TETRAETHYLAMMONIUM-INDUCED CONTRACTIONS OF FROG'S SKELETAL MUSCLE: II. EFFECTS ON INTRAMUSCULAR NERVE ENDINGS

1967 ◽  
Vol 45 (5) ◽  
pp. 833-844 ◽  
Author(s):  
G. Beaulieu ◽  
G. B. Frank ◽  
F. Inoue
Keyword(s):  
Motor Nerve ◽  
Muscle Fibers ◽  
Electrical Stimulus ◽  
Nerve Fibers ◽  
Ventral Root ◽  
Nerve Endings ◽  
Glass Capillary ◽  
Action Potential Firing ◽  
Low Concentrations ◽  
Potential Firing

By recording simultaneously from muscle fibers and from the ventral root supplying the muscle, it was found that low concentrations of tetraethylammonium (TEA) caused the muscle fibers to fire without antidromic impulses being conducted to the ventral root. Exposing the muscles to higher TEA concentrations induced action potential firing in both the muscle and the ventral root. d-Tubocurarine prevented the muscle fiber activity but did not modify the ventral root firing. The application of a single supramaximal electrical stimulus to the sciatic nerve resulted in an afterdischarge of the muscle fibers either alone or simultaneous with an afterdischarge of fibers in the ventral root. By recording from fine intramuscular motor nerve fibers with extracellular glass capillary microelectrodes while simultaneously recording from the ventral root, it was demonstrated that TEA could cause these fine intramuscular motor nerve fibers to fire without the activity being conducted antidromically to the ventral root. A consideration of the patterns of TEA-induced electrical activity and afterdischarging led to the suggestion that TEA causes these effects by displacing calcium from binding sites on the motor nerve endings, making the latter hyperexcitable and unstable and thereby causing afterdischarging and 'spontaneous' activity.

ATP concentrations and muscle tension increase linearly with muscle contraction

2003 ◽  
Vol 95 (2) ◽  
pp. 577-583 ◽  
Author(s):  
Jianhua Li ◽  
Nicholas C. King ◽  
Lawrence I. Sinoway
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Muscle Contraction ◽  
Motor Nerve ◽  
Muscle Tension ◽  
Nerve Fibers ◽  
Ventral Root ◽  
Ventral Roots ◽  
Root Stimulation ◽  
Stimulation Of

Previous studies have suggested that activation of ATP-sensitive P2X receptors in skeletal muscle play a role in mediating the exercise pressor reflex (Li J and Sinoway LI. Am J Physiol Heart Circ Physiol 283: H2636–H2643, 2002). To determine the role ATP plays in this reflex, it is necessary to examine whether muscle interstitial ATP (ATPi) concentrations rise with muscle contraction. Accordingly, in this study, muscle contraction was evoked by electrical stimulation of the L7 and S1 ventral roots of the spinal cord in 12 decerebrate cats. Muscle ATPi was collected from microdialysis probes inserted in the muscle. ATP concentrations were determined by the HPLC method. Electrical stimulation of the ventral roots at 3 and 5 Hz increased mean arterial pressure by 13 ± 2 and 16 ± 3 mmHg ( P < 0.05), respectively, and it increased ATP concentration in contracting muscle by 150% ( P < 0.05) and 200% ( P < 0.05), respectively. ATP measured in the opposite control limb did not rise with ventral root stimulation. Section of the L7 and S1 dorsal roots did not affect the ATPi seen with 5-Hz ventral root stimulation. Finally, ventral roots stimulation sufficient to drive motor nerve fibers did not increase ATP in previously paralyzed cats. Thus ATPi is not largely released from sympathetic or motor nerves and does not require an intact afferent reflex pathway. We conclude that ATPi is due to the release of ATP from contracting skeletal muscle cells.

scholarly journals ANALYTICAL DETERMINATION OF INITIAL CONDITIONS LEADING TO FIRING IN NERVE FIBERS

2007 ◽  
Vol 17 (10) ◽  
pp. 3697-3701
Author(s):  
SABIR JACQUIR ◽  
STEPHANE BINCZAK ◽  
JEAN-MARIE BILBAULT
Keyword(s):  
Initial Conditions ◽  
Travelling Waves ◽  
Stationary Wave ◽  
Nerve Fibers ◽  
Analytical Determination ◽  
Action Potential Firing ◽  
Perturbative Method ◽  
Potential Firing ◽  
The Stability

An analytical solution characterizing initial conditions leading to action potential firing in smooth nerve fibers is determined, using the bistable equation. In the first place, we present a nontrivial stationary solution wave, then, using the perturbative method, we analyze the stability of this stationary wave. We show that it corresponds to a frontier between the initiation of the travelling waves and a decay to the resting state. Eventually, this analytical approach is extended to FitzHugh–Nagumo model.

