title: Presynaptic pH and vesicle fusion in Drosophila larvae neurones.
abstract: Both intracellular pH (pHi) and synaptic cleft pH change during neuronal activity yet little is known about how these pH shifts might affect synaptic transmission by influencing vesicle fusion. To address this we imaged pH- and Ca(2+) -sensitive fluorescent indicators (HPTS, Oregon green) in boutons at neuromuscular junctions. Electrical stimulation of motor nerves evoked presynaptic Ca(2+) i rises and pHi falls (∼0.1 pH units) followed by recovery of both Ca(2+) i and pHi. The plasma-membrane calcium ATPase (PMCA) inhibitor, 5(6)-carboxyeosin diacetate, slowed both the calcium recovery and the acidification. To investigate a possible calcium-independent role for the pHi shifts in modulating vesicle fusion we recorded post-synaptic miniature end-plate potential (mEPP) and current (mEPC) frequency in Ca(2+) -free solution. Acidification by propionate superfusion, NH(4)(+) withdrawal, or the inhibition of acid extrusion on the Na(+)/H(+) exchanger (NHE) induced a rise in miniature frequency. Furthermore, the inhibition of acid extrusion enhanced the rise induced by propionate addition and NH(4)(+) removal. In the presence of NH(4)(+), 10 out of 23 cells showed, after a delay, one or more rises in miniature frequency. These findings suggest that Ca(2+) -dependent pHi shifts, caused by the PMCA and regulated by NHE, may stimulate vesicle release. Furthermore, in the presence of membrane permeant buffers, exocytosed acid or its equivalents may enhance release through positive feedback. This hitherto neglected pH signalling, and the potential feedback role of vesicular acid, could explain some important neuronal excitability changes associated with altered pH and its buffering.
authors: Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3EG, United Kingdom.
authors: Lesley
authors: L
authors: Caldwell
authors: Peter
authors: P
authors: Harries
authors: Sebastian
authors: S
authors: Sydlik
authors: Christof J
authors: CJ
authors: Schwiening
mesh_terms: D064751:Ammonium Compounds / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004330:Drosophila / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D007425:Intracellular Membranes / Q000378:metabolism; D007814:Larva / Q000378:metabolism / Q000502:physiology; D008561:Membrane Fusion; D055369:Miniature Postsynaptic Potentials; D009469:Neuromuscular Junction / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D053499:Plasma Membrane Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D011422:Propionates / Q000494:pharmacology; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors; D013572:Synaptic Vesicles / Q000378:metabolism*
chemical_list: D064751:Ammonium Compounds; D011422:Propionates; D017923:Sodium-Hydrogen Exchangers; D053499:Plasma Membrane Calcium-Transporting ATPases; D002118:Calcium
keywords: Na+/H+ exchanger; exocytosis; intracellular pH; neuromuscular junction; synaptic transmission
references: Br J Pharmacol. 1968 Nov;34(3):451-74
references: 4882190
references: J Physiol. 1976 Nov;262(2):401-14
references: 11340
references: J Neurophysiol. 1994 Jun;71(6):2236-48
references: 7931513
references: J Physiol. 1998 Feb 15;507 ( Pt 1):41-53
references: 9490814
references: Cell. 2011 Oct 28;147(3):491-3
references: 22036557
references: J Neurosci Res. 2003 Mar 1;71(5):670-8
references: 12584725
references: Neuron. 2001 Dec 20;32(6):1107-17
references: 11754841
references: J Neurosci. 2010 Nov 24;30(47):16044-52
references: 21106843
references: J Physiol. 2002 Oct 15;544(2):487-99
references: 12381821
references: Cell Calcium. 1995 Dec;18(6):526-41
references: 8746951
references: J Comp Physiol A. 1994 Aug;175(2):179-91
references: 8071894
references: J Physiol. 1967 Sep;192(2):407-36
