scholarly journals Elastic tissue forces mask muscle fiber forces underlying muscle spindle Ia afferent firing rates in stretch of relaxed rat muscle

2019 ◽  
Vol 222 (15) ◽  
pp. jeb196287 ◽  
Author(s):  
Kyle P. Blum ◽  
Paul Nardelli ◽  
Timothy C. Cope ◽  
Lena H. Ting
Keyword(s):  
Muscle Fiber ◽  
Muscle Spindle ◽  
Elastic Tissue ◽  
Firing Rates ◽  
Ia Afferent ◽  
Rat Muscle

scholarly journals Noncontractile tissue forces mask muscle fiber forces underlying muscle spindle Ia afferent firing rates in stretch of relaxed rat muscle

2018 ◽  
Author(s):  
Kyle P. Blum ◽  
Paul Nardelli ◽  
Timothy C. Cope ◽  
Lena H. Ting
Keyword(s):  
Muscle Fiber ◽  
Muscle Spindle ◽  
Muscle Force ◽  
Muscle Fibers ◽  
Elastic Tissue ◽  
Tissue Model ◽  
Firing Rates ◽  
Ia Afferent ◽  
Rat Muscle ◽  
Cross Bridges

AbstractStretches of relaxed cat and rat muscle elicit similar history-dependent muscle spindle Ia firing rates that resemble history-dependent forces seen in single activated muscle fibers (Nichols and Cope, 2004). During stretch of relaxed cat muscle, whole musculotendon forces exhibit history-dependence that mirror history-dependent muscle spindle firing rates, where both muscle force and muscle spindle firing rates are elevated in the first stretch in a series of stretch-shorten cycles (Blum et al., 2017). By contrast, rat musculotendon are only mildly history-dependent and do not mirror history-dependent muscle spindle firing rates in the same way (Haftel et al., 2004). We hypothesized that history-dependent muscle spindle firing rates elicited in stretch of relaxed rat muscle would mirror history-dependent muscle fiber forces, which are masked by noncontractile tissue at the level of whole musculotendon force. We removed noncontractile tissue force contributions from the recorded musculotendon force using an exponentially-elastic tissue model. We then show that the remaining estimated muscle fiber force resembles history-dependent muscle spindle firing rates recorded simultaneously. These forces also resemble history-dependent forces recorded in stretch of single activated fibers and attributed to muscle cross-bridge mechanisms (Campbell and Moss, 2000). Our results suggest that history-dependent muscle spindle firing in both rats and cats arise from stretch of cross-bridges in muscle fibers.

Effects of ?-endorphin on the development of denervation changes in rat muscle fiber membrane

1988 ◽  
Vol 19 (6) ◽  
pp. 550-555 ◽  
Author(s):  
A. V. Chikin ◽  
A. Kh. Urazaev ◽  
E. M. Volkov ◽  
G. I. Poletaev ◽  
Kh. S. Khamitov
Keyword(s):  
Muscle Fiber ◽  
Fiber Membrane ◽  
Rat Muscle ◽  
Muscle Fiber Membrane

Anisotropic diffusion of oxygen in slices of rat muscle

1984 ◽  
Vol 246 (1) ◽  
pp. R107-R113 ◽  
Author(s):  
L. D. Homer ◽  
J. B. Shelton ◽  
C. H. Dorsey ◽  
T. J. Williams
Keyword(s):  
Diffusion Coefficient ◽  
Fluorescence Quenching ◽  
Muscle Fiber ◽  
Extracellular Space ◽  
Anisotropic Diffusion ◽  
Muscle Fibers ◽  
Rat Muscle ◽  
Hamstring Muscles ◽  
Standard Deviations ◽  
Diffusion Coefficient Of Oxygen

The diffusion coefficient of oxygen (D) and the fluorescence quenching coefficient (K') of pyrenebutyric acid (PBA) were measured in sections of rat hamstring muscles. Values of D and K' at temperatures (Tc) of 20, 30, and 40 degrees C were determined and referred to the values in water. In sections cut parallel to the muscle fibers, D = DH2O (0.380 +/- 0.038), whereas in sections cut across the grain of the fibers, D = DH2O (0.985 +/- 0.039). Oxygen diffuses along the length of a muscle fiber over twice as rapidly as it diffuses in directions perpendicular to the long axis of the fiber. This suggests that fibers, myofibrils, or myofilaments offer substantial barriers to the diffusion of oxygen, whereas extracellular space and spaces around fibers or myofibrils or myofilaments offer no more resistance than water to the diffusion of oxygen. Corresponding estimates for K' were K' = K'H2O[0.14 (1 + 0.25 Tc)] and K' = K'H2O[0.21 (1 + 0.25 Tc)] for slices cut parallel to the long axis of muscle fibers and across the long axis, respectively. Standard deviations of K' were 9%.

scholarly journals Effects of tonic muscle pain on fusimotor control of human muscle spindles during isometric ankle dorsiflexion

2019 ◽  
Vol 121 (4) ◽  
pp. 1143-1149
Author(s):  
Lyndon J. Smith ◽  
Vaughan G. Macefield ◽  
Ingvars Birznieks ◽  
Alexander R. Burton
Keyword(s):  
Muscle Spindle ◽  
Muscle Pain ◽  
Tibialis Anterior Muscle ◽  
Muscle Spindles ◽  
Muscle Spindle Afferents ◽  
Firing Rates ◽  
Leg Muscles ◽  
Tonic Muscle ◽  
Voluntary Contractions ◽  
Ankle Dorsiflexors

