Neuromuscular Physiology of the Longitudinal Muscle of the Earthworm, Lumbricus Terrestris

1974 ◽  
Vol 60 (2) ◽  
pp. 453-467
Author(s):  
C. D. DREWES ◽  
R. A. PAX
Keyword(s):  
Time Course ◽  
Longitudinal Muscle ◽  
Lumbricus Terrestris ◽  
Single Pulse ◽  
Repetitive Stimulation ◽  
Muscle Fibres ◽  
Mechanical Responses ◽  
Segmental Nerve ◽  
Earthworm Lumbricus ◽  
Stimulation Of

1. Patterns of innervation of the longitudinal muscle of the earthworm, Lumbricus terrestris, were examined electrophysiologically. 2. The longitudinal musculature of a segment is innervated by relatively few axons, a fast and slow axon being present in segmental nerve I and in the double nerve, segmental nerve II-III. 3. Single-pulse stimulation of the fast axon produces large external muscle potentials and small twitch-like contractions, which with repetitive stimulation are antifacilitating. 4. Repetitive stimulation of the slow axon produces large, slowly developing and sustained mechanical responses, with electrical and mechanical responses showing summation and facilitation. 5. The amplitude and time course of slow mechanical responses are related to the frequency of stimulation. 6. Individual longitudinal muscle fibres are innervated by either the fast or slow axon in a segmental nerve, or by both fast and slow axons. 7. No evidence was found for peripheral inhibitory innervation of the longitudinal muscle.

Mechanical responses of the body wall muscle of the earthworm, Lumbricus terrestris, to segmental nerve stimulation

1971 ◽  
Vol 49 (12) ◽  
pp. 1527-1534 ◽  
Author(s):  
Charles D. Drewes ◽  
Ralph A. Pax
Keyword(s):  
Nerve Stimulation ◽  
Longitudinal Muscle ◽  
Circular Muscle ◽  
Lumbricus Terrestris ◽  
Repetitive Stimulation ◽  
Second Phase ◽  
Muscle Response ◽  
Mechanical Responses ◽  
Segmental Nerve ◽  
Earthworm Lumbricus

Suitable nerve–muscle preparations are described for recording the electrical and mechanical responses of the longitudinal and circular muscle to segmental nerve stimulation in the earthworm, Lumbricus terrestris. The longitudinal muscle response to prolonged repetitive stimulation consists of a smooth increase in tension to form a peak in less than 10 s followed by a slow decline in tension to about one-half peak tension in 45 s. The circular muscle response to prolonged repetitive stimulation consists of two distinct phases of tension development: an initial, rapidly developing peak resembling that in longitudinal muscle and a slow, irregularly developing second phase. The circular and longitudinal muscle responses are obtained at frequencies above f or 2/s, with the amplitude of each response being a function of the stimulus strength within a range of 0.4–1.4 V (2 ms) and the stimulus frequency within a range of 5–50/s. In addition there is a threshold-dependent inhibition of the second phase of the circular muscle response.Circular and longitudinal responses to single stimuli are obtained with stimulus strengths approximately 10 times greater than those of the responses to repetitive stimulation and the amplitude of these responses appears to be a function of the strength of stimulation. The single stimulus response appears to be a result of repetitive firing in the same motor fibers which mediate the response to repetitive stimulation.

Neuromuscular Physiology of the Longitudinal Muscle of the Earthworm, Lumbricus Terrestris

1974 ◽  
Vol 60 (2) ◽  
pp. 469-475
Author(s):  
C. D. DREWES ◽  
R. A. PAX
Keyword(s):  
Longitudinal Muscle ◽  
Lumbricus Terrestris ◽  
Muscle Fibres ◽  
Posterior Pair ◽  
Anterior Pair ◽  
Earthworm Lumbricus

1. The motor fields of individual segmental nerves have been mapped electrophysiologically in the longitudinal muscle of the earthworm, Lumbricus terrestris. 2. The anterior pair of segmental nerves (SNI) innervates approximately the anterior two-thirds of its segment and a small portion of the segment just anterior to it. 3. The posterior pair of segmental nerves (SNII-III) innervates approximately the posterior two-thirds of its segment and a small portion of the segment just posterior to it. 4. Adjacent nerves (both intrasegmental and intersegmental) have partially overlapping motor fields; that is, adjacent segmental nerves innervate some of the same longitudinal muscle fibres.

