors limiting the production of mechanical work by slow skeletal muscle.

Early effects of ageing on the mechanical performance of isolated locomotory (EDL) and respiratory (diaphragm) skeletal muscle using the work-loop technique

2014 ◽  
Vol 307 (6) ◽  
pp. R670-R684 ◽  
Author(s):  
Jason Tallis ◽  
Rob S. James ◽  
Alexander G. Little ◽  
Val M. Cox ◽  
Michael J. Duncan ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Power Output ◽  
Muscle Performance ◽  
Maximal Power ◽  
Maximal Power Output ◽  
Age Related ◽  
Loop Technique ◽  
Edl Muscle ◽  
Work Loop

Previous isolated muscle studies examining the effects of ageing on contractility have used isometric protocols, which have been shown to have poor relevance to dynamic muscle performance in vivo. The present study uniquely uses the work-loop technique for a more realistic estimation of in vivo muscle function to examine changes in mammalian skeletal muscle mechanical properties with age. Measurements of maximal isometric stress, activation and relaxation time, maximal power output, and sustained power output during repetitive activation and recovery are compared in locomotory extensor digitorum longus (EDL) and core diaphragm muscle isolated from 3-, 10-, 30-, and 50-wk-old female mice to examine the early onset of ageing. A progressive age-related reduction in maximal isometric stress that was of greater magnitude than the decrease in maximal power output occurred in both muscles. Maximal force and power developed earlier in diaphragm than EDL muscle but demonstrated a greater age-related decline. The present study indicates that ability to sustain skeletal muscle power output through repetitive contraction is age- and muscle-dependent, which may help rationalize previously reported equivocal results from examination of the effect of age on muscular endurance. The age-related decline in EDL muscle performance is prevalent without a significant reduction in muscle mass, and biochemical analysis of key marker enzymes suggests that although there is some evidence of a more oxidative fiber type, this is not the primary contributor to the early age-related reduction in muscle contractility.

scholarly journals MODULATION OF NEGATIVE WORK OUTPUT FROM A STEERING MUSCLE OF THE BLOWFLY CALLIPHORA VICINA

1994 ◽  
Vol 192 (1) ◽  
pp. 207-224 ◽  
Author(s):  
M Tu ◽  
M Dickinson
Keyword(s):  
Flight Control ◽  
Beat Frequency ◽  
Calliphora Vicina ◽  
Work Output ◽  
Wing Beat ◽  
Negative Work ◽  
Loop Technique ◽  
Kinetics Of ◽  
Positive Work ◽  
Work Loop

Of the 17 muscles responsible for flight control in flies, only the first basalar muscle (b1) is known to fire an action potential each and every wing beat at a precise phase of the wing-beat period. The phase of action potentials in the b1 is shifted during turns, implicating the b1 in the control of aerodynamic yaw torque. We used the work loop technique to quantify the effects of phase modulation on the mechanical output of the b1 of the blowfly Calliphora vicina. During cyclic length oscillations at 10 and 50 Hz, the magnitude of positive work output by the b1 was similar to that measured previously from other insect muscles. However, when tested at wing-beat frequency (150 Hz), the net work performed in each cycle was negative. The twitch kinetics of the b1 suggest that negative work output reflects intrinsic specializations of the b1 muscle. Our results suggest that, in addition to a possible role as a passive elastic element, the phase-sensitivity of its mechanical properties may endow the b1 with the capacity to modulate wing-beat kinematics during turning maneuvers.

Effect of phase of stimulation on acute damage caused by eccentric contractions in mouse soleus muscle

1996 ◽  
Vol 80 (6) ◽  
pp. 1958-1962 ◽  
Author(s):  
E. D. Stevens
Keyword(s):  
Muscle Damage ◽  
Length Change ◽  
Eccentric Contractions ◽  
Single Trial ◽  
Loop Method ◽  
Significant Damage ◽  
Length Changes ◽  
The Difference ◽  
Work Done ◽  
Work Loop

Eccentric contractions (activation during muscle lengthening) can cause muscle damage. The effect of phase of stimulation on the extent of muscle damage was studied by using the work-loop method. For the work-loop method, the muscle was subjected to sinusoidal length changes at 2 Hz. The muscle was activated at different times during the imposed length-change cycle; this time is called the phase of stimulation. Work was calculated from the loop formed when force was plotted against length. Work done was positive when the muscle was shortening and was negative when the muscle was lengthening; net work was the difference. One complete length-change cycle was 100 (i.e., given as a percentage of the cycle); shortening occurred from 25 to 75. The muscle did the most net work when stimulated at phase 20, that is, when activation started just before shortening. Damage was defined as a decrease in work. Significant damage occurred after a single trial of three consecutive eccentric contractions; the muscle did less positive and less net work because of the damage. Maximal damage occurred at phases 90 and 0, the center of the lengthening part of the length-change cycle (work decreased 10%). Negligible damage occurred at phases 20-40. Negative work (work required to lengthen the muscle) also decreased because of the damage. Eccentric contractions caused much more damage than concentric contractions during oscillatory work.

