The Action of Iontophoretically Applied Glutamate on Insect Muscle Fibres

1968 ◽  
Vol 49 (1) ◽  
pp. 83-93
Author(s):  
R. BERÁNEK ◽  
P. L. MILLER
Keyword(s):  
Equilibrium Point ◽  
Neuromuscular Junctions ◽  
Schistocerca Gregaria ◽  
Locusta Migratoria ◽  
Extracellular Recording ◽  
Fibre Surface ◽  
Adductor Muscle ◽  
Muscle Fibres ◽  
Glass Capillary ◽  
Insect Muscle

1. Electrophoretic application of L-glutamate from glass capillary micro-pipettes was used to investigate the ‘spot sensitivity’ of the membrane of coxal adductor muscle fibres from adult specimens of Schistocerca gregaria Forskål and Locusta migratoria (L.). 2. Circumscribed spots could be detected on the fibre surface where brief applications of L-glutamate produced transient depolarizations (glutamate potentials). 3. Extracellular recording of excitatory junction potentials revealed that focal points of glutamate sensitivity are closely related to, and probably identical with, neuromuscular junctions. 4. Large doses readily de-sensitized the membrane to L-glutamate for periods greatly exceeding the duration of the glutamate potentials. 5. In chronically denervated muscles peaks of sensitivity could still be detected. 6. Spots sensitive to L-glutamate were not depolarized by D-glutamate. 7. The equilibrium point for glutamate potentials coincides with the equilibrium point of miniature excitatory potentials and lies between -10 and -25 mV.

Common Inhibitory Motoneurones in Insects

1969 ◽  
Vol 50 (2) ◽  
pp. 445-471 ◽  
Author(s):  
K. G. PEARSON ◽  
S. J. BERGMAN
Keyword(s):  
Periplaneta Americana ◽  
Schistocerca Gregaria ◽  
Locusta Migratoria ◽  
Adductor Muscle ◽  
Dual Function ◽  
Muscle Fibres ◽  
Inhibitory Conditioning ◽  
Innervation Patterns ◽  
Antagonistic Muscles ◽  
Leg Position

1. The innervation patterns of the metathoracic posterior coxal levator muscles of the cockroach, Periplaneta americana, have been investigated, and the mechanical effects produced by activity in the axons to these muscles studied. 2. These muscles are innervated by four excitatory and two inhibitory axons. The three smallest excitatory axons may be classified as slow and the largest as fast. Some single muscle fibres are quintuply innervated by all but the fast axon, and some may be innervated by all six. 3. One of the inhibitory axons is a branch of a common inhibitory neurone. This neurone sends branches out all but one of the ipsilateral nerve trunks to innervate synergic and antagonistic muscles. 4. A similar common inhibitory motoneurone has been found in both the locust species, Locusta migratoria and Schistocerca gregaria. In the locust two branches of this common inhibitory neurone correspond to the inhibitory axon innervating the extensor tibiae muscle and the inhibitory-conditioning axon innervating the anterior coxal adductor muscle. 5. Possible functions of common inhibitory neurones in insects are discussed. In the cockroach this neurone may have a dual function: (a) to regulate leg position when the animal is standing, and (b) to facilitate relaxation of the depressor muscles; this allows a more rapid and stronger leg levation when the animal is walking.

Innervation of the ventral diaphragm of the locust (Locusta migratoria)

1977 ◽  
Vol 69 (1) ◽  
pp. 23-32
Author(s):  
M. Peters
Keyword(s):  
Electrical Stimulation ◽  
Electrical Properties ◽  
Electrical Activity ◽  
Neuromuscular Junctions ◽  
Motor Nerve ◽  
Locusta Migratoria ◽  
Posterior Segment ◽  
Muscle Fibres ◽  
Inspiratory Muscles ◽  
Motor Neurones

1. Innervation and some electrical properties of the locust ventral diaphragm were investigated with electrophysiological and histological methods. 2. Muscle fibres are coupled electrically. Electrical stimulation evokes a graded active membrane response. 3. Each segment is innervated by four motor neurones as follows. Two motor neurones are situated in each abdominal ganglion. Branches of their axons supply the ventral diaphragm in the respective and the next posterior segment. 4. This pattern of innervation was confirmed by axonal Co and Ni staining of the motor nerve endings. 5. Neuromuscular junctions are excitatory. EPSPs show summation but no facilitation. 6. Spontaneous electrical activity of the diaphragm is to a certain degree coupled to activity of the main inspiratory muscles.

