PMID- 11513483
OWN - NLM
STAT- MEDLINE
DCOM- 20020110
LR  - 20190822
IS  - 0364-3190 (Print)
IS  - 0364-3190 (Linking)
VI  - 26
IP  - 5
DP  - 2001 May
TI  - Synaptic vesicle acidification and exocytosis studied with acridine orange 
      fluorescence in rat brain synaptosomes.
PG  - 549-54
AB  - The acidification of synaptic vesicles (SV) in rat brain synaptosomes was studied 
      using acridine orange (AO) as a fluorescent probe. In synaptosomal suspensions 
      the AO fluorescence was partially quenched, indicating the presence of an acidic 
      compartment. In permeabilized synaptosomes, the quenching was augmented by MgATP 
      and was sensitive to concanamycin A, a specific inhibitor of the V-type 
      H(+)-ATPase known to be present in synaptic vesicles. Some ATP-dependent 
      acidification was also observed without permeabilization, suggesting that a 
      fraction of synaptosomes (ca. 15%) was unsealed, irrespective of the method used 
      to prepare the synaptosomes (sucrose or Ficoll density gradient, sedimentation or 
      flotation). Depolarization of synaptosomes with 30 mM KCl resulted in an 
      immediate, albeit small, rise in AO fluorescence that was prevented by the 
      removal of Ca(2+) or by substituting NaCl for KCl. This response is consistent 
      with depolarization-evoked release of the acidic contents of an 
      exocytosis-competent pool of synaptic vesicles, representing ca. 5% of the total. 
      No further AO release subsequent to the immediate phase was observed in 
      depolarized synaptosomes, which indicates an extremely rapid reacidification. The 
      results demonstrate that AO fluorescence is suitable for monitoring SV 
      acidification within synaptosomes, and may be used to derive an independent 
      estimate of the relative size of the immediately releasable SV pool. In addition, 
      the use of AO might be advantageous for the assessment of synaptosomal integrity 
      by comparing the ATP-dependent acidification in intact and permeabilized 
      synaptosomes.
FAU - Melnik, V I
AU  - Melnik VI
AD  - Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of 
      Sciences, Moscow.
FAU - Bikbulatova, L S
AU  - Bikbulatova LS
FAU - Gulyaeva, N V
AU  - Gulyaeva NV
FAU - Bazyan, A S
AU  - Bazyan AS
LA  - eng
PT  - Journal Article
PL  - United States
TA  - Neurochem Res
JT  - Neurochemical research
JID - 7613461
RN  - 0 (Acids)
RN  - 0 (Fluorescent Dyes)
RN  - 660YQ98I10 (Potassium Chloride)
RN  - 8L70Q75FXE (Adenosine Triphosphate)
RN  - F30N4O6XVV (Acridine Orange)
SB  - IM
MH  - Acids/*metabolism
MH  - Acridine Orange
MH  - Adenosine Triphosphate/pharmacology
MH  - Animals
MH  - Brain/*physiology
MH  - Electrophysiology
MH  - *Exocytosis
MH  - Fluorescence
MH  - Fluorescent Dyes
MH  - Male
MH  - Permeability
MH  - Potassium Chloride/pharmacology
MH  - Rats
MH  - Rats, Wistar
MH  - Synaptic Vesicles/*metabolism
MH  - Synaptosomes/drug effects/*metabolism/physiology
EDAT- 2001/08/22 10:00
MHDA- 2002/01/11 10:01
CRDT- 2001/08/22 10:00
PHST- 2001/08/22 10:00 [pubmed]
PHST- 2002/01/11 10:01 [medline]
PHST- 2001/08/22 10:00 [entrez]
AID - 10.1023/a:1010973214930 [doi]
PST - ppublish
SO  - Neurochem Res. 2001 May;26(5):549-54. doi: 10.1023/a:1010973214930.