Effect of External Calcium and other Divalent Cations on K+ Contractures in Denervated Slow Skeletal Muscle Fibers of the Frog

2019 ◽  
Author(s):  
Leonardo Hernández
Keyword(s):  
Skeletal Muscle ◽  
Binding Capacity ◽  
Divalent Cations ◽  
Muscle Fibers ◽  
Free Calcium ◽  
Slow Skeletal Muscle ◽  
Skeletal Muscle Fibers ◽  
Free Calcium Concentration ◽  
Chronic Denervation ◽  
Denervated Muscles

The influence of Ca2+ and other divalent cations on contractile responses of slow skeletal muscle fibers of the frog (Rana pipiens) under conditions of chronic denervation was investigated.Isometric tension was recorded from slow bundles of normal and denervated cruralis muscle in normal solution and in solutions with free calcium concentration solution or in solutions where other divalent cations (Sr2+, Ni2+, Co2+ or Mn2+) substituted for calcium. In the second week after nerve section, in Ca2+-free solutions, we observed that contractures (evoked from 40 to 80 mM-K+) of non-denervated muscles showed significantly higher tensions (p<0.05), than those from denervated bundles. Likewise, in solutions where calcium was substituted by all divalent cations tested, with exception of Mn2+, the denervated bundles displayed lower tension than non-denervated, also in the second week of denervation. In this case, the Ca2+ substitution by Sr2+ caused the higher decrease in tension, followed by Co2+ and Ni2+, which were different to non-denervated bundles, as the lowest tension was developed by Mn2+, followed by Co2+, and then Ni2+ and Sr2+. After the third week, we observed a recovery in tension. These results suggest that denervation altering the binding capacity to divalent cations of the voltage sensor.

The effect of composition of cobalt-molybdenum catalysts on their surface acidity and isomerisation activity

1980 ◽  
Vol 45 (3) ◽  
pp. 697-702 ◽  
Author(s):  
Vlastimil Vyskočil ◽  
Miroslav Zdražil
Keyword(s):  
Chromatographic Method ◽  
Surface Acidity ◽  
Parallel Reaction ◽  
Molybdenum Catalysts ◽  
The Difference ◽  
Kinetics Of ◽  
Alumina Catalysts

Kinetics of isomerisation of cyclohexene to methylcyclopentene proceeding as parallel reaction to hydrogenation of cyclohexene to cyclohexane on cobalt-molybdenum catalysts of different composition has been measured. The surface acidity of these catalysts was estimated from the difference in the adsorption of toluene and heptane which was measured by chromatographic method. In a series of catalysts containing molybdenum the acidity parallels isomerisation activity. Cobalt on alumina catalysts and alumina itself have greater acidity but exhibit lower isomerisation activity compared to the catalysts containing molybdenum.

Slow skeletal muscle myosin-binding protein-C (MyBPC1) mediates recruitment of muscle-type creatine kinase (CK) to myosin

2011 ◽  
Vol 436 (2) ◽  
pp. 437-445 ◽  
Author(s):  
Zhe Chen ◽  
Tong-Jin Zhao ◽  
Jie Li ◽  
Yan-Song Gao ◽  
Fan-Guo Meng ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Creatine Kinase ◽  
Muscle Contraction ◽  
Binding Protein ◽  
High Energy ◽  
Functional Coupling ◽  
Muscle Type ◽  
Myosin Binding Protein ◽  
Slow Skeletal Muscle ◽  
Myosin Binding

Muscle contraction requires high energy fluxes, which are supplied by MM-CK (muscle-type creatine kinase) which couples to the myofibril. However, little is known about the detailed molecular mechanisms of how MM-CK participates in and is regulated during muscle contraction. In the present study, MM-CK is found to physically interact with the slow skeletal muscle-type MyBPC1 (myosin-binding protein C1). The interaction between MyBPC1 and MM-CK depended on the creatine concentration in a dose-dependent manner, but not on ATP, ADP or phosphocreatine. The MyBPC1–CK interaction favoured acidic conditions, and the two molecules dissociated at above pH 7.5. Domain-mapping experiments indicated that MM-CK binds to the C-terminal domains of MyBPC1, which is also the binding site of myosin. The functional coupling of myosin, MyBPC1 and MM-CK is further corroborated using an ATPase activity assay in which ATP expenditure accelerates upon the association of the three proteins, and the apparent Km value of myosin is therefore reduced. The results of the present study suggest that MyBPC1 acts as an adaptor to connect the ATP consumer (myosin) and the regenerator (MM-CK) for efficient energy metabolism and homoeostasis.

scholarly journals The myosin alkali light chains of mouse ventricular and slow skeletal muscle are indistinguishable and are encoded by the same gene.

1985 ◽  
Vol 260 (14) ◽  
pp. 8578-8584 ◽  
Author(s):  
P J Barton ◽  
A Cohen ◽  
B Robert ◽  
M Y Fiszman ◽  
F Bonhomme ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Light Chains ◽  
Slow Skeletal Muscle
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