title: Post-tetanic increase in the fast-releasing synaptic vesicle pool at the expense of the slowly releasing pool.
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.
authors.affiliation: Department of Physiology and Biomembrane Plasticity Research Center, Seoul National University College of Medicine and Neuroscience Research Institute, Seoul 110-799, Korea.
authors.forename: Jae Sung
authors.initials: JS
authors.lastname: Lee
authors.forename: Won-Kyung
authors.initials: WK
authors.lastname: Ho
authors.forename: Suk-Ho
authors.initials: SH
authors.lastname: Lee
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005071:Evoked Potentials; D019706:Excitatory Postsynaptic Potentials; D066298:In Vitro Techniques; D007700:Kinetics; D024462:Myosin Type II / Q000037:antagonists & inhibitors / Q000378:metabolism; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism; D009473:Neuronal Plasticity / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D017729:Presynaptic Terminals / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects; D013572:Synaptic Vesicles / Q000187:drug effects / Q000378:metabolism*
chemical_list: D002147:Calmodulin; D004791:Enzyme Inhibitors; D011994:Recombinant Proteins; D009219:Myosin-Light-Chain Kinase; D024462:Myosin Type II; D002118:Calcium
references.citation: Trends Neurosci. 2002 Apr;25(4):206-12
references.pmid: 11998689
references.citation: Neuron. 2008 Sep 25;59(6):861-72
references.pmid: 18817727
references.citation: Neuron. 2005 Oct 6;48(1):109-21
references.pmid: 16202712
references.citation: Neuron. 1999 Aug;23(4):821-32
references.pmid: 10482247
references.citation: Nature. 1996 Oct 3;383(6599):431-4
references.pmid: 8837774
references.citation: J Neurosci. 2006 Feb 1;26(5):1366-77
references.pmid: 16452660
references.citation: J Neurosci. 2005 Jun 29;25(26):6057-65
references.pmid: 15987935
references.citation: J Physiol. 2005 Apr 1;564(Pt 1):173-87
references.pmid: 15695246
references.citation: J Neurosci. 2005 May 25;25(21):5127-37
references.pmid: 15917453
references.citation: Nature. 2009 May 7;459(7243):93-7
references.pmid: 19279571
references.citation: J Neurophysiol. 2008 Apr;99(4):1810-24
references.pmid: 18256166
references.citation: J Neurosci. 2002 Mar 1;22(5):1648-67
references.pmid: 11880495
references.citation: Neuron. 2007 Feb 15;53(4):563-75
references.pmid: 17296557
references.citation: J Neurosci. 2005 Apr 13;25(15):3842-50
references.pmid: 15829636
references.citation: Biophys J. 2005 Sep;89(3):2091-102
references.pmid: 15980175
references.citation: J Neurosci. 2007 Dec 26;27(52):14286-98
references.pmid: 18160636
references.citation: Proc Natl Acad Sci U S A. 2007 Oct 2;104(40):15923-8
references.pmid: 17884983
references.citation: Pflugers Arch. 1988 Feb;411(2):204-11
references.pmid: 2451806
references.citation: J Physiol. 2007 Jun 1;581(Pt 2):467-78
references.pmid: 17363387
references.citation: J Neurosci. 2008 Feb 20;28(8):1949-60
references.pmid: 18287511
references.citation: Science. 2008 Mar 14;319(5869):1543-6
references.pmid: 18339943
references.citation: J Neurosci. 2007 Mar 21;27(12):3198-210
references.pmid: 17376981
references.citation: Neuron. 2001 Dec 20;32(6):1119-31
references.pmid: 11754842
references.citation: J Neurosci. 2008 Aug 6;28(32):7945-53
references.pmid: 18685020
references.citation: Science. 2002 Mar 22;295(5563):2276-9
references.pmid: 11910115
references.citation: J Neurosci. 2006 May 31;26(22):5863-71
references.pmid: 16738227
references.citation: J Neurosci. 2006 Nov 8;26(45):11606-14
references.pmid: 17093082
references.citation: J Neurosci. 2002 Dec 15;22(24):10567-79
references.pmid: 12486149
references.citation: J Neurophysiol. 2006 Dec;96(6):2868-76
references.pmid: 16899643
references.citation: J Neurosci. 2008 Aug 13;28(33):8257-67
references.pmid: 18701688
references.citation: Proc Natl Acad Sci U S A. 2001 Jan 2;98(1):331-6
references.pmid: 11134533
references.citation: J Neurosci. 2000 Nov 15;20(22):8377-83
references.pmid: 11069944
references.citation: Protein Sci. 1997 Apr;6(4):794-807
references.pmid: 9098889
references.citation: Neuron. 2003 Mar 6;37(5):801-11
references.pmid: 12628170
references.citation: J Neurosci. 2001 Jan 15;21(2):444-61
references.pmid: 11160425