Bupivacaine Preferentially Blocks Ventral Root Axons in Rats

1997 ◽  
Vol 86 (1) ◽  
pp. 172-180 ◽  
Author(s):  
Friederike B. Dietz ◽  
Richard A. Jaffe
Keyword(s):  
Motor Nerve ◽  
Conduction Block ◽  
Sensory Nerve ◽  
Differential Susceptibility ◽  
Nerve Fibers ◽  
Ventral Root ◽  
Differential Sensitivity ◽  
Male Rats ◽  
Spinal Root

Background Clinically, bupivacaine can provide excellent sensory anesthesia with minimal impairment of motor function. However, the mechanisms by which local anesthetics produce differential sensory-motor nerve block is still unknown. The primary site of action for spinal and epidural anesthetics is thought to be the intradural segment of the spinal root. To determine the differential susceptibility of single motor and sensory nerve fibers to local anesthetic conduction block, bupivacaine effects on individual dorsal root (DR) and ventral root (VR) axons were studied. Methods Lumbar DRs and VRs were excised from anesthetized adult male rats. Single-fiber dissection and recording techniques were used to isolate activity in individual axons. Supramaximal constant-voltage stimuli at 0.3 Hz were delivered to the root. During in vitro perfusion, each root was exposed to increasing concentrations of bupivacaine, and the minimum blocking concentration (C(m)) and the concentration that increased conduction latency by 50% (latency EC50) were measured. Results Ventral root axons were significantly more sensitive to the steady-state conduction blocking effects of bupivacaine than were either myelinated or unmyelinated DR axons (DR-C(m), 32.4 microM; VR-C(m), 13.8 microM; P &lt; 0.0001). In addition, VR axons were more susceptible to the latency-increasing effects of bupivacaine than were DR axons (DR-EC50 = 20.7 microM; VR-EC50 = 8.5 microM; P &lt; 0.0001). Within axon groups, differential sensitivity as a function of conduction velocity (axon diameter), or length of nerve exposed to the anesthetic could not be demonstrated. Conclusions In contrast to clinical expectations, low concentrations of bupivacaine preferentially block motor (VR) axons in the rat.

scholarly journals Regulation of ClC-1 and KATP channels in action potential–firing fast-twitch muscle fibers

2009 ◽  
Vol 134 (6) ◽  
pp. 523-523
Author(s):  
Thomas Holm Pedersen ◽  
Frank Vincenzo de Paoli ◽  
John A. Flatman ◽  
Ole Bækgaard Nielsen
Keyword(s):  
Action Potential ◽  
Muscle Fibers ◽  
Katp Channels ◽  
Action Potential Firing ◽  
Potential Firing ◽  
Fast Twitch Muscle ◽  
Fast Twitch

scholarly journals Hysto-ultrastructure of the facial nerve and mimic muscles in the norm and in the conditions of eхperimental neuropathy

2017 ◽  
Vol 8 (4) ◽  
pp. 569-576
Author(s):  
V. Myhailiuk ◽  
I. Mykhailiuk ◽  
M. Hembarovskyi ◽  
O. Lebid ◽  
K. Duda ◽  
...  
Keyword(s):  
Facial Nerve ◽  
Morphological Changes ◽  
Motor Nerve ◽  
Muscle Fibers ◽  
Small Diameter ◽  
Nerve Fibers ◽  
Residual Effects ◽  
Myelinated Nerve ◽  
Fine Grained ◽  
Argyrophilic Grains

We studied the structural components of the facial nerve in the norm and with cold neuropathy, indicating morphological changes in neuromuscular endings and muscle fibers at 10, 15, 30 and 60 days from the beginning of the simulation of experimental neuropathy, which was caused by local supercooling of the projection portions of the extracranial parts of the facial nerve on the background of the preliminary introduction of Freud’s complete adjuvant. We established that the pathomorphological changes in the endonevral microcirculatory bed have a phase character: the initial spasm (up to 10 days) changes in paralytic vasodilation, and its residual effects remain until the end of the experiment (60 days). Changes in hemomicrocirculation conditions lead to marked disturbances in the structure of myelinic nerve fibers, which have the character of segmental demyelination with signs of delay in axonal transport and reactive restructuring of neuromuscular endings. The change in the metric composition of myelinated nerve fibers is due to an increase in the number of nerve fibers of medium and large diameters (up to 30 days) and small diameter (after 30 days). In different periods of the experiment, a decrease in the branching area of the terminal branches of the motor axon is observed in the nerve cells, local edema of the endonevria, degenerative changes in a part of the nerve fibers develop. Due to the fine-grained decay of the final nerve branches, degeneration of the motor endings took place two weeks after the start of the experiment. Neuropathy for 30 days caused a pronounced inhibition of spotting in the peripheral parts of the motor nerve fibers. After 60 days of experiment, a large number of muscle fibers underwent destructive changes. The size of a significant part of the neuromuscular endings was reduced. In all terms of cold neuropathy, neurolematocytes reacted in the same way: cytoplasm was swollen, argyrophilic grains appeared in the nuclei, fine-grained decay of individual nuclei occurred. 

