scholarly journals The alpha-glucan-uridine diphosphate glucosyltransferase reation for the identification of glycogen-depleted muscle fibers.

1978 ◽  
Vol 26 (9) ◽  
pp. 742-744 ◽  
Author(s):  
C W Pool ◽  
Y E Donselaar ◽  
P A Griep
Keyword(s):  
Periodic Acid ◽  
Muscle Fibers ◽  
Motor Units ◽  
Repetitive Stimulation ◽  
Uridine Diphosphate ◽  
Periodic Acid Schiff ◽  
Single Motor Units ◽  
Longus Muscle ◽  
Pas Reaction ◽  
Stimulation Of

This paper decribes the use of the alpha-glucan uridine di-phosphate glucosyl transferase reaction for enhancing the contrast between glycogen depleted and non-depleted muscle fibers in the periodic acid schiff (PAS) reaction. Muscle fiber glycogen was depleted by prolonged repetitive stimulation of single motor units of the extensor digitorum longus muscle from the rat.

Summation of motor unit tensions in the tibialis posterior muscle of the cat under isometric and nonisometric conditions

1991 ◽  
Vol 66 (6) ◽  
pp. 1838-1846 ◽  
Author(s):  
R. K. Powers ◽  
M. D. Binder
Keyword(s):  
Motor Unit ◽  
Muscle Fibers ◽  
Stimulus Frequency ◽  
Muscle Length ◽  
Motor Units ◽  
Force Transducer ◽  
Tibialis Posterior ◽  
Single Motor Units ◽  
Individual Motor ◽  
Stimulation Of

1. The tension produced by the combined stimulation of two to four single motor units of the cat tibialis posterior muscle was compared with the algebraic sum of the tensions produced by each individual motor unit. Comparisons were made under isometric conditions and during imposed changes in muscle length. 2. Under isometric conditions, the tension resulting from combined stimulation of units displayed marked nonlinear summation, as previously reported in other cat hindlimb muscles. On average, the measured tension was approximately 20% greater than the algebraic sum of the individual unit tensions. However, small trapezoidal movements imposed on the muscle during stimulation significantly reduced the degree of nonlinear summation both during and after the movement. This effect was seen with imposed movements as small as 50 microns. 3. The degree of nonlinear summation was not dependent on motor unit size or on stimulus frequency. The effect was also unrelated to tendon compliance because the degree of nonlinear summation of motor unit forces was unaffected by the inclusion of different amounts of the external tendon between the muscle and the force transducer. 4. Our results support previous suggestions that the force measured when individual motor units are stimulated under isometric conditions is reduced by friction between the active muscle fibers and adjacent passive fibers. These frictional effects are likely to originate in the connective tissue matrix connecting adjacent muscle fibers. However, because these effects are virtually eliminated by small movements, linear summation of motor unit tensions should occur at low force levels under nonisometric conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Maximal force as a function of anatomical features of motor units in the cat tibialis anterior

1987 ◽  
Vol 57 (6) ◽  
pp. 1730-1745 ◽  
Author(s):  
S. C. Bodine ◽  
R. R. Roy ◽  
E. Eldred ◽  
V. R. Edgerton
Keyword(s):  
Motor Unit ◽  
Tibialis Anterior ◽  
Periodic Acid ◽  
Muscle Fibers ◽  
Motor Units ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Periodic Acid Schiff ◽  
Cross Sectional ◽  
Single Motor Unit

In 11 tibialis anterior muscles of the cat, a single motor unit was characterized physiologically and subsequently depleted of its glycogen through repetitive stimulation of an isolated ventral root filament. Muscle cross sections were stained for glycogen using a periodic acid-Schiff reaction, and single-fiber optical densities were determined to identify those fibers belonging to the stimulated motor unit. Innervation ratios were determined by counting the total number of muscle fibers in a motor unit in sections taken through several levels of the muscle. The average innervation ratios for the fast, fatigueable (FF) and fast, fatigue-resistant (FR) units were similar. However, the slow units (S) contained 61% fewer fibers than the fast units (FF and FR). Muscle fibers belonging to S and FR units were similar in cross-sectional area, whereas fibers belonging to FF units were significantly larger than fibers belonging to either S or FR units. Additionally, muscle fibers innervated by a single motoneuron varied by two- to eightfold in cross-sectional area. Specific tensions, based on total cross-sectional area determined by summing the areas of all muscle fibers of each unit, showed a modest difference between fast and slow units, the means being 23.5 and 17.2 N X cm-2, respectively. Variations in maximum tension among units could be explained principally by innervation ratio, although fiber cross-sectional area and specific tension did contribute to differences between unit types.

