PMID- 182964
OWN - NLM
STAT- MEDLINE
DCOM- 19761020
LR  - 20190509
IS  - 0022-3751 (Print)
IS  - 1469-7793 (Electronic)
IS  - 0022-3751 (Linking)
VI  - 259
IP  - 2
DP  - 1976 Jul
TI  - Synaptic depression related to presynaptic axon conduction block.
PG  - 367-93
AB  - 1. The depression of synaptic transmission, which occurs during prolonged 
      repetitive activation, was examined in the opener muscle of the crayfish walking 
      leg. 2. Excitatory post-synaptic potentials (e.p.s.p.s) initially facilitated but 
      then declined to low amplitudes after about 4000 stimulus pulses had been 
      delivered; this depression is presynaptic in origin; 3. Axon conduction blocks 
      occured at points of bifurcation along the entire length of the presynaptic 
      nerve. This resulted in failure of the nerve impulse to invade some branches of 
      the terminal arborization. 4. Nerve terminal invasion failure caused either 
      intermittent or complete inactiviation of some synaptic release sites; this was 
      associated with depression of the post-synaptic response. 5. The statistics of 
      transmitter release during prolonged repetitive stimulation were examined by 
      focal extracellular recording methods. Transmitter release could be described by 
      binomial statistics, and depression involved a drop in m, n and p. 6. The rate of 
      spontaneous quantal release did not decrease, however, arguing against 
      transmitter depletion. 7. It is concluded that repetitive stimulation eventually 
      leads to depolarization of the axon membrane. This causes impulse propagation 
      failure which reduces the number of synaptic release sites that are activated and 
      mimics a drop in the effective stimulation rate; both effects cause synaptic 
      depression.
FAU - Hatt, H
AU  - Hatt H
FAU - Smith, D O
AU  - Smith DO
LA  - eng
PT  - Journal Article
PL  - England
TA  - J Physiol
JT  - The Journal of physiology
JID - 0266262
SB  - IM
MH  - Action Potentials
MH  - Animals
MH  - Astacoidea
MH  - Axons/*physiology
MH  - Electric Stimulation
MH  - Extracellular Space/physiology
MH  - Intracellular Fluid/physiology
MH  - Motor Neurons/physiology
MH  - Muscles/physiology
MH  - Neural Conduction
MH  - Neuromuscular Junction/physiology
MH  - Synapses/*physiology
MH  - Synaptic Transmission
PMC - PMC1309034
EDAT- 1976/07/01 00:00
MHDA- 1976/07/01 00:01
PMCR- 1976/07/01
CRDT- 1976/07/01 00:00
PHST- 1976/07/01 00:00 [pubmed]
PHST- 1976/07/01 00:01 [medline]
PHST- 1976/07/01 00:00 [entrez]
PHST- 1976/07/01 00:00 [pmc-release]
AID - 10.1113/jphysiol.1976.sp011471 [doi]
PST - ppublish
SO  - J Physiol. 1976 Jul;259(2):367-93. doi: 10.1113/jphysiol.1976.sp011471.