scholarly journals Features of structure of nerve motor endings in the tongue of normal and dehydrated rats

2017 ◽  
Vol 8 (3) ◽  
pp. 333-342
Author(s):  
S. L. Popel’ ◽  
О. Т. Bylоus ◽  
I. V. Bylous
Keyword(s):  
Normal Condition ◽  
Complex Analysis ◽  
Motor Nerve ◽  
Muscle Fibers ◽  
The Body ◽  
Nerve Endings ◽  
Functional Changes ◽  
Tongue Muscles ◽  
Active Zones ◽  
Tip Of The Tongue

This study aims at an analytical review of scientific literature on the structure of the tongue of different animals and humans, and also at studying the features of the structure of motor nerve endings in the tongue muscles of healthy rats and rats that have undergone prolonged dehydration. Over 14 days, using histological methods we studied neuromuscular endings and peculiarities of their distribution in the tongue muscles of 25 mature rats, both in normal condition and under dehydration. The analysis of the results showed different structures of differentiated motor nerve endings among the rats in normal condition, and also revealed the peculiarities and quantitative characteristics of the components of the neuromuscular endings in relation to the duration of dehydration. The type of neuromuscular ending reflects the morphologically interdependent structure of efferent neuromediators in relation to a part of the tongue. This may determine the nature of the processes of prehension and chewing of food. The structure of neuromuscular endings of the muscles of the tip of the tongue is the most differentiated, they are more numerous and larger. The tip of the tongue of rats had a higher number of nuclei and larger size of the neuromuscular endings of the muscles than the other parts. This, perhaps, is determined by the speed of the movements of the tongue due to eating different foods. The number of nuclei and the size of neuromuscular endings are characterized by significant variations in the pattern of axon branching, which is determined by the anatomical, physiological and biomechanical conditions of functioning of the rats’ tongue muscles. The quantative analysis of structural peculiarities of axomycin synapses showed that muscle fibers of the tongue have neuroumuscular endings with regulated synaptoarchitectonics which is characterized by the sprouting of the motor axon, a certain length and width of the active zones, number and size of the synaptic folds, number of terminal neurolemmocytes, and the peculiarity in structure of the subsynaptic area. Muscle fibers in the body of the tongue have the most complex special distribution of presynaptic pole of axomuscular synapses, they also have the highest number of active zones and synaptic folds. We determined the main reactive and destructive processes while distinguishing certain phases of morphologically-functional changes in the organism under total dehydration. A complex analysis of the morpho-functional characteristics of the peripheral nervous apparatus of the tongue of rats subject to total dehydration helped reveal the structural rearrangement of the neuromuscular endings over certain periods. During first three days after the beginning of the dehydration modeling, a structural adaptation was manifested in the reorganization of the neuromuscular endings, which is followed by their destructive changes in 6–9 days, and a phase of exhaustion with disorders in the fine architectonics of neuromuscular endings after 14 days. The article discusses the peculiarities of the efferent part of the motor unit of the tongue of rats subject to prolonged dehydration. 

scholarly journals A NOTE ON THE ACTION OF CURARE, ATROPINE, AND NICOTINE ON THE INVERTEBRATE HEART

1922 ◽  
Vol 4 (5) ◽  
pp. 559-568 ◽  
Author(s):  
A. J. Carlson
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Heart Muscle ◽  
Motor Nerve ◽  
Nerve Fibers ◽  
Nerve Endings ◽  
Visceral Muscle ◽  
The Central Nervous System ◽  
Intrinsic Motor

1. The alkaloids (curare, atropine, and nicotine) in molluscs and arthropods stimulate and paralyze the central nervous system and peripheral (visceral) ganglia, but do not paralyze the motor nerve endings to skeletal or visceral muscle. 2. They stimulate and paralyze the denervated heart. 3. They paralyze or block the cardioinhibitory nerves, but not the cardioaccelerator nerves. 4. In the Limulus heart these drugs act primarily on the heart ganglion, not on the heart muscle or the intrinsic motor nerve fibers.

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