Extracellular potentials of single active muscle fibres: Effects of finite fibre length

1986 ◽  
Vol 53 (6) ◽  
pp. 363-372 ◽  
Author(s):  
A. A. Gydikov ◽  
N. A. Trayanova
Keyword(s):  
Fibre Length ◽  
Muscle Fibres ◽  
Active Muscle ◽  
Extracellular Potentials

EFFICIENCY OF ENERGY CONVERSION DURING SINUSOIDAL MOVEMENT OF WHITE MUSCLE FIBRES FROM THE DOGFISH SCYLIORHINUS CANICULA

1993 ◽  
Vol 183 (1) ◽  
pp. 137-147 ◽  
Author(s):  
N. A. Curtin ◽  
R. C. Woledge
Keyword(s):  
Power Output ◽  
High Efficiency ◽  
Fibre Length ◽  
Dry Mass ◽  
Energy Output ◽  
Maximum Efficiency ◽  
Muscle Fibres ◽  
Work Output ◽  
Sinusoidal Movement ◽  
Myotomal Muscle

Net work output and heat production of white myotomal muscle fibres from the dogfish were measured during complete cycles of sinusoidal movement at 12°C. The peak-to-peak movement was about 9 % of the muscle fibre length; three stimuli at 32 ms intervals were given in each mechanical cycle. The frequency of movement and the timing of the stimulation were varied for each preparation to find the optimal conditions for power output and those optimal for efficiency (the ratio of net work output to total energy output as heat+work). To achieve either maximum power or maximum efficiency, the tetanus must start while the muscle fibres are being stretched, before the beginning of the shortening part of the mechanical cycle. The highest power output, averaged over one cycle, was 0.23+/−0.014 W g-1 dry mass (+/−s.e.m., N=9, 46.9+/−2.8 mW g-1 wet mass) and was produced during movement at 3.5 Hz. The highest efficiency, 0.41+/−0.02 (+/−s.e.m., N=13), occurred during movements at 2.0-2.5 Hz. This value is higher than the efficiency previously measured during isovelocity shortening of these fibres. The implications of the high efficiency for crossbridge models of muscle contraction are discussed.

scholarly journals THE CAPILLARY PATTERN IN HUMAN MASSETER MUSCLE DURING AGEING

2013 ◽  
Vol 32 (3) ◽  
pp. 135 ◽  
Author(s):  
Erika Cvetko ◽  
Jiří Janáček ◽  
Lucie Kubínová ◽  
Ida Eržen
Keyword(s):  
Muscle Fibre ◽  
Masseter Muscle ◽  
3D Visualization ◽  
Fibre Length ◽  
Fibre Surface ◽  
Fibre Volume ◽  
Immunohistochemical Method ◽  
Muscle Fibres ◽  
Age Related ◽  
Novel Approach

The effect of ageing on the capillary network in skeletal muscles has produced conflicting results in both, human and animals studies. Some of the inconsistencies are due to non-comparable and biased methods that were applied on thin transversal sections, especially in muscles with complicated morphological structures, such as in human masseter muscle. We present a new immunohistochemical method for staining capillaries and muscle fibres in 100 µm thick sections as well as novel approach to 3D visualization of capillaries and muscle fibres. Applying confocal microscopy and virtual 3D stereological grids, or tracing capillaries in virtual reality, length of capillaries within a muscle volume or length of capillaries adjacent to muscle fibre per fibre length, fibre surface or fibre volume were evaluated in masseter muscle of young and old subjects by an unbiased approach. Our findings show that anatomic capillarity is well maintained in masseter muscle in old subjects; however, vascular remodelling occurs with age, which could be a response to changed muscle function and age-related muscle fibre type transformations.

Differential effects of muscle fibre length and insulin on muscle-specific mRNA content in isolated mature muscle fibres during long-term culture

2006 ◽  
Vol 326 (3) ◽  
pp. 795-808 ◽  
Author(s):  
R. T. Jaspers ◽  
H. M. Feenstra ◽  
B. J. van Beek-Harmsen ◽  
P. A. Huijing ◽  
W. J. van der Laarse
Keyword(s):  
Muscle Fibre ◽  
Fibre Length ◽  
Muscle Fibres ◽  
Long Term Culture ◽  
Differential Effects ◽  
Mrna Content ◽  
Specific Mrna

scholarly journals X-ray diffraction studies of the contractile mechanism in single muscle fibres