Studies on anesthetized animals have revealed that nociceptors can excite fusimotor neurons and thereby change the sensitivity of muscle spindles to stretch; such nociceptive reflexes have been suggested to underlie the mechanisms that lead to chronic musculoskeletal pain syndromes. However, the validity of the “vicious cycle” hypothesis in humans has yielded results contrasting with those found in animals. Given that spindle firing rates are much lower in humans than in animals, it is possible that some of the discrepancies between human experimental data and those obtained in animals could be explained by differences in background fusimotor drive when the leg muscles are relaxed. We examined the effects of tonic muscle pain during voluntary contractions of the ankle dorsiflexors. Unitary recordings were obtained from 10 fusimotor-driven muscle spindle afferents (6 primary, 4 secondary) supplying the ankle dorsiflexors via a microelectrode inserted percutaneously into the common peroneal nerve. A series of 1-min weak contractions was performed at rest and during 1 h of muscle pain induced by intramuscular infusion of 5% hypertonic saline into the tibialis anterior muscle. We did not observe any statistically significant increases in muscle spindle firing rates of six afferents followed during tonic muscle pain, although discharge variability increased slightly. Furthermore, a participant’s capacity to maintain a constant level of force, while relying on proprioceptive feedback in the absence of visual feedback, was not compromised during pain. We conclude that nociceptive inputs from contracting muscle do not excite fusimotor neurons during voluntary isometric contractions in humans. NEW & NOTEWORTHY Data obtained in the cat have shown that muscle pain causes a marked increase in the firing of muscle spindles, attributed to a nociceptor-driven fusimotor reflex. However, our studies of muscle spindles in relaxed leg muscles failed to find any effect on spindle discharge. Here we showed that experimental muscle pain failed to increase the firing of muscle spindle afferents during weak voluntary contractions, when fusimotor drive sufficient to increase their firing is present.

scholarly journals The effects of vibration-induced altered stretch reflex sensitivity on maximal motor unit firing properties

2019 ◽  
Vol 121 (6) ◽  
pp. 2215-2221 ◽  
Author(s):  
Alejandra Barrera-Curiel ◽  
Ryan J. Colquhoun ◽  
Jesus A. Hernandez-Sarabia ◽  
Jason M. DeFreitas
Keyword(s):  
Motor Unit ◽  
Muscle Spindle ◽  
Stretch Reflex ◽  
Muscle Spindles ◽  
Motor Unit Action Potential ◽  
Firing Rates ◽  
Motor Unit Firing ◽  
Firing Properties ◽  
Spindle Function ◽  
Voluntary Strength

It is well known that muscle spindles have a monosynaptic, excitatory connection with α-motoneurons. However, the influence of muscle spindles on human motor unit behavior during maximal efforts remains untested. It has also been shown that muscle spindle function, as assessed by peripheral reflexes, can be systematically manipulated with muscle vibration. Therefore, the purpose of this study was to analyze the effects of brief and prolonged vibration on maximal motor unit firing properties. A crossover design was used, in which each of the 24 participants performed one to three maximal knee extensions under three separate conditions: 1) control, 2) brief vibration that was applied during the contraction, and 3) after prolonged vibration that was applied for ~20 min before the contraction. Multichannel EMG was recorded from the vastus lateralis during each contraction and was decomposed into its constituent motor unit action potential trains. Surprisingly, an approximate 9% reduction in maximal voluntary strength was observed not only after prolonged vibration but also during brief vibration. In addition, both vibration conditions had a large, significant effect on firing rates (a decrease in the rates) and a small to moderate, nonsignificant effect on recruitment thresholds (a small increase in the thresholds). Therefore, vibration had a detrimental influence on both maximal voluntary strength and motor unit firing properties, which we propose is due to altered function of the stretch reflex pathway. NEW & NOTEWORTHY We used vibration to alter muscle spindle function and examined the vibration’s influence on maximal motor unit properties. We discovered that vibration had a detrimental influence on motor unit behavior and motor output by decreasing motor unit firing rates, increasing recruitment thresholds, which led to decreased maximal strength. We believe that understanding the role of muscle spindles during maximal contractions provides a deeper insight into motor control and sensorimotor integration.

Calbindin D-28k-immunoreactivity in rat muscle spindle; a light and electron microscopic study

1992 ◽  
Vol 579 (2) ◽  
pp. 327-332 ◽  
Author(s):  
Marke Hietanen-Peltola ◽  
Markku Pelto-Huikko ◽  
Leena Rechardt ◽  
Piers Emson ◽  
Tomas Hökfelt
Keyword(s):  
Microscopic Study ◽  
Electron Microscopic Study ◽  
Muscle Spindle ◽  
Electron Microscopic ◽  
Rat Muscle ◽  
Calbindin D

Excitation of rat muscle spindle afferents by lyoniol-A

1974 ◽  
Vol 26 (2) ◽  
pp. 136-142 ◽  
Author(s):  
Hideomi Fukuda ◽  
Yoshihisa Kudo ◽  
Hideki Ono
Keyword(s):  
Muscle Spindle ◽  
Muscle Spindle Afferents ◽  
Rat Muscle

Conversion of rat muscle fiber types

1985 ◽  
Vol 83 (6) ◽  
pp. 555-560 ◽  
Author(s):  
C. R. Oakley ◽  
P. D. Gollnick
Keyword(s):  
Muscle Fiber ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Rat Muscle
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