scholarly journals Force velocity relations of single cardiac muscle cells: calcium dependency.

1977 ◽  
Vol 69 (2) ◽  
pp. 221-241 ◽  
Author(s):  
N M De Clerck ◽  
V A Claes ◽  
D L Brutsaert
Keyword(s):  
Calcium Ions ◽  
Mechanical Performance ◽  
Muscle Length ◽  
Longitudinal Axis ◽  
Phase Plane Analysis ◽  
Shortening Velocity ◽  
Cardiac Muscle Cells ◽  
Plane Analysis ◽  
Contractile System ◽  
Force Velocity

Cellular cardiac preparations in which spontaneous activity was suppressed by EGTA buffering were isolated by microdissection. Uniform and reproducible contractions were induced by iontophoretically released calcium ions. No effects of a diffusional barrier to calcium ions between the micropipette and the contractile system were detected since the sensitivity of the mechanical performance for calcium was the same regardless of whether a constant amount of calcium ions was released from a single micropipette or from two micropipettes positioned at different sites along the longitudinal axis of the preparation. Force development, muscle length, and shortening velocity of eitherisometric or isotopic contractions were measured simultaneously. Initial length, and hence preload of the preparation were established by means of an electronic stop and any additional load was sensed as afterload. Mechanical performance was derived from force velocity relations and from the interrelationship between simultaneously measured force, length, and shortening velocity. From phase plane analysis of shortening velocity vs, instantaneous length during shortening and from load clamp experiments, the interrelationship between force, shortening, and velocity was shown to be independent of time during the major portion of shortening. Moreover, peak force, shortening, and velocity of shortening depended on the amount of calcium ions in the medium at low and high ionic strength.

Contraction history modulates isotonic shortening velocity in smooth muscle

1993 ◽  
Vol 265 (2) ◽  
pp. C467-C476 ◽  
Author(s):  
S. J. Gunst ◽  
M. F. Wu ◽  
D. D. Smith
Keyword(s):  
Smooth Muscle ◽  
Muscle Length ◽  
Electrical Field Stimulation ◽  
Contractile Element ◽  
Shortening Velocity ◽  
Linear Rate ◽  
Velocity Relationship ◽  
Force Velocity ◽  
Contractile Activation ◽  
Isotonic Shortening

The effect of contraction history on the isotonic shortening velocity of canine tracheal smooth muscle was investigated. Muscles were contracted isometrically for 20 s at initial lengths of L(o) (length of maximal active force), 85% L(o), or 70% L(o) using electrical field stimulation. Muscles were then allowed to shorten isotonically under different afterloads either with or without first being subjected to a step decrease in length to 70% L(o). Instantaneous velocities were plotted against instantaneous muscle length during isotonic shortening. Regardless of protocol, the velocity at any muscle length during shortening was lower when the muscle was initially activated at a longer length. The isotonic shortening velocity decreased progressively during shortening at a nearly linear rate with respect to instantaneous muscle length under all conditions. Results suggest that a longer muscle length at the time of activation leads to the development of higher loads on the contractile element during subsequent shortening, resulting in a slower shortening velocity. This plasticity of the force-velocity relationship may result from cytostructural reorganization of the smooth muscle cells in response to contractile activation at different muscle lengths.

scholarly journals The Contractile Properties of a Crab Respiratory Muscle

1987 ◽  
Vol 131 (1) ◽  
pp. 265-287 ◽  
Author(s):  
ROBERT K. JOSEPHSON ◽  
DARRELL R. STOKES
Keyword(s):  
Carcinus Maenas ◽  
Stimulus Frequency ◽  
Muscle Length ◽  
Isometric Tension ◽  
Shortening Velocity ◽  
Force Velocity ◽  
Contraction And Relaxation ◽  
Full Activation ◽  
Stimulus Number

1. Contraction of scaphognathite muscle L2B of the green crab Carcinus maenas is strongly dependent on stimulus number and frequency. Single, supramaximal stimuli evoke little or no tension. When stimulated with shocks in either short bursts (10 stimuli in 0.5s or less) or long bursts (5 s of stimulation), the isometric tension from the muscle increases with increasing stimulus frequency to a maximum at about 150 Hz at 15°C, beyond which tension declines with further increase in stimulus frequency. 2. There can be facilitation of both contraction and relaxation between short bursts of stimuli. Facilitation of contraction is seen as increasing tension on successive bursts of a series, even when the interburst interval is long enough for relaxation to be completed during the interval. Interburst facilitation lasts at least 10 s. Facilitation of relaxation is seen as progressively faster relaxation from burst to burst of a series, and relaxation to lower tension levels when the interburst interval is so short that relaxation is incomplete in the interburst interval. 3. Maximum isometric tension occurs at muscle lengths slightly longer than the longest muscle length reached in vivo. Tension declines rapidly with changes in muscle length away from the optimum length. The maximum isometric tension was about 12 N cm−2. 4. The maximum shortening velocity of a tetanically activated muscle was determined as 1.9 lengthss−1 (Ls−1) by extrapolation of force-velocity curves to zero force and 3.3 Ls−1 by slack test measurements. 5. The scaphognathite muscle would be classified as a slow or tonic muscle on the basis of its requirements for multiple stimulation to reach full activation, and as a moderately fast muscle on the basis of its force-velocity properties.