Physiology and Ultrastructure of Phasic and Tonic Skeletal Muscle Fibres in the Locust, Schistocerca Gregaria

1972 ◽  
Vol 10 (2) ◽  
pp. 419-441
Author(s):  
D. G. COCHRANE ◽  
H. Y. ELDER ◽  
P. N. R. USHERWOOD
Keyword(s):  
Mechanical Response ◽  
Schistocerca Gregaria ◽  
Fibre Volume ◽  
Muscle Fibres ◽  
Potassium Depolarization ◽  
Insect Muscle ◽  
Time To Peak ◽  
Decay Times ◽  
T Tubules ◽  
Isometric Twitch

Insect muscle fibres can be classed as either phasic or tonic according to their response to potassium depolarization. The phasic fibres contract only transiently during prolonged potassium depolarization, whereas the tonic fibres give a sustained contracture. The extensor tibiae muscle in the metathoracic leg of the locust contains both tonic (T/et) and phasic (P/et) fibres; the electrical, mechanical and ultrastructural properties of these fibres have been compared with those of phasic fibres from the retractor unguis muscle (P/ru) in the same leg. A broad correlation has been established between the mechanical response and the amount of sarcoplasmic reticulum (SR) in the fibres. At maximal body length the rise time to peak twitch tension for the T/et fibres was found to be 790±60 ms, for the P/et fibres 59±2.5 ms and for the P/ru fibres, 30±1.1 ms. The half-decay times for the isometric twitch contractions were 2950±88 ms for the T/et fibres, 119±4.2 ms for the P/et, and 35±2.3 ms for the P/ru. The P/et and P/ru gave brief isometric contractures during potassium depolarization; under the same treatment the T/et fibres remained contracted throughout the treatment period. The major structural differences between the 3 types lies in the SR. Expressed as percentages of total fibre volume, the SR represents in the T/et 1.1%, in the P/et 6.8%, and in the P/ru 19%. The surface area of the SR, in terms of µm2/µm3 of fibre volume is 1.0±0.1 in the T/et, 2.9±0.2 in the P/et and 11.9±1.0 in the P/ru. Microtubules, often associated with elements of the SR, are sparsely distributed amongst the contractile elements in the T/et fibres. All 3 muscle types have a well developed T-system which forms dyadic associations with the SR. Larger-diameter Z-invaginations which conduct tracheoles into the muscles also give rise to ‘longitudinal T-tubules’, particularly in the T/et fibres. Dyads arise by association of cisternae of the SR: (i) with T-tubules sensu strictu, (ii) with Z-invaginations and T-tubule-like extensions from them, and (iii) directly with the plasma membrane at the surface of the fibre.

Effects of Denervation on the Ultrastructure of Insect Muscle

1972 ◽  
Vol 10 (3) ◽  
pp. 667-682 ◽  
Author(s):  
D. REES ◽  
P. N. R. USHERWOOD
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Motor Neurons ◽  
Muscle Hypertrophy ◽  
Schistocerca Gregaria ◽  
Muscle Volume ◽  
Muscle Fibres ◽  
Denervated Muscle ◽  
Transverse Tubular System ◽  
Insect Muscle ◽  
Tubular System

The structure of normal and denervated muscle fibres in the metathoracic retractor unguis muscle of the locust (Schistocerca gregaria) has been examined. Section of the 2 motor neurons which innervate this muscle results initially in muscle hypertrophy but this is followed about 4 days post neurotomy by progressive atrophy. Atrophy of the retractor unguis muscle is characterized by a decrease in muscle volume and degeneration of muscle organelles, e.g. mitochondria, sarcoplasmic reticulum, transverse tubular system, protein filaments, etc. During its later stages the degeneration of the denervated muscle is possibly assisted by the phagocytic action of haemocytes which invade the muscle.

