Two types of miniature endplate potentials in Xenopus nerve-muscle cultures

1984 ◽  
Vol 1 (3) ◽  
pp. 157-170 ◽  
Author(s):  
Yoshiaki Kidokoro
Keyword(s):  
Muscle Cultures ◽  
Nerve Muscle ◽  
Miniature Endplate Potentials ◽  
Endplate Potentials

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.

The giant miniature endplate potentials frequency is increased in aged rats

2015 ◽  
Vol 584 ◽  
pp. 224-229 ◽  
Author(s):  
Paula A. Pousinha ◽  
Alexandra M. Correia ◽  
Ana M. Sebastião ◽  
Joaquim A. Ribeiro
Keyword(s):  
Aged Rats ◽  
Miniature Endplate Potentials ◽  
Endplate Potentials

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.

scholarly journals Clusters of intramembrane particles associated with binding sites for alpha-bungarotoxin in cultured chick myotubes.

1979 ◽  
Vol 82 (2) ◽  
pp. 494-516 ◽  
Author(s):  
S A Cohen ◽  
D W Pumplin
Keyword(s):  
Acetylcholine Receptors ◽  
High Concentration ◽  
High Particle Concentration ◽  
High Particle ◽  
Cholinergic Synapses ◽  
Muscle Cultures ◽  
High Concentrations ◽  
Nerve Muscle ◽  
Alpha Bungarotoxin ◽  
Angular Particles

Developing chick myotubes in tissue culture were freeze-fractured to yield complementary replicas of large areas of membrane. Regions of muscle fibers with high concentrations of acetylcholine receptors were identified by binding of fluorescent-labeled alpha-bungarotoxin. Membranes in such regions contained clusters of large (100 A Diam) angular particles, similar in appearance to particles found in postsynaptic membranes of cholinergic synapses. Particles appeared in apposing areas of cytoplasmic and external leaflets but were more prevalent in the cytoplasmic leaflet. The areas of high particle concentration were coextensive with the fluorescence due to bound toxin. Treatment of cultures with tetrodotoxin increased the size of fluorescent spots and areas of high concentration of particles relative to those found in control cultures. In muscle cultures grown in the presence of spinal cord explants, some neurites contacted and innervated nearby myotubes. Intense fluorescence due to binding or alpha-bungarotoxin was present at portions of such neurite-myotube contacts. At these same portions, a high concentration of large angular particles was present in the sarcolemma adjacent to the neurite. In addition, an ordered arrangement of large particles was seen in the cytoplasmic leaflet of the neuronal plasmalemma directly apposing the muscle. The possible significance of these arrangements is discussed. Clusters on myotubes tended to be larger (contain more particles) when they occurred in groups, defined as three or more clusters with an intercluster distance of less than 0.5 micrometers. Clusters were also larger in myotubes treated with tetrodotoxin and in myotubes adjacent to some neurites in nerve-muscle cocultures. Several depressions containing particles similar to those in the clusters were found in the sarcolemma. The implications of these depressions are discussed in light of current theories of incorporation of proteins into cell membranes.

Miniature endplate potentials as a tool in neurotoxicology

Toxicology ◽  
1988 ◽  
Vol 49 (1) ◽  
pp. 121-129 ◽  
Author(s):  
Michael Csicsaky ◽  
Herbert Wiegand ◽  
Stefan Uhlig ◽  
Horst Lohmann ◽  
Renos Papadopoulos
Keyword(s):  
Miniature Endplate Potentials ◽  
Endplate Potentials

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.

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