scholarly journals Effect of Saxitoxin on Spontaneous Release of Acetylcholine from the Frog's Motor Nerve Endings

1968 ◽  
Vol 95 (2) ◽  
pp. 201-202 ◽  
Author(s):  
Akinori Nishiyama
Keyword(s):  
Motor Nerve ◽  
Nerve Endings ◽  
Spontaneous Release ◽  
Release Of Acetylcholine

Structural and functional changes of frog neuromuscular junctions in high calcium solutions

1971 ◽  
Vol 178 (1053) ◽  
pp. 407-415 ◽  
Keyword(s):  
Transmitter Release ◽  
Synaptic Vesicles ◽  
Neuromuscular Junctions ◽  
Motor Nerve ◽  
Secretory Response ◽  
Spontaneous Release ◽  
Functional Changes ◽  
High Calcium ◽  
Release Of Acetylcholine ◽  
Evoked Transmitter Release

When frog muscles are exposed for several hours to a solution of isotonic calcium chloride, the secretory response of the motor nerve terminals to imposed depolarization ultimately fails and the rate of spontaneous release of acetylcholine also declines towards zero. The failure of depolarization-evoked transmitter release is irreversible while spontaneous release reappears, though in highly abnormal fashion, when the muscle is returned to a normal ionic medium. Examination of motor end-plates, during various stages of calcium treatment, shows that there is gradual intra-axonal agglutination of synaptic vesicles which is only very incompletely reversible. This effect is presumably the consequence of gradual entry and intracellular accumulation of calcium ions. Analogous treatment with isotonic magnesium, while resulting in immediate loss of evoked transmitter release, does not lead to progressive agglutination of synaptic vesicles, nor to irreversible impairment of the secretory response of the nerve terminal. The possible relations between structural and functional changes during calcium and magnesium treatment are discussed.

Tetrodotoxin and neuromuscular transmission

1967 ◽  
Vol 167 (1006) ◽  
pp. 8-22 ◽  
Keyword(s):  
Muscle Fibre ◽  
Motor Nerve ◽  
Nerve Endings ◽  
Applied Current ◽  
End Plate ◽  
Physiological Properties ◽  
Fish Poison ◽  
Normal Frequency ◽  
Release Of Acetylcholine ◽  
Puffer Fish

1. The puffer fish poison, tetrodotoxin ( T . T .) was applied to eliminate impulse propagation in nerve and muscle fibre, and the physiological properties of the neuromuscular junction were studied under this condition. 2. Spontaneous miniature end-plate potentials of normal frequency and amplitude were recorded in the T . T .-paralysed muscle. 3. Depolarization of motor nerve endings by locally applied current still produces the usual increase in the frequency of miniature end-plate potentials (e. p. ps). 4. When brief current pulses are applied to the nerve endings e. p. ps can be evoked, whose size varies with the intensity of the current. The responses are composed, like normal e. p. ps, of a statistically varying number of miniature potentials. The response fails when calcium is removed from the bath. 5. When two identical pulses are applied at varying intervals, facilitation of the second e. p. p. occurs, similar to that observed normally with pairs of nerve impulses. 6. It is concluded that tetrodotoxin while blocking electric excitation in nerve and muscle does not interfere with the release of acetylcholine from nerve endings nor with its local action on the muscle fibre.

scholarly journals Release of acetylcholine at voluntary motor nerve endings

1936 ◽  
Vol 86 (4) ◽  
pp. 353-380 ◽  
Author(s):  
H. H. Dale ◽  
W. Feldberg ◽  
M. Vogt
Keyword(s):  
Motor Nerve ◽  
Nerve Endings ◽  
Voluntary Motor ◽  
Release Of Acetylcholine
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