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Kinetics of acetylcholine quanta release at the neuromuscular junction during high‐frequency nerve stimulation
Author(s) -
Kovyazina Irina V.,
Tsentsevitsky Andrei N.,
Nikolsky Evgeny E.,
Bukharaeva Ellya A.
Publication year - 2010
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.2010.07430.x
Subject(s) - acetylcholine , motor nerve , neuromuscular junction , postsynaptic potential , neuroscience , stimulation , axon , chemistry , motor endplate , synapse , biophysics , free nerve ending , kinetics , neurotransmitter , excitatory postsynaptic potential , postsynaptic current , pulse (music) , physics , inhibitory postsynaptic potential , anatomy , biology , endocrinology , central nervous system , receptor , voltage , biochemistry , quantum mechanics
The effects of high‐frequency nerve stimulation (10–100 Hz) on the kinetics of evoked acetylcholine quanta secretion from frog motor nerve endings were studied. The amplitude and temporal parameters of uni‐ and multiquantal endplate currents were analysed to estimate the possible changes in the degree of synchrony of quantal release. The frog neuromuscular synapse is unusually long and we have placed special emphasis on evaluating the velocity of propagation of excitation along the nonmyelinated nerve ending as this might influence the synchrony of release from the whole terminal and hence affect the time course of postsynaptic currents. The data show that high‐frequency firing leads to the desynchronization of acetylcholine release from motor nerve endings governed by at least two independent factors, namely a reduction of nerve pulse propagation velocity in the nonmyelinated parts of the axon and a change of secretion kinetics at single active zones. A computer reconstruction of the multiquantal synaptic response was performed to estimate any contribution of each of the above factors to the total rate of release and amplitude and time characteristics of the endplate currents. The results indicate that modification of the kinetics of neurotransmitter quanta release during high‐frequency firing should be taken into account when mechanisms underlying the plasticity of chemical synapses are under investigation.