Slow Activity in the Nervous System of the Earthworm, Lumbricus Terrestris

1967 ◽  
Vol 46 (3) ◽  
pp. 571-583
Author(s):  
M. B. V. ROBERTS
Keyword(s):  
Nervous System ◽  
Nerve Cord ◽  
Action Potentials ◽  
Longitudinal Muscle ◽  
Lumbricus Terrestris ◽  
Longitudinal Contraction ◽  
Peripheral Stimulation ◽  
Segmental Nerve ◽  
Slow Potentials ◽  
Slow Activity

1. Three thresholds are demonstrated in the first segmental nerve and two (sometimes three) in the second and third segmental nerves together. 2. Slow potentials recorded from the ventral nerve cord consist of several peaks. The first peak is composed of three spikes which make their appearance at different thresholds. Transmission of at least some of the slow potentials is decremental. 3. Transmission speeds in the nerve cord and segmental nerves range from 0.4 to 0.6 m./sec. 4. Action potentials in the longitudinal muscle are recorded in response to slow potentials in the nerve cord. 5. Two slow reflexes, one involving elongation, the other longitudinal contraction, are described. The latter has the lower threshold with peripheral stimulation. 6. Slow activity in the nervous system is discussed in relation to reflex activity of the earthworm and the neurone anatomy of the nerve cord and segmental nerves.

Pharmacological Properties of Excitatory Neuromuscular Synapses in the Locust

1968 ◽  
Vol 49 (2) ◽  
pp. 341-361
Author(s):  
P. N. R. USHERWOOD ◽  
P. MACHILI
Keyword(s):  
Muscle Fibres ◽  
Amino Group ◽  
Mechanical Responses ◽  
Neuromuscular Synapses ◽  
Level Of Activity ◽  
Excitatory Activity ◽  
Wide Range ◽  
Nerve Muscle ◽  
Related Compounds ◽  
Stimulation Of

1. The effects of a wide range of amino acids and related compounds on retractor unguis nerve-muscle preparations from the locust, grasshopper and cockroach have been investigated. 2. L-glutamate is the most active excitatory substance. The presence of two acidic groups and one amino group is essential for excitatory activity while the position of the amino group is of some importance in determining the level of activity. 3. When L-glutamate is applied iontophoretically to the muscle fibres, ‘glutamate’ depolarizations are recorded only at the synaptic sites. Other evidence that the action of glutamate is restricted to the synaptic sites is presented. 4. Perfusion of isolated locust retractor unguis nerve-muscle preparations with locust haemolymph does not markedly affect the neurally evoked mechanical responses. It appears that locust haemolymph contains little ‘free’ L-glutamate. 5. Four acidic amino aids have been identified in the perfusate from isolated retractor unguis preparations namely, glycine, alanine, aspartate and L-glutamate. However, only L-glutamate increases in concentration during stimulation of the retractor unguis nerve.

The Giant Fibre Reflex of the Earthworm, Lumbricus Terrestris L

1962 ◽  
Vol 39 (2) ◽  
pp. 229-237
Author(s):  
M. B. V. ROBERTS
Keyword(s):  
Neuromuscular Junctions ◽  
Lumbricus Terrestris ◽  
Repetitive Stimulation ◽  
Motor Neurone ◽  
Giant Fibre ◽  
Sensory Neurones ◽  
Contractile Mechanism ◽  
Motor Neurones ◽  
Earthworm Lumbricus

1. The purpose of this investigation was to locate the site of fatigue in the giant fibre reflex of the earthworm. 2. The following sites do not show rapid fatigue on repetitive stimulation: contractile mechanism of muscle, neuromuscular junctions, junctions in the course of the motor neurone tracts. 3. Rapid failure of transmission (accommodation) occurs between the sensory neurones and the giant fibre, and between the giant fibre and the motor neurones.

The rapid response of Myxicola infundibulum (Grübe)

1962 ◽  
Vol 42 (3) ◽  
pp. 527-539 ◽  
Author(s):  
M. B. V. Roberts
Keyword(s):  
Nerve Cord ◽  
Escape Response ◽  
Longitudinal Muscle ◽  
Repetitive Stimulation ◽  
Rapid Response ◽  
Direct Stimulation ◽  
Giant Fibre ◽  
Single Shock ◽  
Sufficient Strength ◽  
Stimulation Of

In Myxicola the rapid muscular response produced by direct stimulation of the nerve cord with a single shock is usually large and obeys a simple ‘all-or-nothing’ relationship to the intensity of stimulation. A single shock of sufficient strength evokes a single giant fibre impulse which produces an extensive contraction of the longitudinal muscle.The magnitude of the summated contraction obtained by repetitive stimulation of the nerve cord is found to depend on the number and frequency of the shocks, thus providing the animal with a mechanism by which, theoretically, it could grade its escape response.

