scholarly journals GLUTAMATE UPTAKE BY A STIMULATED INSECT NERVE MUSCLE PREPARATION

1970 ◽  
Vol 46 (2) ◽  
pp. 300-307 ◽  
Author(s):  
Isabelle R. Faeder ◽  
Miriam M. Salpeter
Keyword(s):  
Electron Microscope ◽  
Nerve Stimulation ◽  
Neuromuscular Junctions ◽  
Tissue Concentration ◽  
Glutamate Uptake ◽  
Muscle Preparation ◽  
Glutamate Concentration ◽  
Chemical Studies ◽  
Nerve Muscle ◽  
Cellular Compartments

Recent reports suggest that glutamate may be the excitatory neuromuscular transmitter in insects. In this study, glutamate uptake by isolated cockroach nerve muscle preparations was investigated by means of chemical and electron microscope radioautographic techniques. We found that the preparation had a high affinity for glutamate and that nerve stimulation enhanced glutamate uptake. Chemical studies showed that the average tissue concentration of glutamate bound during a 1 hr incubation period in 10-5 M glutamate-3H after nerve stimulation was 2.8 x 10-5 M. Less than 1% of the radioactivity was present in the perchloric acid-precipitated protein fraction. Using electron microscope radioautography, we observed that sheath cells showed the highest glutamate concentration of all cellular compartments. Uptake was greater at neuromuscular junctions than in other regions of the tissue. The data suggest a possible mechanism for transmitter inactivation and protection of synapses from high blood glutamate.

Synaptic vesicle depletion and glutamate uptake in a nerve-muscle preparation of the locust,Locusta migratoria L

1978 ◽  
Vol 34 (2) ◽  
pp. 209-210 ◽  
Author(s):  
R. P. Botham ◽  
D. J. Beadle ◽  
R. J. Hart ◽  
C. Potter ◽  
R. G. Wilson
Keyword(s):  
Synaptic Vesicle ◽  
Glutamate Uptake ◽  
Locusta Migratoria ◽  
Muscle Preparation ◽  
Nerve Muscle

Effect of armin on synaptic transmission in the frog nerve-muscle preparation

1981 ◽  
Vol 91 (6) ◽  
pp. 774-777 ◽  
Author(s):  
I. I. Krivoi ◽  
V. I. Kuleshov ◽  
D. P. Matyushkin ◽  
V. I. Sanotskii ◽  
I. A. Shabunova
Keyword(s):  
Synaptic Transmission ◽  
Muscle Preparation ◽  
Nerve Muscle

scholarly journals Changes in miniature endplate potential frequency during repetitive nerve stimulation in the presence of Ca2+, Ba2+, and Sr2+ at the frog neuromuscular junction.

1981 ◽  
Vol 77 (5) ◽  
pp. 503-529 ◽  
Author(s):  
J E Zengel ◽  
K L Magleby
Keyword(s):  
Nerve Stimulation ◽  
Transmitter Release ◽  
Neuromuscular Junctions ◽  
Fourth Power ◽  
Bathing Solution ◽  
Frog Neuromuscular Junction ◽  
Repetitive Nerve Stimulation ◽  
Time Constants ◽  
Endplate Potential ◽  
Induced Changes

Miniature endplate potentials (MEPPs) were recorded from frog sartorious neuromuscular junctions under conditions of reduced quantal contents to study the effect of repetitive nerve stimulation on asynchronous (tonic) quantal transmitter release. MEPP frequency increased during repetitive stimulation and then decayed back to the control level after the conditioning trains. The decay of the increased MEPP frequency after 100-to 200-impulse conditioning trains can be described by four components that decayed exponentially with time constants of about 50 ms, 500 ms, 7 s, and 80 s. These time constants are similar to those for the decay of stimulation-induced changes in synchronous (phasic) transmitter release, as measured by endplate potential (EPP) amplitudes, corresponding, respectively, to the first and second components of facilitation, augmentation, and potentiation. The addition of small amounts of Ca2+ or Ba2+ to the Ca2+-containing bathing solution, or the replacement of Ca2+ with Sr2+, led to a greater increase in the stimulation-induced increases in MEPP frequency. The Sr-induced increase in MEPP frequency was associated with an increase in the second component of facilitation of MEPP frequency; the Ba-induced increase with an increase in augmentation. These effects of Sr2+ and Ba2+ on stimulation-induced changes in MEPP frequency are similar to the effects of these ions on stimulation-induced changes in EPP amplitude. These ionic similarities and the similar kinetics of decay suggest that stimulation induced changes in MEPP frequency and EPP amplitude have some similar underlying mechanisms. Calculations are presented which show that a fourth power residual calcium model for stimulation-induced changes in transmitter release cannot readily account for the observation that stimulation-induced changes in MEPP frequency and EPP amplitude have similar time-courses.

scholarly journals Regulatory Function of Sympathetic Innervation on the Endo/Lysosomal Trafficking of Acetylcholine Receptor