references: 4383089
references: Proc Natl Acad Sci U S A. 2003 May 13;100(10):5589-90
references: 12732714
references: Nature. 1997 Mar 13;386(6621):173-7
references: 9062189
references: Nat Neurosci. 2005 Sep;8(9):1188-96
references: 16116446
references: J Physiol. 1981 Mar;312:71-80
references: 7265004
references: J Neurosci. 2003 Dec 10;23(36):11332-41
references: 14672997
references: J Physiol. 1952 May;117(1):109-28
references: 14946732
references: J Physiol. 1978 May;278:513-23
references: 209172
references: J Neurosci. 2006 Nov 22;26(47):12283-93
references: 17122054
references: J Neurochem. 2006 Nov;99(4):1224-36
references: 17018119
references: J Physiol. 1976 Nov;262(3):553-81
references: 189009
references: J Biol Chem. 1984 Aug 10;259(15):9496-507
references: 6146615
references: J Physiol. 1976 Oct;262(1):189-214
references: 11339
references: Gastroenterology. 2010 Nov;139(5):1711-20, 1720.e1-5
references: 20691184
references: J Neurophysiol. 1998 Oct;80(4):1702-12
references: 9772233
references: Annu Rev Biochem. 2008;77:615-41
references: 18275379
references: Neuroreport. 1996 Aug 12;7(12):2000-4
references: 8905712
references: J Biol Chem. 2010 Nov 12;285(46):35320-9
references: 20826818
references: Brain Res. 1984 Jun 3;301(2):371-4
references: 6329453
references: EMBO Rep. 2007 Mar;8(3):236-40
references: 17330068
references: J Cell Biol. 2010 Oct 4;191(1):187-97
references: 20921140
references: J Neurochem. 2008 Jul;106(1):231-43
references: 18363831
references: J Neurosci. 1989 Feb;9(2):710-25
references: 2563766
references: Proc Natl Acad Sci U S A. 2011 Jul 19;108(29):11729-30
references: 21737746
references: J Clin Invest. 1985 May;75(5):1638-44
references: 2582000
references: Angew Chem Int Ed Engl. 2011 Apr 4;50(15):3421-4
references: 21413108
references: J Vis Exp. 2007;(6):250
references: 18997898
references: Invert Neurosci. 1996 Mar;1(4):315-22
references: 9372149
references: J Physiol. 1992 Feb;447:693-709
references: 1317439
references: J Biol Chem. 2000 Aug 11;275(32):24552-9
references: 10827195
references: J Membr Biol. 1990 Apr;114(3):195-203
references: 2325117
references: J Neurogenet. 2011 Oct;25(3):104-14
references: 21877902
references: J Physiol. 2013 Apr 1;591(7):1691-706
references: 23401611
references: J Physiol. 1989 Nov;418:163-87
references: 2621616
references: Trends Neurosci. 2000 Feb;23(2):60-8
references: 10652546
references: J Gen Physiol. 1988 Feb;91(2):305-15
references: 3373181
references: J Gen Physiol. 1988 Feb;91(2):289-303
references: 3373180
references: J Neurosci. 1998 Apr 1;18(7):2467-74
references: 9502807
references: Cell. 2006 Sep 22;126(6):1175-87
references: 16990140
references: Curr Opin Neurobiol. 2001 Jun;11(3):320-6
references: 11399430
references: J Physiol. 2002 Jan 15;538(Pt 2):371-82
references: 11790806
references: Biophys J. 2005 Apr;88(4):3018-37
references: 15653720
references: Am J Physiol. 1993 Jun;264(6 Pt 1):C1577-86
references: 7687411
references: J Gen Physiol. 1976 Jan;67(1):91-112
references: 1460
references: J Neurosci. 2000 Feb 15;20(4):1290-6
references: 10662818
references: J Neurophysiol. 2002 Nov;88(5):2659-63
references: 12424301
references: J Neurochem. 2006 Jan;96(2):324-34
references: 16336635
references: J Neurosci. 1997 May 1;17(9):3074-84
references: 9096142
references: Proc Biol Sci. 1993 Sep 22;253(1338):285-9
references: 19213150
references: Neuron. 2010 Dec 22;68(6):1097-108
references: 21172612
references: Eur J Neurosci. 2000 Mar;12(3):839-46
references: 10762313
references: J Biol Chem. 1985 Aug 15;260(17):9678-84
references: 2991259
references: J Neurophysiol. 1999 Jun;81(6):2627-35
references: 10368383
references: Proc R Soc Lond B Biol Sci. 1989 Sep 22;237(1289):489-99
references: 2573902