Further evidence of incomplete neural control of muscle properties in cat tibialis anterior motor units

1995 ◽  
Vol 268 (2) ◽  
pp. C527-C534 ◽  
Author(s):  
G. A. Unguez ◽  
R. R. Roy ◽  
D. J. Pierotti ◽  
S. Bodine-Fowler ◽  
V. R. Edgerton
Keyword(s):  
Motor Unit ◽  
Tibialis Anterior ◽  
Neural Control ◽  
Periodic Acid ◽  
Muscle Fibers ◽  
Motor Units ◽  
Fiber Types ◽  
Muscle Properties ◽  
Periodic Acid Schiff ◽  
The Mean

To examine the influence of a motoneuron in maintaining the phenotype of the muscle fibers it innervates, myosin heavy chain (MHC) expression, succinate dehydrogenase (SDH) activity, and cross-sectional area (CSA) of a sample of fibers belonging to a motor unit were studied in the cat tibialis anterior 6 mo after the nerve branches innervating the anterior compartment were cut and sutured near the point of entry into the muscle. The mean, range, and coefficient of variation for the SDH activity and the CSA for both motor unit and non-motor unit fibers for each MHC profile and from each control and each self-reinnervated muscle studied was obtained. Eight motor units were isolated from self-reinnervated muscles using standard ventral root filament testing techniques, tested physiologically, and compared with four motor units from control muscles. Motor units from self-reinnervated muscles could be classified into the same physiological types as those found in control tibialis anterior muscles. The muscle fibers belonging to a unit were depleted of glycogen via repetitive stimulation and identified in periodic acid-Schiff-stained frozen sections. Whereas muscle fibers in control units expressed similar MHCs, each motor unit from self-reinnervated muscles contained a mixture of fiber types. In each motor unit, however, there was a predominance of fibers with the same MHC profile. The relative differences in the mean SDH activities found among fibers of different MHC profiles within a unit after self-reinnervation and those found among fibers in control muscles were similar, i.e., fast-2 < fast-1 < or = slow MHC fibers.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Nonlinear summation of contractions in cat muscles. I. Early depression.

1981 ◽  
Vol 78 (3) ◽  
pp. 277-293 ◽  
Author(s):  
R B Stein ◽  
F Parmiggiani
Keyword(s):  
Motor Units ◽  
Repetitive Stimulation ◽  
Actin Binding ◽  
Linear Summation ◽  
First Order ◽  
Twitch Response ◽  
Single Motor Units ◽  
Sodium Hydrate ◽  
Slow Twitch ◽  
Stimulation Of

Nerves to fast- and slow-twitch cat muscles were stimulated with various numbers of supramaximal pulses under isometric conditions. By subtracting the force produced by j - 1 pulses from that produced by j pulses, the contribution of the j th pulse could be compared with the response to one pulse (twitch response). A less-than-linear summation (depression) was observed during the rising phase of the twitch. This depression became increasingly prominent and longer in duration with repetitive stimulation. A more-than-linear summation (facilitation) was observed during the falling phase of the twitch, which became increasingly delayed and smaller in amplitude with repetitive stimulation. The early depression could be abolished for the first few pulses by Dantrolene [1-(5-p-nitrophenyl) furfurilidene amino hydantoin sodium hydrate], which reduced Ca++ release from the sarcoplasmic reticulum. The depression was less prominent at short muscle lengths or with stimulation of single motor units. A first-order, saturable reaction such as Ca++ binding to troponin or actin binding to myosin can quantitatively account for the early depression.

Properties of motor units of the frog iliofibularis muscle

1979 ◽  
Vol 236 (1) ◽  
pp. C35-C40 ◽  
Author(s):  
A. R. Luff ◽  
U. Proske
Keyword(s):  
Muscle Fibers ◽  
Motor Units ◽  
Slow Muscle ◽  
Homogeneous Population ◽  
Single Motor Units ◽  
Litoria Aurea ◽  
The Difference ◽  
Low Incidence ◽  
Polyneuronal Innervation ◽  
Stimulation Of

The tension developed by single motor units of the iliofibularis muscle of the frog Litoria aurea was recorded in response to single-shock and repetitive stimulation of motor axons. The majority of units in each muscle, 13 on the average, were of the twitch type; an additional 4 units were slow or tonic. It appeared that slow units comprised a single homogeneous population, but two types of twitch units could be recognized: small fatigue-resistant units with long twitch times to peak (20--40 ms) and larger, fatigable units with briefer times to peak (16--27 ms). Evidence from a comparison of unit tetanic tensions indicated the presence of polyneuronal innervation of both slow and twitch muscle fibers. The relatively low incidence of polyneuronal innervation of twitch fibers in iliofibularis, when compared with a muscle like sartorius (9), was attributed to the difference in lengths of muscle fibers in the two muscles. It was argued that slow muscle fibers probably receive a multiterminal as well as polyneuronal innervation, with the terminals of any one axon lying widely spaced along the muscle fiber.