2004 ◽  
Vol 359 (1452) ◽  
pp. 1883-1893 ◽  
Author(s):  
K. C. Holmes ◽  
D. R. Trentham ◽  
R. Simmons ◽  
Vincenzo Lombardi ◽  
Gabriella Piazzesi ◽  
...  
Keyword(s):  
Fibre Length ◽  
Elastic Response ◽  
Muscle Fibres ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rapid Changes ◽  
Low Load ◽  
Intact Muscle ◽  
Motor Actions

The molecular mechanism of muscle contraction was investigated in intact muscle fibres by X–ray diffraction. Changes in the intensities of the axial X–ray reflections produced by imposing rapid changes in fibre length establish the average conformation of the myosin heads during active isometric contraction, and show that the heads tilt during the elastic response to a change in fibre length and during the elementary force generating process: the working stroke. X–ray interference between the two arrays of myosin heads in each filament allows the axial motions of the heads following a sudden drop in force from the isometric level to be measured in situ with unprecedented precision. At low load, the average working stroke is 12 nm, which is consistent with crystallographic studies. The working stroke is smaller and slower at a higher load. The compliance of the actin and myosin filaments was also determined from the change in the axial spacings of the X–ray reflections following a force step, and shown to be responsible for most of the sarcomere compliance. The mechanical properties of the sarcomere depend on both the motor actions of the myosin heads and the compliance of the myosin and actin filaments.

scholarly journals Modulation of passive force in single skeletal muscle fibres

2005 ◽  
Vol 1 (3) ◽  
pp. 342-345 ◽  
Author(s):  
Dilson E Rassier ◽  
Eun-Jeong Lee ◽  
Walter Herzog
Keyword(s):  
Skeletal Muscle ◽  
Sarcomere Length ◽  
Fibre Length ◽  
Muscle Fibres ◽  
Isometric Contractions ◽  
Passive Force ◽  
Length Relationship ◽  
Lumbrical Muscle ◽  
Single Fibres ◽  
Skeletal Muscle Fibres

In this study, we investigated the effects of activation and stretch on the passive force–sarcomere length relationship in skeletal muscle. Single fibres from the lumbrical muscle of frogs were placed at varying sarcomere lengths on the descending limb of the force–sarcomere length relationship, and tetanic contractions, active stretches and passive stretches (amplitudes of ca 10% of fibre length at a speed of 40% fibre length/s) were performed. The passive forces following stretch of an activated fibre were higher than the forces measured after isometric contractions or after stretches of a passive fibre at the corresponding sarcomere length. This effect was more pronounced at increased sarcomere lengths, and the passive force–sarcomere length relationship following active stretch was shifted upwards on the force axis compared with the corresponding relationship obtained following isometric contractions or passive stretches. These results provide strong evidence for an increase in passive force that is mediated by a length-dependent combination of stretch and activation, while activation or stretch alone does not produce this effect. Based on these results and recently published findings of the effects of Ca 2+ on titin stiffness, we propose that the observed increase in passive force is caused by the molecular spring titin.

scholarly journals Computational modelling of muscle fibre operating ranges in the hindlimb of a small ground bird (Eudromia elegans), with implications for modelling locomotion in extinct species

2021 ◽  
Vol 17 (4) ◽  
pp. e1008843
Author(s):  
Peter J. Bishop ◽  
Krijn B. Michel ◽  
Antoine Falisse ◽  
Andrew R. Cuff ◽  
Vivian R. Allen ◽  
...  
Keyword(s):  
Muscle Function ◽  
Computational Models ◽  
Fibre Length ◽  
Computational Modelling ◽  
Length Change ◽  
Muscle Fibres ◽  
Extinct Species ◽  
Length Changes ◽  
Experimental Findings

