PHONEUTRIA NIGRIVENTER TOXINS BLOCK TITYUSTOXIN-INDUCED CALCIUM INFLUX IN SYNAPTOSOMES

NEUROTOXINS can help the understanding of mechanisms involved in neuro transmission. We here report that two neurotoxin isoforms, Tx3-3 and T x3-4 obtained from the venom of the spider Phoneutria nigriventer inhi bited the Ca-45(2+) influx in rat cortical synaptosomes induced by the scorpion venom tityustoxin. The IC50 for Tx3-3 and Tx3-4 were 0.32 an d 7.9 nM, respectively. The neurotoxins Tx3-3 and Tx3-4 are very effec tive in inhibiting Ca-45(2+) influx and they should be useful in studi es involving Ca2+-dependent processes. (C) 1998 Rapid Science Ltd.