Effect of Cooling on Neuromuscular Transmission in the Frog

1958 ◽  
Vol 192 (3) ◽  
pp. 464-470 ◽  
Author(s):  
Choh-Luh Li ◽  
Peter Gouras
Keyword(s):  
Critical Temperature ◽  
Neuromuscular Junction ◽  
Nerve Stimulation ◽  
Neuromuscular Transmission ◽  
The Other ◽  
Sartorius Muscle ◽  
Single Muscle ◽  
Miniature Endplate Potentials ◽  
Endplate Potentials ◽  
Muscle Responses

Recording with intracellular electrodes from endplate regions of frogs sartorius muscle showed that at –1°C miniature endplate potentials still occurred and that the resting membrane potentials differed very little from those recorded at room temperatures. The miniature potentials, however, were decreased in frequency and increased in amplitude by cooling; and at about 5°C, the amplitude began to fall while the frequency continued to be low. It was also at about 5°C that the muscle responses to nerve stimulation frequently consisted of endplate potentials only. Upon rewarming spike potentials again appeared. These observations suggest that there is a critical temperature for neuromuscular transmission, below which impediment of impulse transmission began; and in the frog it is 5°C. The experiments also demonstrated that during the process of cooling a blockage of impulses at one neuromuscular junction and transmission across the other in a single muscle fiber could occur.

Effect of Hypertonicity on Augmentation and Potentiation and on Corresponding Quantal Parameters of Transmitter Release

1999 ◽  
Vol 81 (3) ◽  
pp. 1428-1431 ◽  
Author(s):  
Hong Cheng ◽  
Michael D. Miyamoto
Keyword(s):  
Nerve Stimulation ◽  
Transmitter Release ◽  
Ringer Solution ◽  
Hypertonic Solution ◽  
Repetitive Nerve Stimulation ◽  
Quantal Transmitter Release ◽  
Before And After ◽  
Miniature Endplate Potentials ◽  
Endplate Potentials ◽  
Made In

Effect of hypertonicity on augmentation and potentiation and on corresponding quantal parameters of transmitter release. Augmentation and (posttetanic) potentiation are two of the four components comprising the enhanced release of transmitter following repetitive nerve stimulation. To examine the quantal basis of these components under isotonic and hypertonic conditions, we recorded miniature endplate potentials (MEPPs) from isolated frog ( Rana pipiens) cutaneous pectoris muscles, before and after repetitive nerve stimulation (40 s at 80 Hz). Continuous recordings were made in low Ca2+ high Mg2+ isotonic Ringer solution, in Ringer that was made hypertonic with 100 mM sucrose, and in wash solution. Estimates were obtained of m (no. of quanta released), n (no. of functional release sites), p (mean probability of release), and vars p (spatial variance in p), using a method that employed MEPP counts. Hypertonicity abolished augmentation without affecting potentiation. There were prolonged poststimulation increases in m, n,and p and a marked but transient increase in vars p in the hypertonic solution. All effects were completely reversed with wash. The time constants of decay for potentiation and for vars p were virtually identical. The results are consistent with the notion that augmentation is caused by Ca2+ influx through voltage-gated calcium channels and that potentiation is due to Na+-induced Ca2+ release from mitochondria. The results also demonstrate the utility of this approach for analyzing the dynamics of quantal transmitter release.

Repetitive Nerve Stimulation Studies

2016 ◽  
pp. 328-346
Author(s):  
Kathleen D. Kennelly
Keyword(s):  
Neuromuscular Junction ◽  
Nerve Stimulation ◽  
Nerve Conduction ◽  
Neuromuscular Transmission ◽  
Repetitive Stimulation ◽  
Nerve Conduction Studies ◽  
Clinical Correlation ◽  
Repetitive Nerve Stimulation ◽  
Anatomy And Physiology