Extracellular recording of localized electrical activity in denervated frog slow muscle fibres

1980 ◽  
Vol 209 (1176) ◽  
pp. 403-413 ◽  
Keyword(s):  
Electrical Activity ◽  
Rana Temporaria ◽  
Extracellular Recording ◽  
Fibre Surface ◽  
Slow Muscle ◽  
Muscle Fibres ◽  
Slow Fibre ◽  
Inward Current ◽  
Inward Currents ◽  
Slow Muscle Fibres

Pyriformis muscles of Rana temporaria were denervated by cutting the sciatic nerve in the pelvis. Slow muscle fibres were depolarized with intracellular current pulses, and the electrical activity was recorded simultaneously with intracellular and extracellular recording electrodes. When the extracellular electrode was moved along the fibre surface, outward and inward currents of variable amplitude were recorded. Inward currents coincided with the fast rising phase of the intracellularly recorded action potential; up to four inward current peaks could be detected in single fibres investigated over 3.4–8 mm of their length. The distance between inward current peaks was generally 1–2 mm, but greater distances were also observed. Composite action potentials could be shown to be due to inward currents arising in separate areas of the slow fibre membrane. It is concluded that after denervation Na-channels are incorporated into spatially limited areas of the membrane of slow muscle fibres.

Linear electrical properties of striated muscle fibres observed with intracellular electrodes

1964 ◽  
Vol 160 (978) ◽  
pp. 69-123 ◽  
Keyword(s):  
Electrical Properties ◽  
Striated Muscle ◽  
Surface Membrane ◽  
Fibre Surface ◽  
Step Function ◽  
Muscle Fibres ◽  
Appreciable Effect ◽  
Current Application ◽  
Current Path ◽  
Wide Range

The linear electrical properties of muscle fibres have been examined using intracellular electrodes for a. c. measurements and analyzing observations on the basis of cable theory. The measurements have covered the frequency range 1 c/s to 10 kc/s. Comparison of the theory for the circular cylindrical fibre with that for the ideal, one-dimensional cable indicates that, under the conditions of the experiments, no serious error would be introduced in the analysis by the geometrical idealization. The impedance locus for frog sartorius and crayfish limb muscle fibres deviates over a wide range of frequencies from that expected for a simple model in which the current path between the inside and the outside of the fibre consists only of a resistance and a capacitance in parallel. A good fit of the experimental results on frog fibres is obtained if the inside-outside admittance is considered to contain, in addition to the parallel elements R m = 3100 Ωcm 2 and C m = 2.6 μF/cm 2 , another path composed of a resistance R e = 330 Ωcm 2 in series with a capacitance C e = 4.1 μF/cm 2 , all referred to unit area of fibre surface. The impedance behaviour of crayfish fibres can be described by a similar model, the corresponding values being R m = 680 Ωcm 2 , C m = 3.9 μF/cm 2 , R e = 35 Ωcm 2 , C e = 17 μF/cm 2 . The response of frog fibres to a step-function current (with the points of voltage recording and current application close together) has been analyzed in terms of the above two-time constant model, and it is shown that neglecting the series resistance would have an appreciable effect on the agreement between theory and experiment only at times less than the halftime of rise of the response. The elements R m and C m are presumed to represent properties of the surface membrane of the fibre. R e and C e are thought to arise not at the surface, but to be indicative of a separate current path from the myoplasm through an intracellular system of channels to the exterior. In the case of crayfish fibres, it is possible that R e (when referred to unit volume) would be a measure of the resistivity of the interior of the channels, and C e the capacitance across the walls of the channels. In the case of frog fibres, it is suggested that the elements R e , C e arise from the properties of adjacent membranes of the triads in the sarcoplasmic reticulum . The possibility is considered that the potential difference across the capacitance C e may control the initiation of contraction.