scholarly journals Altered single cell force-velocity and power properties in exercise-trained rat myocardium

2003 ◽  
Vol 94 (5) ◽  
pp. 1941-1948 ◽  
Author(s):  
Gary M. Diffee ◽  
Eunhee Chung
Keyword(s):  
Exercise Training ◽  
Power Output ◽  
Peak Power ◽  
Muscle Length ◽  
Work Capacity ◽  
Peak Power Output ◽  
Sprague Dawley ◽  
Shortening Velocity ◽  
External Work ◽  
Force Velocity

Myocardial function is enhanced by endurance exercise training, but the cellular mechanisms underlying this improved function remain unclear. The ability of the myocardium to perform external work is a critical aspect of ventricular function, but previous studies of myocardial adaptation to exercise training have been limited to measurements of isometric tension or unloaded shortening velocity, conditions in which work output is zero. We measured force-velocity properties in single permeabilized myocyte preparations to determine the effect of exercise training on loaded shortening and power output. Female Sprague-Dawley rats were divided into sedentary control (C) and exercise trained (T) groups. T rats underwent 11 wk of progressive treadmill exercise. Myocytes were isolated from T and C hearts, chemically skinned, and attached to a force transducer. Shortening velocity was determined during loaded contractions at 15°C by using a force-clamp technique. Power output was calculated by multiplying force times velocity values. We found that unloaded shortening velocity was not significantly different in T vs. C myocytes (T = 1.43 muscle lengths/s, n = 46 myocytes; C = 1.12 muscle lengths/s, n = 43 myocytes). Training increased the velocity of loaded shortening and increased peak power output (peak power = 0.16 P/Po × muscle length/s for T myocytes; peak power = 0.10 P/Po× muscle length/s for C myocytes, where P/Po is relative tension). We found no effect of training on myosin heavy chain isoform content. These results suggest that training alters power output properties of single cardiac myocytes and that this adaptation may improve the work capacity of the myocardium.

scholarly journals Instantaneous force-velocity-length relationship in diaphragmatic sarcomere

1997 ◽  
Vol 82 (2) ◽  
pp. 404-412 ◽  
Author(s):  
Catherine Coirault ◽  
Denis Chemla ◽  
Jean-Claude Pourny ◽  
Francine Lambert ◽  
Yves Lecarpentier
Keyword(s):  
Mechanical Properties ◽  
Striated Muscle ◽  
Mechanical Performance ◽  
Three Dimensional ◽  
Muscle Length ◽  
Total Load ◽  
Length Relationship ◽  
Abrupt Changes ◽  
Force Velocity ◽  
Isometric Twitch

Coirault, Catherine, Denis Chemla, Jean-Claude Pourny, Francine Lambert, and Yves Lecarpentier. Instantaneous force-velocity-length relationship in diaphragmatic sarcomere. J. Appl. Physiol. 82(2): 404–412, 1997.—The simultaneous analysis of muscle force, length, velocity, and time has been shown to precisely characterize the mechanical performance of isolated striated muscle. We tested the hypothesis that the three-dimensional force-velocity-length relationship reflects mechanical properties of sarcomeres. In hamster diaphragm strips, instantaneous sarcomere length (S L) and muscle length were simultaneously measured during afterloaded twitches. S L was measured by means of laser diffraction. We also studied the influence of initial S L, abrupt changes in total load, and 2 × 10−7 M dantrolene. Baseline resting S L at the apex of the length-active tension curve was 2.2 ± 0.1 μm, whereas S L at peak shortening was 1.6 ± 0.1 μm in the preloaded twitch and 2.1 ± 0.1 μm in the “isometric” twitch. Over the whole load continuum and at any given level of isotonic load, there was a unique relationship between instantaneous sarcomere velocity and instantaneous S L. Part of this relationship was time independent and initial S L independent and was markedly downshifted after dantrolene. When five different muscle regions were considered, there were no significant variations of S L and sarcomere kinetics along the muscle. These results indicate that the time- and initial length-independent part of the instantaneous force-velocity-length relationship previously described in muscle strips reflects intrinsic sarcomere mechanical properties.