Repetitive stimulation is a technique that evaluates the function of the neuromuscular junction. It is important not only in the detection, clarification, and follow-up of neuromuscular junction diseases, but also in excluding these disorders in patients with symptoms of fatigue, vague weakness, diplopia, ptosis, and malaise, or with objective weakness of uncertain origin. The technique requires knowledge of the physiology and pathophysiology of neuromuscular transmission and the basic techniques of nerve conduction studies. This chapter includes a brief review of the anatomy and physiology of the neuromuscular junction as it applies to repetitive stimulation, a detailed discussion of the technique, the pitfalls that can occur if not carried out correctly, criteria used to classify the results as normal or abnormal, the patterns of abnormalities that can be seen, and the clinical correlation of those abnormalities with the various different disorders of neuromuscular transmission.

scholarly journals Multimodal Distribution of Frog Miniature Endplate Potentials in Adult, Denervated, and Tadpole Leg Muscle

1974 ◽  
Vol 64 (1) ◽  
pp. 85-103 ◽  
Author(s):  
Mahlon E. Kriebel ◽  
Cordell E. Gross
Keyword(s):  
Mean Amplitude ◽  
Sartorius Muscle ◽  
Integer Multiple ◽  
Major Mode ◽  
Mepp Amplitude ◽  
The Mean ◽  
Almost All ◽  
Increasing Temperature ◽  
Miniature Endplate Potentials ◽  
Endplate Potentials

Amplitude histograms of spontaneous miniature endplate potentials (MEPPs) from adult sartorius muscle cells show a definite bimodality with the mean amplitude of the larger mode five to seven times that of the smaller mode which accounted for 2–5 % of the total MEPPs. Histograms were plotted after high frequency MEPP generation induced by increasing temperature, increasing external calcium or nerve stimulation. These plots showed a reversible left-shift of the major mode as well as a reversible increase in the proportion of small mode MEPPs. Repeated challenges shifted almost all MEPPs into the small mode. An increase in the percentage of small mode MEPPs also occurred spontaneously during the course of denervation before the quiescent period and some of the histogram profiles showed multiple modes whose means were integer multiples of the small mode mean. In the early stages of hind leg development the greatest proportion of MEPPs were of the small mode size; as metamorphosis progressed, the histograms showed a definite multimodality with the mean of each mode being an integer multiple of the small mode mean and with the proportion of MEPPs in each mode about the same. During tail resorption the percentage of larger MEPPs increased until the adult histogram profile was reached. Thus, the changes in MEPP amplitude histograms over the course of metamorphosis are the reverse of those found with denervation.

Effect of Cooling on Neuromuscular Transmission in the Rat

1958 ◽  
Vol 194 (1) ◽  
pp. 200-206 ◽  
Author(s):  
Choh-Luh Li
Keyword(s):  
Body Temperature ◽  
Neuromuscular Transmission ◽  
Mean Value ◽  
Membrane Potentials ◽  
Resting Membrane Potential ◽  
Body Temperatures ◽  
Direct Stimulation ◽  
C 32 ◽  
Miniature Endplate Potentials ◽  
Endplate Potentials

When the rat was being cooled from normal body temperature to 10°C, the resting membrane potentials recorded from the endplate region of the gracilis anticus muscle of the rat showed no significant change, with a mean value of –79.5 ± 4.6 mv (S.D.). The resting membrane potentials at body temperatures below 10°C were lower; the mean value at 10°–4°C was –71 ± 8.5 mv, and at 4°–0°C, –32 ± 10.2 mv. Below 0°C resting membrane potential was not recorded. The responses to nerve stimulation did not change at body temperatures between 36° and 15°C. Below 15°C the duration of the spike responses became longer and at times the responses showed no spike potentials; at 5°–4°C no spikes but endplate potentials were recorded. The miniature endplate potentials could be recorded at body temperature as low as 4°C but not below. The performance of neuromuscular transmission was most efficient at body temperature above 15°C, and was impeded at 15°C and blocked at 5°C. At 4°C the nerve ceased to conduct although contraction of the muscle could be produced by direct stimulation at body temperatures as low as 1°C. During the process of cooling some of the muscle fibers would fibrillate. In frost bite lesions, produced by cooling the extremity to –2°C for 2 hours, muscle resting potentials and miniature endplate potentials were absent and there was no response to direct or indirect stimulation of the muscle.

