Effect of phospholipase A2 on calcium transport in brain synaptosomes

✍ Scribed by Krystyna Noremberg; Jerzy W. Łazarewicz

• Publisher: John Wiley and Sons
• Year: 1982
• Tongue: English
• Weight: 818 KB
• Volume: 7
• Category: Article
• ISSN: 0360-4012
• DOI: 10.1002/jnr.490070302

✦ Synopsis

Pretreatment of isolated brain synaptic endings with commercial phospholipase A, isolated from venom of Apis mellifera, followed by a BSA washing, selectively inhibited the depolarization-dependent portion of 45Ca uptake.

Phospholipase A, 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 Y a or ["IGABA from superfused synaptosomes previously loaded with radioactive calcium or GABA. The treatment of synaptosomes with phospholipase A2 had no effect on the spontaneous efflux of %a or [3H]GABA. However, depolarization-dependent release of [3H]GABA from synaptosomes treated with phospholipase A, was significantly inhibited.

We suggest that the inhibition of depolarization-dependent influx of 4'Ca into synaptosomes treated with phospholipase A, 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.