The arrangement and physiology of muscle fibres can strongly influence musculoskeletal function and whole-organismal performance. However, experimental investigation of muscle function during in vivo activity is typically limited to relatively few muscles in a given system. Computational models and simulations of the musculoskeletal system can partly overcome these limitations, by exploring the dynamics of muscles, tendons and other tissues in a robust and quantitative fashion. Here, a high-fidelity, 26-degree-of-freedom musculoskeletal model was developed of the hindlimb of a small ground bird, the elegant-crested tinamou (Eudromia elegans, ~550 g), including all the major muscles of the limb (36 actuators per leg). The model was integrated with biplanar fluoroscopy (XROMM) and forceplate data for walking and running, where dynamic optimization was used to estimate muscle excitations and fibre length changes throughout both gaits. Following this, a series of static simulations over the total range of physiological limb postures were performed, to circumscribe the bounds of possible variation in fibre length. During gait, fibre lengths for all muscles remained between 0.5 to 1.21 times optimal fibre length, but operated mostly on the ascending limb and plateau of the active force-length curve, a result that parallels previous experimental findings for birds, humans and other species. However, the ranges of fibre length varied considerably among individual muscles, especially when considered across the total possible range of joint excursion. Net length change of muscle–tendon units was mostly less than optimal fibre length, sometimes markedly so, suggesting that approaches that use muscle–tendon length change to estimate optimal fibre length in extinct species are likely underestimating this important parameter for many muscles. The results of this study clarify and broaden understanding of muscle function in extant animals, and can help refine approaches used to study extinct species.

The musculature of Peripatus and its innervation

1980 ◽  
Vol 288 (1031) ◽  
pp. 481-510 ◽  
Keyword(s):  
Body Wall ◽  
Fibre Length ◽  
Gross Anatomy ◽  
Small Degree ◽  
The Body ◽  
Muscle Fibres ◽  
Neuromuscular Synapses ◽  
Thick Filaments ◽  
Small Muscle ◽  
Tubule Diameter

The musculature of the Onychophoran Peripatus dominicae , its ultrastructure and details of innervation are described. Significant differences were noted between its gross anatomy and that reported in previous accounts, notably in the presence of inner circular body wall muscle and a prominent, functionally significant, levator of the leg. The former is important in regard to the evolutionary position of the Onychophora while the latter helps us to understand the control of walking in a lobopodial leg, and therefore the evolution of arthropod locomotion, which was the focus of our interest. Individual muscle fibres are either directly or indirectly attached to the body wall by collagen. There is a small degree of branching of fibres, with or without anastomosis, near their insertions, but most are as long as the muscle of which they are part, and are unbranched except for an occasional thin arm, emerging at an angle, that becomes invaded by collagen fibres and inserts in the skin. Diameters of muscle fibres vary from 1 to 45 pm. They are invaginated by two separate systems of unique wide (0.3 pm) tubules, longitudinal and radial. These are lined with similar material to that forming the basement material of the sarcolemma, and also contain fine strands with collagen-type cross-banding that connect to collagen bundles outside the fibres. In addition there are narrow tubules of ordinary T-tubule diameter. Both wide and narrow tubules make contacts with sarcoplasmic reticulum cysternae. Dense Z bodies are attached to both kinds of wide tubule, to the inside of the sarcolemma, and are scattered, without any obvious array, in the sarcoplasm. Thin myofilaments emerge from the Z bodies parallel to the fibre axis. Thick filaments occur in clusters with a loosely hexagonal array, but without any regular relation to thin ones: relatively few orbits of thin around thick filaments were seen in many muscle fibres regardless of fibre length and conditions during fixation. A unique innervation pattern was found, consisting of a combination of muscle arm to nerve contacts, which appear to be the commonest, and nerve on muscle fibre synapses. At least 13 motor axons were found to supply each small muscle or cluster of muscle fibres in a large muscle. Each muscle arm simultaneously makes synaptic contact with 3 to 7 axons. Nerve on muscle junctions contain from 1 to 8 axons, each making synaptic contacts. The details of the postsynaptic endplate-specializations resemble those seen in mammalian endplates and are markedly different from both arthropod and annelidan neuromuscular synapses.

Light diffraction studies of active muscle fibres as a function of sarcomere length

1981 ◽  
Vol 2 (2) ◽  
pp. 215-224 ◽  
Author(s):  
Toshiharu Oba ◽  
Ronald J. Baskin ◽  
Richard L. Lieber
Keyword(s):  
Sarcomere Length ◽  
Light Diffraction ◽  
Muscle Fibres ◽  
Active Muscle

scholarly journals Non-crossbridge stiffness in active muscle fibres

2016 ◽  
Vol 219 (2) ◽  
pp. 153-160 ◽  
Author(s):  
Barbara Colombini ◽  
Marta Nocella ◽  
Maria Angela Bagni
Keyword(s):  
Muscle Fibres ◽  
Active Muscle
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