Proportion of muscles spindles supplied by skeletofusimotor axons (beta-axons) in peroneus brevis muscle of the cat

1975 ◽  
Vol 38 (6) ◽  
pp. 1390-1394 ◽  
Author(s):  
F. Emonet-Denand ◽  
Y. Laporte
Keyword(s):  
Neuromuscular Junctions ◽  
Muscle Fibers ◽  
Repetitive Stimulation ◽  
Motor Axon ◽  
Dynamic Sensitivity ◽  
Conduction Velocities ◽  
Peroneus Brevis ◽  
Stimulation Of

Of 32 cat peroneus brevis spindles, 23 (72%) were found to be supplied by a least 1 skeletofusimotor or beta-axon. A motor axon was identified as skeletofusimotor when repetitive stimulation of it elicited both the contraction of extrafusal muscle fibers and as acceleration of the discharge of primary ending, which persisted after selective block of the neuromuscular junctions of extrafusal muscle fibers. The block was obtained by stimulating single axons at 400-500/s for a few seconds. Of 135 axons supplying extrafusal muscle fibers, 24 (18%) were shown to be beta-axons; 22 beta-axons had conduction velocities ranging from 45 to 75 m/s. All but three beta-axons increased the dynamic sensitivity of primary endings. Beta-innervated spindles may also be supplied by dynamic gamma-axons.

scholarly journals Phenotypic Modulation of Skeletal Muscle Fibers in LPIN1-Deficient Lipodystrophic (fld) Mice

2018 ◽  
Vol 56 (2) ◽  
pp. 322-331
Author(s):  
Rani S. Sellers ◽  
S. Radma Mahmood ◽  
Geoffrey S. Perumal ◽  
Frank P. Macaluso ◽  
Irwin J. Kurland
Keyword(s):  
Electron Microscopy ◽  
Skeletal Muscle ◽  
Fiber Type ◽  
Periodic Acid ◽  
Muscle Fibers ◽  
Myosin Atpase ◽  
Hybrid Fibers ◽  
Periodic Acid Schiff ◽  
Skeletal Muscle Fibers ◽  
Lipin 1

Lipin-1 ( Lpin1)–deficient lipodystrophic mice have scant and immature adipocytes and develop transient fatty liver early in life. Unlike normal mice, these mice cannot rely on stored triglycerides to generate adenosine triphosphate (ATP) from the β-oxidation of fatty acids during periods of fasting. To compensate, these mice store much higher amounts of glycogen in skeletal muscle and liver than wild-type mice in order to support energy needs during periods of fasting. Our studies demonstrated that there are phenotypic changes in skeletal muscle fibers that reflect an adaptation to this unique metabolic situation. The phenotype of skeletal muscle (soleus, gastrocnemius, plantaris, and extensor digitorum longus [EDL]) from Lpin1-/- was evaluated using various methods including immunohistochemistry for myosin heavy chains (Myh) 1, 2, 2a, 2b, and 2x; enzyme histochemistry for myosin ATPase, cytochrome-c oxidase (COX), and succinyl dehydrogenase (SDH); periodic acid–Schiff; and transmission electron microscopy. Fiber-type changes in the soleus muscle of Lpin1-/- mice were prominent and included decreased Myh1 expression with concomitant increases in Myh2 expression and myosin-ATPase activity; this change was associated with an increase in the presence of Myh1/2a or Myh1/2x hybrid fibers. Alterations in mitochondrial enzyme activity (COX and SDH) were apparent in the myofibers in the soleus, gastrocnemius, plantaris, and EDL muscles. Electron microscopy revealed increases in the subsarcolemmal mitochondrial mass in the muscles of Lpin1-/- mice. These data demonstrate that lipin-1 deficiency results in phenotypic fiber-specific modulation of skeletal muscle necessary for compensatory fuel utilization adaptations in lipodystrophy.

Properties of motor units after immobilization of cat peroneus longus muscle

1993 ◽  
Vol 74 (3) ◽  
pp. 1131-1139 ◽  
Author(s):  
J. Petit ◽  
M. Gioux
Keyword(s):  
Time Course ◽  
Relaxation Times ◽  
Motor Units ◽  
Short Length ◽  
Low Frequencies ◽  
Tetanic Force ◽  
Peroneus Longus ◽  
Single Motor Units ◽  
Longus Muscle ◽  
Selective Immobilization

Changes in contractile properties of cat peroneus longus motor units were studied 2, 5, and 8 wk after selective immobilization of this muscle, which was achieved by fixing the distal tendon of the peroneus longus to the fibula either at the muscle minimal physiological length ("short" length) or at the length for a 90 degree ankle joint ("neutral" length). In each muscle, 75–90% of the units [slow (S), fast resistant to fatigue (FR), fast intermediate (FI), and fast fatigable (FF)] were studied. Immobilization elicited a permanent decrease in tetanic force developed by single motor units, which was larger for resistant-to-fatigue units (S, FR). In most instances this decrease was not related to the immobilization length. In all units, twitch contraction and half-relaxation times underwent a transient increase, the extent and time course of which were influenced by immobilization length. The relationship between the frequency of motor units activation and the ratio of unfused to maximal tetanic force was studied. For fast units, there was a transient shift of the relation toward low frequencies after 2 and 5 wk of immobilization at neutral and short length, respectively.

