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Presynaptic calcium currents evoking quantal transmission from avian ciliary ganglion neurons
Author(s) -
Brosius D. C.,
Hackett J. T.,
Tuttle J. B.
Publication year - 1990
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/syn.890050408
Subject(s) - ciliary ganglion , neuroscience , ganglion , transmission (telecommunications) , calcium , neurotransmission , biology , chemistry , anatomy , computer science , telecommunications , receptor , biochemistry , organic chemistry
Using whole‐cell patch clamp techniques, we simultaneously recorded presynaptic Ca ++ current and excitatory postsynaptic currents (EPSCs) from avian neuromuscular junctions in culture. Quantal synaptic transmission was proportional to evoked presynaptic Ca ++ current except with large stimuli, which evoked brusts of quanta, reflecting a shift to synchronized release. Synaptic delay, measured from the onset of presynaptic depolarization to the appearnce of the first postsynaptic quantal response, was often greater than 100 msec for weak depolarizations but declined as stimulus intensity was increased. Quantal events evoked by Ca ++ tail currents had a mean synaptic delay of 1.67 msec. The single type of presynaptic Ca ++ current observed displayed an inactivation time constant of > 100 msec and tail currents well fit by a single exponential function.