Relative shortening velocity in locomotor muscles: turkey ankle extensors operate at low V/Vmax

2008 ◽  
Vol 294 (1) ◽  
pp. R200-R210 ◽  
Author(s):  
Annette M. Gabaldón ◽  
Frank E. Nelson ◽  
Thomas J. Roberts
Keyword(s):  
Isometric Force ◽  
Muscle Length ◽  
Shortening Velocity ◽  
Velocity Relationship ◽  
Locomotor Muscles ◽  
Force Velocity ◽  
Wild Turkeys ◽  
Strain Gauge Measurements ◽  
All Speeds ◽  
Level Running

The force-velocity properties of skeletal muscle have an important influence on locomotor performance. All skeletal muscles produce less force the faster they shorten and typically develop maximal power at velocities of ∼30% of maximum shortening velocity (Vmax). We used direct measurements of muscle mechanical function in two ankle extensor muscles of wild turkeys to test the hypothesis that during level running muscles operate at velocities that favor force rather than power. Sonomicrometer measurements of muscle length, tendon strain-gauge measurements of muscle force, and bipolar electromyographs were taken as animals ran over a range of speeds and inclines. These measurements were integrated with previously measured values of muscle Vmax for these muscles to calculate relative shortening velocity (V/Vmax). At all speeds for level running the V/Vmax values of the lateral gastrocnemius and the peroneus longus were low (<0.05), corresponding to the region of the force-velocity relationship where the muscles were capable of producing 90% of peak isometric force but only 35% of peak isotonic power. V/Vmax increased in response to the demand for mechanical power with increases in running incline and decreased to negative values to absorb energy during downhill running. Measurements of integrated electromyograph activity indicated that the volume of muscle required to produce a given force increased from level to uphill running. This observation is consistent with the idea that V/Vmax is an important determinant of locomotor cost because it affects the volume of muscle that must be recruited to support body weight.

Whole-body phase plane analysis for standard maximum vertical jump assessment

2021 ◽  
Vol 90 ◽  
pp. 203-204
Author(s):  
C. Rodrigues ◽  
M. Correia ◽  
J. Abrantes ◽  
B. Rodrigues ◽  
J. Nadal
Keyword(s):  
Phase Plane ◽  
Vertical Jump ◽  
Whole Body ◽  
Phase Plane Analysis ◽  
Plane Analysis

Force-velocity and force-power properties of single muscle fibers from elite master runners and sedentary men

1996 ◽  
Vol 271 (2) ◽  
pp. C676-C683 ◽  
Author(s):  
J. J. Widrick ◽  
S. W. Trappe ◽  
D. L. Costill ◽  
R. H. Fitts
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Power Output ◽  
Peak Power ◽  
Isometric Force ◽  
Peak Force ◽  
Peak Power Output ◽  
Type I ◽  
Shortening Velocity ◽  
Force Velocity

Gastrocnemius muscle fiber bundles were obtained by needle biopsy from five middle-aged sedentary men (SED group) and six age-matched endurance-trained master runners (RUN group). A single chemically permeabilized fiber segment was mounted between a force transducer and a position motor, subjected to a series of isotonic contractions at maximal Ca2+ activation (15 degrees C), and subsequently run on a 5% polyacrylamide gel to determine myosin heavy chain composition. The Hill equation was fit to the data obtained for each individual fiber (r2 > or = 0.98). For the SED group, fiber force-velocity parameters varied (P < 0.05) with fiber myosin heavy chain expression as follows: peak force, no differences: peak tension (force/fiber cross-sectional area), type IIx > type IIa > type I; maximal shortening velocity (Vmax, defined as y-intercept of force-velocity relationship), type IIx = type IIa > type I; a/Pzero (where a is a constant with dimensions of force and Pzero is peak isometric force), type IIx > type IIa > type I. Consequently, type IIx fibers produced twice as much peak power as type IIa fibers, whereas type IIa fibers produced about five times more peak power than type I fibers. RUN type I and IIa fibers were smaller in diameter and produced less peak force than SED type I and IIa fibers. The absolute peak power output of RUN type I and IIa fibers was 13 and 27% less, respectively, than peak power of similarly typed SED fibers. However, type I and IIa Vmax and a/Pzero were not different between the SED and RUN groups, and RUN type I and IIa power deficits disappeared after power was normalized for differences in fiber diameter. Thus the reduced absolute peak power output of the type I and IIa fibers from the master runners was a result of the smaller diameter of these fibers and a corresponding reduction in their peak isometric force production. This impairment in absolute peak power production at the single fiber level may be in part responsible for the reduced in vivo power output previously observed for endurance-trained athletes.

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