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Effect of phospholipase A 2 on calcium transport in brain synaptosomes
Author(s) -
Noremberg Krystyna,
Łazarewicz Jerzy W.
Publication year - 1982
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.490070302
Subject(s) - calcium , phospholipase a2 , synaptosome , chemistry , neuroscience , biophysics , biochemistry , psychology , biology , enzyme , organic chemistry
Pretreatment of isolated brain synaptic endings with commercial phospholipase A 2 isolated from venom of Apis mellifera, followed by a BSA washing, selectively inhibited the depolarization‐dependent portion of 45 Ca uptake. Phospholipase A 2 initially caused an increase of synaptosome respiration and subsequently inhibited their oxygen uptake, but this effect was completely abolished in BSA‐containing media. The classical uncoupler of oxidative phosphorylation, DNP, produced release of 45 Ca or [ 3 H]GABA from superfused synaptosomes previously loaded with radioactive calcium or GABA. The treatment of synaptosomes with phospholipase A 2 had no effect on the spontaneous efflux of 45 Ca or [ 3 H]GABA. However, depolarization‐dependent release of [ 3 H]GABA from synaptosomes treated with phospholipase A 2 was significantly inhibited. We suggest that the inhibition of depolarization‐dependent influx of 45 Ca into synaptosomes treated with phospholipase A 2 may be attributed to the lesion of the specific function of plasma membrane rather than to the impairment of the calcium‐sequestrating function of intraterminal structures.