2021 ◽  
Vol 12 ◽  
Author(s):  
Tatjana Straka ◽  
Charlotte Schröder ◽  
Andreas Roos ◽  
Laxmikanth Kollipara ◽  
Albert Sickmann ◽  
...  
Keyword(s):  
Neuromuscular Junction ◽  
Acetylcholine Receptor ◽  
Ribosomal Proteins ◽  
Neuromuscular Junctions ◽  
Sympathetic Neurons ◽  
Sympathetic Innervation ◽  
Regulatory Function ◽  
Hindlimb Muscles ◽  
Nerve Muscle

Recent studies have demonstrated that neuromuscular junctions are co-innervated by sympathetic neurons. This co-innervation has been shown to be crucial for neuromuscular junction morphology and functional maintenance. To improve our understanding of how sympathetic innervation affects nerve–muscle synapse homeostasis, we here used in vivo imaging, proteomic, biochemical, and microscopic approaches to compare normal and sympathectomized mouse hindlimb muscles. Live confocal microscopy revealed reduced fiber diameters, enhanced acetylcholine receptor turnover, and increased amounts of endo/lysosomal acetylcholine-receptor-bearing vesicles. Proteomics analysis of sympathectomized skeletal muscles showed that besides massive changes in mitochondrial, sarcomeric, and ribosomal proteins, the relative abundance of vesicular trafficking markers was affected by sympathectomy. Immunofluorescence and Western blot approaches corroborated these findings and, in addition, suggested local upregulation and enrichment of endo/lysosomal progression and autophagy markers, Rab 7 and p62, at the sarcomeric regions of muscle fibers and neuromuscular junctions. In summary, these data give novel insights into the relevance of sympathetic innervation for the homeostasis of muscle and neuromuscular junctions. They are consistent with an upregulation of endocytic and autophagic trafficking at the whole muscle level and at the neuromuscular junction.

Effect of Bothrops insularis venom on the mouse and chick nerve-muscle preparation

Toxicon ◽  
1993 ◽  
Vol 31 (10) ◽  
pp. 1237-1247 ◽  
Author(s):  
J.C. Cogo ◽  
J. Prado-Franceschi ◽  
M.A. Cruz-Hofling ◽  
A.P. Corrado ◽  
L. Rodrigues-Simioni
Keyword(s):  
Muscle Preparation ◽  
Nerve Muscle

scholarly journals I. Croonian Lecture .—Observations on isolated nerve (with particular reference to carbon dioxide)

1897 ◽  
Vol 188 ◽  
pp. 1-101 ◽  
Keyword(s):  
Weak Link ◽  
Nerve Degeneration ◽  
Muscle Preparation ◽  
Marked Contrast ◽  
Functional Failure ◽  
Du Bois ◽  
Motor End Plates ◽  
Nerve Muscle ◽  
Long Endurance ◽  
Experimental Disturbance

As was pointed out ten years ago by Wedenski, from telephone observations of the negative variation, by Waller, from galvanometric observations of the same, and by Bowditch from the observation of long-persisting excitability in the nerves of temporarily curarised mammals, nerve is now admitted to be practically inexhaustible. The apparent exhaustion of nerve when a nerve-muscle preparation is submitted to prolonged excitation is, as was first demonstrated in Bernstein’s experiment, not an exhaustion of nerve, but an exhaustion of the organ of intermediation between nerve and muscle, which, as pointed out by Waller, is the weak link in the neuro-muscular chain, being the point at which functional failure is first manifested, in fatigue, in nerve degeneration, in intoxication by curare (Bernard), and at death. Taking as the sign of action artificially excited in a nerve, the negative variation of its current of rest (du Bois-Reymond) or current of injury (Hermann), the long endurance by nerve of excitation excessive in strength and in length, is well shown by prolonged photographic records of the galvanometric indications, which exhibit little or no decline, in marked contrast with similar records of the negative variation of muscle which declines pari passu with the declining contraction due to fatigue of the motor end plates. This steady regularity of response renders nerve pre-eminently suitable to the systematic study of its experimental disturbance.

scholarly journals Org NC 45 Reduces Quantal Release of Acetylcholine (a Preliminary Communication)

1982 ◽  
Vol 10 (2) ◽  
pp. 127-129 ◽  
Author(s):  
T. A. Torda ◽  
N. Kiloh
Keyword(s):  
Neuromuscular Blocker ◽  
Variance Ratio ◽  
Muscle Preparation ◽  
Quantal Release ◽  
End Plate ◽  
Release Of Acetylcholine ◽  
Preliminary Communication ◽  
Nerve Muscle

The new neuromuscular blocker, Org NC 45 was applied to the toad sartorius nerve-muscle preparation. Measurement of the variance ratio of end-plate potentials recorded by micro-electrodes demonstrated that in concentrations greater than that required to block myoneural transmission, Org NC 45 reduced the quantal release of acetylcholine.

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