scholarly journals Neuromuscular transmission studies in human chronic Chagas' disease

1989 ◽  
Vol 47 (3) ◽  
pp. 279-282 ◽  
Author(s):  
Marcela Garcia Erro ◽  
O. Genovese ◽  
J. Correale ◽  
R. E. P. Sica
Keyword(s):  
Chagas Disease ◽  
Nerve Stimulation ◽  
Neuromuscular Transmission ◽  
Evoked Potential ◽  
The State ◽  
Electrophysiological Investigation ◽  
Transmission Studies ◽  
Chronic Chagas Disease ◽  
Muscle Responses

An electrophysiological investigation of the state of the neuromuscular transmission (nmt) was carried out in 58 patients with the diagnosis of chronic Chagas' disease. On repetitive supramaximal nerve stimulation it was found that some patients did not show abnormalities, others had decremental muscle responses, others developed enhancement of the muscle evoked potential amplitudes, while some other patients combined both types of pathological responses. The findings suggest that some patients with chronic Chagas' disease develop impairement of nmt, though data obtained in this study do not give information about neither the type of impairement nor the localization (pre or postsynaptic, or both) of the damage.

POSTSYNAPTIC EFFECTS OF HC-3 AT THE NEUROMUSCULAR JUNCTION OF THE FROG

1961 ◽  
Vol 39 (2) ◽  
pp. 343-349 ◽  
Author(s):  
A. R. Martin ◽  
R. K. Orkand
Keyword(s):  
Neuromuscular Junction ◽  
Intracellular Recording ◽  
Neuromuscular Transmission ◽  
Muscle Fibers ◽  
Marked Change ◽  
Single Muscle ◽  
End Plate ◽  
Quantum Content ◽  
Iontophoretic Application

Intracellular recording from single muscle fibers has been used to study the effects of hemicholinium No. 3 (HC-3) on neuromuscular transmission in the excised m. ext. l. dig. IV of the frog. Concentrations of HC-3 greater than 10−5 M decreased the amplitude of the end-plate potentials (e.p.p.'s) and the magnitude of the depolarization produced by iontophoretic application of acetylcholine. Neither a decrease in e.p.p. quantum content nor depolarization of the end plate accompanied the decreased e.p.p. amplitude. The duration of the potential produced by the application of ACh was increased and the falling phase of the e.p.p. prolonged. 10−4 M HC-3 produced a marked change in the shape of the e.p.p., the effect being similar to that produced by procaine.

Case 17

2018 ◽  
Author(s):  
Bashar Katirji
Keyword(s):  
Neuromuscular Junction ◽  
Myasthenia Gravis ◽  
Nerve Stimulation ◽  
Neuromuscular Transmission ◽  
Diagnostic Sensitivity ◽  
Repetitive Nerve Stimulation ◽  
Tensilon Test ◽  
Diagnostic Modalities ◽  
Ice Pack

Myasthenia gravis is a relatively common neuromuscular junction disorder. The diagnosis of myasthenia gravis may be challenging particularly in seronegative patients. This case starts by discussing the diagnostic modalities available to confirm the diagnosis of myasthenia gravis including serum antibodies, the Tensilon test, and the ice pack test. After a detailed discussion of the physiology of neuromuscular transmission, the case emphasizes the role of electrodiagnostic studies in the diagnosis of myasthenic gravis. This includes detailed findings on repetitive nerve stimulation recording distal and proximal muscles as well as single-fiber electromyography jitter studies. Finally, the diagnostic sensitivity of the available tests in myasthenia gravis is compared and a suggested electrodiagnostic strategy for patients with suspected myasthenic gravis is outlined.

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