ACETYLCHOLINE-RELEASE FROM RAT-BRAIN CORTICAL SLICES EVOKED BY THE FRACTION P4 OF THE VENOM OF THE SPIDER PHONEUTRIA NIGRIVENTER HAS CA2+ AND TEMPERATURE INDEPENDENT COMPONENTS

Fractionation of the venom of the spider Phoneutria nigriventer reveal ed that it was a mixture of several neurotoxic peptides. The peptides so far characterized either inhibited or induced neurotransmitter rele ase. These effects were mediated by Ca2+ channels or increasing Na+ pe rmeability through voltage sensitive Na+-channels, respectively. The p ooled toxic components (fraction P4) showed stimulatory effects on ace tylcholine release from brain cortical slices. In addition, a componen t of the observed effects resembling that of alpha-latrotoxin was iden tified, which was characterized by the ability to provoke release of a cetylcholine (ACh) at low temperature and in a manner independent of e xtracellular Ca2+ and of voltage sensitive Na+-channels.