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Post-tetanic increase in the fast-releasing synaptic vesicle pool at the expense of the slowly releasing pool

Cited 32 time in Web of Science Cited 31 time in Scopus
Authors
Lee, Jae Sung; Ho, Won-Kyung; Lee, Suk-Ho
Issue Date
2010-08
Publisher
ROCKEFELLER UNIV PRESS
Citation
JOURNAL OF GENERAL PHYSIOLOGY; Vol.136 3; 259-272
Abstract
Post-tetanic potentiation (PTP) at the calyx of Held synapse is caused by increases not only in release probability (P(r)) but also in the readily releasable pool size estimated from a cumulative plot of excitatory post-synaptic current amplitudes (RRP(cum)), which contribute to the augmentation phase and the late phase of PTP, respectively. The vesicle pool dynamics underlying the latter has not been investigated, because PTP is abolished by presynaptic whole-cell patch clamp. We found that supplement of recombinant calmodulin to the presynaptic pipette solution rescued the increase in the RRP(cum) after high-frequency stimulation (100 Hz for 4-s duration, HFS), but not the increase in P(r). Release-competent synaptic vesicles (SVs) are heterogeneous in their releasing kinetics. To investigate post-tetanic changes of fast and slowly releasing SV pool (FRP and SRP) sizes, we estimated quantal release rates before and 40 s after HFS using the deconvolution method. After HFS, the FRP size increased by 19.1% and the SRP size decreased by 25.4%, whereas the sum of FRP and SRP sizes did not increase. Similar changes in the RRP were induced by a single long depolarizing pulse (100 ms). The post-tetanic complementary changes of FRP and SRP sizes were abolished by inhibitors of myosin II or myosin light chain kinase. The post-tetanic increase in the FRP size coupled to a decrease in the SRP size provides the first line of evidence for the idea that a slowly releasing SV can be converted to a fast releasing one.
ISSN
0022-1295
Language
English
URI
https://hdl.handle.net/10371/76216
DOI
https://doi.org/10.1085/jgp.201010437
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College of Medicine/School of Medicine (의과대학/대학원)Dept. of Physiology (생리학교실)Journal Papers (저널논문_생리학교실)
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