Physiol. Res. 52: 475-480, 2003

Long Release Latencies are Increased by Acetylcholine
at Frog Endplate


1Institute of Biochemistry and Biophysics, Russian Academy of Sciences, Kazan, 2State Medical University, Kazan, Russia, 3Third Surgical Department, First Faculty of Medicine, Charles University, Prague, 4Department of Animal Physiology and Developmental Biology, Faculty of Sciences, Charles University, Prague, and 5Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic

Received  November 27, 2002
Accepted February 20, 2003

Uni-quantal endplate currents (EPCs) were recorded extracellularly at the frog neuromuscular synapse and their latency dispersions expressed as P90 were estimated in the presence of acetylcholine. Stimulation-evoked EPCs with long release latencies increased in number when acetylcholine was applied. P90, which is designated as the interval between the minimal synaptic delay and the time at which 90 % of all measured uni-quantal EPCs had occurred, was significantly and reversibly increased by 66% from 0.51 ms to 0.85 ms in the presence of 5x10-4 M acetylcholine. This indicates that the evoked release pattern is less synchronous and the increased asynchrony leads to a substantial drop (by 28%) in the amplitude of reconstructed multi-quantal currents.

Key words
Quantal release • Synaptic latency • Acetylcholine • Model endplate current

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Prof. MUDr. F. Vyskočil, DrSc, Institute of Physiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20 Prague 4, Czech Republic, E-mail:

© 2003 by the Institute of Physiology, Czech Academy of Sciences