Neuromuscular Physiology of the Longitudinal Muscle of the Earthworm, Lumbricus Terrestris

1974 ◽  
Vol 60 (2) ◽  
pp. 445-452
Author(s):  
C. D. DREWES ◽  
R. A. PAX
Keyword(s):  
Longitudinal Muscle ◽  
Ionic Composition ◽  
Lumbricus Terrestris ◽  
Physiological Saline ◽  
Body Fluids ◽  
Resting Potential ◽  
Muscle Fibres ◽  
The Mean ◽  
Nerve Muscle ◽  
Increased Susceptibility

1. An earthworm saline commonly used in previous investigations of earthworm neuromuscular physiology has been shown to be inappropriate for such studies because the ionic composition of the saline does not correspond to that of earthworm body fluids. 2. Problems encountered when using this saline include: increased excitability of motor axons innervating the longitudinal muscle, a decrease in the amplitude of external electrical responses of the muscle, an increased susceptibility of longitudinal muscle fibres to injury spiking, and a decrease in resting potentials of longitudinal muscle fibres (to a mean of -36.1 mV). 3. Such problems have been overcome by the development of a new physiological saline whose composition closely corresponds to the ionic composition of earthworm body fluids. 4. In the new saline responses of the nerve-muscle preparation remain stable for more than 1 h. 5. Resting potentials of longitudinal muscle fibres are also stable with time, the mean resting potential being -47.9 mV.

Absence of staircase following disuse in rat gastrocnemius muscle

1988 ◽  
Vol 66 (6) ◽  
pp. 707-713 ◽  
Author(s):  
Brian R. MacIntosh ◽  
Marie-Cristine Roberge ◽  
Phillip F. Gardiner
Keyword(s):  
Skeletal Muscles ◽  
Time Course ◽  
Gastrocnemius Muscle ◽  
Repetitive Stimulation ◽  
Muscle Weight ◽  
Twitch Contraction ◽  
Fast Twitch ◽  
Pulse Stimulation ◽  
Stimulation Of

Repetitive stimulation of mammalian fast-twitch skeletal muscles will normally result in a positive staircase response. This phenomenon was investigated in the rat gastrocnemius muscle following a 2-week period of tetrodotoxin-induced disuse. Muscle inactivity was imposed by superfusing tetrodotoxin in saline over the left sciatic nerve via an implanted osmotic pump. In situ isometric contractile responses to double pulse stimulation and repetitive stimulation at 10 Hz were determined the day after removal of the pump. Two weeks of disuse resulted in 40% muscle weight loss. A twitch contraction gave the same force when expressed per gram of wet muscle weight in control muscles, 317 ± 24.6 [Formula: see text] g/g, as compared with tetrodotoxin-treated muscles, 328 ± 24.2 g/g. Both contraction time and half-relaxation time were prolonged following treatment with tetrodotoxin. Repetitive stimulation at 10 Hz resulted in a positive staircase response in the control muscles, but not in muscles of the tetrodotoxin-treated rats. The observed changes in the time course of the twitch contraction with repetitive stimulation following tetrodotoxin-induced disuse are consistent with alterations in sarcoplasmic reticulum handling of calcium. It is not certain if there is a change following disuse in the mechanism normally associated with staircase or if this mechanism is merely opposed by an early fatigue.

scholarly journals THE STRUCTURE OF THE SMOOTH MUSCLE FIBRES IN THE BODY WALL OF THE EARTHWORM

1957 ◽  
Vol 3 (1) ◽  
pp. 111-122 ◽  
Author(s):  
Jean Hanson
Keyword(s):  
Smooth Muscle ◽  
Phase Contrast ◽  
Body Wall ◽  
Longitudinal Muscle ◽  
Lumbricus Terrestris ◽  
Mirror Image ◽  
The Body ◽  
The Other ◽  
Muscle Fibres ◽  
Muscle Coat

1. The structure of the smooth muscle fibres in the longitudinal muscle coat of the body wall of Lumbricus terrestris has been investigated by phase contrast light microscopy and electron microscopy. 2. The muscle fibre is ribbon-shaped, and attached to each of its two surfaces is a set of myofibrils. These are also ribbon-shaped, and they lie with their surfaces perpendicular to the surfaces of the fibre, and their inner edges nearly meeting in the middle of the fibre. These fibrils are oriented at an angle to the fibre axis, and diminish greatly in width as they approach the edge of the fibre. The orientation of the set of fibrils belonging to one surface of the fibre is the mirror image of that of the set belonging to the other surface; thus, when both sets are in view in a fibre lying flat on one face, the fibre exhibits double oblique striation. A comparison of extended and contracted fibres indicates that as the fibre contracts, the angle made between fibre and fibril axes increases (e.g. from 5 to 30°) and so does the angle made between the two sets of fibrils (e.g. from 10 to 60°). 3. The myofibril, throughout its length, contains irregularly packed filaments, commonly 250 A in diameter, which are parallel to its long axis and remain straight in contracted muscles. Between them is material which probably consists of much finer filaments. Thus A and I bands are absent. 4. Bound to one face of each fibril, but not penetrating inside it, is a regularly spaced series of transverse stripes. They are of two kinds, alternating along the length of the fibril, and it is suggested that they are comparable to the Z and M lines of a cross-striated fibril. The spacing of these stripes is about 0.5 µ ("Z" to "Z") in extended muscles, and 0.25 µ in contracted muscles. A bridge extends from each stripe across to the stripeless surface of the next fibril.

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