THE POTENTIAL OF BACTERIA FOR THE MICROBIAL CONTROL OF GRASSHOPPERS AND LOCUSTS

1997 ◽  
Vol 129 (S171) ◽  
pp. 147-156 ◽  
Author(s):  
B. Zelazny ◽  
M.S. Goettel ◽  
B. Keller
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Bacillus Thuringiensis ◽  
Serratia Marcescens ◽  
Schistocerca Gregaria ◽  
Locusta Migratoria ◽  
Microbial Control ◽  
Control Agent ◽  
Promising Agent ◽  
Laboratory Populations ◽  
The Many

AbstractBacteria have been implicated in disease epizootics observed in field populations and laboratory-reared locusts and grasshoppers. Two species [Serratia marcescens Bizio and Pseudomonas aeruginosa (Schroeter) Migula] consistently infect locusts when ingested with food and can spread in laboratory populations. However, research on developing these organisms for microbial control of locusts and grasshoppers begun in the 1950s has not been continued. In recent years strains of Bacillus thuringiensis Berliner have been studied for activity against locusts and grasshoppers. Results of additional trials by the authors are reported. Among 393 B. thuringiensis isolates and 93 preparations of other sporeforming bacteria fed to nymphs of Locusta migratoria (L.) and/or Schistocerca gregaria Forsk., none has shown any pathogenicity to the insects. The recent discovery of novel B. thuringiensis strains active against various diverse pests and the many properties of a sporeforming bacterium that satisfy the requirements for a microbial control agent, and the development of Serratia entomophila as a promising agent for control of grass grubs, provide incentive to continue the search for an orthopteran-active sporeforming bacterium and to re-investigate the potential of non-sporeforming bacterial pathogens as microbial control agents of grasshoppers and locusts.

Effects of stimulation and rest on the ultrastructure of the excitatory neuromuscular junctions of Locusta migratoria L.

1979 ◽  
Vol 203 (3) ◽  
Author(s):  
R.P. Botham ◽  
D.J. Beadle ◽  
R.J. Hart ◽  
C. Potter ◽  
R.G. Wilson
Keyword(s):  
Neuromuscular Junctions ◽  
Locusta Migratoria

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.

scholarly journals Post-synaptic morphology of mouse neuromuscular junctions is linked to muscle fibre type

2020 ◽  
Author(s):  
Aleksandra M. Mech ◽  
Anna-Leigh Brown ◽  
Giampietro Schiavo ◽  
James N. Sleigh
Keyword(s):  
Motor Neuron ◽  
Muscle Fibre ◽  
Fibre Type ◽  
Neuromuscular Junctions ◽  
Fibre Diameter ◽  
Neuromuscular Diseases ◽  
Neuronal Morphology ◽  
Muscle Fibre Type ◽  
Muscle Membrane ◽  
Muscle Fibres

AbstractThe neuromuscular junction (NMJ) is the highly specialised peripheral synapse formed between lower motor neuron terminals and muscle fibres. Post-synaptic acetylcholine receptors (AChRs), which are found in high density in the muscle membrane, bind to acetylcholine released into the synaptic cleft of the NMJ, ultimately facilitating the conversion of motor action potentials to muscle contractions. NMJs have been studied for many years as a general model for synapse formation, development and function, and are known to be early sites of pathological changes in many neuromuscular diseases. However, information is limited on the diversity of NMJs in different muscles, whether muscle fibre type impacts NMJ morphology and growth, and the relevance of these parameters to neuropathology. Here, this crucial gap was addressed using a robust and standardised semi-automated workflow called NMJ-morph to quantify features of pre- and post-synaptic NMJ architecture in an unbiased manner. Five wholemount muscles from wild-type mice were dissected and compared at immature (post-natal day, P7) and early adult (P31-32) timepoints. Post-synaptic AChR morphology was found to be more variable between muscles than that of the motor neuron terminal and there were greater differences in the developing NMJ than at the mature synapse. Post-synaptic architecture, but not neuronal morphology or post-natal synapse growth, correlates with fibre type and is largely independent of muscle fibre diameter. Counter to previous observations, this study indicates that smaller NMJs tend to innervate muscles with higher proportions of fast twitch fibres and that NMJ growth rate is not conserved across all muscles. Furthermore, healthy pre- and post-synaptic NMJ morphological parameters were collected for five anatomically and functionally distinct mouse muscles, generating reference data that will be useful for the future assessment of neuromuscular disease models.Graphical Abstract

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