Long Release Latencies are Increased by Acetylcholine
at Frog Endplate
D. SAMIGULLIN1,
E. A. BUKHARAEVA1,2, E. NIKOLSKY1,2
S. ADÁMEK3, F. VYSKOČIL4,5
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
Summary
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
Reprint
requests
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:
vyskocil@biomed.cas.cz
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