Reflex responses in active muscles elicited by stimulation of low-threshold afferents from the human foot

1992 ◽  
Vol 67 (5) ◽  
pp. 1375-1384 ◽  
Author(s):  
A. M. Aniss ◽  
S. C. Gandevia ◽  
D. Burke
Keyword(s):  
Motor Units ◽  
Medial Gastrocnemius ◽  
Emg Activity ◽  
Onset Latency ◽  
Single Motor ◽  
Reflex Responses ◽  
Posterior Tibial ◽  
Single Motor Units ◽  
Low Threshold ◽  
Stimulation Of

1. Reflex responses were elicited in muscles that act at the ankle by electrical stimulation of low-threshold afferents from the foot in human subjects who were reclining supine. During steady voluntary contractions, stimulus trains (5 pulses at 300 Hz) were delivered at two intensities to the sural nerve (1.2-4.0 times sensory threshold) or to the posterior tibial nerve (1.1-3.0 times motor threshold for the intrinsic muscles of the foot). Electromyographic (EMG) recordings were made from tibialis anterior (TA), peroneus longus (PL), soleus (SOL), medial gastrocnemius (MG), and lateral gastrocnemius (LG) muscles by the use of intramuscular wire electrodes. 2. As assessed by averages of rectified EMG, stimulation of the sural or posterior tibial nerves at nonpainful levels evoked a complex oscillation with onset latencies as early as 40 ms and lasting up to 200 ms in each muscle. The most common initial responses in TA were a decrease in EMG activity at an onset latency of 54 ms for sural stimuli, and an increase at an onset latency of 49 ms for posterior tibial stimuli. The response of PL to stimulation of the two nerves began with a strong facilitation of 44 ms (sural) and 49 ms (posterior tibial). With SOL, stimulation of both nerves produced early inhibition beginning at 45 and 50 ms, respectively. With both LG and MG, sural stimuli produced an early facilitation at 52-53 ms. However, posterior tibial stimuli produced different initial responses in these two muscles: facilitation in LG at 50 ms and inhibition in MG at 51 ms. 3. Perstimulus time histograms of the discharge of 61 single motor units revealed generally similar reflex responses as in multiunit EMG. However, different reflex components were not equally apparent in the responses of different single motor units: an individual motor unit could respond slightly differently with a change in stimulus intensity or background contraction level. The multiunit EMG record represents a global average that does not necessarily depict the precise pattern of all motor units contributing to the average. 4. When subjects stood erect without support and with eyes closed, reflex patterns were seen only in active muscles, and the patterns were similar to those in the reclining posture. 5. It is concluded that afferents from mechanoreceptors in the sole of the foot have multisynaptic reflex connections with the motoneuron pools innervating the muscles that act at the ankle. When the muscles are active in standing or walking, cutaneous feedback may play a role in modulating motoneuron output and thereby contribute to stabilization of stance and gait.

Mucopolysaccharides and the Calcification of the Scale of the Roach (Leuciscus rutilus)

1956 ◽  
Vol s3-97 (39) ◽  
pp. 329-332
Author(s):  
O. WALLIN
Keyword(s):  
Transition Zone ◽  
Great Increase ◽  
Periodic Acid ◽  
Mineral Matter ◽  
Large Crystal ◽  
Periodic Acid Schiff ◽  
Acid Mucopolysaccharides ◽  
Pas Reaction ◽  
Inorganic Fraction

1. The scale of the roach (Leuciscus rutilus L.) was examined for state of calcification, metachromasy, and reaction to the periodic acid / Schiff (PAS) test. 2. Metachromasy and a positive PAS-reaction imply acid mucopolysaccharides in the bony layer. 3. There is a great increase in these reactions and in reactions for bone salts in the transition zone between the uncalcified and calcified part of the bony layer. 4. These reactions imply that the bond between the osseoid and the inorganic fraction of the bony layer is through SO2- and PO4- groupings. 5. The fibrillary plate lacks metachromasy, but shows a positive PAS-reaction. Before calcification a strong orthochromasy points to acid groups in connexion with the collagen. Under the radii there is no orthochromasy, and the PAS-reaction is negative. 6. When calcifying, the fibrillary plate loses its orthochromasy and the mineral matter is deposited as large crystal-complexes. 7. In regenerating scales the reactions are weaker than in normal scales.

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